The NIOSH Retrospective Pesticide Reference Database.

For the National Institute for Occupational Safety and Health (NIOSH) case-control study of glioma among non-metropolitan residents, pesticide information was considered critical. Responses to open-ended questions about pesticide exposures had to be grouped for analysis. Our aim was to classify pesticide responses in biologically relevant categories. We built the NIOSH Retrospective Pesticide Reference Database (NIOSH-RPRD) on over 1000 pesticide products and chemicals, particularly those likely to be used in the upper Midwest, using multiple sources. We obtained first and last years of product registration and product pesticide ingredients and their relative weights from the U.S. Environmental Protection Agency's Pesticide Product Information System. We added fields for pesticide class (organophosphate, etc.), carcinogenicity ratings, and evidence regarding endocrine-disrupting activity. Participant data were merged with the database, allowing each product recalled by a respondent to be linked to one or more chemicals, as appropriate. Respondents named 1347 different pesticides (or pesticide-targeted species) used on the farm, at non-farm jobs, or at home. Database usefulness was assessed by comparing numbers of responses naming actual chemicals to total responses linked to those chemicals. Sixty percent of farm pesticide, 59% of non-farm occupational, and 65% of house and garden responses named products, not chemicals. Among farm pesticide users, 182 (46%) reported using a total of 440 pesticides 1 to 40 years (mean 8.5 years) before those pesticides actually were marketed. The NIOSH-RPRD, now available to other investigators, has been a useful tool for us and other researchers to evaluate, group, and correct pesticide responses.

Single-nucleotide polymorphisms in selected cytokine genes and risk of adult glioma.

A role of immunological factors in glioma etiology is suggested by reports of an inverse relationship with history of allergy or autoimmune disease. To test whether single-nucleotide polymorphisms (SNPs) in cytokine genes were related to risk of adult glioma, we genotyped 11 SNPs in seven cytokine genes within a hospital-based study conducted by the National Cancer Institute and an independent, population-based study by the National Institute for Occupational Safety and Health (overall 756 cases and 1190 controls with blood samples). The IL4 (rs2243248, -1098T>G) and IL6 (rs1800795, -174G>C) polymorphisms were significantly associated with risk of glioma in the pooled analysis (P trend = 0.006 and 0.04, respectively), although these became attenuated after controlling for the false discovery rate (P trend = 0.07 and 0.22, respectively). Our results underscore the importance of pooled analyses in genetic association studies and suggest that SNPs in cytokine genes may influence susceptibility to glioma.

The Upper Midwest Health Study: a case-control study of primary intracranial gliomas in farm and rural residents.

Since several studies indicated that farmers and agricultural workers had an excess risk of brain cancer, the National Institute for Occupational Safety and Health initiated the Upper Midwest Health Study to examine risk of intracranial glioma in the non-metropolitan population. This population-based, case-control study evaluated associations between gliomas and rural and farm exposures among adults (ages 18 to 80) in four upper midwestern states (Iowa, Michigan, Minnesota, Wisconsin). At diagnosis/selection, participants lived in non-metropolitan counties where the largest population center had fewer than 250,000 residents. Cases were diagnosed 1 January 1995 through 31 January 1997. Over 90% of 873 eligible ascertained cases and over 70% of 1670 eligible controls consented to participate. Participants and nonparticipants, evaluated for "critical questions" on main and refusant questionnaires, differed significantly in farming and occupational experience, ethnicity, education, and lifestyle. The 1,175 controls were more likely than the 798 cases to have reported ever drinking alcohol (77% vs. 73%, adjusted odds ratio (OR) 0. 73, 95% confidence interval (CI) 0.59-0.92) and having had panoramic dental x-rays (34% vs. 29%, OR 0. 75, CI 0.61-0.92). Controls spent a greater percentage of their lives in non-metropolitan counties (78% vs. 75%, OR 0.81, CI 0.67-1.09). Among ever-farmers, controls were more likely to have had exposure to farm insecticides (57% vs. 50%, OR 0.75, CI 0.59-0.95) and farm animals (96% vs. 91%, OR 0.48, CI 0.25-0.90). Moving to a farm as an adolescent (ages 11 to 20) vs. as an adult was associated with a greater risk of glioma. In our study sample, farm or rural residence and summary farm exposures were associated with decreased glioma risk. However, nonparticipation by never-farming eligible controls could have affected results. Comparisons of farm chemical exposures may clarify associations between farming and glioma that others have reported.

Mortality in dry-cleaning workers: an update.

BACKGROUND: A cohort of 1,708 dry-cleaning workers identified from union records was exposed to perchloroethylene (PCE), a known animal carcinogen and probable human carcinogen, for at least 1 year before 1960. Many workers also had exposure to Stoddard solvent, a petroleum-based dry-cleaning solvent. METHODS: Vital status was updated through 1996 and life table analyses conducted. RESULTS: The cohort had excess cancer mortality (271 deaths, standardized mortality ratio [SMR] 1.25, 95% confidence interval [CI] 1.11-1.41). Elevated SMRs for tongue, bladder, esophagus, intestine, lung, and cervical cancer, pneumonia, and diseases of the stomach and duodenum were statistically significant. CONCLUSION: The current study confirms findings of prior updates and other studies that dry-cleaning workers have excess cancer mortality at several sites. Although important lifestyle and socioeconomic risk factors exist for both cervical and esophageal cancer mortality, excesses of these sites in the PCE only subcohort and among workers with longer duration of PCE exposure suggest an association with PCE exposure.

Mortality among rubber chemical manufacturing workers.

BACKGROUND: A retrospective cohort mortality study evaluated ischemic heart disease (IHD) among workers in the "rubber chemicals" manufacturing department of a Western New York plant. A previous study at the plant found elevated chest pain and angina among workers in this department. METHODS: Mortality experience of workers employed from 1946-1988 was followed through December 31, 1994. Mortality was compared to U.S. population rates and to local Niagara county rates by using the NIOSH life table analysis system. Poisson regression was used to examine patterns of IHD within the cohort. RESULTS: The standardized mortality ratio (SMR) for IHD among workers in the rubber chemicals department was 1.51 (U.S. rates) and 1.19 (Niagara county rates). Increased mortality from IHD in the rubber chemicals department was most pronounced at younger ages (< 50, SMR = 2.4); workers in a second chemical production department also had an elevated (but not statistically significant) SMR of 1.5 for IHD. CONCLUSIONS: IHD mortality among workers in the rubber chemicals department was elevated, particularly among those under 50 years of age. Potential occupational risk factors for IHD include the rotating shift pattern for employees assigned to two chemical production departments and chemical exposures present in the rubber chemicals department.

Proportionate mortality among unionized roofers and waterproofers.

BACKGROUND: The United Union of Roofers, Waterproofers, and Allied Workers (UURWAW) is one of the 15 building and construction trades departments in the AFL-CIO. The U.S. roofing industry, including both roofing and waterproofing applications, both unionized and nonunionized, comprises about 25,000 firms, employing approximately 300,000 people, about 200,000 of whom are involved in the application of roofs. The specific toxins to which roofers may be exposed at the job site include, among others, bitumens (asphalt and/or coal tar pitch) as well as asbestos and fiberglass from roof removal operations. Excess deaths from occupational injuries are also of concern. METHODS: This study evaluated causes of mortality among 11,144 members of the UURWAW. Age-adjusted proportionate mortality ratios (PMRs) were computed with 95% confidence intervals (CI) using U.S. age-, gender-, and race-specific proportional mortality rates for the years of the study, 1950-1996. RESULTS: Statistically significant increased PMRs were found for all injuries (PMR = 142, CI = 134-150), especially falls (PMR = 464, CI = 419-513) and other injuries (PMR = 121, CI = 107-137), cancers of the lung (PMR = 139, CI = 131-148), bladder (PMR = 138, CI = 111-170), esophagus (PMR = 134, CI = 107-166), larynx (PMR = 145, CI = 106-193), and cancers of other and unspecified sites (PMR = 130, CI = 112-149), pneumoconioses and other nonmalignant respiratory diseases (PMR = 115, CI = 103-128), and homicides (PMR = 153, CI = 135-172). The occupational exposures which may have contributed to the excess risks of malignant and nonmalignant respiratory diseases include, among others, asphalt fumes, coal tar pitch volatiles and asbestos; however, cigarette smoking must also be considered a contributing factor. CONCLUSIONS: The present study underscores the need to control airborne exposures to hazardous substances and especially to examine fall prevention efforts within the roofing industry. Am. J. Ind. Med. 37:478-492, 2000. Published 2000 Wiley-Liss, Inc.

Concerns of the dry-cleaning industry: a qualitative investigation of labor and management.

BACKGROUND: Occupational scientists agree there are hazards associated with dry-cleaning, but do dry-cleaning owners and workers concur? Knowledge of owners' and workers' perceptions can help guide intervention efforts to reduce worker exposure. To better understand these issues, a qualitative study was conducted using focus group methodology and constant comparative analysis. METHODS: Two owner and four worker focus groups were held. RESULTS: Findings suggest that overall, health and safety issues were not of great concern. Owners were primarily concerned with the economic impact of regulations. Workers did express some anxiety about solvent exposure and burns, but most felt that these hazards were "just part of the job." Also, other than the installation of air-conditioning in the shops and the provision of health benefits, workers could not think of ways health and safety on the job could be improved. CONCLUSIONS: These findings will be used to develop comprehensive safety and health interventions (e.g., engineering plus education and training) in dry-cleaning shops.

Mortality study of workers employed in 1,3-butadiene production units identified from a large chemical workers cohort.

The IARC has given the designations of "sufficient evidence" of carcinogenicity of 1,3-butadiene in experimental animals and "limited evidence" of carcinogenicity in humans. To investigate the carcinogenic effect in humans, a cohort mortality study was conducted among 364 men who were assigned to any of three 1,3-butadiene production units located within several chemical plants in the Kanawha Valley of West Virginia, including 277 men employed in a U.S. Rubber Reserve Plant which operated during World War II. The butadiene production units included in this study were selected from an index developed by the Union Carbide Corporation which listed for each chemical production unit within their South Charleston and Institute plants all products, by-products and reactants. Departments included in the study were those where butadiene was a primary product and neither benzene nor ethylene oxide was present. A total of 185 deaths were observed; the standardized mortality ratio (SMR) for all causes of death was 91, reflecting lower mortality among the study population than the U.S. population. The study found a significantly elevated standardized mortality ratio (SMR) for lymphosarcoma and reticulosarcoma based on four observed cases (SMR = 577; 95% confidence interval (CI) = 157-1480), which persisted in an analysis using county referent rates. An excess of lymphosarcoma and reticulosarcoma among all workers and among workers with routine exposure to 1,3-butadiene was also observed in the only other cohort of 1,3-butadiene production workers previously studied. A statistically non-significant excess of stomach cancer was observed in the overall cohort (five cases; SMR = 243; CI = 79-568) that was most pronounced among workers employed in the Rubber Reserve plant for 2 or more years (five cases; SMR = 657; CI = 213-1530). We conclude that the results of this study add to the weight of evidence suggesting that butadiene is carcinogenic in humans.

Monitoring of aromatic amine exposures in workers at a chemical plant with a known bladder cancer excess.

BACKGROUND: In April 1991, an excess of bladder cancer cases among workers employed at a chemical manufacturing facility in Niagara Falls, NY, was reported. This excess was primarily confined to 708 workers who had ever been employed in the rubber chemicals manufacturing area of the plant, where the aromatic amines aniline and o-toluidine have historically been used. PURPOSE: An environmental and biological monitoring survey was conducted to evaluate current exposures to aniline and o-toluidine in the rubber chemicals department. METHODS: Personal air sampling for aniline and o-toluidine was conducted with the use of a modified Occupational Safety and Health Administration (OSHA) 73 method. Urine samples were collected before and after work (i.e., pre-shift and post-shift, respectively) and stored at -70 degrees C. Base hydrolysis was used to convert acetanilide and N-acetyl-o-toluidine, metabolites of aniline and o-toluidine present in the urine, to the parent compounds. The parent compounds were extracted from the alkaline urine into butyl chloride and then back-extracted from the butyl chloride into aqueous hydrochloric acid. An aliquot of each acidic extract was subjected to ion-interaction reversed-phase liquid chromatography with coulometric electrochemical detection. Hemoglobin (Hb) was extracted from blood and stored at -70 degrees C. For the measurement of adducts of aniline, o-toluidine, and 4-aminobiphenyl (4-ABP), precipitated Hb was dissolved in 0.1 M sodium hydroxide in the presence of recovery standards, and the hydrolysate was extracted with hexane, derivatized with pentafluoropropionic anhydride, and analyzed by gas chromatography-mass spectrometry with negative chemical ionization. RESULTS: A total of 73 workers, including 46 of 64 exposed workers who were employed in the rubber chemicals department and had the potential for exposure to aniline and o-toluidine and 27 of 52 unexposed workers employed in other departments where aniline and o-toluidine were not used or produced, had data available for both aniline and o-toluidine and Hb adducts; 28 of the workers in the former group also had personal air-sampling data. Personal air sample measurements showed that airborne concentrations of aniline and o-toluidine were well within the limits allowed in the workplace by OSHA. Urinary aniline and o-toluidine levels, however, were substantially higher among exposed workers than among unexposed control subjects. The most striking differential was for post-shift urinary o-toluidine levels, which averaged (+/- standard deviation) 2.8 micrograms/L (+/- 1.4 micrograms/L) in unexposed subjects and 98.7 micrograms/L (+/- 119.4 micrograms/L) in exposed subjects (P = .0001). Average aniline-Hb and o-toluidine-Hb adduct levels were also significantly higher (P = .0001) among exposed workers than among unexposed control subjects. Average levels of adducts to 4-ABP, a potential contaminant of process chemicals, were not significantly different (P = .48), although three exposed workers had 4-ABP levels above the range in unexposed workers. CONCLUSIONS: The adduct data suggest that, among current workers, o-toluidine exposure substantially exceeds aniline exposure and that 4-ABP exposure, if it occurs at all, is not widespread. These data support the conclusion that occupational exposure to o-toluidine is the most likely causal agent of the bladder cancer excess observed among workers in the rubber chemicals department of the plant under study, although exposures to aniline and 4-ABP cannot be ruled out.

Acute and chronic liver toxicity resulting from exposure to chlorinated naphthalenes at a cable manufacturing plant during World War II.

Historical records were used to reconstruct an outbreak of chlorance and acute liver toxicity due to chlorinated naphthalene exposure at a New York State plant which manufactured "Navy cables" during World War II. A cohort mortality study was conducted of the population (n = 9,028) employed at the plant from 1940 to 1944. Vital status was followed through December 31, 1985. The study found an excess of deaths from cirrhosis of the liver [observed (OBS) = 150; standardized mortality ratio (SMR) = 1.84; 95% confidence interval (CI) = 1.56-2.16]; cirrhosis deaths were elevated to a similar degree in the 460 individuals who had chlorance (OBS = 8; SMR = 1.51; CI = 0.65-2.98). The SMR for "non-alcoholic cirrhosis" (OBS = 83; SMR = 1.67; CI = 1.33-2.07) was similar to the SMR for "alcoholic cirrhosis" (OBS = 59; SMR = 1.96; CI = 1.49-2.53). There was no evidence for increased alcoholism in the overall cohort based on mortality from alcohol-related causes of death other than cirrhosis (SMR for esophageal cancer = 1.01 and for deaths from alcoholism = 0.99). We conclude that the excess mortality from cirrhosis of the liver observed in this cohort is due to the chronic effect of chlorinated naphthalene exposure.

Epidemiology of occupational carcinogens and mutagens.

The author outlines the methods by which the International Agency for Research on Cancer evaluates study design and results when it reviews epidemiologic studies to determine carcinogenicity and mutagenicity. The chapter concludes with an extensive series of tables summarizing (1) the tests relevant to mutagenicity and (2) the IARC rating system for carcinogens, categorizing industrial and agricultural chemicals according to evidence of mutagenicity.

Mortality study of workers in 1,3-butadiene production units identified from a chemical workers cohort.

The International Agency for Research on Cancer has given the designations of "sufficient evidence" of carcinogenicity of 1,3-butadiene in experimental animals and "limited evidence" of carcinogenicity in humans. To investigate the carcinogenic effect in humans, we conducted a cohort mortality study among 364 men who were assigned to any of three 1,3-butadiene production units located within several chemical plants in the Kanawha Valley of West Virginia, including 277 men employed in a U.S. Rubber Reserve Plant which operated during World War II. The butadiene production units included in this study were selected from an index developed by the Union Carbide Corporation, which listed for each chemical production unit within their South Charleston, West Virginia and Institute, West Virginia, plants all products, by-products, and reactants. Departments included in the study were those where butadiene was a primary product and neither benzene nor ethylene oxide was present. A total of 185 deaths were observed; the standardized mortality ratio (SMR) for all causes of death was 91, reflecting lower mortality among the study population than the U.S. population. The study found a significantly elevated standardized mortality ratio (SMR) for lymphosarcoma and reticulosarcoma based on four observed cases (SMR = 577; 95% CI = 157-1480), which persisted in an analysis using county referent rates. An excess of lymphosarcoma and reticulosarcoma among all workers and among workers with routine exposure to 1,3-butadiene was also observed in the only other cohort of 1,3-butadiene production workers previously studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Cancer mortality patterns among female and male workers employed in a cable manufacturing plant during World War II.

A cohort mortality study was conducted among 9028 (3042 women, 5986 men) workers potentially exposed to chlorinated naphthalenes (chloracnegens structurally similar to dioxins) and asbestos in the manufacture of Navy cable during World War II. Based on mortality through December 31, 1985, standardized mortality ratios (SMRs) for all cancers was 1.03 in women (95% confidence interval [CI] = 0.9 to 1.17) and 1.18 in men (95% CI = 1.10 to 1.26). There were no significant elevations in causes of death hypothesized a prior to be associated with chlorinated naphthalene exposure (malignant neoplasms [MN] of connective tissue, liver, and lymphatic and hematopoietic organs). An excess of MN of the connective tissue was suggested for workers with over 1 year of exposure and 25 years of latency (SMR = 3.54; 95% CI = 0.97 to 9.07). Among cancer sites not hypothesized to be related a priori, three showed concordant excesses among both genders (MN of stomach; rectum; and trachea, bronchus, and lung). No significant elevations occurred in hormonally related cancers among women. Cancer mortality among 460 individuals with chloracne (431 men, 29 women) was similar to that of the entire cohort, although the chloracne subcohort showed significant excesses in two rare causes of death (MN of esophagus, SMR = 3.26; "benign and unspecified neoplasms," SMR = 4.93). Use of county referent rates decreased SMRs for stomach, rectal, and buccal cavity cancer, suggesting a role for nonoccupational risk factors. It is difficult to draw conclusions about carcinogenicity of chlorinated naphthalenes because of study limitations, most importantly, concomitant asbestos exposure and the relatively short duration of exposure to chlorinated naphthalenes among most of the cohort.

Cancer mortality in female and male dry-cleaning workers.

A cohort study of dry-cleaning workers (1109 women, 592 men) in the mid-1980s revealed significant excess bladder cancer mortality. This article updates vital status through 1990. Significant excesses were seen for bladder cancer (nine deaths, standardized mortality ratio [SMR] = 2.54, 95% confidence interval [CI] = 1.16-4.82), esophageal cancer (10 deaths, SMR = 2.14, 95% CI = 1.02-3.94), and intestinal cancer (26 deaths, SMR = 1.56, 95% CI = 1.02-2.29). In a subcohort exposed only to perchloroethylene (PCE), those with 5 or more years of employment and 20 or more years since first exposure had a significant increased risk of esophageal cancer (four deaths, SMR = 7.17, 95% CI = 1.92-19.82). Women had significant excess esophageal cancer (five deaths, SMR = 3.24, 95% CI = 1.05-7.58) and elevated SMRs for intestinal, pancreatic, and bladder cancer mortality. This study confirms the esophageal cancer risk among dry-cleaning workers seen in another study and suggests an association with PCE. It further documents the risks for intestinal, pancreatic, and bladder cancers in this industry.

National estimates of occupational exposure to animal bladder tumorigens.

A prevention program for occupational bladder cancer should be based on an estimate of the number of workers previously and currently exposed to bladder carcinogens. The National Occupational Exposure Survey (NOES), which identified potential occupational exposures in approximately 5000 private sector firms in 1981 to 1983, is the best available source for recent hazard estimates; the National Occupational Hazard Survey (NOHS), conducted in 1972 and 1974, for past exposure estimates. The National Institute for Occupational Safety and Health Registry of Toxic Effects of Chemical Substances (RTECS) identified nearly 200 substances associated with animal bladder tumors. From NOES and NOHS, the numbers of workers with full time (greater than or equal to 4 hours/day) or any potential occupational exposure were estimated for the United States. About 60,000 workers were potentially exposed in the early 1970s and about 700,000 in the early 1980s on a full-time basis to the compounds on the RTECS list also appearing in NOES, and about 1.8 million workers in the 1970s and almost 3.5 million in the 1980s had some occupational exposure. Because matches were not found for many compounds and because NOES covers only part of the US work force, these are probably underestimates. The estimates for the number of exposed workers do not imply that these workers all have increased risk of developing bladder cancer, because some animal tumorigens may not be human carcinogens and our estimates are based on potential rather than measured exposures. The risk would depend on the potency, duration, and intensity of the actual exposures. Nevertheless these estimates are useful in estimating the approximate magnitude of the potential occupational exposure to animal bladder tumorigens.

AIDS education: evaluation of school and worksite based presentations.

From 1986 through mid-1988, the Westchester County (NY) Health Department made AIDS education presentations upon request to junior and senior high school students and to adult educators and supervisors. In 1987, an evaluation component was added to measure the effectiveness of the presentations in increasing knowledge on AIDS-related topics. Questionnaires were field tested in a pilot study. During 1988, pre- and post-tests were administered 10-14 days before and after each scheduled presentation. Multivariate linear regression on the 847 pre- and 574 post-tests that were returned shows a statistically significant pre-test/post-test difference, controlling for test type, age, and gender, in both overall score (t = 9.00, p less than 0.0001) and in total number of questions answered rather than left blank (t = 6.27, p less than 0.0001). In logistic analyses controlling for test type, age, and gender, the greatest post-test improvements were in questions about differences between AIDS and HIV-related disorders (then called ARC) (adjusted odds ratio, 1.86; 95% confidence limits, 1.65, 2.10); AIDS and drug use (1.73; 1.40, 2.14); sexual practices and AIDS (1.64; 1.40, 1.91); and the definition of AIDS (1.52; 1.29, 1.81). There was also significant post-test improvement on questions dealing with risks in social proximity to persons with AIDS, virus transmission by persons with AIDS, and differences between AIDS and HIV.(ABSTRACT TRUNCATED AT 250 WORDS)

Estrogen and progesterone receptors in breast cancer patients. Epidemiologic characteristics and survival differences.

Risk factors commonly associated with breast cancer were studied in relation to: (1) tumor estrogen receptor (ER) or progesterone receptor (PR) status and (2) the presence of tumor hormone receptors in relation to subsequent survival. For 171 Israeli women diagnosed with breast cancer in 1976 to 1979, tumor hormone receptor status (positive if greater than 20 fmol receptors/mg protein; negative if less than or equal to 20 fmol/mg) and survival as of April 1984 were ascertained. There were 77 ER- versus 94 ER+ and (for 134 PR analyses) 69 PR- versus 65 PR+. Although ER status and PR status were found to be highly positively related, the epidemiologic features of women with an ER+ tumor were different from those with a PR+ tumor. Age tended to be associated positively with both ER+ and PR+. Being postmenopausal, older at menopause or at first birth, nulliparous, having more years of schooling, and a higher body mass index for older women or a lower body mass index for younger women were correlated positively with ER and negatively with PR. Among women with Stage III or IV tumors at diagnosis significant differences existed: restricted mean survival for follow-up time was 47.2 months for ER-, 73.8 months for ER+, 45.8 months for PR-, and 61.9 months for PR+. The combined hormone effects on survival at Stages III to IV showed a similar trend: restricted mean survival of 38.4 months for ER-PR-, intermediate survival with one positive hormone receptor status, and 74.6 months for ER+PR+.

Epidemiology of coca and alcohol use among high-altitude miners in Argentina.

A medical survey of 107 high-altitude miners was conducted in Argentina in 1976-1977. Daily chewing of coca leaves was reported by 70 (65%) respondents. Another 15 (14%) used coca occasionally. Weekly alcohol drinking was reported by 36 (34%) respondents, and 14 (14%) drank occasionally. Thirty-five of the weekly drinkers were also daily users of coca. Habitual users did not differ from other workers in mean age or total number of years worked. Daily use of coca was significantly higher among miners with a heavy work load as compared with those having a moderate-to-light work load (unadjusted odds ratio [OR] 4.24); it was also higher among those who had worked only underground rather than always or ever aboveground (OR 7.25), among those working as drillers or cart pushers as opposed to other tasks (OR 6.56), and among Mestizos and Indians compared with whites (OR 3.33). Weekly alcohol use was significantly higher among miners with a heavy work load (OR 6.49), those always working underground (OR 5.57), and those working as drillers or cart pushers (OR 3.67). Adjusting for possible confounding effects of these parameters on each other, the significant associations with habituation were clearly work site, work load, and task.