INTERNATIONAL PROGRAMME ON CHEMICAL SAFETY
ENVIRONMENTAL HEALTH CRITERIA 15
TIN AND ORGANOTIN COMPOUNDS
A Preliminary Review
This report contains the collective views of an international group of
experts and does not necessarily represent the decisions or the stated
policy of either the World Health Organization or the United Nations
Environment Programme.
Published under the joint sponsorship of the United Nations
Environment Programme and the World Health Organization
World Health Organization
Geneva, 1980
ISBN 92 4 154075 3
(c) World Health Organization 1980
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CONTENTS
TIN AND ORGANOTIN COMPOUNDS: A PRELIMINARY REVIEW
1. SUMMARY AND RECOMMENDATIONS FOR FURTHER RESEARCH
1.1. Chemistry and uses of tin compounds
1.1.1. Inorganic tin
1.1.2. Organotin compounds
1.2. Analytical methods
1.3. Environmental concentrations and exposures
1.3.1. Environmental exposures
1.3.2. Occupational exposure
1.4. Metabolism
1.4.1. Inorganic tin
1.4.2. Organotin compounds
1.5. Effects on experimental animals
1.5.1. Inorganic tin
1.5.1.1 Local effects
1.5.1.2 Systemic effects
1.5.2. Organotin compounds
1.5.2.1 Local effects
1.5.2.2 Systemic effects
1.6. Effects in man
1.6.1. Inorganic tin
1.6.2. Organotin compounds
1.6.2.1 Local effects
1.6.2.2 Systemic effects
1.7. Recommendations for further studies
1.7.1. Analytical methods
1.7.2. Environmental data
1.7.3. Metabolism
1.7.4. Effects
2. CHEMISTRY AND ANALYTICAL METHODS
2.1. Elemental tin
2.2. Tin(II) compounds
2.3. Tin(IV) compounds
2.4. Organometallic compounds of tin
2.5. Analytical methods
2.5.1. Determination of inorganic tin
2.5.1.1 Atomic absorption spectrocopy
2.5.1.2 Emission spectroscopy
2.5.1.3 Neutron activation analysis
2.5.1.4 X-ray fluorescence
2.5.1.5 Miscellaneous analytical methods
2.5.2. Determination of organotin compounds
2.5.2.1 Diorganotin compounds
2.5.2.2 Triorganotin compounds
3. SOURCES OF ENVIRONMENTAL POLLUTION35
3.1. Natural occurrence
3.2. Industrial production
3.3. Tin consumption
3.4. Uses of tin
3.4.1. Tin and inorganic tin compounds
3.4.2. Organotin compounds
3.5. Tin-containing waste
4. ENVIRONMENTAL TRANSPORT AND TRANSFORMATIONS
4.1. Transport and bioconcentration
4.2. Environmental chemistry of tin
4.3. Degradation of organometallic tin compounds
5. ENVIRONMENTAL CONCENTRATIONS AND EXPOSURES
5.1. Ambient air
5.2. Soils and plants
5.3. Water and marine organisms
5.4. Food
5.5. Organotin residues
5.6. Working environment
5.7. Estimate of effective exposure of man through environmental
media
6. METABOLISM
6.1. Inorganic tin
6.1.1. Absorption
6.1.2. Distribution
6.1.2.1 Distribution in human tissues and
biological fluids
6.1.3. Excretion
6.1.4. Biological half-time
6.2. Organotin compounds
6.2.1. Absorption
6.2.2. Distribution
6.2.3. Excretion
6.2.4. Biotransformation
7. EFFECTS ON ANIMALS
7.1. Inorganic tin compounds
7.1.1. Effects on the skin
7.1.2. Respiratory system effects
7.1.3. Effects on the gastrointestinal system
7.1.4. Effects on the liver
7.1.5. Effects on the kidney
7.1.6. Effects on the blood-forming organs
7.1.7. Central nervous system effects
7.1.8. Effects on the reproductive system and the fetus
7.1.9. Carcinogenicity and mutagenicity
7.1.10. Other effects
7.1.11. Effective doses and dose rates
7.1.11.1 Lethal doses
7.1.11.2 Minimum effective and no-observed effects
doses
7.2. Organotin compounds
7.2.1. Effects on the skin and eyes
7.2.2. Respiratory system effects
7.2.3. Effects on the gastrointestinal system
7.2.4. Effects on the liver and bile duct
7.2.5. Effects on the kidney
7.2.6. Effects on lymphatic tissue and immunological
effects
7.2.7. Haematological effects
7.2.8. Central nervous system effects
7.2.9. Effects on reproduction and the fetus
7.2.10. Carcinogenicity
7.2.11. Effects on chromosomes
7.2.12. Other effects
7.2.13. Mechanisms of action
7.2.14. Effective doses and dose rates
7.2.14.1 Lethal doses
7.2.14.2 Minimum effective and no-observed-effect
doses
8. EFFECTS ON MAN
8.1. Inorganic tin compounds
8.1.1. Acute poisoning
8.1.2. Prolonged exposure
8.1.2.1 Effects of inhalation
8.1.2.2 Effects of ingestion
8.2. Organotin compounds
8.2.1. Local effects
8.2.2. Systemic effects
8.2.2.1 Effects of dermal exposure
8.2.2.2 Effects of inhalation
8.2.2.3 Effects of ingestion
8.3. Treatment of poisoning
REFERENCES
NOTE TO READERS OF THE CRITERIA DOCUMENTS
While every effort has been made to present information in the
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In addition, experts in any particular field dealt with in the
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WHO TASK GROUP ON ENVIRONMENTAL HEALTH ASPECTS OF TIN AND ORGANOTIN
COMPOUNDS
Members
Professor R. Lauwerys, Unité de Toxicologie industrielle et médicale,
Université catholique de Louvain, Bruxelles, Belgium
(Rapporteur)
Dr J. G. Noltes, Department of Organic and Organo-Element Chemistry,
Institute for Organic Chemistry, Organization for Applied
Scientific Research (TNO), Utrecht, Netherlands
Professor M. Piscator, Department of Environmental Hygiene, The
Karolinska Institute, Stockholm, Sweden
Professor A.B. Roscin, Department of Occupational Hygiene, Central
Institute for Advanced Medical Training, Moscow, USSR
Dr M. Sharratt, Division of Environmental Health & Chemical Hazards,
Department of Health & Social Security, London, England
(Chairman)
Professor M. Timar, State Institute of Occupational Health, Budapest,
Hungary (Vice-Chairman)
Dr L. Cemisanska, Department of Occupational Toxicology, Centre of
Hygiene, Sofia, Bulgaria
Secretariat
Dr L. Fishbein, National Centre for Toxicological Research, US Food &
Drug Administration, Jefferson, AR, USA (Temporary Adviser)
Dr Y. Hasegawa, Control of Environmental Pollution and Hazards,
Division of Environmental Health, WHO, Geneva, Switzerland
Dr J. E. Korneev, Control of Environmental Pollution and Hazards,
Division of Environmental Health, WHO, Geneva, Switzerland
Dr A. Stiles, Division of Vector Biology and Control, WHO, Geneva,
Switzerland
Dr V. B. Vouk, Control of Environmental Pollution and Hazards,
Division of Environmental Health, WHO, Geneva, Switzerland
(Secretary)
The following list of organotin compounds includes the trivial name of the compound used throughout the document, the Chemical Abstracts
Service (CAS) name and number, the molecular formula, and alternative names,
ORGANOTIN COMPOUNDS
Name used in text CAS Index name CAS number Molecular Synonyms
formula
Monosubstituted compounds
ethyltin trichloride stannane, trichloroethyl-(9Cl) (8Cl) 1066-57-5 C2H5Cl3Sn trichloroethylstannane;
trichloroethyltin;
ethyltrichlorostannane;
ethyltrichlorotin
ethyltin triiodide stannane, ethyltriiodo- (9Cl) (8Cl) 3646-94-46 C2H5I3Sn triiodoethyltin
butyltin trichloride stannane, butyltrichloro- (9Cl) (8Cl) 1118-46-3 C4H9Cl3Sn monobutyltin trichloride;
trichlorobutyltin;
butyltrichlorostannane;
butyltrichlorotin;
trichlorobutyltin;
trichlorobutylstannane;
stannane, trichlorobutyl-
butylstannoic acid stannane, butylhydroxyoxo- (9Cl) (8Cl) 2273-43-0 C4H10O2Sn 1-butanestannoic acid;
butyltin hydroxide
oxide; butylstannoic acid (VAN)
butylthiostannoic acid stannane, butylmercaptooxo- (8Cl) 26410-42-4 C4H10O S Sn
butyltin-S,S',S"-tris acetic acid, 2,2',2"- 25852-70-4 C34H66O6S3Sn butyltin tris(isooctyl
thioglycolate);
ORGANOTIN COMPOUNDS
Name used in text CAS Index name CAS number Molecular Synonyms
formula
Monosubstituted compounds cont'd.
(isooctylmercaptoacetate) ((butylstannylidyne)) tris (thio) stannane, butyltris
tris-, triisooctyl ester ((carboxymethyl) thio)-,
(9Cl); triisooctyl ester; butyltin
acetic acid, ((butylstannylidyne) tris(isooctyl thioglycollate);
trithio) tri,-triisooctylester (8Cl) monobutyltin tris
(isooctylthioglycolate);
monobutyltin tris(isooctyltin
thioglycolate); butyltin tris
(isooctyl mercaptoacetate);
triisooctyl(butylstannylidyne)
trithio) triacetate;
butylstannane tris(isooctyl
mercaptoacetate)
butyltin-S,S',S"-tris 8 oxa-3,5-dithia-4- 26864-37-9 C34H66O6S3Sn monobutyltin tris(2-ethylhexyl
(2-ethyl stannatetradecanoic acid, thioacetate), monobutyltin
hexylmercaptoacetate) 4 butyl-10-ethyl-4-((2-((2- tris(2-ethylhexyl thioglycolate)
ethylhexyl)oxyl)-2-oxoethyl)
thio)-7-oxo-, 2-ethylhexyl
ester (9Cl); acetic acid,
((butylstannylidyne)
trithio)tri-,tris(2-ethylhexyl)
ester (8Cl)
butyltin sulfide distannathiane, 15666-29-2 C8H18S3Sn2 butyl thiostannoic arthydride;
dibutyldithioxo-(9Cl); monobutyltin sulfide
distannthiane, 1,3-dibutyl-
1,3-dithioxo- (8Cl)
ORGANOTIN COMPOUNDS
Name used in text CAS Index name CAS number Molecular Synonyms
formula
Monosubstituted compounds cont'd.
octyltin trichloride stannanne, 3091-25-6 C8H17Cl3Sn trichlorooctylstannane;
trichlorooctyl-(9Cl) (8Cl) octyltrichlorostannane;
n-octyltin trichloride;
n-octyltri-chlorostannane;
mono-n-octyltin tri-chloride;
trichloro-n-octylstannane
octyltin tris(2-ethyl 8-oxa-3,5-dithia-4- 27107-89-7 C38H74O6S3Sn
hexylmercaptoacetate) stannatetradecanoic acid,
10-ethyl-4-((2-((2-ethylhexyl)oxy)
-2-oxoethyl) thio)-4-octyl-7-oxo-,
2-ethylhexylester (9Cl);
acetic acid, ((octylstannylidyne)
trithio)tri-, tris(2-ethylhexyl)
ester (8Cl)
cyclohexylstannoic acid stannano, cyclohexylhydroxyoxo- 22771-18-2 C6H12O2Sn cyclohexanestannoic acid
(9Cl) (8Cl)
Disubstituted compounds
dimethyltin dichloride stannane, dichlorodimethyl- 753-73-1 C2H6Cl2Sn dichlorodimethylstannane;
(9Cl) (8Cl) dichlorodimethyltin;
dimethyldichlorostannane
ORGANOTIN COMPOUNDS
Name used in text CAS Index name CAS number Molecular Synonyms
formula
Disubstituted compounds cont'd.
dimethyltin S,S'-bis acetic acid, 2,2'-((dimethyl- 26636-01-1 C22H44O4S2Sn TM 181; diisooctyl
(isooctyl mercaptoacetate) stannylene) bis (thio))bis-, ((dimethylstannylene)
diisooctyl ester (9Cl) dithio)diacetate;
dimethylfin bis
(isooctylthioglycolate);
dimethyltin-S,S'-bis
(iso-octylthyoglycolate);
bis((((isooctyloxy)-
carbonyl)methyl)thio)
dimethylfin; T 40 (ester);
TM 181S; Advastab TM 181S;
Advastab TM 181 S
diethyltin dichloride stannane, dichlorodiethyl- 866-55-7 C4H10Cl2Sn tin, dichlorodiethyl-;
dichlorodiethyltin;
diethyldichlorotin;
dichlorodiethylstannane;
diethyldichlorostannane
diethyltin diiodide stannanne, diethyldiiodo- 2767-55-7 C4H10I2Sn tin, diethyldiiodo-;
diethyltin dioctanoate stannane, diethylbis((1-oxo 2641-56-7 C20H40O4Sn diethyldiiodostannane
octyl)oxy) (9Cl); diethyltin dicaprylate
stannane, diethylbis
(octanoyloxy) (8Cl)
dipropyltin dichloride stannane, dichlorodipropyl- 867-36-7 C6H14Cl2Sn dipropyltin chloride;
(9Cl) (8Cl) dichlorodipropylstannane;
di-n-propyltin dichloride
diisopropryltin dichloride stannane, dichlorobis 38802-82-3 C6H14Cl2Sn
(1-methylethyl)- (9Cl)
ORGANOTIN COMPOUNDS
Name used in text CAS Index name CAS number Molecular Synonyms
formula
Disubstituted compounds cont'd.
dibutyltin dichloride stannane, dibutyldichloro- (9Cl) (8Cl) 683-18-1 C8H18Cl2Sn dichlorodibutyltin; dibutyltin
chloride;
dichlorodibutylstannane;
dibutyldichlorotin;
di-n-butyltin dichlorlde;
dibutyldi-chlorostannane
dibutyltin oxide stannane, dibutyloxo- (9Cl) (8Cl) 818-08-6 C8H18OSn di-n-butyltin oxide; tin,
dibutyloxo-;
dibutylstannane oxide;
dibutyloxotin;
dibutyloxostannane
dibutyltin diacetate stannane, bis(acetyloxy)dibutyl- (9Cl) 1067-33-0 C12H24OSn diacetoxydibutyltin;
T 1[catalyst]; T 1 (VAN);
Ba 2726
dibutyltin dilaurate stannane, dibutylbis 77-58-7 C32H64O4Sn Butynorate; DBTL; dibutylbis
((1-oxododecyl)oxy)- (lauroyloxy)-tin; Stabilizer
D-22; tin dibutyl dilaurate;
Stanclere DBTL; Davainex;
TVS Tin Lau;
dibutyltin didodecanoate;
dibutylbis-(laurato)tin;
Mark 1038; Tinostat; dibutyl-
tin n-dodecanoate; Stavinor
1200 SN; T 12 (catalyst);
dibutylstannylene dilaurate;
T 12 (VAN)
ORGANOTIN COMPOUNDS
Name used in text CAS Index name CAS number Molecular Synonyms
formula
Disubstituted compounds cont'd.
dibutyltin maleate 1,3,2-dioxastannepin-4,7-dione, 78-04-6 C12H20O4Sn dibutyl(maleoyldioxy)tin;
Advastab DBTM;
2,2'-dibutyl-(9Cl) (8Cl) Advastab T 290; Stavinor
1300 SN; dibutyl-stannylene
maleate; Advastab T 340;
Nuodex V 1525; Irgastab T 290
dibutyltin sulfide stannane, dibutylthioxo- 4253-22-9 C12H20O4Sn tin dibutyl mercaptide
(9Cl) (8Cl)
dibutyltin di stannane, dibutylbis 2781-10-4 C24H48O4Sn dibutyltin bis
(2-ethylhexoate) ((2-ethyl-1-oxohexyl)oxy)- (9Cl) (2-ethylhexanoate); dibutyltin
bis(alpha-ethylhexanoate)
dibutyltin dioctanoate stannane, dibutyl- 4731-77-5 C24H48O4Sn dibutyltin dioctoate;
bis((1-oxooctyl)oxy)- (9Cl); dibutyltin dicaprylate;
stannane, dibutyl dibutyltin octanoate
bis(octanoyloxy)- (8Cl)
dibutyltin di 5,7,12-trioxa-6-stannahexa 15546-16-4 C24H40O8Sn dibutyltin bis(monobutyl
(butyl maleate) deca-2,9-dienoic acid,6,6-dibutyl- maleate); maleic acid
4,8,11-trioxo, butyl ester, dibutyltin salt (2:1)
(Z,Z)- (9Cl) stannane, dibutylbis diisobutyl ester; B5
(3-carboxyacryloyl)oxy-, [stabilizer]; dibutyltin
dibutyl ester,(Z,Z)-(8Cl) bis(butyl maleate)
dibutyltin di stannane, dibutylbis 10584-97-1 C34H60O8Sn
(nonylmaleate) ((3-carboxyacryloyl)oxy)
-dinonyl ester, (z,z)-(8Cl)
ORGANOTIN COMPOUNDS
Name used in text CAS Index name CAS number Molecular Synonyms
formula
Disubstituted compounds cont'd.
dibutyltin ß-mercapto 6H-1,3,2-oxathiastannin-6-one, 78-06-8 C11H22O2S Sn Thermolite 35; Advastab T-306;
propanoate 2,2-dibutyldihydro- Mark 488; dibutyltin
O,S'-mercaptopropionate,
dibutyltin
S,O-mercaptopropionate;
dibutyltin ß-mercaptopropionate
dibutyltin bis(lauryl stannane, dibutylbis 1185-81-5 C32H68S2Sn dibutylbis(dodecylthio)tin;
mercaptide) (dodecylthio)-(9Cl) (8Cl) Mellite 39; dibutyltin
bis(dodecylmercaptide);
bis-(dodecylthio)dibutyltin;
dibutylbis(dodecyl-thio)
dibutyltin; dibutylbis
(dodecylthio)-stannane;
Advastab TM 98; Mellite 139;
Thermolite 20; dibutyltin
S,S'-bis(dode-cylmercaptide)
dibutyltin "laurate- 2-butenoic acid, 4,4'- 73246-84-1 C32H64O4Sn solution of dibutyltin dilaurate
maleate" [(dibutylstannylene)bis(oxy)] C16H24O8Sn and dibutyltin maleate;
bis [4-oxo-, (Z,Z)- mixed with dibutyl Thermolite 17
bis [(1-oxododecyl)oxy] stannane (1-1)
(9Cl)
dibutyltin S,S'-bis acetic acid, 2,2' (dibutyl 25168-24-5 C28H56O4S2Sn dibutyltin bis(isooctyl
(isooctylthioglycolate) stannylene)bis(thio)bis-, mercaptoacetate); dibutyltin
diisooctyl ester (9Cl); S,S'-bis(isooctyl
acetic acid, ((dibutylstannylene) mercapto-acetate);
dithio)di, diisooctyl ester (8Cl) diisooctyl((dibutylstannylene)-
dithio)diacetate;
Thermolite 31; bis(iso-
ORGANOTIN COMPOUNDS
Name used in text CAS Index name CAS number Molecular Synonyms
formula
Disubstituted compounds cont'd.
dibutyltin S,S'-bis octyioxycarbonylmethylthiolato)
(isooctylthioglycolate) dibutyibis((((isooctyloxy)
cont'd. carbonyl)methyl)-thio)tin;
BTS 70; T 101 (accelerator);
Irgastab 17M; T 101
dibutyltin S,S'-bis(2- 8-oxa-3,5-dithia-4-stannatetra 10584-98-2 C28H56O4S2Sn dibutyltin bis(2-ethyihexyl
ethylhexylmercaptoacetate) decanoic acid 4,4-dibutyl-10- thioglycolate); dibutyltin
ethyl-7-oxo-2-ethylhexyl ester (9Cl); S,S'-bis(2-ethylhexyl
acetic acid, ((dibutylstannylene) thio-glycolate)
dithio)di-, bis(2-ethylhexyl)
ester (9Cl)
dipentyitin dichloride stannane, dichlorodipentyl- (9Cl) 1118-42-9 C10H22Cl2Sn dichlorodipentyltin
dioctyltin dichloride stannane, dichlorodioctyl- (9Cl) (8Cl) 3542-36-7 C16H34Cl2Sn dichlorodioctyltin;
dichlorodioctylstannane
dioctyltin oxide stannane, dioctyloxo- (9Cl) (8Cl) 870-08-6 C16H34O Sn tin, dioctyloxo-; di-n-octyltin
oxide; dioctyloxostannane
dioctyltin acetate stannane, bis(acetyloxy)dioctyl- (9Cl) 17586-94-6 C20H40O4Sn dioctyldiacetoxytin
dioctyltin dilnurate stannane, dioctylbis 3648-18-8 C40H30O4Sn lauric acid, dioctyltin deriv;
((1-oxododecyl)oxy)-(9Cl); dioctyl-dilauroyloxytin;
stannane, bis(lauroyloxy) dioctyltin didodecanoate
dioctyl-(8Cl)
dioctyltin maleate 1,3,2-dioxastannepin-4,7-dione, 16091-18-2 C20H36O4Sn di-n-octyltin maleate;
2,2-dioctyl- (9Cl); Thermolite 813; Estabex U 18;
dioctylstannylene maleate;
Mellite 825
ORGANOTIN COMPOUNDS
Name used in text CAS Index name CAS number Molecular Synonyms
formula
Disubstituted compounds cont'd.
dioctyltin dibutylmaleate 5,7,12-trioxa-6-stannahexadeca- 29575-02-8 C32H36O8Sn dioctyltinbis(butylmaleate)
2,9-dienoic acid, 6,6-dioctyl-
4,8,11-trioxo-, butyl ester,
(Z,Z)-(9Cl);
stannane, bis(3-carboxyacryloyl)
oxy)dioctyl-, dibutyl ester (Z,Z)-
(8Cl)
dioctyltin-S,S'-(ethylene 1,3-dioxa-6,9-d ithia-2-stanna 56875-68-4 C22H42O4S2Sn ethylenebisthioglycolate
glycol-bis-mercaptoacetate) cycloundecane-4,11-dione,2,2- dioctyltin
dioctyl-(9Cl)
dioctyltin-S,S'-bis acetic acid, 2,2'- 26401-97-8 C36H72O4S2Sn diisooctyl((dioctylstannylene)
(isooctyl-mercaptoacetate) ((dioctylstannylene)bis(thio) dithio)-diacetate; dioctyltin
bis-,diisooctyl ester (9Cl); bis(isooctylmercapto-acetate);
acetic acid, ((dioctylstannylene) Thermalite 831; dioctyltin
dithio)di-, diisooctyl ester (8Cl) di(iso- octylthyoglycolate);
di-n-octyltin bis(iso-
octylmercaptoacetate), bis
((((isooctyloxy)-carbonyl)
methyl)thio)dioctyltin; Mellite
831C; Irsastab 17 MOK;
dioctyltin bis
(iso-octylthyoglycolate);
dioctyltin bis
(diiso-octylthioglycolate)
dioctyltin mercaptoacetate 1,3,2-oxathiastannolan-5-one, 15535-79-2 C18H36O2S Sn dioctyltin S,O-mercaptoacetate
2,2-dioctyl-(9Cl) (8Cl)
ORGANOTIN COMPOUNDS
Name used in text CAS Index name CAS number Molecular Synonyms
formula
Disubstituted compounds cont'd.
dioctyltin ß-mercapto 6H-1,3,2-oxathiastannin-6-one, 3033-29-2 C19H38O2S Sn dioctyltin
propanoate dihydro-2,2-dioctyl- (9Cl) (8Cl) S,O-3-mercaptopropionate;
dioctyltin mercaptopropionate
dioctyltin-S,S'-bis 8-oxa-3,5-dithia-4-stanna 27107-88-6 C28H56O4S2Sn
(butyl mercaptoacetate) dodecanoic acid, 4,4-dioctyi-7-oxo-,
butyl ester (9Cl)
acetic acid, (((dioctylstannylene)
dithio)di-, butyl ester (8Cl)
dioctyltin-S,S'-bis(2- 8-oxa-3,5-dithia-4-stannatetra 15571-58-1 C36H72O4S2Sn bis(2-ethylhexyl)
ethylhexylmercaptoacetate) decanoic acid, 10-ethyl-4,4- (dioctylstannylene)
dioctyl-7-oxo-, 2-ethylhexyl dithio)diacetate; dioctyltin
ester (9Cl); bis(2-ethyl-hexyl thioglycolate);
bis(2-ethylhexylthyo-glycolato)
dioctyltin; Advastab 17 MOK
acetic acid, ((dioctylstannylene)
dithio)di-, bis(2-ethylhexyl)
ester (8Cl)
dioctyltin-S,S'-bis 8-oxa-3,5-dithia-4-stannaeicosanoic 73246-85-2 C44H88O4S2Sn dioctyltin bis
(laurylmercaptoacetate) acid, 4,4-dioctyl-7-oxo, dodecyl ester (laurylthioglycolate)
(9Cl)
dioctyltin bis(2- 5,7,12-trioxa-6-stannaoctadeca-2,9- 10039-33-5 C40H72O8Sn di-n-octyltin bis
ethylhexylmaleate) dienoic acid, 14-ethyl-6,6- (2-ethylhexylmaleate)
dioctyl-4,8,11-trioxo, 2-ethylhexyl
ester, (Z,Z) (9Cl)
dioctyltin bis(dodecyl stannane, bis(dodecylthio) 22205-30-7 C40H84S2Sn bis(dodecylthio)dioctyltin;
mercaptide) dioctyl-(9Cl) (8Cl) dioctyltin bis(lauryl
mercaptide); dioctyltin,
dilauryl mercaptan salt
ORGANOTIN COMPOUNDS
Name used in text CAS Index name CAS number Molecular Synonyms
formula
Disubstituted compounds cont'd.
dioctyltin-S,S'-(1,4- 1,9-dioxa-4,6-dithia-5- 69226-46-6 C24H46O4S2Sn
butanediol-bis-mercapto stannacyclotridecane-2,8-
acetate) dione, 5,5-dioctyl- (9Cl)
dioctyltin di(1,2- 1,3,8,11-tetraoxa-2- 69226-45-5 C27H44O8Sn
propyleneglycolmaleate) stannacyclo-pentadeca-5,13-diene
4,7,12,15-tetrone, 9-methyl-2,2-
dioctyl-, (Z,Z)-(9Cl)
dioctyltin bis(isobutyl stannane, bis[(3-carboxy- 15571-59-2 C32H56O8Sn dioctyltin bis(isobutylmaleato)
maleate) acryloyl)oxy]dioctyl-, diisobutyl tin; 5,7,12-triox-6-stannapenta-
ester, (Z,Z)- (9Cl) 2,9-dienoic acid, 6,6-dioctyl-
13-methyl-4,8,11-trioxo,
1-methyl-propyl ester
diphenyltin dichloride stannane, dichlorodiphenyl- (9Cl) (8Cl) 1135-99-5 C12H10Cl2Sn dichlorodiphenyltin;
diphenylstannyl dichloride;
diphenyldichlorotin;
diphenyl-tin chloride;
dichlorodiphenylstannane
dicyclohexyltin oxide stannane, dicyclohexyloxo- 22771-17-1 C12H22O Sn
(9Cl) (8Cl)
didodecyltin dibromide stannane, dibromodidodecyl- 65264-08-6 C24H50Br2Sn di-n-dodecyltin dibromide
(9Cl)
dioctadecyltin dibromide stannane, dibromodioctadecyl- 65264-09-7 C36H74Br2Sn di-n-octadecyltin dibromide
(9Cl)
ORGANOTIN COMPOUNDS
Name used in text CAS Index name CAS number Molecular Synonyms
formula
TRISUBSTITUTED COMPOUNDS
triethyltin bromide stannane, bromotriethyl- (9Cl) (8Cl) 2767-54-6 C6H15Br Sn
triethyltin chloride stannane, chlorotriehyl- (9Cl) (8Cl) 994-31-0 C6H15Cl Sn chlorotriethyistannane;
chlorotriethyltin;
triethylstannyl chloride;
triethylchloro-stannane;
triethylchlorotin
triethyltin iodide stannane, triethyliodo- 2943-86-4 C6H15I Sn triethyliodostannane;
(9Cl) (8Cl) triethylstannyl iodide;
iodotriethylstannane
triethyltin suifate 4,6-dioxa-5-thia-3,7-distannanonane, 57-52-3 C12H30O4S Sn2 triethylhydroxytin sulfate;
3,3,7,7-tetraethyl- 5,5-dioxide (9Cl) bis(triethyltin)
stannane, triethylhydroxy- sulfate
sulfate (2:1) (8Cl)
triethyltin acetate stannane, (acetyloxy) 1907-13-7 C8H18O2Sn acetoxytriethylstannane
triethyl-(9Cl);
stannane, acetoxytriethyl-
(8Cl)
triethyltin hydroxide stannane, triethylhydroxy- 994-32-1 C6H16O Sn triethylstannanol;
(9Cl) (8Cl) triethylstannol;
triethyl-hydroxystannane;
hydroxytriethylstannane
trlethylstannylmethyl stannane, triethyl(3-methoxy 17869-84-0 C11H22O2Sn
(1-propynyl) formal methoxy)-l-propynyl-
triethylstannylphenyl stannane, trlethyl(phenylethynyl)- 1015-27-6 C14H20Sn
acetylene (9Cl) (8Cl)
1-triethylstannyl-3- silane, trimethyl((3-triethylstannyl)- 4628-88-0 C12H26O SiSn
trimethylsiloxi-1-propyne 2-propynyl)oxy)-
ORGANOTIN COMPOUNDS
Name used in text CAS Index name CAS number Molecular Synonyms
formula
TRISUBSTITUTED COMPOUNDS
2-trichloro-1-(butine- stannane, (1-(3-butinyloxy) 17869-91-9 C12H21C13O2Sn
1'-oxide)-1-(triethyl -2,2,2-trichloroethoxy)triethyl-
stannyloxy)ethane
trivinyltin chloride stannane, chlorotriethenyl- 10008-90-9 C6H9Cl Sn chlorotrivinyltin;
(9Cl); chlorotrivinylstannane
stannane, chlorotrivinyl-
(8Cl)
tributyltin chloride stannane, tributylchloro- 1461-22-9 C12H27Cl Sn tributylchlorotin;
(9Cl) (8Cl) chlorotributylstannane;
tributylstannyl chloride
tributyltin fluoride stannane, tributylfluoro- 1983-10-4 C12H27F Sn tributylfluorostannane;
(9Cl) (8Cl) fluorotributyltin;
tri-n-butylstannyl fluoride
bis(tributyltin) oxide hexabutyldistannoxane 56-35-9 C24H54O2 Sn2 C-Sn-9; BioMeT TBTO; Bultinox;
distannoxane, hexabutyl- (9Cl) (8Cl) hexabutyl-distannoxane;
oxybis(tributyitin); TBTO;
6-oxa-5,7-distannaundecane,
5,5,7,7-tetra-butyl-;
Lastanox T; Vikol AF-25;
Vikol LO-25; BioMeT 66;
oxybis(tributylstannane);
BioMeT SRM; Lastanox T20;
bis(tri-butylstannyl)oxide;
Lastanox Q; Lastanox
F; Stannicide A; tributyltin
oxide; Myko-lastanox F
ORGANOTIN COMPOUNDS
Name used in text CAS Index name CAS number Molecular Synonyms
formula
TRISUBSTITUTED COMPOUNDS
tributyltin acetate stannane, (acetyloxy)tributyl- (9Cl); 56-36-0 C14H30O2Sn acetoxytributyltin;
stannane, acetoxytributyl- (8Cl) tributylacetoxystannane;
tri-n-butyltin acetate;
acetoxytributyl-
tributyltin linoleate stannane, tributyl((1-oxo-9,12- 24124-25-2 C30H58O2Sn stannane; tributylstannylacetate
octadecad ienyl)oxy)-(Z,Z)-(9Cl);
stannane, tributyl(linoleoyloxy)-
(8Cl)
tributyltin benzoate stannane, (benzoyloxy)tributyl- 4342-36-3 C19H32O2Sn tri-n-butyltin benzoate; tin,
(9Cl) (8Cl) (benzoyloxy) tributyl-
tributyltin salicylate phenol, 2-[[(tributylstannyl)oxy] 4342-30-7 C19H32O3Sn tin, tributyl(salicyloyloxy)-
carbonyl]- (9Cl)
stannane, tributyl(salicyloyloxy)-
(8Cl)
tributyltin methacrylate stannane, tributyl((2-methyl-1- 2155-70-6 C16H32O2Sn tributylstannyl methacrylate;
oxo-2-propenyl)oxy)-(9Cl); tributyl- (methacryloxy)stannane;
stannane, tributyl(methacryloyloxy- tin, tributyl-
(8Cl) methacrylate; (methacryloyloxy)
tributyl-stannane;
tributylmethacryloyloxystannane
tributyltin laurate stannane, tributyl 3090-36-6 C24H50O2Sn tin, tributyl(lauroyloxy)-;
((1-oxo-dodecyl)oxy)-(9Cl) tributyltin laurate;
stannane, tributyl(lauroyloxy)- (8Cl) tributyltin dodecanoate
tributyltin oleate stannane, tributyl((1-oxo-9-octa 3090-35-5 C30H60O2Sn tin, tributyl(oleoyloxy)-;
decenyl)oxy)-, (Z)-(9Cl); N 5117 (Stauffer); N 5117
stannane, tributyl(oleoyloxy)- (8Cl)
trihexyltin acetate stannane, (acetyloxy)trihexyl- 2897-46-3 C20H42O2Sn tin, acetoxytrihexyl-;
(9Cl); acetoxytrihexyltin
stannane, acetoxytrihexyl- (8Cl)
ORGANOTIN COMPOUNDS
Name used in text CAS Index name CAS number Molecular Synonyms
formula
TRISUBSTITUTED COMPOUNDS
tricyclohexyltin hydroxide stannane, tricyclohexylhydroxy- 13121-70-5 C18H34O Sn Plictran;
(9Cl) (8Cl) tricyclohexylhydroxystannane;
tricyclohexylhydroxytin;
Plyctran; M 3180; Cyhexatin;
hydroxytricyclohexylstannane;
Dowco 213; tricyclohexylstannanol
trioctyltin chloride stannane, chlotrioctyl- (9Cl) (8Cl) 2587-76-0 C24H51ClSn tin, chlorotrioctyl-;
chlorotrioctyltin; tri-n-
chlorotrioctylstannane
octyltin chloride;
triphenyltin chloride stannane, chlorotriphenyl- 639-58-7 C18H15ClSn LS 4442; GC 8993; General
(9Cl) (8Cl) Chemicals 8993; TPTC; HOE 2872;
Brestanoi; Fentin chloride;
chlorotriphenyltin;
chlorotri-phenylstannane;
triphenylchlorostannane;
triphenylchlorotin
triphenyltin hydroxide stannane, hydroxytriphenyl- 76-87-9 C18H16OSn hydroxytriphenyttin;
(9Cl) (8Cl) hydroxytriphenyl-stannane;
TPTH; triphenylstannanol; K 19
(VAN); Tenhide; Fenolovo; Du-Ter
Extra; Erithane; Vancide KS;
Dowco 186; ENT 28009; Du-Ter;
Fentin hydroxide
ORGANOTIN COMPOUNDS
Name used in text CAS Index name CAS number Molecular Synonyms
formula
TRISUBSTITUTED COMPOUNDS
triphenyltin acetate stannane, (acetyloxy)triphenyl- 900-95-8 C20H18O2Sn Brestan;
(9Cl); acetoxytriphenylstannane;
stannane, acetyloxytriphenyl- (8Cl) Batasan; Phentin acetate;
Suzu; acetato-triphenylstannane;
GC 6936; ENT 25208; Fentin
acetate; Lirostanol; tin
triphenyl acetate; TPTA;
triphenylacetostannane;
VP 19-40; Brestan 60; Liromatin
p-bromophenoxy triethyltin stannane, (p-bromophenoxy) 20961-09-5 C12H19BrOSn
triethyl- (8Cl)
TETRASUBSTITUTED COMPOUNDS
tetrarnethyltin stannane, tetramethyl- (9Cl) (8Cl) 594-27-4 C4H12Sn tetramethylstannane
tetraethyltin stannane, tetraethyl- (9Cl) (8Cl) 597-64-8 C8H20Sn tetraethylstannane
tetrabutyltin stannane, tetrabutyl- (9Cl) (8Cl) 1461-25-2 C16H36Sn tetra-n-butyltin;
tetrabutylstannane
tetraisobutyltin stannane, tetrakis(2-methylpropyl)- 3531-43-9 C16H36Sn tetraisobutylstannane
(9Cl)
stannane, tetraisobutyl- (8Cl)
tetraphenyltin stannane, tetraphenyl- (9Cl) (8Cl) 595-90-4 C24H20Sn tetraphenylstannane
tetraoctyltin stannane, tetraoctyl- (9Cl) (8Cl) 3590-84-9 C32H68Sn tetra-n-octyltin;
tetra-n-octylstannane
stannous octanoate octanoic acid, tin(2+) salt 1912-83-0 C8H16O2 1/2Sn tin octanoate; stannous
(9Cl) (8Cl) dioctanoate; tin(II)octanoate;
stannous caprylate;
stannous octcate
tin (II) cyclopentadienyl stannocene (9Cl) 1294-75-3 C10H10Sn tin, di-pi-cyclopentadienyl-
TIN AND ORGANOTIN COMPOUNDS: A PRELIMINARY REVIEW
This is the first volume in the UNEP/WHO Environmental Health
Criteria series containing a preliminary review of environmental
health aspects of a group of chemicals. Such reports are prepared in
accordance with the second objective of the WHO Environmental Health
Criteria Programme "to identify new or potential pollutants by
preparing preliminary reviews on health effects of agents likely to be
used in industry, agriculture, in the house, and elsewhere" (WHO,
1976). Organometallic tin compounds are being used in increasing
amounts for a variety of applications and the annual world production
has risen from less than 50 tonnes in 1950 to about 25 000 tonnes in
1975. One of the main applications is the use of dialkyland, to a much
lesser extent, monoalkytin compounds in the stabilization of
poly(vinyl chloride). Other applications include the use of
tributyltin compounds as industrial biocides and surface disinfectants
and the use of triphenyltin and tricylohexyltin compounds as
agricultural fungicides and agricultural acaricides.
Preliminary reviews differ from the criteria documents in that
they do not contain a separate section on health risk evaluation and
that the procedure for their preparation is simpler. Draft preliminary
reviews are not submitted for comments to the national focal points
for the WHO Environmental Health Criteria Programme. The first draft
is reviewed by a Task Group of experts, and on the basis of their
comments, a final draft is prepared and scientifically edited by the
WHO Secretariat. However, individual members of the Task Group and
other experts may be consulted during the scientific editing of the
documents.
The first draft of the present document was prepared by Dr L.
Fishbein, National Center for Toxicological Research, Jefferson, AR,
USA. Dr A. E. Martin, formerly Principal Medical Officer, Department
of Health and Social Security, London, England, assisted the
Secretariat in the preparation of a revised first draft, which was
circulated to the members of the Task Group prior to the meeting. The
Task Group on Environmental Health Aspects of Tin and Organotin
Compounds met in Geneva from 10-14 March 1975 to review and revise
this draft, and, on the basis of their comments, a final draft was
prepared by the Secretariat. The Secretariat wishes to acknowledge the
most valuable assistance in the final phases of preparation of the
document of Dr Renate Kimbrough, Center for Disease Control, Atlanta,
GA, USA, Professor Magnus Piscator, Department of Environmental
Hygiene, Karolinska Institute, Stockholm, Sweden, Dr Robert J. Horton,
US Environmental Protection Agency, Research Triangle Park, NC, and Dr
Warren T. Piver, National Institute of Environmental Health Sciences,
Research Triangle Park, NC, USA. The help is also gratefully
acknowledged of Dr H. Nordman, Institute of Occupational Health,
Helsinki, Finland, who assisted both in the preparation of the final
draft and in the final scientific editing of the document and of
Professor C. Schlatter and Dr R. Utzinger, Institué de Toxicologie,
Ecole Fédérale Polytechnique et Université de ZÜrich, Dr. D. S. Valley
Dr D. F. Walker, National Library of Medicine, Department of Health,
Education and Welfare, USA, and Dr A. Stiles, Consultant, Department
of Environmental Health, WHO, Geneva, who helped in compiling the list
of organotin compounds.
This document is based primarily on original publications listed
in the reference section. However, several publications reviewing the
health effects of inorganic and organotin compounds have also been
used. These include reviews by Barnes & Stoner (1959), Browning
(1969), FAO/WHO (1971), International Labour Office (1972), Kimbrough
(1976), MacIntosh (1969), National Institute of Occupational Safety
and Health (1976), and Piver (1973).
Details of the WHO Environmental Health Criteria Programme,
including definitions of some of the terms used in the documents, may
be found in the general introduction to the Environmental Health
Criteria Programme, published together with the environmental health
criteria document on mercury (Environmental Health Criteria I M
Mercury, Geneva, World Health Organization, 1976) and now available as
a reprint.
1. SUMMARY AND RECOMMENDATIONS FOR FURTHER RESEARCH
1.1 Chemistry and Uses of Tin Compounds
1.1.1 Inorganic tin
The annual world production of tin is around 225 000 tonnes, about
70% of which is obtained from ores, the remaining 30% being recovered
from scrap metal. Tin is mainly used in tinplated containers, but it
is also extensively used in solders, in alloys such as bronzes,
babbit, pewter, and type metal, and in more specialized alloys such as
dental amalgams and the titanium alloys used in aircraft engineering.
Inorganic tin compounds, in which the element may be present in
the oxidation states of +2 or +4 are used in a variety of industrial
processes for the strengthening of glass, as a base for colours, as
catalysts, as stabilizers in perfumes and soaps, and as dental
anticariogenic agents.
1.1.2 Organotin compounds
Organotin compounds are classified as R4Sn, R3SnX, R2SnX2, and
RSnX3. In compounds of industrial importance, R is usually a butyl,
octyl, or phenyl group and X, a chloride, fluoride, oxide, hydroxide,
carboxylate, or thiloate. So far, monosubstituted organotin compounds
(RSnX3) have had a very limited application, but they are used as
stabilizers in poly(vinyl chloride) films. Disubstituted organotin
compounds R2SnX2) are mainly used in the plastics industry,
particularly as stabilizers in poly(vinyl chloride). They are also
used as catalysts in the production of polyurethane foams and in the
room-temperature vulcanization of silicones. Trisubstituted organotin
compounds (R3SnX) have biocidal properties that are strongly
influenced by the R-groups. The most important of these compounds are
the tributyl-, triphenyl-, and tricyclohexyltin compounds, which are
used as agricultural and general fungicides, bactericides,
antihelminthics, miticides, herbicides, molluscicides, insecticides,
nematocides, ovicides, rodent repellents, and antifoulants in boat
paints. The tetrasubstituted organotin compounds (R4Sn) are mainly
used as intermediates in the preparation of other organotin compounds.
1.2 Analytical Methods
A wide variety of analytical methods is available for the
determination of tin at low concentrations.a However, these methods
have rarely been compared with regard to their suitability for
application to a particular problem and, on the basis of available
information, it is not possible to recommend a specific analytical
technique for a particular application.
Inorganic tin in food and biological materials is usually
determined by atomic absorption. Other spectroscopic methods have also
been used with satisfactory accuracy and precision, including emission
spectroscopy for air, water, and food samples and neutron activation
analysis for geological samples.
Many analytical methods have been used for the determination of
organotin compounds. Atomic absorption and other spectroscopic methods
combined with chromatography have been used for the estimation of
diorganotin compounds. Pesticide residues have been determined by
spectroscopic methods and gas-liquid or thin-layer chromatography.
However, reliable methods have still to be developed for the
quantitative extraction, separation, and determination of many
individual tin species in mixtures containing both inorganic tin and
organotin compounds that may occur in various media.
1.3 Environmental Concentrations and Exposures
1.3.1 Environmental exposures
On the whole, contamination of the environment by tin is only
slight. The levels of pollution arising from gases and fumes, waste
slag, and liquid wastes from tin processing are low because of the
high degree of recovery and reprocessing used in this industry.
Concentrations of tin in air are often below the detection limits
and, when detected, the levels are generally below 0.2-0.3 µg/m3,
except in the vicinity of industrial sources of emission, where
concentrations up to 5 µg/m3 may occur.
a Throughout the document the word concentration indicates mass
concentration unless otherwise stated.
Tin has not always been found in soils and plants; however, it is
possible that in some cases, concentrations have been below the
detection limits. Tin concentrations in soils are generally below
200 mg/kg but in regions of tin-containing minerals, the levels may
exceed 1000 mg/kg. The small amount of evidence available concerning
the uptake of tin by crops suggests that soil concentrations do not
markedly influence its uptake by plants.
Tin has been detected only occasionally in river and municipal
waters. Values exceeding 1 µg/litre are exceptional, although values
as high as 30 µg/litre have been found in drinking water. Sea water
concentrations are of the order of 3 µg/litre. Organotin compounds may
enter water, for example, from antifouling paints on the bottoms of
ships or from molluscicides, which, to be effective, should be present
at concentrations of about 1 mg/litre.
Food is the main source of tin for man. A diet composed
principally of fresh meat, cereals, and vegetables, is likely to
contain a mean tin concentration of about 1 mg/kg. Larger amounts of
tin exceeding 100 mg/kg may be found in foods stored in plain cans
and, occasionally, in foods stored in lacquered cans. Some foods such
as asparagus, tomatoes, fruits, and their juices tend to contain high
concentrations of tin if stored in unlaquered cans. Organotin
compounds may be introduced into foods through the use of such
compounds as pesticides and, to some extent, through migration of tin
from poly(vinyl chloride) materials. However, the levels of organotin
compounds in food are generally below 2 mg/kg.
Experimental studies have provided evidence of the
biotransformation of some triphenyl-, and tricyclohexyltin compounds.
There are also limited data suggesting methylation of tin by organisms
present in the environment. From the available information, it appears
that bioconcentration of tin and organotin compounds of a magnitude
that might endanger life or the environment is unlikely to occur.
The estimated mean total daily intake of tin by man ranges from
200 µg to 17 mg. A diet consisting of fresh foods probably provides
about 1-4 mg/day. The likely daily intake from water is estimated to
be less than 30 µg/day, and the daily amount entering the body from
air, less than 1 µg.
1.3.2 Occupational exposure
Several technological operations associated with the processing of
tin are known to cause excessive occupational inhalation exposure to
tin oxide which may result in a benign pneumoconiosis termed
stannosis, many cases of which have been reported in the past.
Workers involved in the processing of di- and trisubstituted
organotin compounds may be subject to excessive exposure from time to
time. Workers spraying fields or treating plants with trialkyl- or
triaryltin compounds may also run the risk of exposure to these
compounds.
1.4 Metabolism
1.4.1 Inorganic tin
The extent of absorption through the respiratory route has still
to be assessed. The absorption of ingested inorganic tin is likely to
be less than 5% although figures as high as 20% have been suggested.
Gastrointestinal absorption is influenced by the oxidation state,
tin(II) compounds being more readily absorbed than tin(IV) compounds.
The anion complement may also influence the rate of absorption.
Absorbed tin leaves the vascular system rapidly. Bone is the main
site of deposition and the highest concentrations of tin are found in
the lung, kidney, liver, and bone. Penetration of the blood-brain and
placental barriers appears to be very slight. With the exception of
the lungs, inorganic tin does not accumulate in organs with increasing
age.
Absorbed inorganic tin is mainly excreted in the urine. The
fraction excreted with the bile varies with the type of compound and
is probably below 15%.
1.4.2 Organotin compounds
In general, organotin compounds are more readily absorbed from the
gut than inorganic tin compounds; allowance must be made, however, for
the great variations found between different compounds and different
species. As a rule, tin compounds with a short alkyl chain are more
readily absorbed from the intestinal tract. The trialkyltin compounds
are usually well absorbed through the skin. As far as distribution is
concerned, the highest concentrations in rats, guineapigs, rabbits,
and hamsters have mostly been detected in the liver. Trisubstituted
organotin compounds have been found in the brain of various species
but the form of tin present in the brain has not been satisfactorily
identified.
Many organotin compounds are transformed, to some extent, in the
tissues. The dealkylation and dearylation of tetra-, tri-, and
disubstituted organotin compounds seem to occur in the liver, but the
dealkylation of diethyltin compounds appears to take place both in the
gut and in tissues of other organs. The mode of excretion of organotin
compounds largely depends on the type of the compound. For example,
ethyltin trichloride seems to be mainly excreted with the urine, but
diethyltin is eliminated with the faeces, urine, and the bile.
Triethyltin is not only excreted with the urine, but, at least in
lactating sheep, also with the milk. The route of excretion for many
compounds is not known. The biological half-time of different
organotin compounds varies and many compounds are slow to disappear
from the organs. Usually the biological half-time seems to be longer
in the brain than in other organs.
1.5 Effects on Experimental Animals
Although there is evidence that tin is essential for the normal
growth of rats, no evidence exists that it is essential for other
species including man.
1.5.1 Inorganic tin
1.5.1.1 Local effects
Many of the reported effects of inorganic tin are localized
because of its irritant properties. Vomiting and diarrhoea are typical
signs that follow oral intake of foods with a high tin content. In
cats, tin concentrations of 540 mg/litre or 1370 mg/litre in orange
juice caused vomiting in 1/11 animals and 3/10 animals, respectively.
However, these levels did not produce any effects in dogs. The only
adverse effect produced in guineapigs by both short-term and prolonged
exposure to 3 mg of tin tetrachloride per m3 of air was transient
irritation of the nose and eyes, but these findings have not been
corroborated. Application of 1% tin(II) chloride or 0.25% tin(II)
fluoride to the abraded skin of rabbits caused intradermal pustule
formation and epidermal destruction, but did not have any effect on
intact skin.
1.5.1.2 Systemic effects
The major systemic effects of inorganic tin salts in animals
include ataxia, twitching of the limbs, and fore-and hindleg weakness
progressing to paralysis. In rats, growth retardation and decreased
haemoglobin levels may follow administration of tin(II) chloride,
orthophosphate, sulfate, oxalate, and tartrate at a dietary level of
3 g/kg. However, administration of iron prevents the development of
anaemia. Higher dietary levels of tin (10 g/kg) over several weeks may
induce testicular degeneration, pancreatic atrophy, and a spongy state
of the white matter of the brain. Doses of pentafluorostannite of
100 mg/kg body weight may also affect growth, and a dose-related
decrease in haemoglobin levels may be seen with doses exceeding
100 mg/kg; no effect on growth was found at a dose of 20 mg/kg
administered orally to rats. A single intravenous injection of
pentafluorostannite at a concentration of 35 mg/kg body weight or
tin(II) chloride dihydrate (SnCl2-2H20) at 44.4 mg/kg in rats
produced extensive necrosis, mainly in the proximal tubules of the
kidney. A subcutaneous dose of tin(II) chloride at a concentration of
5.6 mg/kg body weight caused a 20-30 fold increase in the haem
oxidation activity in the kidney; this effect was dose-related.
Administration of tin(II) chloride at a concentration of 5 mg/litre,
from weaning to natural death, did not affect longevity in mice or in
male rats, but caused a decrease in longevity in female rats combined
with an increased incidence of fatty degeneration of the liver. There
is no conclusive evidence concerning the carcinogenicity or
teratogenicity of inorganic tin.
1.5.2 Organotin compounds
1.5.2.1 Local effects
Some butyltin compounds are known to produce gastrointestinal
irritation; submucosal, subserosal, and intraluminar haemorrhages were
seen in mice after a single oral dose of 4000 mg/kg body weight.
Dibutyltin dichloride administered at a dose of 50 mg/kg body weight
per day, for one week, produced gastroenteritis in rats.
Gastroenteritis was also produced in rats by administration of
tricyclhexyltin hydroxide (25 mg/kg body weight per day, for 19 days).
Dermal application of dibutyltin dichloride (10 mg/kg body weight
per day, for 12 days) caused severe local damage. Local irritation was
produced in rats by applications to the shaved skin of
bis(tributyltin) oxide in doses of 0.36-0.95 mg/kg; necrosis was
produced at doses of 1.4-185 mg/kg. Triphenyltin acetate also
irritated the skin of the rat, whereas triphenyltin hydroxide was
reported not to irritate the skin of the rabbit but to be extremely
irritating to the eyes.
1.5.2.2 Systemic effects
The systemic effects of monosubstituted, disubstituted, and
tri-substituted organotin compounds differ. In general, mono- and
di-organotin compounds are less toxic than triorganotin compounds. The
toxicity of trialkyltin compounds decreases as the number of carbon
atoms in the alkyl chain increases.
Dibutyltin compounds can produce inflammatory changes in the bile
duct. Single oral doses of dibutyltin dichloride at 50 mg/kg body
weight produced this effect in rats, and higher doses produced more
severe injury; necrotic changes were also produced in the liver of
mice and rats. Bile duct injury in rats and rabbits was seen following
dermal application of dibutyltin dichloride (10 mg/kg body weight).
Dioctyltin compounds produced slight changes in the germinal centres
of the spleen and steatosis of hepatocytes in mice at a single oral
dose of 4000 mg/kg body weight. Pulmonary oedema may be seen in rats
following intravenous administration of diethyl-, dipropyl-,
diisopropyl-, and dipentyltin compounds. Dibutyltin compounds can slow
down growth in rats. The no-observed-effect dietary level was reported
to be 40 mg/kg for a 3 month feeding period and 20 mg/kg for 6 months.
Recent studies showed that dioctyltin dichloride and dibutyltin
dichloride administered at dietary levels of 50 and 150 mg/kg,
respectively for 6 weeks, caused a dose-dependent atrophy of the
thymus and thymus-dependent organs and suppression of the
immunological response in rats, but not in mice and guineapigs.
Some trialkyltin compounds produce a characteristic lesion in the
central nervous system consisting of oedema throughout the white
matter. Orally administered trimethyl- and triethyltin compounds are
more potent in inducing this lesion than the higher homologues. The
first changes in the rat brain were visible after 3 days of
administration of triethyltin hydroxide at a dietary level of
20 mg/kg. Maximum changes were found after 2 weeks. Typical signs of
such intoxication included prostration and weakness of the progressing
to flaccid paralysis. The effects disappeared when exposure ceased.
Administration of triphenyltin compounds produced a reduction in
weight and in food intake in many species. Lethargy was a typical
symptom and histological changes in the liver and spleen were also
seen. A decreased immunological response with a reduction in the
number of leukocytes and of plasma cells in the lymph nodes of
guineapigs has been reported. A 2-year study indicated a
no-observed-effect level for triphenyltin acetate of 0.1 mg/kg body
weight per day.
A single intrarumenal dose of tricyclohexyltin hydroxide at
50 mg/kg body weight produced central nervous depression and diarrhoea
in sheep, whereas a dose of 15 mg/kg did not result in any adverse
effects. At higher doses, pulmonary congestion, tracheal haemorrhage,
enteritis, and eleotrocardiographic changes were seen.
No-observed-effect doses for long-term intake in the rat and dog were
given as 3 mg/kg body weight per day and 0.75 (mg/kg) per day,
respectively.
Tetraalkyltin compounds may produce muscular weakness, paralysis,
respiratory failure, tremors, and hyperexcitability as acute effects
in mice and dogs, while late effects are similar to those seen with
triorganotin poisoning.
There is no evidence that organotin compounds are carcinogenic or
teratogenic. Reported effects of triphenyltin hydroxide on the testes
and ovaries of rats require further confirmation.
Information concerning the mechanism of the toxic action of
organotin compounds is inadequate. Several dimethyl- and dioctyltin
compounds inhibit the oxidation of keto-acids and block mitochondrial
respiration. Trialkyltin compounds inhibit oxidative phosphorylation.
1.6 Effects in Man
1.6.1 Inorganic tin
Inhalation of elemental tin does not produce any effects in man,
whereas extended exposure to tin(IV) oxide dust and fumes can produce
a benign pneumoconiosis termed stannosis. This condition develops
after at least 3-5 years of exposure and is characterized by small
dense shadows in the pulmonary X-ray picture without impairment of
pulmonary function. Fibrosis is not seen. The generally-accepted
maximum allowable concentration of tin(IV) oxide in the air of work
rooms of 2 mg/m3 appears to give protection against this disorder.
Symptoms that have been reported following ingestion of food with
a high tin content include nausea, vomiting, diarrhoea, stomach
cramps, fatigue, and headache. The lowest concentration of tin
reported in association with such outbreaks was about 250 mg/litre in
canned orange and apple juice. Five human volunteers did not
experience any symptoms from the ingestion of fruit juices containing
concentrations of 500-730 mg/litre but all had gastrointestinal
disturbances at a level of 1370 mg/litre (corresponding to
4.4-6.7 mg/kg body weight). Ingestion of 50 mg of tin through eating
canned peaches that contained tin concentrations of about
300-600 mg/kg caused acute symptoms in 2 out of 7 persons. The
relative importance of, on one hand, the total amount of tin ingested
and, on the other hand, the concentration of tin in relation to the
development of symptoms has not been satisfactorily assessed.
1.6.2 Organotin compounds
1.6.2.1 Local effects
Dibutyl- and tributyltin compounds produced skin irritation in
workers 1-8 h after contact. Experimental application to the skin of
volunteers showed that some compounds (e.g., dibutyltin dichloride and
tributyltin chloride) produced this effect, whereas others such as
dibutyltin maleate and tetrabutyltin did not. Di- and tributyltin
compounds caused eye irritation after brief contact. A 20% solution of
triphenyltin acetate produced irritation of the skin and the mucous
membranes of the upper respiratory tract while tricyclohexyltin
hydroxide was reported not to cause skin irritation at a concentration
of 0.01 mg/kg body weight.
1.6.2.2 Systemic effects
The majority of accidental poisonings involving systemic effects
have been due to occupational exposure to triphenyltin acetate.
Systemic effects reported to have followed both dermal and inhalation
exposure include general malaise, nausea, gastric pain, dryness of the
mouth, vision disturbance, and shortness of breath. Hepatomegaly and
elevated levels of liver transaminase activity have been found in some
cases. Recovery has generally been complete but liver damage has been
known to persist for up to 2 years.
The hazard associated with the use of organotin compounds was
unmasked by an episode of intoxication in 1954 involving over 200
cases, 100 of which were fatal. The cause was the ingestion of an oral
preparation containing diethyltin diiodide at 15 mg/capsule. It was
suggested, however, that ethyltin triiodide, triethyltin iodide, and
tetraethyltin were present as impurities. Predominant symptoms and
signs included severe headache, nausea and vomiting, visual and
psychological disturbances, and sometimes loss of consciousness. At
autopsies and decompressive surgery, cerebral oedema of the white
matter was found. In many cases, symptoms lasted for at least 4 years;
follow-up information on the subjects involved is not available.
1.7 Recommendations for Further Studies
1.7.1 Analytical methods
More information is needed on the specificity, precision, and
accuracy of methods for the determination of inorganic tin compounds.
Data concerning interlaboratory comparisons of the methods used are
also lacking. In view of the variable results obtained in studies on
the tin contents of various materials and tissues, the use of
reference laboratories is recommended. Better methods are needed for
the quantitative extraction and separation of the various organotin
compounds present in environmental and biological samples. As
organotin compounds used as pesticides or stabilizers occur in foods
in minute amounts only, mare sensitive methods for their measurement
are needed.
1.7.2 Environmental data
More information regarding bioconcentration is needed. The fate of
organotin compounds entering water is largely unknown. The possibility
of the methylation of tin by organisms present in the environment is
of particular interest.
A wide variety of results concerning the daily intake of tin has
been reported. Although a certain range is to be expected, further
investigations of the concentrations of tin in food and water, and of
dietary intake are needed.
1.7.3 Metabolism
Information on the rate of absorption of tin from the
gastrointestinal tract is insufficient and little is known about the
absorption of various compounds through the respiratory tract which
may be of importance in occupational exposure. Furthermore, there is a
gap in information concerning the rate of absorption of organotin
compounds through the skin.
Many of the studies conducted on the distribution of tin in human
tissues may be unreliable because of the analytical methods available
at that time: thus, data on tissue contents should be obtained using
as sensitive methods as possible with emphasis on the precision,
specificity, and accuracy of the assays employed. Information on tin
concentrations in newborn infants compared with adults is lacking, and
data concerning tin concentrations in the tissues of occupationally-
exposed persons compared with unexposed populations are not available.
The increasing development and use of new organotin compounds will
necessitate further studies on the metabolism of such compounds.
At present, there is an obvious lack of information on the
bio-transformation of several organotin compounds. Data concerning the
accumulation and retention times of various compounds in animal
tissues are also desirable. Finally, the route or routes of excretion
of many organotin compounds are completely unknown.
1.7.4 Effects
Probably the most conspicuous lack of information concerns the
mechanism of action of various organotin compounds. More information
should be obtained on the carcinogenicity, teratogenicity, and
mutagenicity of these compounds. Compounds used industrially should be
studied with reference to possible allergenic properties. Recently
reported results suggest that the effects of various organotin
derivatives on the immune system should be studied in more detail.
Moreover, properly conducted studies on the effects on the sex glands
of different species using multigeneration studies seem urgent. The
importance of longitudinal epidemiological studies on
occupationally-exposed populations and the usefulness of information
that may be obtained through follow-up studies of accidental
intoxication should be emphasized.
2. CHEMISTRY AND ANALYTICAL METHODS
Tin can form a variety of both inorganic and organometallic
compounds. These two classes of compounds have different chemical and
physical properties which make them suitable for different
applications in industry, agriculture and elsewhere. They also have
different toxicities and require separate assessments of health risk.
The inorganic chemistry of tin has been described in standard texts on
inorganic chemistry such as those by Cotton & Wilkinson (1972, 1976)
and Heslop & Jones (1976). Sources of information on new developments
in the organometallic chemistry of tin include a review by van der
Verk (1972) and a collection of papers presented at a symposium of the
American Chemical Society (Zuckerman, 1976).
2.1 Elemental Tin
Tin (atomic number 50; relative atomic mass 118.70) is an element
of group IVb of the periodic system, together with carbon, silicon,
germanium, and lead. It exits in three allotropic modifications. At
room temperature, the stable form is a metallic form called ß- or
white tin. White tin is a silver-white, lustrous and soft metal with
considerable ductility, and can be rolled into very thin "tin foil".
Its density is 7.27, melting point 231.9°C, and boiling point 2507°C.
At ordinary temperatures, it is stable in both air and water. Below
13.3°C, the stable form of tin is the non-metallic grey tin
(alpha-tin). Above 161°C, the stable modification is the so-called
brittle tin, another metallic modification.
Metallic tin is normally covered with a thin protective film of
tin dioxide. Because tin is resistant to cold acids, a cohesive tin
layer will protect iron from corrosion (tin plate). However, if the
layer is damaged, the iron will rapidly corrode. Tin-plate used in the
food industry should not contain lead, not only because lead is toxic,
but also because its presence aids the corrosion of tin by dilute
organic acids.
Neutral aqueous salt solutions react slowly with metallic tin in
the presence of oxygen but solutions containing nitrates, iron(II)
chloride or sulfate, aluminium chloride or tin(IV) chloride dissolve
elemental tin.
Tin can form inorganic compounds in the oxidation state +2 (SnII,
tin(II) compounds, or stannous compounds), and in the oxidation state
+4 (SnIV, tin(IV) compounds, or stannic compounds). Because of their
different physieochemical properties, it is useful to discuss the 2
groups of compounds separately.
2.2 Tin(II) Compounds
Tin(II) compounds are generally more ionic than tin(IV) compounds.
They are unstable in dilute aqueous solutions, are easily oxidized,
and normally contain some SnIV; after some time, hydrolysis occurs
with the formation of the hydrated tin(II) oxide ion [Sn3(OH)4]2+.
Tin(II) chloride is readily soluble in small amounts of water. It
is a fairly good reducing agent, and has many uses in industry,
particularly as a mordant in dye printing. Aqueous solutions of
tin(II) chloride become turbid on dilution because a basic salt is
precipitated. The fluoride (SnF2) is slightly soluble in water. It is
used in fluoride-containing toothpastes. In aqueous solutions,
SnF3- is the major ion but other ions such as SnF+ and Sn3F5-
are also present. Tin(II) sulfate is a good source of SnII. Its
solubility decreases with temperature.
Tin(II) oxide (SnO) is a stable, blue-black crystalline solid. It
reacts with both mineral and organic acids, and dissolves in sodium
hydroxide solutions forming stannites, which probably contain the
SnO22- ion.
Other tin(II) compounds that have practical applications are
tin(II) acetate, tin(II) arsenate, tin(II) fluoroborate, tin(II)
pyrophosphate, and several tin(II) salts or organic acids, such as
tin(II) oxalate and tin(II)-2-ethylhexoate (tin(II)"octoate").
2.3 Tin(IV) Compounds
Tin in the oxidation state + 4 forms a large number of inorganic
compounds as well as organometallic compounds, which are discussed in
section 2.4. Some tin(IV) compounds, such as tin(IV) oxide (SnO2),
have long been used in industry; Others, e.g., tin(IV) chloride
(SnCl4), have found technological applications more recently. Also of
practical importance are the stannates, compounds in which the tin
atom is part of an anion. The structure of stannates can be
represented by MnSn(OH)6, where M is a metal ion.
The physical properties of tin tetrahalides, except those of
SnF4, correspond to the properties of covalent halides of carbon and
silicon. Tin(IV) chloride is a colourless liquid that fumes in moist
air and becomes turbid because of hydrolysis when complex ions such as
[SnCl3(OH)3]2- are formed. The addition of a limited amount, of
water to tin(IV) chloride results in the formation of a crystalline
hydrate, SnCl4.5H2O, the ionic character of which is probably due to
the presence of a complex ion [Sn(H2O4]4+.
Tin(IV) oxide occurs naturally as the mineral cassiterite. It has
a very high melting point (1127°C) and has wide application in
industry. The fusion of tin(IV) oxide with sodium or potassium
hydroxide yields stannates.
Other tin(IV) compounds that have found practical applications
include tin(IV) sulfide, tin(IV) vanadate, and tin(IV) molybdate.
2.4 Organometallic Compounds of Tin
Organometallic tin compounds or organotin compounds have one or
more carbon-tin covalent bonds that are responsible for the specific
properties of such molecules. Essentially all organometallic tin
compounds are of the SnIV type. The only well established compound
with tin in the oxidation state + 2 is the tin(II)cyclopentadienyl,
C10H10Sn. There are four series of organotin compounds depending on
the number of carbon-tin bonds. These series are designated as mono-,
di-, tri-, and tetraorganotin compounds with the general structure:
RnSn X4-n
where R = an alkyl or aryl group
Sn = the central tin atom in the oxidation state +4
X = a singly charged anion or an anionic organic group.
In the organotin compounds of practical importance, R is usually a
butyl, octyl, or phenyl group and X is commonly chloride, fluoride,
oxide, hydroxide, carboxylate, or thiolate.
Monoorganotin compounds, RSnX3, are known but so far have found
only limited application, for example, butyltin sulfide is used as a
stabilizer in poly(vinyl chloride) (PVC) film.
Diorganotin compounds, R2SnX2, are chemically reactive and most
of their applications are based on this property. They are used. as
stabilizers of PVC, as catalysts in the production of polyurethane
foams, and in the cold-curing of silicon elastomers.
Triorganotin compounds, R3SnX, are the most important class of
organotin chemicals. They are biologically very active and are widely
used as biocides. The chemical nature of the R group has a strong
influence on the biological properties of these compounds. The
X-group, on the other hand, influences their solubility and
volatility. The two most important groups of triorganotin compounds
are tributyltin and triphenyltin derivatives.
Tetraalkyl- and tetraaryltin compounds are primarily used as
intermediates in the preparation of other organotin compounds.
Tetraalkyltin compounds are colourless and the compounds of lower
molecular weight are liquids at room temperature. The tetraaryltin
compounds are solids. Tetraorganotin compounds possess typical
covalent bonds and are stable in the presence of air and water.
Tetrabutyltin, Sn(C4H9)4 is a colourless oily liquid with a
distinct odour. Tetraphenyltin, Sn(C6H5)4, is a white crystalline
powder, soluble in organic solvents and insoluble in water.
Since 1974, a new class of organotin compounds, called estertins,
has been developed for use as stabilizers in poly(vinyl chloride).
Their general structure is (R-O-CO-CH2-CH2)2SnX2 or
R-O-CO-CH2-CH2SnX3 where X may be, for example,
isooctylmercaptoacetate. They have a comparatively low volatility and
ex,tractability (Lanigon & Weinberg, 1976).
Solubility data for organotin compounds are incomplete. In
general, their solubility in water at ambient temperatures is of the
order of 5 to 50 mg/litre, but they are very soluble in many common
organic solvents, such as alcohol, ethers, and halogenated
hydrocarbons.
Commercial products are usually pure chemicals since, for
technological reasons, scrupulous care must be taken to avoid metal
contamination during manufacture. The impurities are primarily solvent
residues remaining from the product purification and separation
processes.
The carbon-tin bond is susceptible to nucleophilic and
electrophilic attack, e.g., hydrolysis, solvolysis, acidic and basic
attack, and halogenation. Water has little effect on symmetrical
saturated organotin compounds. Dialkyltin compounds react
spontaneously with moisture and air to form dialkyl hydrated oxides.
Photochemical reactions of organotin compounds are mentioned in
connexion with environmental transport and transformations (section
4). The physicochemical properties of some organotin compounds have
been listed by Weast (1976).
2.5 Analytical Methods
2.5.1 Determination of inorganic tin
2.5.1.1 Atomic absorption spectroscopy
Atomic absorption spectroscopy is the method most widely used for
the detection of low concentrations of tin. In general, the lowest
limit of detection is obtained with a fuel-rich, air-hydrogen flame,
e.g., about 1-1.5 mg/kg compared with 2-2.5, and 4-5 mg/kg for
air-ethylene and nitrous oxide-ethylene flames, respectively
(Christian & Feldman, 1970). The detection limits at the 3 absorption
lines, 2246.1, 2354.8, and 2863.3 nm do not differ much. Using some of
the procedures mentioned later, the detection limit may be reduced to
about 0.1-0.5 mg/kg.
Several atomic absorption techniques, modified to suit specific
purposes, have been reported. A detection limit of 0.5 µg/litre was
obtained when a hydride generation technique using sodium borohydride
and a flame-heated silica atomizing tube was used in the air-acetylene
atomic absorption determination of tin in solution (Thompson &
Thomerson, 1974). Capacho-Delgado & Manning (1966), using a high
intensity hollow cathode lamp as the source, reported a detection
limit of 0.1 mg/litre for water solutions of metallurgical samples,
while Schallis & Kann (1968) determined tin in lubricating oils with a
detection limit of about 0.5 mg/litre. Carbon filament atomic
absorption spectroscopy was employed by Everett et al. (1974) to
determine tin(II) chloride in aqueous and xylene solutions and tin
octoate in oil solution.
Atomic absorption spectroscopy has been used extensively for the
determination of tin in foods (Allan, 1962; Amos & Willis, 1966;
Capacho-Delgado & Manning, 1966; Christian & Feldman, 1970; Gatehouse
& Willis, 1961) and particularly in canned foods, including fruit
juice, fruits, and vegetables (Catala et al., 1971; Price & Roos,
1969; Sato et al., 1973; Shiraishi et al., 1972; Woidich &
Pfannhäuser, 1973). A detection limit of 0.5 mg/kg has been reported
for the determination of tin in canned fruit juice using a nitrous
oxide-acetylene flame (Price & Roos, 1969).
Engberg (1973) compared atomic absorption with a
spectrophotometric method using 2-(3,4,-dihydroxyphenyl)-3,5,7-
trihydroxy-4H-1-benzopyran-4-one (quercetin) for the determination
of tin in food. The methods gave similar results at concentrations of
tin generally found in canned food, but at very low concentrations
(e.g., organotin residues), the quercetin method was more suitable
because of its lower detection limit (section 2.5.1.5).
Atomic absorption spectroscopy has also been used for the
determination of tin in biological samples (Pearlman et al., 1970).
2.5.1.2 Emission spectroscopy
Emission spectroscopy is a rapid and specific method that has
frequently been used for the simultaneous determination of several
elements. Unfortunately, this method is exacting, demanding highly
qualified personnel, and the cost of the instrument is high. It has
been used for the determination of tin in atmospheric samples
(Hasegawa & Sugimae, 1971; Keenan & Byers, 1952; Laamanen et al.,
1971, Lee et al., 1972; Schroll & Krachsberger, 1970; Sugimae, 1974;
Tabor & Warren, 1958), tin in water (Ghafouri, 1970; Konovalov &
Kolesnikova, 1969; Rittenhouse et al, 1969), and for tin in various
foods including meats (Krylova & Balabuh, 1970), fruits, and
vegetables (Chisaka et al., 1973). A sensitivity of 0.04 mg/kg fresh
weight was reported by Tihonova & Zore (1968) for vegetables and
berries. Several investigators have used emission spectroscopy for the
determination of tin in biological samples (Avtandilov, 1967;
Geldmacher-von Mallinckrodt & Pooth, 1969; Kas'yanenko & Kul'skaya,
1969; Kehoe et al., 1940; Mulay et al., 1971; Saito & Endo, 1970
Tipton et al., 1963).
2.5.1.3 Neutron activation analysis
Although the limit of detection of tin by neutron activation is
comparatively high, the technique has been used to determine tin in
air samples (Bogen, 1973; Tuttle et al., 1970). It is also the most
commonly used method for the determination of tin in geological
samples (soils, sediments, rocks, off) (Johansen & Steinnes, 1969;
Obrusnik, 1969; Schramel et al, 1973). A neutron activation electron
probe was used by Kurosaki & Fusayama (1973) for the estimation of tin
in teeth. Disadvantages of neutron activation include the need for a
nuclear reactor and the possibility of interference from formation of
other isotopes.
2.5.1.4 X-ray fluorescence
X-ray fluorescence, a non-destructive method for the determination
of tin, has been used in the analysis of air for elements ranging from
titanium to caesium with a detection limit of 0.5 µg/m3 of air
(Dittrich & Cothern, 1971) and for river water with a detection limit
of 20-30 µg/litre for metals in the suspended or particulate form, and
0.25-0.4 mg/litre for ionic metals (Blasius et al., 1972).
2.5.1.5 Miscellaneous analytical methods
Among the spectrophotometric methods reported, Kirk & Pocklington
(1969) recommended the tin-quercetin method for the estimation of the
tin contents of foods at concentrations ranging from 10 to over
500 mg/kg. The smallest absolute amount of tin detectable with the
quercetin method has been reported to be about 1 µg (Engberg, 1973).
The pyrocatechol violet method