Toluene diisocyanate induced asthma: outcome according to persistence or cessation of exposure.
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Asthma↗
Biomedical subjects
G M Liss
Publications and source records attributed to G M Liss.
Use of provincial health insurance plan billing data to estimate carpal tunnel syndrome morbidity and surgery rates.
Following a work refusal at a plant manufacturing ice cream novelties in Ontario, we were asked to document cases of cumulative trauma disorders (CTDs) and carpal tunnel syndrome (CTS) in this workplace. There were 17 employees with possible hand and wrist problems identified from Workers Compensation Board (WCB) Forms, and from a list prepared at the time of the refusal. After obtaining consents, confirmations of the diagnoses of CTDs, CTS, and of surgical procedures for CTS were obtained from the physicians involved. The relative risk for these disorders among plant employees was estimated in two ways: 1) the rate of CTS operations between 1979 and 1990 was compared to that in the general population using Ontario Health Insurance Plan (OHIP) data on physicians' billings for these operations; and 2) the frequency of WCB first payment claims for tendinitis and CTS during 1987 to 1989 at the plant was compared to that among the entire labor force of Ontario. CTDs had been diagnosed in all 17 workers: 9 had had operations for CTS, but one had had this operation prior to working at the plant. Compared to the remaining 8 workers who had CTS operations, an estimated 0.08 CTS operations would be expected among the 150 employees on the plant's seniority lists between 1979 and 1990, if the estimated rates in the general population were present at the plant, giving a Standardized Morbidity Ratio of 10.0 (95% confidence interval [CI] 4.3-19.7; one-sided p = 2.1 x 10(-6)). There were 6 WCB claims for tendinitis and CTS among plant employees during 1987 through 1989. This frequency was about 68 times that in the entire Ontario labor force (95% CI 24.7-150). This investigation has shown that CTDs, and particularly CTS, documented by medical records, have occurred at least 10 times more frequently than expected at this plant. Use of health insurance billing data to estimate CTS operation rates represents a simple method for estimating the burden of illness at the individual plant level due to CTS (at least for that portion proceeding to surgery), using an objective outcome that can be confirmed from medical records.
Adult↗
Peak expiratory flow rates in possible occupational asthma.
Objective criteria for interpretation of peak expiratory flow rate readings were assessed in 50 patients evaluated for suspected occupational asthma who had at least two weeks of PEFR readings and an objective diagnosis based on other investigations. The prevalence of OA was 36 percent. Peak flows were interpreted by two observers blinded to other results. Criteria for a PEFR interpretation of OA were as follow: diurnal variation greater than or equal to 20 percent relatively more frequently or with greater variation on working days than days off work. With the objective diagnoses as the gold standard, the sensitivity of the PEFR interpretations was 72 percent for OA; specificity for no asthma was 53 percent. Excluding those with greater than or equal to 20 percent variation on only one day sensitivity improved to 93 percent for OA, and specificity to 77 percent. There was an acceptable level of interobserver variation (kappa 62 to 83 percent). We conclude that simple objective criteria for PEFR interpretation can be developed with acceptable interobserver variation.
Adult↗
Peak expiratory flow rates in possible occupational asthma.
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Asthma↗
Peripheral neuropathy in two workers exposed to 1,1,1-trichloroethane.
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Adult↗
Pulmonary and immunologic evaluation of foundry workers exposed to methylene diphenyldiisocyanate (MDI).
A cross-sectional evaluation was performed of workers in a steel foundry in which methylene diphenyldiisocyanate (MDI) was used as a component of a binder system used to make cores and molds. Preshift and postshift spirometry and clinical evaluations were performed on 26 currently exposed (group I), on six formerly exposed (group II), and on 14 nonexposed workers to MDI (group III). Serum samples were assayed for total antibody binding, specific IgG by ELISA, and specific IgE by the RAST method to MDI-human serum albumin (HSA). Symptoms compatible with occupational asthma were elicited from seven (27%) of 26 group I workers and from three of six group II workers. No symptoms were reported by group III workers. Intrashift change in FEV1 (a mean decrease of 0.049 L) in group I workers was significantly decreased compared to that in unexposed group III workers (a mean increase of 65 ml; p = 0.043). Specific IgG and total antibody responses to MDI-HSA were detected only in workers with current or former exposure to MDI. Only one worker was identified with IgE-mediated occupational asthma exhibiting a positive prick test and elevated RAST to MDI-HSA of 25.5% bound. In this occupational setting, polyclonal immune responses to MDI-HSA and clinical sensitization to MDI were demonstrated to occur.
Adult↗
Selection bias in occupational case-control studies that use death registries to select subjects: a discussion and demonstration.
Some epidemiologic studies have selected subjects from death registries. This method is, however, subject to substantial systematic bias that arises from the fact that different segments of society have different risks of death in any year. Different occupational groups will thus have unequal probabilities of entering the pool of potential controls, and biased estimates of the odds ratios that relate occupation to disease will result. Failure to recognize the bias may lead to invalid conclusions. This selection bias is discussed, with particular reference to studies of malignancies among farmers. The bias is demonstrated by using data from studies of Parkinson's disease and sinonasal cancer.
Aged↗
Mortality among workers receiving compensation awards for silicosis in Ontario 1940-85.
The mortality experience of 1190 miners and 289 surface industry workers receiving workers' compensation awards for silicosis in Ontario since 1940 has been studied up to mid-1985. Both groups were found to have a significantly increased mortality from lung cancer (miners' SMR: 230; surface workers' SMR: 302) and stomach cancer (miners' SMR: 188; surface workers' SMR: 366). Adjustment for smoking and country of origin did not explain the excesses observed. The lung cancer findings are consistent with observations from silicosis registries in Europe. Possible explanatory factors are discussed.
Cause of Death↗
Tests for hepatotoxicity: usefulness in screening workers.
General tests of hepatotoxicity must be selected to identify all seven different types of exposure effect--cytotoxicity, cholestasis, fibrosis, vascular injury, metabolic dysfunction, impairment of the reticuloendothelial system, and carcinogenesis--whereas specific tests need only identify one or more. The liver's multifunctional character requires using sets of tests that include blood, urine, breath, isotopic, sonic, radiological, histological, and genetic tests. In this paper, traditional studies (eg, enzymes, proteins) are reviewed for medical screening and biological monitoring for specificity, sensitivity, selectivity, and cost-effectiveness. Status of newer tests (eg, clearance, radioisotopic assay, scans) will be reviewed, and developing tests (eg, molecular, genetic) for occupational use will be introduced. Practical application of these tests will be reviewed regarding clinical evaluations, interpretation, and triage. Finally, the medical-socioeconomic implications at initial medical screening and during subsequent monitoring will be illustrated.
Breath Tests↗
Use of serum bile acids in the identification of vinyl chloride hepatotoxicity.
Most previous studies proposing serum bile acids as indicators of hepatic function have been performed in hospitalized patients in whom overt symptomatic liver disease was present. The ability of fasting levels of serum bile acids to identify mild, clinically inapparent chemical liver injury in an occupational setting was compared with that of indocyanine green clearance and routine biochemical liver tests in 67 asymptomatic chemical workers in whom liver biopsies had been performed for medical indications. Histologically, 15 were found to have chemical liver injury, 27 had nonchemical liver disease, and 25 were normal. Two serum bile acids, cholylglycine and conjugates of cholic acid, were determined by radioimmunoassay, using 466 "normal" males from the same worker cohort as a reference range. The geometric mean concentrations of cholylglycine in patients with chemical liver injury, patients with nonchemical liver disease, and normal subjects were 47.9, 19.1, and 20.0 micrograms/dl, respectively (p = 0.036 by analysis of variance). Conjugates of cholic acid showed similar differences (p = 0.027), as did indocyanine green clearance with mean half-life of 4.2, 3.2, and 3.3 minutes in the three biopsy subgroups, respectively (p = 0.043). Such differences were not observed for biochemical liver tests. The fasting level of serum bile acids provided high specificity but lower sensitivity in the detection of all types of liver disease. However, serum bile acids and indocyanine green clearance provided a higher specificity and sensitivity for chemical liver injury than for nonchemical liver disease. An index of average exposure to vinyl chloride was significantly greater in the subgroup with chemical liver injury than in the other two groups, further supporting the association of chemical type injury with impaired anion uptake. These data identify the fasting level of serum bile acids as a clinically usable indicator of early chemical injury in chemically exposed asymptomatic worker populations with liver dysfunction. Further investigation is needed in other occupational hepatotoxic environments to determine if this association is limited to vinyl monomer type injury.
Adult↗
Urine phthalate determinations as an index of occupational exposure to phthalic anhydride and di(2-ethylhexyl)phthalate.
Although it has been estimated that over 600 000 workers in the United States are exposed to di(2-ethylhexyl)phthalate (DEHP), an animal carcinogen, and that over 100 000 are exposed to phthalic anhydride (PA), few data are available on levels of phthalates in biological fluids of these workers. For a determination of occupational exposure to PA and DEHP at a plant manufacturing DEHP from PA and 2-ethylhexanol, air samples were taken for PA and DEHP, and pre- and postshift urine samples were collected for the determination of total phthalates. Urine samples were obtained from 48 workers in jobs with high exposure to phthalates and from 47 workers in jobs with low exposure. The airborne concentrations of DEHP ranged from 20 to 4 110 micrograms/m3, and the concentrations of PA ranged from 4 to 203 micrograms/m3. The most heavily exposed workers had the highest mean postshift urine phthalate concentration (geometric mean 7.6 nmol/ml) (p = 0.015), and also the greatest mean increase (4.4 nmol/ml) in preshift to postshift urine phthalate levels. Twofold increases over the shift in urine phthalate concentration and postshift phthalate levels of greater than 10 nmol/ml were observed in 8 (25%) of 32 chemical operators, but in none of 52 other workers. These data suggest that measurement of urine phthalate levels may have utility for monitoring the exposure of workers manufacturing or using PA.
Air Pollutants, Occupational↗
Failure of enzyme encapsulation to prevent sensitization of workers in the dry bleach industry.
BDE added to dry bleach have been associated with immunologic sensitization and development of clinical allergic disease in detergent workers and occasionally in consumers. However, improved dust control and modification of the manufacturing process through encapsulation of enzyme were believed to have reduced or eliminated these problems. To determine whether or not immunologic sensitization could still develop in the detergent industry, we studied employees of a dry bleach manufacturing plant that incorporated encapsulated BDE into a consumer product. We performed air sampling for enzyme dust and total particulates, administered questionnaires, conducted physical examinations, and spirometry in 13 currently exposed, two previously exposed and nine nonexposed, employees. To assess sensitization status, RAST and ELISA were performed. Air concentrations of enzyme dust ranged from 0.002 to 1.57 micrograms/m3; all of these levels were below the TLV of 3.9 micrograms/m3. Positive BDE-specific RAST results (3.4%, 4.4%, and 8.0% binding) were obtained in three of 12 currently exposed workers. Results of personal breathing-zone air sampling indicated that these workers had high dust-exposure levels. Specificity of RAST was verified by RAST inhibition with BDE. BDE-RAST binding was not significantly elevated in the nonworkers (range: 0.6% to 1.4% binding). Positive results for specific IgG by ELISA were obtained in four of 12 currently exposed and in one of two previously exposed workers but in none of the nonexposed workers. We conclude that immunologic sensitization can develop after occupational exposure to encapsulated BDE in the dry bleach industry. We have not proved, however, that this immunologic reactivity is related to clinical sensitivity.
Adult↗
Occupational asthma in a home pieceworker.
A 67-yr-old woman presented to a free-standing medical center with respiratory distress of 1 day's duration. She was found on evaluation to have asthma associated with "dipping" the ends of polyurethane-coated wire into molten solder in the production, in her home, of components for the electronics industry. This process has been known to result in the evolution of isocyanates. The patient's sister had also developed cough and wheeze after she performed similar home piecework. Neither the manufacturer nor the distributors of the wire had provided a warning of its potential respiratory hazards. This episode emphasizes the importance of the occupational history, and of following-back thoroughly on cases of occupational disease. In addition, this episode reminds us that home pieceworkers are unlikely to have benefit of advice from industrial hygienists or others skilled in recognizing potentially hazardous situations.
Acute Disease↗
Peripheral sensory neuropathy associated with 1,1,1-trichloroethane.
A case is described of peripheral sensory neuropathy in a woman who had daily exposure to 1,1,1-trichloroethane, used as a degreasing agent. Although previous reviews of the health effects of 1,1,1-trichloroethane have not indicated long-term neurotoxicity, there are recent animal studies that suggest chronic central neurotoxic effects and previous case reports of peripheral neuropathy in three exposed workers in one plant. Our case provides additional evidence that 1,1,1-trichloroethane exposure may be associated with peripheral sensory neuropathy. Reporting of similar cases is encouraged and investigation of the neurotoxic effects of 1,1,1-trichloroethane is recommended.
Adult↗
Mortality among workers exposed to carbon disulfide.
Mortality experience was investigated at a plant in Ontario that produced viscose rayon, with carbon disulfide as a main raw material. Work-history records for 279 deceased workers at the plant (plant A) were obtained and compared with those for 511 deceased workers at a pulp and paper plant in the same city (plant B). In a proportional mortality analysis, using as a reference the general population of Ontario, at both plants there were fewer deaths from ischemic heart disease than expected (the proportional mortality ratios [PMRs] were 83 at plant A and 95 at plant B) but more deaths than expected from cerebrovascular disease (PMRs were 115 at plant A and 149 at plant B). In a subgroup of plant A workers who had been employed in high-carbon-disulfide exposure areas, deaths from ischemic heart disease were less than expected (PMR = 82), particularly among those who worked in these areas for more than 5 y. Most deaths occurred among those aged 65 y or more. Mortality from strokes, however, was greater than expected (PMR = 207, p < .05); the excess was confined to workers who died at age 65 y or older (PMR = 229, p = .01). Proportional mortality from strokes was also increased in the pulp workers among those who died at age 65 y or older (PMR = 153). In a case-control analysis, the risk of ischemic heart disease at plant A was slightly less than at plant B (odds ratio (OR] = 0.92, 95% confidence interval [CI] = 0.60-1.42), with no association between risk and years worked in high-carbon-disulfide areas (OR/y = 0.99, 95% CI = 0.94-1.03). Among those who died at age 65 y or older, the risk of stroke in the high-exposure subgroup was (a) increased significantly, compared with other plant A workers (OR = 4.92, 95% CI = 1.66-14.65); and (b) increased slightly, compared with plant B workers (OR = 1.37, 95% CI = 0.83-2.26). These results suggested an unusually low risk of strokes among other plant A workers. The risk of stroke was associated with years in high-carbon-disulfide areas (OR/y = 1.03, 95% CI = 0.96-1.1 0). The observed increase in proportional mortality from strokes may represent a chance finding, but a causal role for exposure cannot be excluded.
Age Factors↗
Improper office disposal of needles and other sharps: an occupational hazard outside of health care institutions.
An employee of a private disposal company suffered a finger needlestick injury while collecting waste at curbside from a building containing medical offices. Subsequent inspection of the contents of the garbage bags revealed the presence of used syringes and unsheathed needles. The Ministry of the Environment has developed a regulation and guidelines for the handling and disposal of biomedical waste including needles and other sharps. These specify that approved carriers and receivers are required for disposal; properly decontaminated waste is considered non-hazardous solid waste and can go to landfills. However, responsibility for curbside pickup of waste lies with municipalities; some municipalities have enacted by-laws which prohibit collection of this waste at the curbside. This incident illustrates that improper disposal of biomedical waste (including that from private practitioners' offices) may occur despite efforts to control its handling, and that needlestick injuries can occur outside of health care facilities among personnel who are not health care workers. Efforts are needed to increase the level of awareness among health professionals regarding their responsibility to ensure proper biomedical waste disposal from private offices. In addition, efforts should be made to bridge the gap between all levels of government regarding the disposal of biomedical waste.
Accidents, Occupational↗
Homicide in the workplace in Ontario: occupations at risk and limitations of existing data sources.
This study has identified workplace homicides in Ontario from 1975 to 1985, described those at risk, and examined what existing data sources are most suitable for locating the occurrence of these events. Homicides were identified from two sources: the Office of the Chief Coroner and the Ontario Mortality Database (OMDB). Of the 84 homicides identified, 87% occurred among males; the average annual work-related homicide rate was 0.17 per 100,000 workers, with a male-to-female ratio of 5.2:1. The rates in males were about one-eighth of those reported in California and Texas. The highest rates occurred among policemen, gas station attendants, security guards, and taxi drivers, and in restaurants and in certain retail operations such as jewelry stores. These homicides represented about 4% of all traumatic workplace fatalities. Firearms were responsible for 56% of these homicides and the motive was robbery in 50%. The OMDB proved to be an awkward source from which to identify such deaths because there is no "injury-at-work" field on death certificates. Other existing sources of data were not able to locate work-related homicides. Guidelines to protect those at high risk of assault and homicide should be developed.
Adolescent↗
Occupational exposure to Mycobacterium bovis infection in deer and elk in Ontario.
In late 1991, two herds of deer and elk were depopulated at a slaughtering plant in Ontario, followed by processing of infected animals at a rendering plant. We conducted a questionnaire plus tuberculin skin-test survey of 104 exposed slaughtering and rendering plant workers, and government veterinarians and inspectors. Overall, 17 participants were skin-test positive, one of 51 initially skin-test negative subjects tested a second time three months later became positive, consistent with the risk associated with occupational exposure during the depopulation of tuberculous elk previously observed in Alberta. Deer farming is widespread, with 263 herds in Ontario. The likely route of transmission is through aerosols. Possible reasons for the low conversion rate include the use of respiratory protection, absence of a tanning plant, an enclosed rendering plant process, and late skin testing which may have underestimated the number of conversions. Recommendations for prevention are summarized; in particular, respiratory protection for work with infected herds should probably include high efficiency particulate face masks.
Abattoirs↗