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Biomedical subjects

M Gérin

Publications and source records attributed to M Gérin.

At least 37 records · Page 2Linked to original sources
PubMed1993

Sources of discrepancies between a job exposure matrix and a case by case expert assessment for occupational exposure to formaldehyde and wood-dust.

Two methods used for retrospective evaluation of occupational exposures, a case by case assessment by expert and the application of a job exposure matrix (JEM), are compared using occupational histories collected for a case-control study on sinonasal cancer. The objective was to identify the main sources of discrepancies and to contribute to an optimal use of a JEM for population-based case-control studies. Comparisons were based on job periods, and were performed separately for two substances: formaldehyde and wood-dust. Job periods were classified according to the category of exposure assigned by the matrix, and to the probability and level of exposure assessed by the study expert. The sources of discrepancies were examined for job periods probably or definitely exposed according to the JEM and unexposed for the expert, or unexposed in the JEM and probably or definitely exposed to medium or high level for the expert. Such discrepancies were observed for 8% of the job periods for formaldehyde and 3% of the job periods for wood-dust. The agreement between the two approaches was better for wood-dust than for formaldehyde. The relative importance of different sources of discrepancies was not the same for formaldehyde and wood-dust. For formaldehyde a substantial part of the discrepancies was due to disagreements between the study expert and the matrix experts, which were mostly differences in threshold limits between 'not exposed' and 'definitely exposed at a low level'. Differences between experts' opinions did not explain the discordances observed for wood-dust. The presence of additional information in the questionnaire was an important source of discrepancy for the two substances.(ABSTRACT TRUNCATED AT 250 WORDS)

Case-Control Studies↗
PubMed1993

Development and use of a welding process exposure matrix in a historical prospective study of lung cancer risk in European welders.

A welding process exposure matrix has been developed relating 13 welding process-welded metal combinations to average exposure levels for total welding fumes, total chromium, chromium (VI) and nickel. Quantitative estimates were derived from consultation of literature sources and of some company data. This matrix was applied to the welding histories of 11,092 welders in the framework of an IARC multicentre study. When detailed welding history was not available at the individual level the average company welding practice profile was applied. No dose-response relationship emerged for lung cancer risk with cumulative dose of the carcinogens chromium (VI) and nickel for stainless steel welders. Dilution of the dose-response relationship could result from between-plant and within-plant variability, and exposure in jobs not accounted for in the study, but not from the partial use of company versus individual data. It is also possible that there is no increased risk related to chromium and nickel exposure in this group of workers. Matrix exposure estimates would need to be validated and the matrix possibly refined by comparison with a variety of comprehensive welding exposure data sets.

Air Pollutants, Occupational↗
PubMed1992

Occupational risk factors for sinonasal cancer: a case-control study in France.

A case-control study was conducted in France to examine occupational risk factors for sinonasal cancer; 207 cases and 409 controls were included in the study. Detailed information was collected on occupational history and other potential risk factors for nasal cancer. Results are presented for three histologic types: adenocarcinoma, squamous cell carcinoma, and others. Among males, the risk of adenocarcinoma was significantly elevated for cabinetmakers (odds-ratio = 35.4, 95% confidence interval = 18.1-69.3), carpenters and joiners (OR = 25.2, 95% CI = 14.6-43.6), and wood-working machine operators (OR = 7.4, 95% CI = 3.4-15.8), whereas the odds-ratios were less than 1 for loggers and wood preparation workers. Odds-ratios associated with cabinetmakers (OR = 11.2, 95% CI = 2.7-45.9)) and carpenters and joiners (OR = 5.8, 95% CI = 1.8-18.6) were also significantly elevated for the other-histologic-types category. Significant excesses in risk of squamous cell cancer were noted for "bakers, pastry cooks, grain millers" (OR = 3.9, 1.2-12.8), construction workers (OR = 3.7, 95% CI = 1.7-8.0), and carpenters and joiners having worked for at least 15 years in the wood manufacturing industry (OR = 8.1, 95% CI = 1.3-50.3). Among females, a significant increase in risk of squamous cell carcinoma (OR = 9.5, 95% CI = 1.7-54.1) and a moderate increase in risk of adenocarcinoma (OR = 4.0, 95% CI = 0.7-23.5) was observed for textile workers. Elevated risks of squamous cell cancer were noted for farm workers of both sexes (males: OR = 2.2, 95% CI = 1.1-4.4; females: OR = 4.9, 95% CI = 1.0-24.9).

Adenocarcinoma↗
PubMed1991

A historical prospective study of European stainless steel, mild steel, and shipyard welders.

A multicentre cohort of 11,092 male welders from 135 companies located in nine European countries has been assembled with the aim of investigating the relation of potential cancer risk, lung cancer in particular, with occupational exposure. The observation period and the criteria for inclusion of welders varied from country to country. Follow up was successful for 96.9% of the cohort and observed numbers of deaths (and for some countries incident cancer cases) were compared with expected numbers calculated from national reference rates. Mortality and cancer incidence ratios were analysed by cause category, time since first exposure, duration of employment, and estimated cumulative dose to total fumes, chromium (Cr), Cr VI, and nickel (Ni). Overall a statistically significant excess was reported for mortality from lung cancer (116 observed v 86.81 expected deaths, SMR = 134). When analysed by type of welding an increasing pattern with time since first exposure was present for both mild steel and stainless steel welders, which was more noticeable for the subcohort of predominantly stainless steel welders. No clear relation was apparent between mortality from lung cancer and duration of exposure to or estimated cumulative dose of Ni or Cr. Whereas the patterns of lung cancer mortality in these results suggest that the risk of lung cancer is higher for stainless steel than mild steel welders the different level of risk for these two categories of welding exposure cannot be quantified with precision. The report of five deaths from pleural mesothelioma unrelated to the type of welding draws attention to the risk of exposure to asbestos in welding activities.

Europe↗
PubMed1990

Urinary excretion of mandelic, phenylglyoxylic, and specific mercapturic acids in rats exposed repeatedly by inhalation to various concentrations of styrene vapors.

Adult male Sprague-Dawley rats were exposed by inhalation to various concentrations of styrene vapors (25, 50, 100, or 200 ppm) 6 h/day, 5 days/week, for 4 consecutive weeks. The concentrations were varied from day to day according to a random pattern allowing treated animals to be exposed five times to each concentration of styrene. Each day, the following urinary metabolites were analysed from samples collected during exposure (0-6 h) and after exposure (6-24 h): mandelic acid; phenylglyoxylic acid; and two mercapturic acids, N-acetyl-S-(1-phenyl-2-hydroxyethyl)-L-cysteine (M1) and N-acetyl-S-(2-phenyl-2-hydroxyethyl)-L-cysteine (M2). Various parameters of renal toxicity and hepatic microsomal and cytosolic enzyme activities were also measured. The results show that there is a very good relationship between the excretion of all four styrene metabolites and the degree of daily exposure to styrene over the entire period of urine collection, with correlation coefficients ranging from 0.82 to 0.98. The correlation was poor for mandelic acid during the 0-6 h period. There was no evidence that repeated exposure to styrene caused renal toxicity, nor induced hepatic microsomal enzyme activities; cytosolic glutathione S-transferase activity was increased moderately by 1.5 times. Thus, under conditions of exposure to styrene likely to be found in the workplace, all four metabolites measured were good indicators of styrene exposure throughout the length of the experiment. Since mercapturic acids result from the conjugation of styrene oxide with glutathione, the data suggest that measurement of these metabolites offers the possibility to monitor internal exposure to a toxic electrophilic compound more directly.

Acetylcysteine↗
PubMed1990

Silica and cancer associations from a multicancer occupational exposure case-referent study.

A multicancer site, multifactor case-control study was undertaken to generate hypotheses about possible occupational carcinogens. Eligible cases, comprising all incident cases of cancer at 14 sites who were male, aged 35-70 and resident in Montreal, were subjected to probing interviews designed to obtain detailed lifetime job histories and information on potential confounders. Each job history was reviewed by a team of chemists who translated it into a history of occupational exposures. These occupational exposures were then analysed as potential risk factors in relation to the sites of cancer included. Over 3700 cases were interviewed and processed. For each site of cancer analysed as a case series, controls were selected from subjects with cancer at the other sites covered in the study. This report concerns the associations between silica exposure and each site of cancer. In initial screening analyses, there were significantly elevated odds ratios for silica and stomach cancer and for silica and non-adenocarcinoma lung cancer. More detailed analyses confirmed these associations, though there was no evidence of a dose-response relationship for stomach cancer. For lung cancer, there were significantly elevated risks in those with high-level long-term exposure. These results, which took into account several potential confounders including cigarette smoking and asbestos exposure, lend credence to the hypothesis that silica exposure increases the risk of lung cancer, and suggest the possibility of an effect on stomach cancer.

Adult↗
PubMed1989

Cancer risks due to occupational exposure to formaldehyde: results of a multi-site case-control study in Montreal.

A case-control study was undertaken in Montreal to investigate the possible associations between occupational exposures and cancers of the following sites: oesophagus, stomach, colo-rectum, liver, pancreas, lung, prostate, bladder, kidney, melanoma and lymphoid tissue. In total, 3,726 cancer patients and 533 population controls were interviewed to obtain detailed lifetime job histories and information on potential confounders. Each job history was translated into a history of occupational exposures. Because of current concerns about formaldehyde carcinogenicity, we carried out a special analysis of the association between exposure to formaldehyde and each type of cancer covered by this study. Separate statistical analyses were carried out for each type of cancer using population controls as well as a control series drawn from among the other cancer sites in the study. Although nearly a quarter of all subjects had undergone occupational exposure to formaldehyde, the levels of exposure were in general quite low. There was no persuasive evidence of an increased risk of any type of cancer among men exposed to these levels of formaldehyde. However, the possibility of a small increase in risk could not be ruled out.

Adult↗
PubMed1989

Cancer risks associated with 10 inorganic dusts: results from a case-control study in Montreal.

A multicancer site, multifactor case-control study was undertaken to generate hypotheses about possible occupational carcinogens. Probing interviews were carried out with eligible cases, comprising all incident cases of 20 types of cancer who were male, aged 35-70 years, and a resident in Montreal. The interview was designed to obtain detailed lifetime job histories and information on potential confounders. Each job history was reviewed by a team of chemists and industrial hygienists who translated it into a history of occupational exposures. These occupational exposures were then analyzed as potential risk factors in relation to the sites of cancer included; 3,726 cases were interviewed. For each site of cancer analyzed, controls were selected from among the other sites in the study. This report concerns the associations between the 12 main types of cancer in our series and 10 inorganic dusts that are found mainly in construction and metal industries. All site-exposure combinations were investigated. After intensive control for confounding, nonadenocarcinoma (NAC) of the lung was associated with long duration-high level exposure to silica (odds ratio [OR] = 1.4), excavation dust (OR = 1.9), concrete dust (OR = 2.5), abrasives dust (OR = 1.4), and alumina (OR = 1.5). It was difficult to disentangle the relative effects of those substances, and confounding among them was a distinct possibility. Although residual confounding by some uncontrolled factors may explain the elevated ORs, the results were compatible with the hypothesis of a nonspecific relation between NAC of the lung and respirable inorganic dusts as a class. Other associations that remained suggestive after in-depth analysis were silica and stomach cancer (OR = 1.2) and concrete dust and lymphoma (OR = 2.9).

Adult↗
PubMed1989

Specific determination of bromobenzene metabolites by high-performance liquid chromatography.

A chromatographic method for the quantitative and simultaneous determination of phenolic and mercapturic acid type metabolites of bromobenzene is presented. Acid hydrolysis (1.5 N HCl, 100 degrees C, 10 min) yielded unconjugated bromophenols. After extraction (ethyl acetate, pH 2), evaporation to dryness and dissolution in methanol, samples were analysed by high-performance liquid chromatography (HPLC) with a c18 reverse-phase column and a phosphate buffer (0.1 M,pH 9 + 5 mM tetrabutylammonium dihydrogen phosphate) - acetonitrile gradient with ultraviolet detection (225 nm). Benzylmercapturic acid and o-chlorophenol were used as internal standards. Using this method, it was possible to determine simultaneously o, m- and p-bromophenols together with o-, m- and p-bromophenylmercapturic acids. Additional validation data were obtained by analysis of urine samples from rats treated with bromobenzene. This new method was compared to existing procedures.

Acetylcysteine↗
PubMed1988

Smoking and degree of occupational exposure: are internal analyses in cohort studies likely to be confounded by smoking status?

Occupational cohort studies are usually carried out without the benefit of information on smoking habits of cohort members. One common approach to avoid confounding bias related to smoking habits is to carry out an internal analysis, comparing workers with different degrees of occupational exposure. The premise behind this approach is that within a cohort there is unlikely to be correlation between degree of exposure and smoking habits. If this were untrue, smoking could confound the disease-exposure relationships. Our purpose was to verify the premise. The study sample consisted of 857 French-Canadian men born between 1910 and 1930, with 11 or fewer years of education, and interviewed around 1980 in the context of an occupational cancer case-control study. For each man we had information on smoking habits, job history, and a history of the chemicals he was exposed to in each of his jobs. We computed two indices of the dirtiness of workers' job histories: one based on the job titles held by the man and a second based on the degree of exposures to workplace substances. There was no correlation between these indices of job dirtiness and smoking history. We also examined the smoking-exposure relationship among the subsets of men who had been occupationally exposed to ten especially noticeable substances. Within the subsets, there was no indication of a consistent difference among the smoking subgroups in level or duration of exposure to these index substances. These findings do not support the view that nonsmokers sought out cleaner job environments than smokers; they imply that internal analyses of "dose-response" in cohort studies are unlikely to be seriously confounded by smoking habits.

Adult↗
PubMed1988

Aviation gasoline: comparative subchronic nephrotoxicity study in the male rat.

Biochemical and histopathologic parameters of nephrotoxicity were measured in groups of male Fischer-344 rats after a 2-week, 5-days-a-week schedule of oral administration (0.5 ml/kg) of the following substances: aviation gasoline (grade 100) (AVG), automobile regular unleaded gasoline (ULG) and 2,2,4-trimethylpentane (TMP). Results of renal histopathologic examinations and biochemical parameters were compatible with the following order of increasing nephrotoxicity: ULG less than TMP less than AVG. The high nephrotoxic potential of aviation gasoline may be related to its elevated content in branched hydrocarbons.

Acetylglucosaminidase↗
PubMed1988

Associations between several sites of cancer and ten types of exhaust and combustion products. Results from a case-referent study in Montreal.

A population-based case-referent study provided information on the associations between several types of cancer and 10 types of exhaust and combustion products. All site-exposure combinations were investigated. An increased lung cancer risk, in particular squamous-cell cancers, due to exposure to gasoline and diesel exhausts was found. Among the associations that have not been subject to previous attention, the most promising leads for further investigation are the possible relations between gasoline and diesel exhaust and colorectal cancers, gasoline exhaust and kidney cancer, coal combustion products and pancreatic cancer (and possibly nonadenocarcinoma lung cancer), combustion products of heating oil and prostatic cancer, and natural-gas combustion products and bladder cancer.

Adult↗
PubMed1988

Determination of specific urinary thioethers derived from acrylonitrile and ethylene oxide.

A simple analytical method has been developed for the determination of specific urinary thioethers. Mercapturic acids present in urine are first de-acetylated enzymatically or by acid hydrolysis. Cysteine conjugates thus formed are reacted with o-phthalaldehyde and mercaptoethanol, yielding fluorescent derivatives, which are further separated by high-performance liquid chromatography (HPLC) in a reverse-phase system. The method is applicable to the determination of the following thioethers: 2-hydroxyethylmercapturic acid (N-acetyl-S-2-hydroxyethyl-L-cysteine; HMA), carboxymethylmercapturic acid (N-acetyl-S-carboxymethyl-L-cysteine; CAMA) and 2-cyanoethylmercapturic acid (N-acetyl-S-2-cyanoethyl-L-cysteine; CYMA), and the corresponding cysteine conjugates, S-2-hydroxyethyl-L-cysteine (HCYS), S-2-carboxymethyl-L-cysteine (CACYS) and S-2-cyanoethyl-L-cysteine (CYCYS). The excretion pattern of these thioethers in rats exposed to acrylonitrile and various rodents exposed to ethylene oxide is reported. Thioether excretion can be dependent on species and route of administration. The analytical procedure may prove to be applicable to the biological monitoring in humans of exposure to acrylonitrile, ethylene oxide, vinyl chloride, 1,2-dibromoethane and 1,2-dichloroethane.

Acetylcysteine↗
PubMed1987

Species differences in the urinary disposition of some metabolites of ethylene oxide.

Some aspects of the qualitative and quantitative urinary disposition of some metabolites of ethylene oxide in three rodent species, mouse, rat, and rabbit, were examined by determining urinary N-acetyl-S-(2-hydroxyethyl)-L-cysteine, S-(2-hydroxyethyl)-L-cysteine, S-carboxymethyl-L-cysteine, and ethylene glycol after ethylene oxide exposure by iv and inhalation routes. The animals were given ethylene oxide at 20 and 60 mg/kg, and urine samples were collected at 6 and 24 hr. Important differences were observed between the three species in the urinary metabolic disposition of ethylene oxide. Mice excreted significant quantities of N-acetyl-S-(2-hydroxyethyl)-L-cysteine, S-(2-hydroxyethyl)-L-cysteine, S-carboxymethyl-L-cysteine, and ethylene glycol (8.3, 5.8, 1.9, and 3.3% of the lower dose, respectively, in 24 hr), whereas in rats only N-acetyl-S-(2-hydroxyethyl)-L-cysteine (31%) and ethylene glycol (6%) were apparent. In contrast, the rabbits were found to excrete only ethylene glycol (2%). This study further reveals species-related differences in the urinary excretion of N-acetyl-S-(2-hydroxyethyl)-L-cysteine and ethylene glycol during the two collection periods. The observed differences between the three species in the metabolic disposition of ethylene oxide were found to be qualitatively independent of the route of exposure, i.e., inhalation at 200 ppm or iv. These results suggest that care should be exercised when using an animal species as a model for human disposition of ethylene oxide.

Administration, Inhalation↗
PubMed1987

Urinary excretion of mercapturic acids and thiocyanate in rats exposed to acrylonitrile: influence of dose and route of administration.

Adult male Sprague-Dawley rats were exposed acutely to acrylonitrile (ACN) according to 1 of 3 different routes of administration: inhalation (6 h), i.v., or i.p. Urinary metabolites measured 24 h after administration were 2-cyanoethylmercapturic acid (CMA), 2-hydroxyethylmercapturic acid (HMA) and thiocyanate (TCN). In all 3 series of experiments, the relationship between excretion of total urinary metabolites and the degree of exposure was reasonably linear. However, there was a marked influence of the route of administration on the pattern of metabolic excretion. For example, after i.p. and i.v. injection CMA was the most important metabolite while after inhalation it was TCN. Our results also indicate an important effect of the dose on the pattern of excretion for all types of administration.

Acetylcysteine↗
PubMed1987

Associations between several sites of cancer and twelve petroleum-derived liquids. Results from a case-referent study in Montreal.

A population-based case-referent study provided information on the associations between several types of cancer and 12 petroleum-derived liquids. All site-exposure combinations were investigated. The most interesting results concerned the following combinations: leaded gasoline-stomach cancer, aviation gasoline-kidney cancer (and the possible implications of this association for a similar effect of unleaded automotive gasoline), mineral spirits-squamous-cell cancer of the lung, diesel fuel-nonadenocarcinoma lung cancer, lubricating oils-squamous-cell lung cancer, cutting fluids-bladder cancer, other mineral oils-bladder cancer, mineral spirits-prostate cancer, diesel fuel-prostate cancer, and lubricating oils-prostate cancer.

Humans↗
PubMed1987

Discovering carcinogens in the occupational environment. Methods of data collection and analysis of a large case-referent monitoring system.

A multi-cancer site, multi-factor, case-referent study was undertaken to generate hypotheses about possible occupational carcinogens. About 20 types of cancer were included. Incident cases among men aged 35-70 years and diagnosed in any of the major Montreal hospitals were eligible. Probing interviews were carried out for 3 726 eligible cases. The interview was designed to obtain detailed lifetime job histories and information on potential confounders. Each job history was reviewed by a team of chemists who translated it into a history of occupational exposures. These occupational exposures were then analyzed as potential risk factors in relation to the sites of cancer included. For each site of cancer analyzed, referents were selected from among the other sites in the study. The analysis was carried out in stages. First a Mantel-Haenszel analysis was undertaken of all cancer-substance associations, stratifying on a limited number of covariates, and, then, for those associations which were noteworthy in the initial analysis, a logistic regression analysis was made taking into account all potential confounders. This report describes the fieldwork and analytical methods.

Carcinogens, Environmental↗