International Agency for Research on Cancer (IARC) - Summaries & Evaluations


VOL.: 25 (1981) (p. 249)

5. Summary of Data Reported and Evaluation

5.1 Summary of data

The incidence rates of nasal cancers in workers engaged in boot and shoe manufacture in Northamptonshire, UK, in the 1960s were more than ten times greater than those of the general population. The relative risks were in the order of 35-fold for adenocarcinomas and 4 for squamous-cell carcinomas. A study in Florence has confirmed the association between shoemaking and nasal adenocarcinoma. This is also supported by a number of case reports from other countries.

A UK case-control study (in which the occupational histories of patients with nasal adenocarcinomas were compared with those of patients with other nasal cancers) indicated a relative risk of about 8 associated with work in the leather industry. A substantial proportion of the cases had been engaged in shoe production or repair. In the Northamptonshire study, the elevated risk was confined almost entirely to workers in the preparation and finishing departments: work in these areas entailed cutting, trimming and sanding, which were the dustiest operations.

A substantial proportion of the nasal cancer patients described in the study in Florence were engaged in trimming.

No observations on laryngeal cancer specifically related to boot and shoe manufacturers were available. In a large, multi-tumour-site case-control survey in New York State, the relative risk for development of laryngeal cancer associated with employment for more than five years in the 'leather industry' was 5.5 (based on six cases).

In England and Wales in 1951, SMRs for lung cancer in factory and non-factory employed boot and shoemakers were 73 and 158, respectively (p < 0.05 for both); in 1961, the SMR for all shoemakers was 154 (p < 0.05). SMRs for lung cancer in footwear workers in the US and for shoemakers or repairers and leather workers in Washington State were slightly but not significantly elevated. In a cross-sectional study in Los Angeles in 1972-1973, the risk ratio for shoe repairers was 2.33 (p < 0.05, based on 7 cases).

None of these studies took smoking habits into consideration.

Increased risks of bladder cancer were found in death certificate surveys in The Netherlands in the 1930s (PMR = 170 for shoemakers) and in the US in 1950 (SMR = 288, based on 9 cases, for shoemakers and repairers). No increases were seen in the UK or in Washington State more recently.

An association between work in the leather industry and bladder cancer is supported by three (all in the US) of four case-control studies, with relative risks in the order of 2-6. In two of the studies, no distinction was made between shoemakers and other leather workers. In one of these, 8 of 16 cases among leather workers had worked in the same shoe manufacturing company, which also included a leather tannery. In a third study, with equal numbers of cases and controls, there were seven shoe repairers and one shoemaker among the cases, and one shoe repairer and two shoemakers among the controls.

SMRs for leukaemia in England and Wales in 1951 and in 1961 and the PMR in Washington State ranged between 131 and 186, all based on 7 to 8 deaths.

Series of cases of benzene haemopathies1 among shoemakers have been described in Italy and in Turkey. Erythroleukaemia was particularly frequent in these groups. Benzene was a constituent of the adhesives, and benzene levels were measured in some of the shoe factories in which leukaemia patients had worked. A study in Sweden showed 21 observed cases of leukaemia versus 13.5 expected. The association with benzene is further supported by a report suggesting that the occurrence of leukaemia in shoemakers has decreased following the replacement of benzene with petrol.

The PMR for lymphomas among shoemakers and repairers in Washington State was 40 (based on 2 deaths). In a large multi-tumour-site case- control study in New York State, the relative risk for workers in the leather industry was 3.4 in men (based on 7 cases, p < 0.05) and 2.6 in women (based on 8 cases, p < 0.05).

The PMR for cancer of the oral cavity and pharynx among shoemakers/'shoehands' in The Netherlands in the 1930s was 260 (based on 5 deaths). In a large, multi-tumour-site case-control study in New York State, the relative risk for shoemakers/shoe repairers was 3.6 (p < 0.05, based on 8 cases).

In England and Wales in 1951, SMRs for stomach cancer in factory- and non-factory-employed boot and shoemakers were 122 and 120, respectively; in 1961, the SMR for shoemakers was 106 and that for cutters in the footwear industry 135.

Handling of leather in boot and shoe manufacture may entail exposure to some of the chemicals used in the tanning and finishing processes and to other chemicals for which there is evidence of carcinogenicity in humans and/or experimental animals (see Appendix 5, in this volume).

5.2 Evaluation

Employment in the boot and shoe industry is causally associated with the development of nasal adenocarcinomas; and relative risks well in excess of 10-fold have been reported in England and in Italy. It is most likely that exposure to leather dust plays a role in the association. There is also evidence that an increased risk may exist for other types of nasal cancers for employment in boot and shoe repairing shops.

There is evidence of an increased risk of bladder cancer associated with employment in the leather industry. Although boot and shoemakers were included in these studies, it is not possible to determine whether the risk relates to them in particular or to other occupational subgroups.

The occurrence of leukaemia and aplastic anaemia among shoemakers exposed to benzene is well documented (see also IARC, 1974).

Hypothesis-generating surveys have suggested associations between boot and shoe manufacture/repair and cancer of the lung, oral cavity and pharynx and stomach. The same surveys have suggested associations between work in the leather industry (occupation not further specified) and cancer of the larynx and lymphoma. Most of these associations were positive. In view of the design of the pertinent studies these findings cannot be evaluated.

1Benzene-associated haemopathies include pancytopenia, erythroleukaemia and leukaemia.

Subsequent evaluation: Suppl. 7 (1987)

Last updated: 8 April 1998

    See Also:
       Toxicological Abbreviations
       Boot and Shoe Manufacture and Repair  (IARC Summary & Evaluation, Supplement7, 1987)