Biomedical subjects

M Gérin

Publications and source records attributed to M Gérin.

44 records · Page 3Linked to original sources

PubMed1986

Associations between several sites of cancer and nine organic dusts: results from an hypothesis-generating case-control study in Montreal, 1979-1983.

A multi-cancer site, multi-factor case-control study was undertaken to generate hypotheses about possible occupational carcinogens. Probing interviews were carried out with over 2,000 subjects. All incident cases of 19 sites of cancer in males aged 35-70 and resident in Montreal were eligible. 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 as a case series, controls were selected from among the other cancer sites in the study. This report concerns the associations between sites of cancer for which there were over 100 cases processed (stomach; colorectal, also analyzed by subsites; lung; prostate; bladder; kidney; non-Hodgkin's lymphoma) and nine organic dusts (wood; paper; grain; flour; fabrics; cotton; wool; synthetics; fur). All site-exposure combinations were investigated. The ones that provided the most interesting leads were lung-wood dust (odds ratio (OR) = 1.5), stomach-wood dust (OR = 1.5), colorectal-synthetic fiber (OR = 1.5), bladder-synthetic fiber (OR = 1.8), non-Hodgkin's lymphoma-cotton dust (OR = 1.9), colon-grain dust (OR = 2.6), prostate-grain dust (OR = 2.2), and prostate-paper dust (OR = 2.0). Only the associations with wood dust, synthetic fibers and cotton dust showed some evidence of "dose-response" with duration of exposure. Because it is such a common exposure and appears to increase lung and stomach cancer risks, wood dust may be responsible for a great deal of occupational cancer.

Adult↗

PubMed1986

Inter-rater agreement in assessing occupational exposure in a case-control study.

The identification of occupational carcinogens in the workplace is a major concern of epidemiologists. A novel case-control approach has been developed which includes as a key component the assessment of a subject's occupational exposure history by a two stage process. Firstly, the subject is interviewed to obtain a detailed lifetime job history. Then a team of chemists and hygienists, hired and trained to do this work on a full time basis, translates each job into a list of potential occupational exposures. The present study investigated the inter-rater agreement in this type of retrospective exposure assessment. Six trials were carried out over a four year period with different raters and different sets of job files. Some trials involved only internal raters from the "in house" group whereas others involved comparisons between the internal raters and other external raters who had expertise in certain industries. In assessing exposure as simply present or absent, two summary indices of agreement were used: per cent with perfect agreement and Cohen's kappa. In most of the trials the per cent with perfect agreement among raters ranged from 95% to 98%, with kappa ranging from 0.5 to 0.7. The kappas were slightly higher for internal-internal comparisons than for internal-external ones. These results indicate a relatively high degree of inter-rater agreement and lend credibility to the validity of this type of retrospective exposure assessment.

Adult↗

PubMed1986

Urinary N-acetyl-S-2-hydroxyethyl-L-cysteine in rats as biological indicator of ethylene oxide exposure.

There is no simple method known for the biological monitoring of ethylene oxide exposure. N-Acetyl-S-2-hydroxyethyl-L-cysteine (2-hydroxyethylmercapturic acid) excretion was evaluated as a potential indicator of exposure to this gas. Groups of Sprague-Dawley rats were given iv doses of 1, 10, or 100 mg/kg of ethylene oxide dissolved in water. Urines were collected after 12 and 24 hr. In another experiment groups of Sprague-Dawley rats were exposed by inhalation to concentrations of 1, 5, 10, 25, 50, and 200 ppm of ethylene oxide during a 6-hr period and 24-hr urines were collected subsequently. 2-Hydroxyethylmercapturic acid was analyzed in rat urine after enzymatic deacetylation into S-2-hydroxyethyl-L-cysteine, formation of a fluorescent derivative, and separation from other amino acid derivatives by high performance liquid chromatography. No S-2-hydroxyethyl-L-cysteine was observed in any sample when analysis proceeded without the deacetylation step. 2-Hydroxyethylmercapturic acid, however, was present in the urine of all exposed groups. Doses of 1 and 10 mg/kg were excreted at a fairly constant percentage of the dose, ca. 30% from 0 to 12 hr and 5% from 12 to 24 hr, while at 100 mg/kg the equivalent percentages were 16 and 5%, indicating a possible saturation of glutathione conjugation in the first 12 hr. In inhalation experiments, the amount of 2-hydroxyethylmercapturic acid excreted in 24 hr varied linearly with exposure concentration, averaging 0.27 mumol/ppm. The consistency of the excretion of this metabolite over a wide dose span points to 2-hydroxyethylmercapturic acid as a potential biological indicator of exposure to ethylene oxide.

Acetylcysteine↗

PubMed1985

Obtaining occupational exposure histories in epidemiologic case-control studies.

In a large population-based case-control study designed to generate hypotheses regarding possible associations between cancer sites and occupational exposures, an innovative methodology is utilized to infer the subjects' chemical exposures. It features (1) a probing interview to obtain a detailed portrait of each job the subject has held, (2) exposure coding by a team of chemists and hygienists who review each interview, (3) a coding checklist of nearly 300 occupational exposures including the most common ones, and (4) indication by the coders of the level, frequency, and mode of exposure, as well as of their degree of confidence that the exposure occurred. In making coding decisions, the chemists draw upon their experience and upon consultants and bibliographic sources. Resultant data can be combined to produce a variety of semi-quantitative indices of exposure for epidemiologic analyses.

Adult↗

PubMed1982

Preliminary report of an exposure-based, case-control monitoring system for discovering occupational carcinogens.

There is no evidence concerning human carcinogenic potential of most substances to which workers are exposed. A case-control type method has been developed to discover heretofore unsuspected occupational carcinogens. Incident cases of cancer of several sites are ascertained and the subjects are interviewed to obtain detailed job histories. The job histories are subsequently examined by chemists and engineers who infer for each job a list of potential chemical and physical exposures. These lists of exposures then become the basis of case-control type statistical analyses, wherein each site included and each exposure noted in any history are evaluated for possible association. Controls can be selected in the general population, among non-cancer hospital patients or, as we do, among other cancer patients. Preliminary findings from a pilot study in Montreal show that 1) an efficient case ascertainment system and an acceptable interview procedure can be set up, 2) job histories provided by respondents are quite valid, 3) chemists' translations of job histories into histories of chemical exposures seem to be meaningful and useful, and 4) at least one carcinogenic agent, cigarette smoking, is detectable whether a population control series or a cancer control series is used.

Adult↗

PubMedDate not supplied

A study on the substitution of trichloroethylene as a spot remover in the textile industry.

Since the ban on 1,1,1-trichloroethane, the textile industry has been using trichloroethylene (TCE) as a spot remover to clean oil and grease stains from fabrics at inspection stations. TCE is a toxic substance recently classified as a probable human carcinogen. The purpose of this study was to use a systematic substitution procedure to replace TCE with a less hazardous option for spot removing in a textile company. After documenting the problem and understanding the processes involved, numerous sources of information were searched to identify the greatest number of plausible solutions. Then criteria were established to help consider only the options that seemed technically acceptable. Five options were retained: 1-bromopropane, a petroleum-based solvent, a hydrochlorofluorocarbon-based solvent, an appliance that uses hot steam, and the elimination of the oil and grease spots at the source. The latter option, which had been partially implemented by the textile company, was not considered in this study. After being tested in the workplace and evaluated on their technical plausibility and impact on health, safety, and environment, the remaining four options were not considered as suitable replacements for TCE. Thus, local ventilation with the implementation of further measures for the reduction/elimination of stains at the source were recommended to lower TCE exposure for workers.

Alkanes↗

PubMedDate not supplied

Gas chromatographic analysis of bromophenylmercapturic acids in urine.

A gas chromatographic assay specific for the analysis of bromophenylmercapturic acids in urine is described. The mercapturic acids are first hydrolyzed to form bromothiophenols, which are acetylated, extracted into dichloromethane, and analyzed by gas chromatography with a flame ionization detector. Using samples from rats and mice treated with bromobenzene, the authors make a comparison between this specific method and a nonspecific assay for the determination of total thioethers in urines.

Acetylcysteine↗

PubMedDate not supplied

Simultaneous determination of urinary mandelic, phenylglyoxylic, and mercapturic acids of styrene by high-performance liquid chromatography.

We have developed a relatively simple and reproducible HPLC procedure for the determination of urinary metabolites of styrene. Urine samples (pH 2) are extracted with ethyl acetate, the organic layer is evaporated to dryness, and the residues are dissolved in water-methanol (1:1). Samples are analyzed by HPLC with a C18 reversed-phase column and a water (pH 6, 5mM tetrabutylammonium dihydrogen phosphate)-acetonitrile gradient and ultraviolet detection at 225 nm. Using this method, it is possible to determine simultaneously mandelic and phenylglyoxylic acids, N-acetyl-S-(1-phenyl-2-hydroxyethyl)-L-cysteine (M1), and N-acetyl-S-(2-phenyl-2-hydroxyethyl)-L-cysteine (M2). The internal standard is p-hydroxybenzoic acid. Additional validation data are obtained by analysis of urine samples obtained from rats treated with a wide range of styrene doses.

Acetylcysteine↗