WORLD HEALTH ORGANIZATION FOOD AND AGRICULTURE
ORGANIZATION
ORGANISATION MONDIALE DE LA SANTE ORGANISATION POUR L'ALIMENTATION
ET L'AGRICULTURE
VBC/DS/77.21
ORIGINAL: ENGLISH
DATA SHEETS ON PESTICIDES No. 21
December 1976
DDT
It must be noted that the issue of a Data Sheet for a
particular pesticide does not imply endorsement of the pesticide by
WHO or FAO for any particular use, or exclude its use for other
purposes not stated. While the information provided is believed to
be accurate according to data available at the time when the sheet
was compiled, neither WHO nor FAO are responsible for any errors or
omissions, or any consequences therefrom.
The issue of this document does Ce document ne constitue pas une
not constitute formal publication. Il ne doit faire
publication. It should not be l'objet d'aucun compte rendu ou
reviewed, abstracted or quoted résumé ni d'aucune citation sans
without the agreement of the l'autorisation de l'Organisation
Food and Agriculture des Nations Unies pour
Organization of the United l'Alimentation et l'Agriculture
Nations or of the World Health ou de l'Organisation Mondiale de
Organization. la Santé.
Part 1. General Information
CLASSIFICATION:
Primary use: Insecticide
Secondary use: None
Chemical group: Organochlorine compound
Data Sheet: No. 21
Date issued: December 1976
1.1 COMMON NAME - DDT (ISO)
1.1.1 Identity: 2,2-bis-(p-chlorophenyl)-1,1,1-trichloroethane
1.1.2 Synonyms Local synonyms
Chlorophenothane
Dicophane
Dichlorodiphenyltrichloroethane
OMS-16
1.2 SYNOPSIS: A persistent organochlorine pesticide of moderate
mammalian toxicity. No ill effects have been observed in
personnel exposed for many years both in its manufacture and field
use. It accumulates in body fat to a plateau level related to
absorption. It is cumulative in the natural enviroranent.
1.3 SELECTED PROPERTIES
1.3.1 Physical characteristics: Technical DDT is of variable
composition and may consist of 11 or more compounds of
which the pp'-isomer of DDT contributes 63-77%, the
op'-isomer 8-21% and the oo'-isomer 0.1-1.0%. Pure pp'-
DDT is a white crystalline solid of melting point 108.5-
109°C. The technical material, however, takes the form of
a white or cream coloured waxy solid or amorphous powder
of indefinite mp.
1.3.2 Solubility
Practically insoluble in water. Moderately soluble in
hydroxylic and polar solvents and in petroleum oils.
Readily soluble in most aromatic and chlorinated solvents.
1.3.3 Stability
Dechlorinated at temperatures above its melting point
into a non-insecticidal ethylene derivative, a reaction
catalysed by ferric and aluminium chloride and by UV
light. In solution it is readily dehydrochlorinated by
alkalis or organic bases, otherwise it is stable being
unattacked by acid and alkaline permanganate and by
aqueous acids and alkalis. With technical DDT
dehydrochlorination may proceed at temperatures as low
as 50°C.
1.3.4 Vapour pressure (volatility)
pp'-isomer 1.9 x 10-7 mm Hg at 20°C
1.4 AGRICULTURE, HORTICULTURE AND FORESTRY
1.4.1 Common formulations
Wettable powders, dusts, aerosols, emulsifiable
concentrates. Concentrations of solid and liquid
formulations are mostly between 20% and 25%.
1.4.2 Susceptible pests
In agriculture and horticulture for control, where
permitted, of susceptible pests (e.g. cutworms,
leafhoppers, leatherjackets, midgets, millepedes,
mushroomflies, thrips, sandflies, wasps, weevils,
whiteflies, woodlice).
1.4.3 Use pattern
Cotton, 2 quarts of 25% emulsifiable concentrate (e.c.)
in sufficient water to give good cover per acre;
brassicae 56 lbs 5% dust per acre, cornborer in maize, 3
quarts 25% e.c. in 10 gallons applied at 15 gallons per
acre.
1.4.4 Unintended effects
It should not be used on curcubits and certain barley
varieties as damage may occur. It should also not be
used on permanent and temporary grass for grazing,
silage or hay, brassicae seed crops, peas, beans and
bush fruit.
1.5 PUBLIC HEALTH PROGRAMME
Still widely used in public health programmes where the vector is
not resistant. The predominant use is for residual indoor
application against anopheline mosquitos in malaria control
programmes using 5% w.d.p. applied at 1-2 g/m2.
In tsetse fly control, 25% e.c. has been applied as a residual
insecticide on vegetation. Until recently, DDT was used
extensively for blackfly (Simulium) control being introduced into
streams at 0.1-1 mg/l using 20-25% e.c. As a general mosquito
larvicide 1.25-5% e.c. is used.
1.6 HOUSEHOLD USE
Active against most household pests, including ants, cockroaches,
house-flies, mosquitos, bedbugs and fleas, etc. Some strains of
insect species have developed resistance. Bedbugs 5% spray, also
for fleas, ticks, wasps 5% to 10% dust.
Part 2. Toxicology and risks
Common name: DDT
Data Sheet: No. 21
Date issued: December 1976
2.1 TOXICOLOGY - MAMMALS
2.1.1 Absorption route: Absorbed from the gastrointestinal tract
and by inhalation. It may also be absorbed by the
intact skin when in oily solution.
2.1.2 Mode of action: Central nervous system stimulant producing
hyperactivity and tremor; convulsions may occur but are
less common than with other organochlorine pesticides.
2.1.3 Excretion products: Intact DDT is found in fatty tissues
along with its metabolites DDD and DDE. DDD may be
further metabolised to DDA and excreted in urine.
2.1.4 Toxicity, single dose:
Oral: LD50 Rats (M and F) 250 mg/kg
Dermal: LD50 Rata 250-500 mg/kg in oil
3000 mg/kg as powder
Rat (F) 2510 mg/kg as powder
Dermal: LD50 Rabbita 300 mg kg in oil
2820 mg/kg as powder
Most susceptible species: rat
a Sex not stated.
2.1.5 Toxicity, repeated dose
DDT administered as a 10% solution in kerosene at 100
mg/kg/day orally to five rabbits proved fatal in six
days. Similarly 200 mg/kg was fatal to five guineapigs
and five rats in 12 and 14 days respectively when dosed
under the same conditions.
Dermal: Rats treated with 200 mg/kg/day in kerosene were
severely affected, with some fatalities after 14 days.
Inhalation: Exposure of rats to a concentration of 1000
ppm DDT in air for two hours a day caused some deaths
after 4-10 exposures.
Cumulation of compound:
DDT and its metabolites accumulate in body fats and
other tissues, either as pp'-DDT, DDD or DDE. Under
normal circumstances a plateau level is reached where
intake and storage are in equilibrium with excretion,
therefore the amount stored in fat will remain constant
as long as exposure remains constant. Central nervous
stimulation is related to brain level of DDT; this may
be reached by a single acute dose or by smaller repeated
doses.
2.1.6 Dietary studies
Short-term: 2000 ppm in rats gave a 50% kill in
nine days. 600 ppm was tolerated for 14 weeks but was
100% fatal after 52 weeks.
Long-term: 250 ppm produced no toxic effects over one year
in rats. However, dietary feeding as low as 5-10 ppm has
been reported to produce slight hepatic cell enlargement
especially centrolobularly and increased cytoplasmic
oxvphilia. At higher doses, 500 and 1000, ppm focal
necrosis, atrophy and hydropic degeneration were observed.
2.1.7 Supplementary studies of toxicity
Carcinogenicity:
DDT has been shown to be carcinogenic in a two-
generation life span study. (CF 1 mice) at 2,
10, 50 and 250 ppm, all levels increased tumour
incidence in females and two highest levels in
males. While early work of DDT suggested that it
might be tumorigenic in rats, no convincing
evidence of carcinogenicity to this species has
been provided. The significance of the finding in
mice for man cannot yet be assessed. No increased
incidence of tumours has been observed in
formulators and spraymen exposed to excessive
quantities of DDT for 20 or more years (see 2.2.3).
Teratogenicity:
DDT has been shown not to be teratogenic in rats in
a three-generation study at dose levels of 20 and
200 ppm DDT. The number of pregnancies and
fertility were unaffected at these dose levels.
Survival of offspring during weaning at 200 ppm was
reduced.
Mutagenicity:
DDT caused moderate mitotic inhibition at 20-50
µg/ml in an in vitro test using a kangaroo rat
cell line culture. At 10 µg/ml pp'-DDT,
chromosome aberrations and damage were observed in
22.4% of cells. Test in mice to determine whether DDT
produces dominant lethal mutations proved negative.
2.1.8 Modification of toxicity
The chronic toxicity of DDT has been shown to increase
in association with lowering of the protein content of
the fat.
2.2 TOXICOLOGY - MAN
2.2.1 Absorption: (see 2.1.1)
Only massive ingestion (accidental or suicidal) has
given rise to cases of poisoning.
2.2.2 Dangerous doses
Single: 10 mg/kg produces illness in some but not all
subjects. 16 mg/kg or above will cause convulsions.
Dosages as high as 285 mg/kg have been taken without
fatal results. Estimated lethal dose for man 500 mg/kg
and in kerosene solut4ion 150 mg/kg.
Repeated: Exposure to an aerosol mist containing 80 mg
DDT in a room of 113 m3 on five consecutive days
for two hours twice a day gave no evidence of toxic
effects.
2.2.3 Observations of occupationally exposed workers
Over 150 persons with heavy and prolonged occupational
exposure to DDT in manufacturing plants have been
subjected to exhaustive medical examinations. The only
relevant findings were increased storage and excretion
of DDT and its metabolites and a mild stimulation of
microsomal enzymes of the liver.
Extensive observations of spraymen heavily exposed both
with and without protective clothing have revealed no
evidence of ill effects with regard to the clinical
examination, blood picture and urine tests.
Spraymen recruited from areas where the normal diet is
of a poor nutritional standard have shown no
predisposition to poisoning with DDT.
2.2.4 Observations on exposure of the general population
Food is the main source of exposure and due to its low
biodegradability and high lipophilic properties, traces
of DDT (and its analogues) are found in adipose tissue.
The mean levels vary from country to country (in recent
years, 2.3-21.3 ppm, expressed as total DDT), while age,
sex, race and social class have been described as
important demographic variables influencing the
frequency distribution of DDT residue in the general
population. Accumulation in other tissues is markedly
smaller, and is proportional to their neutral fat
content.
A high degree of safety of DDT for the general
population is indicated by the studies on people
occupationally exposed (2.2.3) and volunteers (2.2.5).
2.2.5 Observations in volunteers
Exposure to 1 mg DDT/3 m3 for 1 h/day for six days
produced no untoward effects. Oral dosage with 500 mg
in olive oil gave no toxic effect and 11 mg/kg (770 mg
total) pure DDT in 25 cc olive oil gave no subjective
signs, tremor, twitching or EEG abnormalities. Twenty-
four volunteers ingested technical or p,p'-DDT at rates
up to 35 mg per man per day for 21.5 months. They were
then observed for an additional 25.5 months and 16 were
followed up for five years. Storage of DDT and DDE and
excretion of DDA were proportional to dosage. The fat of
those receiving technical insecticide at the highest rate
contained 105 to 619 ppm of DDT when feeding stopped. The
average dosage of p,p'-DDT administered in this study was
555 times the average intake of all DDT-related compounds by
19-year-old men in the general population and 1250 times
their intake of p,p'-DDT. Since no definite clinical or
laboratory evidence of injury by DDT was found in this
study, these factors indicate a high degree of safety of
DDT for the general population.
2.2.6 Reported mishaps
In spite of the prolonged exposure of the entire
population of the world and the heavy occupational
exposure of a substantial number, the only reported
poisoning cases were due to intentional or accidental
ingestion. In most of these cases only moderate nervous
symptoms were observed and convulsions were rare.
2.3 TOXICITY TO NON-MAMMALIAN SPECIES
2.3.1 Fish: Harmful
2.3.2 Birds: Moderately toxic
2.3.3 Other species: Harmful to bees.
Part 3. For regulatory authorities
Common name: DDT
Data Sheet: No. 21
Date issued: December 1976
RECOMMENDATIONS ON REGULATION OF COMPOUND
3.1 RECOMMENDED RESTRICTIONS ON AVAILABILITY
(for definition of categories, see introduction)
Formulations of 10% and above and all liquid formulations over 2%
- category 4. Formulations below 10% - category 5.
3.2 TRANSPORTATION AND STORAGE
Formulations in category 4
Should be transported or stored in clearly labelled rigid leak-
proof containers and away from containers of food and drink.
Storage should be under lock and key and secure from access by
unauthorized persons and children.
Formulations in category 5
Should be transported or stored in clearly labelled leak-proof
containers, out of reach of children and away from food and drink.
3.3 HANDLING
Formulations in category 4
Protective clothing should be used by those handling concentrates.
Adequate washing facilities should be available close at hand.
Eating, drinking and smoking should be prohibited during handling
and before washing, after handling.
Formulations in category 5
No special facilities other than those needed for handling of any
chemicals need be required.
3.4 DISPOSAL AND/OR DECONTAMINATION OF CONTAINER
Containers containing residues must either be burned or crushed
and buried below topsoil. Care must be taken to avoid subsequent
contamination of water sources. Decontamination of containers in
order to use them for other purposes should not be permitted.
3.5 SELECTION: TRAINING AND MEDICAL SUPERVISION OF WORKERS
Formulations in category 4
Pre-employment medical examination desirable. Workers suffering
from active hepatic or renal disease should be excluded from
contact. Monitoring of DDT levels in fat, gives little or no
indication of degree of acute exposure.
Formulations in category 5
Warning of workers to minimize contact essential.
3.6 ADDITIONAL REGULATIONS RECOMMENDED IF DISTRIBUTED BY AIRCRAFT
Pilot and loaders should have special training in application
methods.
3.7 LABELLING
Formulations in category 4
Minimum cautionary statement
This formulation contains DDT, a toxic substance which is
poisonous if swallowed. Keep the material out of the reach of
children and well away from foodstuffs, animal feed and their
containers.
Formulations in category 5
Minimum cautionary statement
DDT is an organochlorine insecticide.
Keep the material out of the reach of children and well away from
foodstuffs, animal feed and their containers.
3.8 RESIDUES IN FOOD
Maximum residue limits for DDT have been recommended by the Joint
FAO/WHO Meeting on Pesticide Residues.
Part 4. Prevention of poisoning in man and emergency aid
Common name: DDT
Data Sheet: No. 21
Date issued: December 1976
4.1 PRECAUTIONS IN USE
4.1.1 General
DDT is a moderately toxic organochloride
insecticide which is slowly metabolised and stored
in body tissues and can act as both an acute and
chronic poison. It can be absorbed by mouth, by
inhalation of dust and also through the intact skin
when in an oil-based formulation. It is important
that concentrated formulations be washed
immediately from the skin and eyes.
4.1.2 Manufacture and formulation
TLV
(ACGIH) 1 mg/m3 (USSR) 0.1 mg/m3. Although
volatility is low, vapour and dust should be
controlled preferably by mechanical means.
Protective equipment for the skin and respiratory
protection is advisable.
4.1.3 Mixers and applicators
When opening the container and when mixing care
should be taken to avoid contact with the mouth and
eyes. If necessary a facial visor and gloves
should be worn. Mixing, if not mechanical, should
always be carried out with a paddle of appropriate
length.
Before eating, drinking, or smoking, hands and
other exposed skin should be washed.
4.1.4 Other associated workers (including flagmen in aerial
operations)
Persons exposed to DDT and associated with its
application should observe the precautions
described above in 4.1.3 under "mixers and
applicators".
4.1.5 Other populations likely to be affected
With good agricultural practice subject to 4.2 below
other populations should not be exposed to hazardous
amounts of DDT.
4.2 ENTRY OF PERSONS INTO TREATED AREAS
The general population should be kept out of treated areas for at
least one day.
4.3 DECONTAMINATION OF SPILLAGE
Spillage of DDT and its formulations should be removed by washing
with large quantities of water.
4.4 EMERGENCY AID
4.4.1 Early symptoms of poisoning
Early symptoms may include parasthesia (tingling) of the
tongue, lip and parts of the face, in severe cases
extending to the extremities. The patient may have a
sense of apprehension and disturbance of equilibrium,
dizziness, confusion and a characteristic tremor. In
severe poisoning, convulsions occur.
More general symptoms include headache, nausea and
fatigue. Sensitivity to touch and pain are exaggerated
in areas in which parasthesia is evident.
4.4.2 Treatment before person is seen by a physician, if these
symptoms appear following exposure
Remove contaminated clothing and wash the affected skin
with water and soap and flush the area with large
quantities of water.
If swallowed, vomiting should be induced if the person
is conscious. Patient should be calmed and kept in
quiet, shaded conditions until medical help arrives.
Part 5. For medical and laboratory personnel
Common name: DDT
Data sheet: No. 21
Date issued: December 1976
5.1 MEDICAL DIAGNOSIS AND TREATMENT IN CASES OF POISONING
5.1.1 General information
DDT is an organochlorine insecticide of moderate
toxicity. It is absorbed from the gastrointestinal
tract and by inhalation. It may also be absorbed
through the intact skin, more especially in the case of
oil-based formulations. Cases of poisoning reported
only after massive ingestion. Its mode of action is by
stimulation of the CNS. It is slowly metabolized and
eliminated from the tissues and may be stored in body
fat.
5.1.2 Symptoms and signs
Symptoms of poisoning may include headache, nausea and
vomiting, weakness, dizziness and confusion,
disturbances of equilibrium, parasthesia and a
characteristic tremor. In more severe poisoning
convulsions occur.
5.1.3 Laboratory
Measurement of blood or fat levels of DDT and urine
levels of DDA will confirm absorption of DDT but will
not necessarily reflect degree of poisoning. High
levels of DDT and its metabolites will be found in
body fats, these levels may continue to increase after
acute dosage, when symptoms of poisoning have abated.
Treatment should never be deferred pending the results
of a laboratory test.
5.1.4 Treatment
If the pesticide has been ingested, rapid gastric lavage
should be performed using 5% sodium bicarbonate, if
available. For skin contact, the skin should be washed
with soap and water. If the compound has entered the
eyes they should be washed with isotonic saline. There
is no specific antidote and treatment must be
symptomatic. Soluble barbiturate, diazepam or
paraldehyde should be used to calm patient and control
convulsions.
5.1.5 Prognosis
If the acute toxic effect is survived the chances of
complete recovery are good with great improvement within
24-48 hours after ingestion.
5.1.6 References of previously reported cases
Case histories and general methods for treatment are
given in:
1. Cunningham & Hill (1952) Pediatrics, 9, 745
2. Dreisbach, R. H. (1974) Handbook of poisoning, pp.
91-93, 8th ed. Lange Med. Pub., Los Altos,
California
3. Hayes, W. J. jr (1963) Clinical handbook of
economic poisons, US Public Health Service Publ.
No. 476 revised
4. Von Oettingen (1955) The halogenated hydrocarbons,
toxicity and potential dangers, US Dept of Hlth
Educ. and Welfare
5.2 SURVEILLANCE TESTS
There are no readily available techniques to determine the degree
of exposure prior to the appearance of symptoms.
5.3 LABORATORY METHODS
5.3.1 Detection and assay of compound
The analysis of blood, urine and faeces is of extreme
importance when studying transport and elimination of
p,p'-DDT and p,p'-DDT-derived metabolites. The
examination of urine is of particular interest because
p,p'-DDA, a predominant metabolite of p,p'-DDT, is
excreted by this route. Excretion levels of this
metabolite have been established as sensitive indicators
of exposure to p,p'-DDT (Durham et al., 1965). A rapid
sensitive gas chromatograhic procedure for the analysis
of this metabolite was developed as a dual analytical
procedure to determine DDT and its polar and non-polar
metabolites in human urine (Cranmer et al., 1969).
Utilizing electrolytic conductivity, or micro-
colormetric detection, the procedure can be readily
adapted for the exclusive determination of p,p'-DDA
excretion levels.
5.3.2 Other tests in cases of poisoning
Liver function.
REFERENCES
Cranmer, M. F., Carroll, J. J. & Copeland, M. F. (1969) Determination
of DDT and metabolites including DDA in human urine by gas
chromatography, Bull. Environ. Contamin. & Toxicol., 4, 214
Cueto, C., Barnes, A. G. & Mattson, A. M. (1956) Determination of DDA
in urine using an ion exchange resin, J. Agr. Food Chem., 4, 943
Durham, W. F., Armstrong, J. F. & Quinby, G. E. (1965) DDA excretion
levels, Arch. Environm. Health, 11, 76