Cancer mortality among shoe manufacturing workers: an analysis of two cohorts

Occupational benzene exposure and colorectal cancer: A systematic review and meta-analysis

Recent reports suggest that benzene exposure may be associated with solid cancers, such as lung and bladder cancers. Instead, evidence on the association between benzene and colorectal cancer (CRC) is sparse. Thus, we aimed to summarize current literature on the association between occupational benzene exposure and CRC. We searched Pubmed, Embase (through Ovid), and Scopus to retrieve cohort and nested case-control studies on the association between occupational benzene exposure and solid cancers. The search was initially completed in December 2022 and later updated in April 2024. We assessed quality of included studies using a modified version of Newcastle-Ottawa Scale. We computed pooled relative risks (RRs) and corresponding 95% confidence intervals (CIs) of CRC according to occupational benzene exposure, using the Paule-Mandel method. Twenty-eight studies were included in the meta-analysis. Most of them were conducted in Europe or North America (82.1%) and were industry-based (89.3%). Pooled RRs comparing workers exposed to benzene with those who were unexposed for incidence and mortality were 1.10 (95% CI: 1.06, 1.15) and 1.04 (95% CI: 0.97, 1.11) for CRC, 1.12 (95% CI: 1.01, 1.24) and 1.08 (95% CI: 0.99, 1.19) for colon cancer, and 1.04 (95% CI: 0.94, 1.14) and 1.05 (95% CI: 0.92, 1.19) for rectal cancer, respectively. Only one study supported the occurrence of a dose-response relationship between occupational benzene exposure and CRC, while others found no increase in risk according to dose of exposure or duration of employment. Our findings suggest that occupational benzene exposure may be associated with CRC. Further research with detailed assessment of individual-level exposure is warranted to confirm our results.

Head and neck cancer and occupational exposure to leather dust: results from the ICARE study, a French case-control study

BACKGROUND

Leather dust is an established carcinogen of the sinonasal cavities; however, evidence is lacking regarding its association with other head and neck cancers (HNC). To date, few studies have been conducted on the association between occupational leather dust exposure and the risk of oral, pharyngeal, and laryngeal cancers. The objective of this study was to investigate the association between the risk of HNC and occupational exposure to leather dust.

METHODS

Lifestyle habits and occupational history were collected for 2161 patients with squamous cell carcinoma of oral cavity, pharynx, and larynx, and 3555 controls, using a standardized questionnaire. Occupational exposure to leather dust was assessed using a job-exposure matrix. Odds ratios (OR) and 95% confidence intervals (CI) for HNC globally and by subsite were estimated using multivariate unconditional, and polytomous logistic regressions, respectively.

RESULTS

Cumulative lifetime exposure to leather dust < 6 mg/m3-years was associated with an increased risk of laryngeal cancer (OR = 2.26, 95% CI: 1.07-4.76); higher levels were not related to elevated risks of HNC. Some tasks performed and the use of some glues were associated with elevated, although non-significant, risks of HNC. No dose-response relationships were observed.

CONCLUSION

Our study did not provide enough evidence for an increased risk of HNC related to occupational exposure to leather dust. Further studies are needed to understand the risks of specific tasks in the leather industry.

The Effect of Hexavalent Chromium on the Incidence and Mortality of Human Cancers: A Meta-Analysis Based on Published Epidemiological Cohort Studies

Background: Hexavalent chromium [Cr(VI)] is an occupational carcinogen that can cause lung and nasal cancers, but its association with mortality and incidence in many other cancers is unclear.

Objectives: In this meta-analysis, we aimed to evaluate the relationship between exposure to Cr(VI) and the mortality and incidence of human cancers.

Methods: We performed a search of the literature and extracted the standardized mortality ratios (SMRs), standardized incidence ratios (SIRs), and their corresponding 95% confidence intervals (CIs), to estimate risk values. Subgroup analyses were conducted by sex, occupation, and types of cancer to identify groups that were at high-risk or predisposed to certain cancers.

Results: A total of 47 cohort studies covering the period 1985–2016 were included (37 studies reporting SMRs and 16 studies reporting SIRs). The summary SMR for all studies combined was 1.07 (95% CI: 1.01–1.15). Summary SMRs were higher among chromate production workers, chrome platers, and masons, and especially male workers. In the subgroup analysis, Cr(VI) exposure was related to a higher risk of death owing to lung, larynx, bladder, kidney, testicular, bone, and thyroid cancer. The meta-SIR of all studies combined was 1.06 (95% CI: 1.04–1.09). Summary SIRs were elevated among cement industry workers and tanners. Cr(VI) exposure was related to an elevated risk of respiratory system, buccal cavity, pharynx, prostate, and stomach cancers.

Conclusions: Cr(VI) might cause cancers of the respiratory system, buccal cavity and pharynx, prostate, and stomach in humans, and it is related to increased risk of overall mortality owing to lung, larynx, bladder, kidney, testicular, bone, and thyroid cancer. In addition, there was a strong association between incidence and mortality risk of cancers and concentration of Cr(VI) in the air and the exposure time.

New insights on 'old' toxicants in occupational toxicology (Review)

In order to deliver the best possible working environment, it is essential to identify professional conditions that could be harmful for worker's health and prevent (or limit) the occurrence of such conditions. The appropriate use of personal protective equipment and the development of appropriate regulations allowed to reduce the prevalence of 'classic' occupational diseases, such as occupational hearing loss or asbestosis, just to name a few. Nowadays, environmental pollution seems to be one of the most relevant concerns for human and animal health, and toxicology is becoming one of the most prominent fields of interest in occupational settings. An increasing number of studies demonstrate that the presence of toxicants in the workplace could be responsible for the development of chronic diseases, even at doses that were considered 'safe'. The present review summarizes some of the most recent advancements in occupational toxicology, focusing on topics that have long been debated in the past and that have recently returned to the fore.

Occupational exposure to carcinogens: Benzene, pesticides and fibers (Review)

It is well known that the occupational exposure to contaminants and carcinogens leads to the development of cancer in exposed workers. In the 18th century, Percivall Pott was the first to hypothesize that chronic exposure to dust in the London chimney sweeps was associated with an increased risk of developing cancer. Subsequently a growing body of evidence indicated that other physical factors were also responsible for oncogenic mutations. Over the past decades, many carcinogens have been found in the occupational environment and their presence is often associated with an increased incidence of cancer. Occupational exposure involves several factors and the association between carcinogens, occupational exposure and cancer is still unclear. Only a fraction of factors is recognized as occupational carcinogens and for each factor, there is an increased risk of cancer development associated with a specific work activity. According to the International Agency for Research on Cancer (IARC), the majority of carcinogens are classified as 'probable' and 'possible' human carcinogens, while, direct evidence of carcinogenicity is provided in epidemiological and experimental studies. In the present review, exposures to benzene, pesticides and mineral fibers are discussed as the most important cancer risk factors during work activities.

Occupation and Risk of Non-Hodgkin Lymphoma and Its Subtypes: A Pooled Analysis from the InterLymph Consortium

BACKGROUND

Various occupations have been associated with an elevated risk of non-Hodgkin lymphoma (NHL), but results have been inconsistent across studies.

OBJECTIVES

We investigated occupational risk of NHL and of four common NHL subtypes with particular focus on occupations of a priori interest.

METHODS

We conducted a pooled analysis of 10,046 cases and 12,025 controls from 10 NHL studies participating in the InterLymph Consortium. We harmonized the occupational coding using the 1968 International Standard Classification of Occupations (ISCO-1968) and grouped occupations previously associated with NHL into 25 a priori groups. Odds ratios (ORs) adjusted for center, age, and sex were determined for NHL overall and for the following four subtypes: diffuse large B-cell lymphoma (DLBCL), follicular lymphoma (FL), chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), and peripheral T-cell lymphoma (PTCL).

RESULTS

We confirmed previously reported positive associations between NHL and farming occupations [field crop/vegetable farm workers OR = 1.26; 95% confidence interval (CI): 1.05, 1.51; general farm workers OR = 1.19; 95% CI: 1.03, 1.37]; we also confirmed associations of NHL with specific occupations such as women's hairdressers (OR = 1.34; 95% CI: 1.02, 1.74), charworkers/cleaners (OR = 1.17; 95% CI: 1.01, 1.36), spray-painters (OR = 2.07; 95% CI: 1.30, 3.29), electrical wiremen (OR = 1.24; 95% CI: 1.00, 1.54), and carpenters (OR = 1.42; 95% CI: 1.04, 1.93). We observed subtype-specific associations for DLBCL and CLL/SLL in women's hairdressers and for DLBCL and PTCL in textile workers.

CONCLUSIONS

Our pooled analysis of 10 international studies adds to evidence suggesting that farming, hairdressing, and textile industry-related exposures may contribute to NHL risk. Associations with women's hairdresser and textile occupations may be specific for certain NHL subtypes.

CITATION

't Mannetje A, De Roos AJ, Boffetta P, Vermeulen R, Benke G, Fritschi L, Brennan P, Foretova L, Maynadié M, Becker N, Nieters A, Staines A, Campagna M, Chiu B, Clavel J, de Sanjose S, Hartge P, Holly EA, Bracci P, Linet MS, Monnereau A, Orsi L, Purdue MP, Rothman N, Lan Q, Kane E, Seniori Costantini A, Miligi L, Spinelli JJ, Zheng T, Cocco P, Kricker A. 2016. Occupation and risk of non-Hodgkin lymphoma and its subtypes: a pooled analysis from the InterLymph Consortium. Environ Health Perspect 124:396-405; http://dx.doi.org/10.1289/ehp.1409294.

A retrospective cohort study of cause-specific mortality and incidence of hematopoietic malignancies in Chinese benzene-exposed workers

Benzene exposure has been causally linked with acute myeloid leukemia (AML), but inconsistently associated with other hematopoietic, lymphoproliferative and related disorders (HLD) or solid tumors in humans. Many neoplasms have been described in experimental animals exposed to benzene. We used Poisson regression to estimate adjusted relative risks (RR) and the likelihood ratio statistic to derive confidence intervals for cause-specific mortality and HLD incidence in 73,789 benzene-exposed compared with 34,504 unexposed workers in a retrospective cohort study in 12 cities in China. Follow-up and outcome assessment was based on factory, medical and other records. Benzene-exposed workers experienced increased risks for all-cause mortality (RR = 1.1, 95% CI = 1.1, 1.2) due to excesses of all neoplasms (RR = 1.3, 95% CI = 1.2, 1.4), respiratory diseases (RR = 1.7, 95% CI = 1.2, 2.3) and diseases of blood forming organs (RR = ∞, 95% CI = 3.4, ∞). Lung cancer mortality was significantly elevated (RR = 1.5, 95% CI = 1.2, 1.9) with similar RRs for males and females, based on three-fold more cases than in our previous follow-up. Significantly elevated incidence of all myeloid disorders reflected excesses of myelodysplastic syndrome/acute myeloid leukemia (RR = 2.7, 95% CI = 1.2, 6.6) and chronic myeloid leukemia (RR = 2.5, 95% CI = 0.8, 11), and increases of all lymphoid disorders included excesses of non-Hodgkin lymphoma (RR = 3.9, 95%CI = 1.5, 13) and all lymphoid leukemia (RR = 5.4, 95%CI = 1.0, 99). The 28-year follow-up of Chinese benzene-exposed workers demonstrated increased risks of a broad range of myeloid and lymphoid neoplasms, lung cancer, and respiratory diseases and suggested possible associations with other malignant and non-malignant disorders.

Occupational exposure and sinonasal cancer: a systematic review and meta-analysis

Background

Sinonasal cancer (SNC) has been related to occupational exposures, but the relative risk associated to specific jobs and/or carcinogen exposures other than wood and leather dust is generally based on small or inadequate sample sizes and the range of observed estimates is large. This paper is aimed at investigating such relationship through a systematic review of the literature followed by a meta-analysis of studies meeting specific inclusion criteria.

Methods

Systematic search was made with PubMed, Google Scholar and Scopus engines using related keywords. Occupational exposures include wood and leather dust, formaldehyde, nickel and chromium compounds, textile industry, farming and construction. Meta-analysis of published studies after 1985 with a case-control or cohort design was performed, firstly using the fixed-effect model. Heterogeneity was assessed with the Q statistical test and quantified by the I² index. When the heterogeneity hypothesis appeared relevant, the random-effect model was chosen. Sources of heterogeneity were explored using subgroup analyses.

Results

Out of 63 reviewed articles, 28 (11 cohort, 17 case-control) were used in the meta-analysis. Heterogeneity among studies was observed and random-effects models were used. Exposure to wood dust results associated with SNC (RR_pooled = 5.91, 95% CI: 4.31-8.11 for the case-control studies and 1.61, 95% CI: 1.10-2.37 for the cohort studies), as well as to leather dust (11.89, 95% CI: 7.69-18.36). The strongest associations are with adenocarcinomas (29.43, 95% CI: 16.46-52.61 and 35.26, 95% CI: 20.62-60.28 respectively). An increased risk of SNC for exposures to formaldehyde (1.68, 95% CI: 1.37-2.06 for the case control and 1.09, 95% CI: 0.66-1.79 for the cohort studies), textile industry (2.03, 95% CI: 1.47-2.8), construction (1.62, 95% CI: 1.11-2.36) and nickel and chromium compounds (18.0, 95% CI: 14.55-22.27) was found. Subset analyses identified several sources of heterogeneity and an exposure-response relationship was suggested for wood dust (p = 0.001).

Conclusions

By confirming the strength of association between occupational exposure to causal carcinogens and SNC risk, our results may provide indications to the occupational etiology of SNC (not only wood and leather dusts). Future studies could be focused on specific occupational groups to confirm causative agents and to define appropriate preventive measures.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1042-2) contains supplementary material, which is available to authorized users.

Medical follow-up for workers exposed to bladder carcinogens: the French evidence-based and pragmatic statement

BACKGROUND

The aim of this work was to establish recommendations for the medical follow-up of workers currently or previously exposed to carcinogenic substances for the bladder.

METHODS

A critical synthesis of the literature was conducted. Sectors of activity where workers are or were exposed to carcinogenic substances for the bladder were listed and classified according to the level of bladder cancer risk. Performances of techniques available for the targeted screening of bladder cancer were analysed, including a simulation of results among high-risk populations in France.

RESULTS

The risk level for the professional group and the latency period between the start of exposure and the natural history of the disease were selected to define a targeted screening protocol. The NMP22BC test, exclusive haematuria testing, and combinations of urine cytology with, respectively, the NMP22BC test and haematuria test, generated an extremely high proportion of false positive results.

CONCLUSION

Urine cytology is the test that offers the best specificity. Although poor for all bladder cancer stages and grades combined, its sensitivity is better for high grades, which require early diagnosis since late-stage cancers are of very poor prognosis. These results suggest that urine cytology is currently the only technique suitable for proposal within the context of a first line targeted screening strategy for occupational bladder cancer. An algorithm summarising the recommended medical follow-up for workers currently or previously exposed to carcinogenic substances for the bladder is proposed, based on the level of risk of bladder cancer.

Worker evaluation of a macroergonomic intervention in a Brazilian footwear company

This article presents a macroergonomic intervention in a Brazilian footwear company and its evaluation by the workers. Using participatory ergonomics, the traditional Taylor/Ford production system was transformed into a socio-technical one and tested by 100 volunteers working during 3.5 years in a pilot production line. Multiskilling and teamwork were the major changes promoted to enlarge and enrich work and make it more flexible. The workers' evaluation pre- and post-intervention showed an increase in overall satisfaction with the work and more commitment to the results and company targets.

STATEMENT OF RELEVANCE

This study showed that problems and solutions can be identified through participatory ergonomics, that it is easier to involve workers than the managerial staff, and that a macroergonomic intervention, mainly focusing on work organization, led to positive personnel, health and production outcomes, despite management's resistance to changes.

Occupation and risk of lymphoid and myeloid leukaemia in the European Prospective Investigation into Cancer and Nutrition (EPIC)

OBJECTIVES

Established risk factors for leukaemia do not explain the majority of leukaemia cases. Previous studies have suggested the importance of occupation and related exposures in leukaemogenesis. We evaluated possible associations between job title and selected hazardous agents and leukaemia in the European Prospective Investigation into Cancer and Nutrition.

METHODS

The mean follow-up time for 241 465 subjects was 11.20 years (SD 2.42 years). During the follow-up period, 477 incident cases of myeloid and lymphoid leukaemia occurred. Data on 52 occupations considered a priori to be at high risk of developing cancer were collected through standardised questionnaires. Occupational exposures were estimated by linking the reported occupations to a job exposure matrix. Cox proportional hazard models were used to explore the association between occupation and related exposures and risk of leukaemia.

RESULTS

The risk of lymphoid leukaemia significantly increased for working in chemical laboratories (HR 8.35, 95% CI 1.58 to 44.24), while the risk of myeloid leukaemia increased for working in the shoe or other leather goods industry (HR 2.54, 95% CI 1.28 to 5.06). Exposure-specific analyses showed a non-significant increased risk of myeloid leukaemias for exposure to benzene (HR 1.15, 95% CI 0.75 to 1.40; HR=1.60, 95% CI 0.95 to 2.69 for the low and high exposure categories, respectively). This association was present both for acute and chronic myeloid leukaemia at high exposure levels. However, numbers were too small to reach statistical significance.

CONCLUSIONS

Our findings suggest a possible role of occupational exposures in the development of both lymphoid and myeloid leukaemia. Exposure to benzene seemed to be associated with both acute and chronic myeloid leukaemia.

Occupation and leukemia in Nordic countries

OBJECTIVE

We studied occupational variation of the risk of acute myeloid leukemia, chronic lymphocytic leukemia, and other leukemia in Nordic countries.

METHODS

The study cohort comprised 15 million persons older than 30 years who participated in the population censuses in 1960, 1970, 1980/1981, 1990, or all of these years in five Nordic countries. Standardized incidence ratios (SIRs) were estimated for 53 occupations and one group of economically inactive persons.

RESULTS

Significantly increased risks were observed for acute myeloid leukemia among drivers (SIR = 1.16; 95% confidence interval [CI], 1.07-1.26) and food workers (SIR = 1.13; 95% CI, 1.01-1.27); for chronic lymphocytic leukemia among farmers (SIR = 1.09; 95% CI, 1.04-1.14) and clerical workers (SIR = 1.07; 95% CI, 1.01-1.14); and for other leukemia among seamen (SIR = 1.24; 95% CI, 1.04-1.49), "other health workers" (SIR = 1.22; 95% CI, 1.02-1.47), chemical process workers (SIR = 1.18; 95% CI, 1.01-1.38), and sales agents (SIR = 1.15; 95% CI, 1.06-1.25).

CONCLUSION

Observed modest occupational variation of leukemia risk might be associated with occupational or lifestyle factors.

Working conditions and related neuropsychiatric problems among shoemakers in Turkey: Do child workers differ from others?

Objective:

In this cross-sectional study, we investigated working conditions and related neuropsychiatric problems of shoemakers, including child workers, working in poor conditions with high health risks. Clinical diagnosis was not the objective of this study.

Materials and Methods:

We collected data from 318 workers ranging from 8-66 years of age. We evaluated working conditions, neuropathy symptoms and signs; urinary 2,5-hexanedione was used to estimate hexane exposure. We used the Zung depression scale for adult shoemakers to evaluate depression.

Results:

All workshops employed fewer than 10 workers with median daily work duration of 12h. Smoking and alcohol consumption were high among all workers including children. Peripheral neuropathy symptoms and signs were observed in 88 workers (27.8%) and it was related to alcohol consumption. Sixty-eight workers (47.9%) had depression and it was associated with daily work duration.

Conclusion:

Extremely poor, unhygienic, working conditions and a high prevalence of neuropsychiatric disorders were the main problems observed among shoemakers. A high number of child workers increased the scale of these observed problems.

Occupational benzene exposure and the risk of lymphoma subtypes: a meta-analysis of cohort studies incorporating three study quality dimensions

BACKGROUND

The use of occupational cohort studies to assess the association of benzene and lymphoma is complicated by problems with exposure misclassification, outcome classification, and low statistical power.

OBJECTIVE

We performed meta-analyses of occupational cohort studies for five different lymphoma categories: Hodgkin lymphoma (HL), non-Hodgkin lymphoma (NHL), multiple myeloma (MM), acute lymphocytic leukemia (ALL), and chronic lymphocytic leukemia (CLL).

DATA EXTRACTION

We assessed three study quality dimensions to evaluate the impact of study quality variations on meta-relative risks (mRRs): stratification by the year of start of follow-up, stratification by the strength of the reported acute myelogenous leukemia association, and stratification by the quality of benzene exposure assessment.

DATA SYNTHESIS

mRRs for MM, ALL, and CLL increased with increasing study quality, regardless of the study quality dimension. mRRs for NHL also increased with increasing study quality, although this effect was less pronounced. We observed no association between occupational benzene exposure and HL.

CONCLUSIONS

Our meta-analysis provides support for an association between occupational benzene exposure and risk of MM, ALL, and CLL. The evidence for an association with NHL is less clear, but this is likely complicated by the etiologic heterogeneity of this group of diseases. Further consideration of the association between benzene and NHL will require delineation of risks by NHL subtype.

Cancer incidence among children and adolescents in Brazil: first report of 14 population-based cancer registries

The Brazilian Population-Based Cancer Registry (PBCR) was started in 1967; today there are 20 PBCRs in Brazil. We report the first descriptive analysis of the incidence of childhood cancer based on data from 14 PBCRs, corresponding to 15% of the child and adolescent population in Brazil. Data were obtained from registry databases, including information on population coverage and data quality indicators. The International Classification of Childhood Cancer was used. Age-adjusted rates were calculated by world population. Incidence by cancer registry, age, sex, and cancer type were calculated per 1,000,000 children. Age-adjusted rates per 1,000,000 children/adolescents ranged from 92 to 220 among the 14 PBCRs. The principal groups of cancers were leukemia, lymphoma and central nervous tumors. The median incidence rate of childhood cancer in the 14 PBCRs was 154.3 per million; children 1-4 years of age had the highest incidence rates. The Brazilian PBCRs provide important information about pediatric cancer incidence in an emerging country. The observed incidence rates of childhood leukemia were similar to previous reported rates, and the age-specific incidence rates of retinoblastoma (0-4 years of age) were higher than those for developed countries. These data can be used as baseline incidence rates of childhood and adolescent cancer in Brazil in future epidemiological studies.

Occupation/industry and risk of non-Hodgkin's lymphoma in the United States

AIMS

To identify occupations and industries associated with non-Hodgkin's lymphoma (NHL) in a large population-based, case-control study in the USA.

METHODS

Cases (n = 1189) of histologically confirmed malignant NHL ages 20-74 were prospectively identified in four geographic areas covered by the National Cancer Institute SEER Program. Controls (n = 982) were selected from the general population by random digit dialling (<65 years of age) and from residents listed in Medicare files (65-74 years of age). Odds ratios and 95% confidence intervals for occupations and industries were calculated by unconditional logistic regression analyses, adjusting for age, gender, ethnicity and study centre. Further analyses stratified for gender and histological subtype were also performed.

RESULTS

Risk of NHL was increased for a few occupations and industries. Several white collar occupations, with no obvious hazardous exposures, had elevated risks, including purchasing agents and buyers, religious workers, physical therapists and information clerks. Occupations with excesses that may have exposures of interest include launderers and ironers, service occupations, food/beverage preparation supervisors, hand packers and packagers, roofing and siding, leather and leather products, transportation by air, nursing and personal care facilities, and specialty outpatient clinics. Significantly decreased risks of NHL were found for a number of occupations and industries including post-secondary teachers and chemical and allied products.

CONCLUSIONS

The results of this study suggest that several occupations and industries may alter the risk of NHL. Our results support previously reported increased risks among farmers, printers, medical professionals, electronic workers and leather workers. These findings should be evaluated further in larger studies that have the power to focus on specific exposures and histological subtypes of NHL.

A survey of airborne and skin exposures to chemicals in footwear and equipment factories in Thailand

This research reports on a pilot industrial hygiene study that was performed at four footwear factories and two equipment factories in Thailand. Workers in these factories were exposed through inhalation and dermal contact to a large number of organic vapors from solvents and cements that were hand applied. In addition, these workers were exposed to highly toxic isocyanates primarily through the dermal route. A total of 286 personal air samples were obtained at the four footwear factories using organic vapor monitors; individual job tasks were monitored using a real-time MIRAN Spectrometer. A total of 64 surface, tool, or hand samples were monitored for isocyanates using surface contamination detectors. Real-time measurements were also obtained for organic vapors in two equipment factories. From 8% to 21% of the workers sampled in each footwear factory were overexposed to mixtures of chemicals from solvents and cements. Up to 100% of the workers performing specific job tasks were overexposed to mixtures of chemicals. From 39% to 69% of the surface samples were positive for unreacted isocyanates. Many of the real-time measurements obtained in the equipment factories exceeded occupational exposure limits. Personal protective equipment and engineering controls were inadequate in all of the factories.

The non-Hodgkin lymphomas: a review of the epidemiologic literature

The non-Hodgkin lymphomas (NHL) are a heterogeneous group of B-cell and T-cell neoplasms that arise primarily in the lymph nodes. NHL incidence rates in the US doubled between about 1970 and 1990, and stabilized during the 1990s. NHL accounts for approximately 3.4% of cancer deaths in the US. Although some of the observed patterns in NHL have been related to HIV/AIDS, these conditions cannot fully explain the magnitude of the changes; neither do changes in classification systems nor improved diagnostic capabilities. Studies of occupational and environmental exposures (e.g., pesticides, solvents) have produced no consistent pattern of significant positive associations. Inverse associations with ultraviolet radiation exposure and alcohol and fish intake, and positive associations with meat and saturated fat intake have been reported in several studies; additional studies are needed to confirm or refute these associations. Family history of NHL or other hematolympho-proliferative cancers and personal history of several autoimmune disorders are associated with increased risk of NHL, but are not likely to account for a large proportion of cases. HIV and other infectious agents, such as human herpesvirus 8 and Epstein-Barr, appear to be associated with differing types of NHL, such as some B-cell lymphomas. Future epidemiologic studies should evaluate associations by NHL type, enhance exposure information collected, and elucidate factors that may identify susceptible (or resistant) subpopulations because of genetic, immunologic or other characteristics. The extent to which the etiology of NHL types may differ is important to resolve in ongoing and future studies.

Multiple myeloma: A review of the epidemiologic literature

Multiple myeloma, a neoplasm of plasma cells, accounts for approximately approximately 15% of lymphatohematopoietic cancers (LHC) and 2% of all cancers in the US. Incidence rates increase with age, particularly after age 40, and are higher in men, particularly African American men. The etiology is unknown with no established lifestyle, occupational or environmental risk factors. Although several factors have been implicated as potentially etiologic, findings are inconsistent. We reviewed epidemiologic studies that evaluated lifestyle, dietary, occupational and environmental factors; immune function, family history and genetic factors; and the hypothesized precursor, monoclonal gammopathies of undetermined significance (MGUS). Because multiple myeloma is an uncommon disease, etiologic assessments can be difficult because of small numbers of cases in occupational cohort studies, and few subjects reporting exposure to specific agents in case-control studies. Elevated risks have been reported consistently among persons with a positive family history of LHC. A few studies have reported a relationship between obesity and multiple myeloma, and this may be a promising area of research. Factors underlying higher incidence rates of multiple myeloma in African Americans are not understood. The progression from MGUS to multiple myeloma has been reported in several studies; however, there are no established risk factors for MGUS. To improve our understanding of the causes of multiple myeloma, future research efforts should seek the causes of MGUS. More research is also needed on the genetic factors of multiple myeloma, given the strong familial clustering of the disease.

Occupational exposure to eight organic dusts and respiratory cancer among Finns

BACKGROUND

There is inconclusive evidence concerning cancer risks of organic dusts.

AIM

The carcinogenic exposures are mainly inhalatory and the authors therefore studied associations between occupational exposure to eight different organic dusts and respiratory cancers in Finland.

METHODS

The authors followed up a cohort of all economically active Finns born between 1906 and 1945 for 30 million person-years during 1971-95. Incident cases of nasal, laryngeal, and lung cancer and mesotheliomas were identified through a record linkage with the Finnish Cancer Registry. Occupations from the population census in 1970 were converted to exposures to eight organic dusts with a job-exposure matrix (FINJEM). Cumulative exposure (CE) was calculated as a product of prevalence, level, and estimated duration of exposure. Standardised incidence ratios (SIR) and 95% confidence intervals (CI) adjusted for age, period, and social class were calculated for each organic dust using the economically active population as the reference.

RESULTS

A total of 20 426 incident cases of respiratory cancer were observed. Slightly increased risk was observed among men exposed to wood dust for nasal cancer (SIR 1.42, 95% CI 0.79 to 2.44). For laryngeal cancer, men exposed to plant dust (mainly grain millers) had a raised SIR in the high exposure class (SIR 3.55, 95% CI 1.30 to 7.72). Men exposed to wood dust had a raised SIR for lung cancer, but only in the low exposure class (SIR 1.11, 95% CI 1.04 to 1.18). Women exposed to wood dust showed an increased SIR for mesotheliomas in the low exposure class (SIR 4.57, 95% CI 1.25 to 11.7) and some excess in the medium exposure category.

CONCLUSIONS

Exposure to organic dusts is unlikely to be a major risk factor of respiratory cancer. Even exposure to wood dust which is a major exposure in Finland seems to have minor effect for nasal cancer. The authors found suggestive evidence that exposure to grain dust may increase the risk of laryngeal cancer, and some support to the hypothesis that exposure to textile dust, and to plant and animal dust (agricultural dusts) may decrease the risk of lung cancer.

Benzene Exposure and Multiple Myeloma: A Detailed Meta-analysis of Benzene Cohort Studies

Case reports and epidemiological studies of workers exposed to benzene have demonstrated associations with a number of lymphohematopoietic diseases, but the association with multiple myeloma (MM) has been less apparent. Data from all of the "benzene cohort studies" conducted to date have been selected and evaluated for inclusion in a meta-analysis. The analysis demonstrates a significant excess in the relative risk (RR) of MM in relation to benzene exposure. Pooling the data from seven cohort studies, a meta-analysis yields a statistically significant weighted RR estimate of 2.13 (95% CI = 1.31-3.46). In the analysis of cohort data, an understanding of the cohort follow-up period in relation to benzene exposure and RR of MM is important. Exposure-related RRs of disease decline after the median latency periods are exceeded, particularly when exposure has terminated decades earlier. The positive epidemiological evidence for benzene as a cause of MM is supported by biological plausibility for such an effect from benzene exposure. Studies of refinery workers are difficult to interpret in relation to benzene exposure and risk of MM, but are limited in the study design and analysis. Nonetheless, they provide some support for an association between refinery work and MM.

Mortality of workers employed in shoe manufacturing: an update

BACKGROUND

In the late 1970s, the National Institute for Occupational Safety and Health identified two shoe manufacturing facilities where workers experienced relatively "pure" exposures to toluene. A mortality study was conducted through December 31, 1982. An original study did not detect elevated leukemia mortality but did detect increased lung cancer mortality. The present study is an update of the mortality of the original cohort.

METHODS

The study cohort consisted of workers employed 1 month or more between 1940 and 1979 at two Ohio shoe manufacturing plants. Vital status was ascertained through December 31, 1999.

RESULTS

Seven thousand eight hundred twenty eight workers, contributing 300,777 person years, were available for analysis. An excess of lung cancer deaths persisted with additional years of follow-up (SMR = 1.36, 95% confidence interval (CI) = 1.19-1.54). Trend tests did not indicate a positive trend between lung cancer risk and duration of employment. Mortality from leukemia was not significantly elevated in the updated analysis.

CONCLUSIONS

Results indicate a possible association between lung cancer mortality and exposure to chronic, low-levels of organic solvents. Although the strength of this conclusion was weakened by the lack of increasing lung cancer risk in relation to duration of employment, other studies have supported this association.

Non-Hodgkin lymphoma and benzene exposure: A systematic literature review

Epidemiological papers that address an association between benzene exposure and non-Hodgkin lymphoma (NHL) were identified and separated by study design. Eighteen studies contained 21 study groups-11 population-based case-control study groups, 3 nested occupation-based case-control study groups and 7 occupational benzene cohort study groups. Petroleum industry studies were not included. Only two of these 21 study groups showed statistically significant associations. However, these were among workers with multiple exposures across industries. Eleven of the 21 study groups presented ratios less than one, two equaled one, and eight were greater than one. Over all, about as many cases were observed (404) as expected (390.0) for an observed to expected ratio of 1.04 (0.94-1.14). After removal of the studies with multiple chemical exposures problems, the observed was 359 cases with 373.2 cases expected, yielding an odds ratio of 0.96 (0.86-1.06). Further assessment of an association with NHL should document the benzene exposure and separate out the contribution of non-benzene exposures.

[Lung cancer risk in shoe manufacturing]

OBJECTIVE

Workers in shoe manufacturing have been reported to be at a greater relative risk for bronchogenic carcinoma. Given the implications for our practice setting, we carried out a study to a) clarify whether working in shoe manufacturing is a risk factor for lung cancer and b) detect histological differences between lung cancers in shoe manufacturers and in other lung cancer patients.

PATIENTS AND METHODS

This case-control study compared all lung cancer patients diagnosed in Hospital Elda, Alicante, Spain, between January 1994 and December 1999, with a control group composed of patients admitted to the same hospital for accidental fractures. Information on occupational history and tobacco dependency was collected from all patients by telephone questionnaire.

RESULTS

One hundred and ninety-one case patients and 192 control patients were included in the study; 52 of the cases (27.2%) and 48 controls (25%) worked in shoe manufacturing. No statistically significant differences were found between the 2 groups, not even when we limited the cases and controls to only those who had worked more than 30 years in shoe manufacturing or when we analyzed only subjects who had had especially high risk occupations. No differences in tumor histology were found between cancer patients who worked in shoe manufacture and those who did not.

CONCLUSIONS

Working in shoe manufacturing has not proven to be a risk factor for bronchogenic carcinoma.

Leukaemia incidence among workers in the shoe and boot manufacturing industry: a case-control study

BACKGROUND

Previous reports have indicated an excess of leukaemia in Broome County, New York, particularly in the Town of Union. Surveillance of cancer incidence data indicates that a large proportion of these cases occurred among males ages 65 and older. Shoe and boot manufacturing has been the largest single industry in this area throughout much of the past century. Occupational studies from Europe suggest a link between leukaemia and employment in the shoe and boot manufacturing industry. However, researchers have not found a positive association between leukaemia and employment in the shoe industry among workers in the United States.

METHODS

A matched case-control study was conducted to investigate the association between leukaemia incidence among males 65 and older and employment in the shoe and boot manufacturing industry. Thirty-six cases of leukaemia occurring between 1981-1990; among males age 65 and older; residing in the town of Union met the study case criteria. Death certificates were obtained for each of the cases. These were matched to death certificates of 144 controls on date of death and date of birth +/- 1 year. Death certificates were then examined to determine the employer and occupation of each study subject. Conditional logistic regression was used to determine the risk of leukaemia among those working in the industry.

RESULTS

The risk of both leukaemia (OR = 1.47; 95% CI 0.70, 3.09) and acute myeloid leukaemia (OR = 1.19; 95% CI 0.33, 4.28) were elevated among those employed in the shoe and boot manufacturing industry, however neither was statistically significant.

CONCLUSION

The results, though suggestive of an association between leukaemia and employment in the shoe and boot manufacturing industry, were not statistically conclusive due mainly to limited study power. Several additional limitations may also have prevented the observance of more conclusive findings. Better exposure assessment, information on length of exposure and types of job held, control of confounding factors and information on chemicals used by this company would strengthen any future investigation.

Occupational prolonged organic solvent exposure in shoemakers: brain MR spectroscopy findings

Our purpose was to investigate, by magnetic resonance (MR) spectroscopy, the metabolite changes in the brains of subjects in the shoemaking industry who had been chronically exposed to organic solvents. A total of 49 male subjects and 30 age-matched healthy volunteers underwent detailed neurological and psychiatric examinations. All subjects had long-echo [repetition time (TR) 2000 ms, echo time (TE) 136 ms] single-voxel MR spectroscopy. Voxels (15 x 15 x 15 mm(3)) were placed in the parietal white matter, thalamus, and basal ganglia. N-acetylaspartate (NAA)/creatine (Cr) and choline (Cho)/Cr ratios were calculated. There was no significant difference between the study subjects and the control group in NAA/Cr ratios obtained from thalamus, basal ganglia, and parietal white matter. Cho/Cr ratios in thalamus, basal ganglia, and parietal white matter were found to be significantly increased compared to controls. There was a positive correlation between basal ganglia Cho/Cr ratio and duration of exposure (r = 0.63). MR spectroscopy should be performed to reveal metabolite changes and determine the degree of brain involvement in solvent-related industry workers.

Critical literature review of determinants and levels of occupational benzene exposure for United States community-based case-control studies

This article presents the results of an extensive literature review identifying the uses or occurrences of, and exposures to, benzene in a variety of industries for a community-based case-control study of childhood brain cancer in the United States and Canada. We focused on industries for which quantitative exposure data were identified in studies conducted in North America in the 1980s. Each industry was coded according to the 1987 Standard Industrial Classification (SIC) system. For each industry, information relevant to exposure assessment, including process descriptions, job titles, tasks, and work practices, was summarized when available. Estimates of probability and intensity of exposure, and our confidence in these estimates are presented. Arithmetic means (AMs), weighted for the number of measurements for each industry, were calculated based on measurement data from long-term (i.e., 60+ minutes) personal sampling; short-term or area samples were only used when no other data were available for a given industry. Industries for which no quantitative exposure levels were identified in the North American literature but for which information was found on benzene use are briefly described. Published exposure data indicate that workers in most industries in the 1980s experienced exposure levels below the current standard of 1 part per million (ppm), with a weighted AM of 0.33 ppm across all industries. Despite the longtime recognition of the hematological effects of benzene, little information was available on exposure levels and determinants for many industries with potential exposure. Nevertheless, this review may clarify some of the procedures involved in assessing occupational exposures in community-based studies and may aid in the interpretation of previous occupational studies that relied on job title or industry.

Occupations with increased risk of pancreatic cancer in the Swedish population

AIMS

To identify occupations with increased risk of pancreatic cancer in the Swedish population gainfully employed in 1970 over the period 1971-89.

METHODS

The base population was made up of Swedish men (1 779 646) and Swedish women (1 101 669) gainfully employed at the time of the 1970 census and were still alive and over age 24 on 1 January 1971. Information was drawn from two data sets: the Swedish cancer environment register and a background population register. After 19 years of follow up, 4420 men and 2143 women were diagnosed with histologically confirmed incident pancreatic adenocarcinoma. Log linear Poisson models were fitted, allowing for geographical area and town size. Risk estimators were also calculated for workers reporting the same occupation in 1960 and 1970.

RESULTS

Among women, a statistically significant risk excess of pancreatic cancer was observed for "educational methods advisors", "librarian, archivist, curator", "motor vehicle driver", "typographer, lithographer", "purser, steward, stewardess", "other housekeeping and related workers", and the groups of occupations of "electrical, electronic, and related" and "glass, pottery, and tile workers". Men showed a higher incidence of pancreatic cancer among "technical assistants", "travelling agents", "other metal processing workers", "baker and pastry cook", "docker and freight handler", and "waiters".

CONCLUSIONS

This study does not indicate that occupational factors play an important role in the aetiology of pancreatic cancer in Sweden. Few occupations were at increased risk of pancreatic cancer in both men and women, and the associations observed are in accordance with some previous studies from Western countries.

Non-Hodgkin's lymphomas and organic solvents

Organic solvents have been suggested as a possible risk factor for non-Hodgkin's lymphomas (NHL). We studied 109 NHL incident cases and 276 controls with other cancers (1990/1996) in the city of Salvador, Brazil. Occupational exposure to organic solvents was evaluated through standardized questionnaires and defined by industrial hygienists, taking into account individuals' lifetime history. An association between occupational exposure to organic solvents and NHL was observed, OR = 1.67 (95% CI, 0.97 to 2.87), especially among individuals less than 64 years, OR = 1.91 (95% CI, 0.99 to 3.67), and among those who used domestic insecticides, OR = 2.24 (95% CI, 1.01 to 3.97). Odds ratios were similar for nodal and diffuse NHL. These results suggest that organic solvents may contribute to the causation of NHL, especially among young individuals, and that synergism may play a role in the process of lymphomagenesis.

Myeloma aetiology and epidemiology

Recently there have been substantial improvements in our understanding of the biology of myeloma. These findings have important implications for aetiological studies aimed at defining the causative factors for myeloma. Myeloma is closely related to monoclonal gammopathy of unknown significance (MGUS), which is now recognized to be very common in the older population. The epidemiology of these conditions is presented and discussed in the context of the genetic factors governing both the risk of developing MGUS or of transformation to myeloma. Biological studies support a role for aberrant class switch recombination early in the natural history of myeloma suggesting that factors in the environment may interact with this mechanism to increase myeloma risk. Case-control and cohort studies have identified several known and suspected environmental exposures. These exposures include high doses of ionizing radiation, and occupational exposure in the farming and petrochemical industries. The data supporting these associations are presented and discussed in the context of the molecular mechanisms underlying these exposures. In particular DNA damage occurring as a consequence could readily interact with the class switch recombination process to increase the risk of chromosomal translocations, oncogene deregulation and malignant transformation. A further hypothesis, which has been extensively investigated, is the role of chronic immune/antigenic stimulation and the risk of myeloma. This concept is difficult to explain in the context of our current immunological concepts. The data supporting the association and how molecular epidemiological studies using genetic variants in cytokine genes are allowing us to revisit this concept are discussed in detail.

Harm to the liver among employees of the Municipal Police Force

The purpose of the study is to assess whether employees of the Municipal Police Force of a big city exposed to urban pollution are at risk of hepatotoxicity. The usual clinical practice tests like AST, ALT, gamma-GT, AP, conjugated and total bilirubin were carried out, accompanied by a questionnaire designed to identify the possible risk factors and the principal non-professional confounding factors for hepatotoxicity. The study covered 118 male Municipal Police employees performing traffic duties and 118 male blood donors engaged in office work. There were significant differences between exposed and controls with regard to the average AST and ALT values and values above the normal laboratory range; this was also the case for the distribution. The results suggest that there may be the possibility of liver damage among asymptomatic members of the Municipal Police Force and that periodic hepatic screening, with the above-mentioned tests, could be useful. It is presumed that chemical agents present in urban air in big cities may cause damage to the liver, even at exposure levels that fluctuate around the admissible environmental concentrations.

Sister chromatid exchanges and micronuclei in peripheral lymphocytes of shoe factory workers exposed to solvents

We examined sister chromatid exchanges (SCEs) and micronuclei (MN; cytokinesis-block method) in cultured peripheral lymphocytes from 52 female workers of two shoe factories and from 36 unexposed age- and sex-matched referents. The factory workers showed an elevated level of urinary hippuric acid, a biomarker of toluene exposure, and workplace air contained high concentrations of various organic solvents such as toluene, gasoline, acetone, and (in one of the plants only) ethylacetate and methylenediphenyl diisocyanate. The shoe factory workers showed a statistically significant higher frequency of micronucleated binucleate lymphocytes in comparison with the referents. This finding agreed with three preliminary MN determinations (each comprising 27-32 shoe workers and 16-20 controls) performed in one of the plants 2-5 years earlier. The shoe factory workers also had a lower average level of blood hemoglobin than the referents. In contrast, no difference was found between the groups in SCE analysis. Smokers showed significantly higher mean frequencies of SCEs per cell and high frequency cells (HFC) than nonsmokers. Aging was associated with increased MN rates and reduced cell proliferation. Polymorphism of the glutathione S-transferase M1 gene (GSTM1) did not affect the individual level of SCEs; but in smoking shoe workers an effect of the occupational exposure on the frequency of micronucleated cells could be seen only in GSTM1 null subjects. The low prevalence of the glutathione S-transferase T1 (GSTT1) null genotype precluded the evaluation of the influence of GSTT1 polymorphism. Our results show that the shoe factory workers have experienced genotoxic exposure, which is manifest as an increase in the frequency of MN, but not of SCEs, in peripheral lymphocytes. The exposures responsible for the MN induction could not be identified with certainty, but exposure to benzene in gasoline and methylenediphenyl diisocyanate may explain some of the findings.

Cohort studies of chloroprene-exposed workers in Russia

Two retrospective cohort studies were conducted to assess the risk of cancer among workers exposed to chloroprene (2-chloro-1,3-butadiene) (CP). One is a study of incidence and mortality among 2314 production workers employed in the CP production plant in Yerevan, Armenia, between 1940 and 1988. The cohort was followed up for cancer incidence for the years 1979-1990 and for cancer mortality for 1979-1988. The second study is a mortality study among 5185 shoe manufacturing workers in Moscow who used polychloroprene latex and glue. Shoe workers were employed between 1940 and 1976, and followed from 1979 through 1993. The standardized incidence ratios (SIR) and standardized mortality ratios (SMR) were calculated using the Armenian and Moscow population as reference. An internal comparison analysis based on Poisson regression modeling was conducted. In the Yerenan cohort, incidence and mortality from all cancers were below expectation, but increased incidence (SIR, 3.27; 95% confidence interval (CI), 1.47-7.27), and mortality (SMR, 3.39; CI, 1.09-10.5) from liver cancer were noted. A dose-response relationship was suggested between the risk of liver cancer and indices of CP exposure. For the entire Moscow cohort, all-cause mortality was close to expectation and all-cancer mortality was increased. There was an increase in the mortality from liver cancer (SMR, 2.4; CI, 1.1-4.3), kidney cancer (SMR, 1.8; CI, 0.9-3.4), and leukemia (SMR, 1.9; CI, 1.0-3.3). Mortality from liver cancer and leukemia was associated with various indicators of CP exposure. A similar, although less consistent, pattern was found for kidney cancer. The association between CP exposure and risk of leukemia may be due to concomitant exposure to benzene. The results for liver cancer point towards a carcinogenic effect of CP.

Case-control study of leatherwork and male infertility

OBJECTIVES

To test the hypothesis that leatherwork is associated with male infertility mediated through the development of oligozoospermia. The basis of any association was postulated, at the outset, to be with exposure to the solvents used in leatherwork.

METHODS

All new referrals with infertility presenting in Leicestershire hospital clinics between November 1988 and September 1992 and Kettering District General Hospital from August 1990 were eligible to participate; 88.5% agreed to be interviewed. Exposure to leatherwork and work with solvents was defined by job title. Comparisons were made with fertile controls and in an analysis within men from infertile couples with oligozoospermia as the primary outcome. Effects on sperm motility and deformity were investigated secondarily. Analyses used logistic regression for binary outcomes and multilevel modelling for continuous outcomes.

RESULTS

1906 men were interviewed. Compared with the fertile controls the men from infertile couples were 1.10 times (95% confidence interval (95% CI) 0.46 to 2.63; p=0.99) more likely to be leatherworkers and 1.73 times (95% CI 1.26 to 2.38; p<0.001) more likely to work with solvents. Compared with other men, leatherworkers were 1.20 times (95% CI 0.43 to 3.33; p=0.73) more likely to present with oligozoospermia and 1.65 times (95% CI 0.37 to 7.30; p=0.51) more likely to present with teratozoospermia. Being a leatherworker was associated with only a 6% reduction in sperm concentration; motility and deformity were similarly unaffected by this exposure. Work with solvents did not statistically, nor clinically, increase the risk of oligozoospermia, teratozoospermia, or asthenozoospermia.

CONCLUSIONS

There was little evidence to support the hypothesis that leatherwork is associated with an increased risk of presenting with infertility or oligozoospermia. There was limited evidence that leatherwork is a risk factor for teratozoospermia. Workers with solvents were at an increased risk of presenting with infertility, although this was not mediated through effects on standard measures of semen quality; this finding merits further investigation.

Workplace exposures and oesophageal cancer

OBJECTIVES

To describe the relation between oesophageal cancer and many occupational circumstances with data from a population based case-control study.

METHODS

Cases were 99 histologically confirmed incident cases of cancer of the oesophagus, 63 of which were squamous cell carcinomas. Various control groups were available; for the present analysis a group was used that comprised 533 population controls and 533 patients with other types of cancer. Detailed job histories were elicited from all subjects and were translated by a team of chemists and hygienists for evidence of exposure to 294 occupational agents. Based on preliminary results and a review of literature, a set of 35 occupational agents and 19 occupations and industry titles were selected for this analysis. Logistic regression analyses were adjusted for age, birthplace, education, respondent (self or proxy), smoking, alcohol, and beta-carotene intake.

RESULTS

Sulphuric acid and carbon black showed the strongest evidence of an association with oesophageal cancer, particularly squamous cell carcinoma. Other substances showed excess risks, but the evidence was more equivocal-namely chrysotile asbestos, alumina, mineral spirits, toluene, synthetic adhesives, other paints and varnishes, iron compounds, and mild steel dust. There was considerable overlap in occupational exposure patterns and results for some of these substances may be mutually confounded. None of the occupations or industry titles showed a clear excess risk; the strongest hints were for warehouse workers, food services workers, and workers from the miscellaneous food industry.

CONCLUSIONS

The data provide some support for an association between oesophageal cancer and a handful of occupational exposures, particularly sulphuric acid and carbon black. Many of the associations found have never been examined before and warrant further investigation.

Liver damage among shoe repairers

BACKGROUND

The risk of hepatotoxicity in the shoe industry has already been suggested, however, there has been no investigation among the craftsmen who repair shoes.

METHODS

A group of 33 shoe repairers who work in supermarkets, and who use the same glues which contain mixtures of potentially hepatotoxic solvents were identified. A control group of 61 workers not exposed to hepatotoxic substances was also examined. All participants completed a questionnaire designed to identify potential risk factors and the main non-occupational confounding factors for hepatotoxicity. Laboratory tests, commonly used in clinical practice, were done to check whether they were useful markers of hepatotoxicity due to exposure to solvent mixtures, and to investigate which tests should be used in the screening campaigns.

RESULTS

The exposed workers had a higher prevalence of elevated mean alanine aminotransferase (ALT), aspartate aminotransferase (AST), conjugated bilirubin (P=0.0001), and alkaline phosphatase (AP) (P=0.004) than controls did. The number of workers who had values outside the upper limit of normal for our laboratory was significantly higher (ALT P=0.034, AST P=0. 037, conjugated bilirubin P=0.014). Exposed workers all had a ratio of ALT to AST greater than 1, with a mean of 1.5; it was > 1.6 in more than half the exposed workers.

CONCLUSIONS

The findings suggest that there is the possibility of liver involvement among even asymptomatic shoe repairers, and that periodic liver screening may be useful; furthermore, use of these tests (especially the ratio of ALT to AST) for craftsmen who repair shoes, and are exposed to solvent mixtures, is advisable even when environmental monitoring indicates levels below the threshold limit values (TLVs).

Evaluation of DNA damage by the Comet assay in shoe workers exposed to toluene and other organic solvents

The alkaline single-cell gel electrophoresis (or Comet) assay was applied to evaluate DNA damage in cryopreserved peripheral blood mononuclear leukocytes from 34 female shoe workers exposed to organic solvents and a group of 19 non-exposed women. We also investigated whether the polymorphisms of glutathione S-transferase M1 (GSTM1) and T1 (GSTT1) genes affect individual level of DNA damage possibly induced by the solvent exposure. Chemical measurements of workplace air in the two factories studied showed that the workers were exposed to acetone, gasoline, and toluene in both factories and to ethylacetate and diisocyanate in one factory. In the exposed workers, the average level of blood hemoglobin was lower and that of urinary hippuric acid higher than in the non-exposed individuals. However, the occupational exposure to organic solvents did not affect the Comet values. Neither did age, smoking, or the GSTM1 genotype have any effect on the outcome of this assay. The low prevalence of the GSTT1-null genotype precluded conclusions on the influence of GSTT1 polymorphism.

Benzene--a review of the literature from a health effects perspective

A literature review of the impact on human health of exposure to benzene was conducted. Special emphasis in this report is given to the health effects reported in excess of national norms by participants in the Benzene Subregistry of the National Exposure Registry--people having documented exposure to benzene through the use of benzene-contaminated water for domestic purposes. The health effects reported in excess (p < or = .01) by some or all of the sex and age groups studied were diabetes, kidney disease, respiratory allergies, skin rashes, and urinary tract disorders; anemia was also increased for females, but not significantly so.