Occupational risk factors for congenital heart disease

Summary To investigate possible associations between cardiovascular malformations and maternal occupational exposure to various factors during the first trimester of pregnancy, 406 cases and 756 controls were studied retrospectively. The cases were taken from all infants diagnosed with cardiovascular malformations born in Finland during 1982 and 1983. The controls were randomly selected from all normal births in the country during the same period. All mothers were interviewed approximately 3 months after delivery by a midwife, using a structured questionnaire. Maternal overall exposure to chemicals at work was more prevalent among the case group (35.8%) than the control group (26.2%,P < 0.01). Among the specific chemical groups, maternal exposure to dyes, lacquers, or paints was significantly associated with the risk of congenital heart disease. Exposure to organic solvents during the first trimester seemed to increase to risk of ventricular septal defect (P < 0.05). Work at video display terminals was slightly more prevalent among the case group (6.3%) than among the control group (5.0%). The mothers' education level, regular exposure to passive smoking at work, or temperature at the workplace were not risk factors for congenital heart disease in the offspring, neither was maternal exposure to microwave ovens, disinfectants, pesticides, or anesthetic gases. It is concluded that many maternal exposures at work seem not to have a teratogenic effect on the fetal heart, although the limited power of this investigation needs to be borne in mind.     

Occupational titles as risk factors for Parkinson's disease

BACKGROUND: Job title or employment sector may be associated with Parkinson's disease (PD). METHODS: In a case-control study, in four European centres, lifetime occupational histories were coded using modified International Standard Industrial Classification (ISIC) and Dictionary of Occupational Titles (DOT). We employed multiple logistic regression analyses adjusting for age, gender, smoking and family history of PD. RESULTS: A total of 649 cases and 1587 controls were recruited. Scottish data showed a non-significant increased risk for agriculture (DOT: OR 1.32, 95% CI 0.81-2.16; ISIC: OR 1.30, 95% CI 0.84-2.02) and reduced risk for 'transport and communication' (ISIC: OR 0.60, 95% CI 0.37-0.97). Subsequent four-centre analyses showed reduced risk for processing occupations (DOT: OR 0.69, 95% CI 0.5-0.95). An association with pesticide exposure, found using detailed exposure assessment, was not apparent using job classification. CONCLUSIONS: In contrast to retrospective exposure assessment, job or industrial sector is a weak indicator of toxic exposures such that true associations may be missed.     

Occupational risk factors in Parkinson's disease

BACKGROUND: An apparent excess of teachers and healthcare workers among the Parkinson's disease patients of a large tertiary care movement disorders clinic suggested the hypothesis that high exposure to viral (or other) respiratory infections in these occupations might be a risk factor for Parkinson's disease. METHODS: A case-control study of the association between occupation and Parkinson's disease was conducted. Cases (414) were all Parkinson's disease patients seen at the University of British Columbia Hospital Movement Disorders Clinic between 1986 and 1993, residing in Greater Vancouver, and under 65 in 1991. Controls (6,659) were randomly selected from the 1991 Canadian Census. FINDINGS: Parkinson's disease was associated with teaching (OR 2.50, 95% CI 1.67-3.74) and occupation in healthcare services (OR 2.07, 95% CI 1.34-3.20), but there were several other substantial associations, both positive and negative. INTERPRETATION: While referral bias cannot be ruled out, the authors find the consistency of the overall pattern of associations with the respiratory infection hypothesis striking.     

A case-control study of Creutzfeldt-Jakob disease. Dietary risk factors

The mode of natural transmission of Creutzfeldt-Jakob disease remains unknown. In a case-control study conducted in 1981-1983 to evaluate possible dietary and other sources of the disease, 26 cases were ascertained in the mid-Atlantic region of the United States, 23 of which were obtained from accumulated records of the Laboratory of Central Nervous System Studies of the National Institutes of Health. Controls included 18 family members and 22 hospital-matched individuals (total sample size, 66). An increased consumption among patients was found for roast pork, ham, hot dogs (p less than 0.05), roast lamb, pork chops, smoked pork, and scrapple (p less than 0.1). An excess consumption of rare meat (p less than 0.01) and raw oysters/clams (p less than 0.1) was also reported among the patients. Liver consumption, among organ foods, was greater (p less than 0.1) among the cases. If Creutzfeldt-Jakob disease is acquired through ingestion of foods containing the agent, then the food items identified may be among those which need to be evaluated more intensively. Larger case-control studies with more focused dietary questions are warranted.     

European surveillance on Creutzfeldt-Jakob disease: a case-control study for medical risk factors

Medical risk factors for Creutzfeldt-Jakob disease (CJD) were analyzed in a prospective ongoing case-control study based on European CJD surveillance. Detailed data on past and recent medical history were analyzed in 405 cases and controls matched by sex, age, and hospital. Data were correlated with polymorphism at codon 129 of the prion protein gene. Our analysis did not support a number of previously reported associations and failed to identify any common medical risk factor for CJD. Although not statistically significant, brain surgery was associated with an increased risk of CJD. A detailed medical history should be obtained in every suspected CJD case in order to identify iatrogenic sources of CJD.     

Tissue classification for the epidemiological assessment of surgical transmission of sporadic Creutzfeldt-Jakob disease. A proposal on hypothetical risk levels

Background  

Epidemiological studies on the potential role of surgery in Creutzfeldt-Jakob Disease transmission have disclosed associations with history of specific surgical interventions or reported negative results.     

Assessing prion infectivity of human urine in sporadic Creutzfeldt-Jakob disease

Prion diseases are neurodegenerative conditions associated with a misfolded and infectious protein, scrapie prion protein (PrP(Sc)). PrP(Sc) propagate prion diseases within and between species and thus pose risks to public health. Prion infectivity or PrP(Sc) presence has been demonstrated in urine of experimentally infected animals, but there are no recent studies of urine from patients with Creutzfeldt-Jakob disease (CJD). We performed bioassays in transgenic mice expressing human PrP to assess prion infectivity in urine from patients affected by a common subtype of sporadic CJD, sCJDMM1. We tested raw urine and 100-fold concentrated and dialyzed urine and assessed the sensitivity of the bioassay along with the effect of concentration and dialysis on prion infectivity. Intracerebral inoculation of transgenic mice with urine from 3 sCJDMM1 patients failed to demonstrate prion disease transmission, indicating that prion infectivity in urine from sCJDMM1 patients is either not present or is <0.38 infectious units/mL.     

Occupational risk factors for prostate cancer

BACKGROUND: Occupational risk factors for prostate cancer have been investigated with inconsistent findings. METHODS: This was a population-based case-control study of men in Northeastern Ontario, Canada. Cases (n = 760) were from the Ontario Cancer Registry, 50 to 84 years old, and diagnosed with prostate cancer between 1995 and 1998. Age-frequency matched controls (n = 1,632) were obtained from telephone listings. A questionnaire yielded information on occupational history and self-reported exposures to a list of occupational hazards. Exposures to these hazards were assessed by an occupational hygienist. RESULTS: An odds ratio estimate (OR) of 1.21 (95 percent confidence interval (% CI) 1.01, 1.46) was found for employment in trades, transport and equipment operators and related occupations, possibly related to exposure to whole-body vibration (OR = 1.38, 95% CI 1.07, 1.78). For the highest quartile of lifetime cumulative workplace physical activity an OR of 1.33 (95% CI 1.02, 1.74) was found. No statistically significant associations were found for any other occupational category or exposure. CONCLUSIONS: This study does not provide strong evidence for significant occupational risk factors for prostate cancer. However, whole-body vibration exposures, as well as physical activity, may be worth pursuing in future occupational studies.     

Occupational risk factors for sarcoma subtypes

Herbicides, chlorophenols, and other occupational exposures are suspected risk factors for soft-tissue sarcoma, but the epidemiologic evidence is inconsistent. Given that soft-tissue sarcomas represent a heterogeneous mix of cancer subtypes and that these subtypes have different disease patterns by race, sex, and age at diagnosis, studying all soft-tissue sarcomas combined may mask subtype-specific associations. Using the Selected Cancers Study, a large population-based case-control study of sarcoma conducted among U.S. men aged 30 to 60 in 1984 to 1988, we explored the occupational risk factors for soft-tissue sarcoma subtypes and skeletal sarcoma. The analysis included 251 living sarcoma cases (48 dermatofibrosarcoma protuberans, 32 malignant fibrohistiocytic sarcoma, 67 leiomyosarcoma, 53 liposarcoma, and 51 skeletal sarcoma) and 1908 living controls. Exact conditional logistic regression models suggested patterns of subtype specificity for occupational exposures. Self-reported herbicide use was associated with malignant fibrohistiocytic sarcoma (OR = 2.9, 95% CI = 1.1-7.3). We found elevated risks for chlorophenol exposure and cutting oil exposure and malignant fibrohistiocytic sarcoma and leiomyosarcoma. We found no occupational risk factor for liposarcoma. Polytomous regression models identified different odds ratios across subtypes for plywood exposure and exposure to wood and saw dust. Although exploratory, this analysis suggests that occupational risk factors for sarcoma are not uniform across subtypes.     

Occupational risk factors for developing tuberculosis

We sought to assess whether there is an increased risk of tuberculosis among individuals who work in certain industries or occupations. A case-referent study of 149 male tuberculosis (TB) patients reported to the New Jersey Health Department from 1985 to 1987 and 290 referents was performed. Standardized interviews were conducted via the telephone or in person. Increased risk of TB was highest in heavy drinkers (OR = 3.33, 95% CL 1.99-5.59) and those who had a history of living with someone who had a history of TB (OR = 10.92, 95% CL 4.92-24.22). Occupations and industries associated with elevated risk for TB included: four silica-using industries—quarrying (OR = 3.96, 95% CL 0.36-44.02), pottery and related products (OR = 1.99, 95% CL 0.49-8.06), nonmetallic mineral and stone products (OR = 4.00, 95% CL 0.72-22.10), and ship and boat building and repair (OR = 1.84, 95% CL 0.76-4.43); hospitals (OR = 2.10, 95% CL 1.08-4.10); light truck drivers (OR = 2.49, 95% CL 1.30-4.77); agriculture (OR = 2.31, 95% CL 0.82-6.50); eating and drinking establishments (OR = 2.83, 95% CL 1.11-7.20); and janitors/cleaners (OR = 2.00, 95% CL 0.63-6.31). Except for janitors/cleaners, these elevated odds ratios remained for the above occupations/industries after controlling for alcohol or a history of having lived with someone with tuberculosis. Limitations of the study include a poor response rate (38%) and the exclusion of women from the study. © 1996 Wiley-Liss, Inc.     

Classification of sporadic Creutzfeldt-Jakob disease based on clinical and neuropathological characteristics

Creutzfeldt-Jakob disease (CJD) is a rare and fatal neurodegenerative disease of unknown cause. Patients are usually aged between 50 and 75 and typical clinical features include rapidly progressive dementia associated with myoclonus and a characteristic electroencephalographic pattern. Neuropathological examination reveals cortical spongiform change, hence the term 'spongiform encephalopathy'. Several statistical techniques were applied to classify patients with sporadic CJD (sCJD), based on clinical and neuropathological investigation. We focus on the classification of neuropathologically confirmed sCJD patients. In order to obtain a classification rule that correctly classifies this type of patients and at the same time controls the overall error rate, we apply several classification techniques, which in general, produce comparable results. The boosting method produces the best results and the variable 14-3-3 protein in cerebrospinal fluid plays the most important role in the prediction of neuropathologically confirmed sCJD.     

On the question of sporadic or atypical bovine spongiform encephalopathy and Creutzfeldt-Jakob disease

Strategies to investigate the possible existence of sporadic bovine spongiform encephalopathy (BSE) require systematic testing programs to identify cases in countries considered to have little or no risk of orally acquired disease or to detect a stable occurrence of atypical cases in countries in which orally acquired disease is disappearing. To achieve 95% statistical confidence that the prevalence for sporadic BSE is no greater than 1 per million (i.e., the annual incidence of sporadic Creutzfeldt-Jakob disease [CJD] in humans) would require negative tests in 3 million randomly selected older cattle. A link between BSE and sporadic CJD has been suggested on the basis of laboratory studies but is unsupported by epidemiologic observation. Such a link might yet be established by the discovery of a specific molecular marker or of particular combinations of trends over time of typical and atypical BSE and various subtypes of sporadic CJD, as their numbers are influenced by a continuation of current public health measures that exclude high-risk bovine tissues from the animal and human food chains.     

Occupational categories at risk for Parkinson's disease

BACKGROUND: The etiology of Parkinson's disease (PD) is considered to have a strong environmental component, but relatively few studies have investigated the potential association between occupation and the disease. METHODS: In a population-based case-control study, we collected comprehensive occupational histories from all study participants, 144 case and 464 control subjects. RESULTS: Chi-square analysis revealed that working in an agricultural occupation increased estimated PD risk (OR = 1.74; 95% CI = 0.85, 3.60). In contrast, a history of ever working in a service occupation was negatively associated with PD risk (OR = 0.69; 95% CI = 0.47, 1.00). Risk estimates were close to one for specific service occupations. Adjusted odds ratios for all non-service occupational and industrial categories were similar, and working in a service occupation was the only significant inverse predictor of PD risk. CONCLUSIONS: Future investigations focusing on lifestyle factors and environmental exposures within the agricultural and service occupational categories are warranted.     

Occupational risk factors for brain cancer in Canada

OBJECTIVE: We sought to examine the impact of occupational exposure on brain cancer risk. METHODS: Mailed questionnaires were used to collect information on lifetime employment history, occupational exposure to 18 chemicals, and other risk factors for 1009 incident cases of brain cancer and 5039 control subjects in Canada in 1994 to 1997. RESULTS: People exposed to asphalt and welding had respective odds ratio (and 95% confidence interval) of 1.29 (1.02-1.62) and 1.26 (0.98-1.45). An increased risk of brain cancer might be associated with exposure to asbestos, benzene, mineral or lubricating oil, isopropyl oil, and wood dust and with following occupations: teaching; protective service; metal processing and related jobs, and metal shaping and forming; knitting in textile processing; construction trades; and transport equipment operating. CONCLUSIONS: Our study suggests a possible role for occupational exposure in the etiology of brain cancer.     

Analysis of the geographical distribution of sporadic Creutzfeldt-Jakob disease in France between 1992 and 1998

BACKGROUND: Creutzfeldt-Jakob disease (CJD) is a rare fatal dementia caused by a transmissible agent. However, the mechanism leading to the disease is unknown in the majority of cases. The presence of geographically clustered cases might indicate a common environmental exposure to the transmissible agent, or case-to-case transmission of the agent. This study sought evidence of clustering of cases of sporadic CJD in France. METHODS: A total of 402 individuals who died from definite or probable sporadic CJD in France between 1992 and 1998 were analysed. The geographical distribution of cases was analysed using three different clustering methods. An analysis of the distribution of the distances between pairs was performed to look for evidence of clustering. Then, two methods of cluster detection were used to identify the locations of clusters. RESULTS: Each of our analyses found some evidence of clustering, though the extent of that clustering differed between approaches. The strongest evidence, statistically, related to three cases living in a small rural area in South-West France (P = 0.001). Two of the three cases lived in the same area throughout life. They had also both undergone surgery on several occasions. Little information is available on the third case. CONCLUSION: Some sporadic CJD cases in France may be aetiologically linked. There was strong evidence that three cases in South-West France formed a cluster but the precise mechanism underlying this cluster of cases remains unclear. The potentially long incubation period of the disease makes the identification of links between such cases difficult.     

Age-specific risk factors for sporadic Campylobacter infection in regional Australia

In a case-control study in the Hunter region of New South Wales, Australia, 354 cases and 593 controls were recruited to investigate meat, other food, and environmental exposures as potential risk factors for domestically acquired Campylobacter illness. In a multivariable model, illness was significantly associated with household exposure to diarrheal illness, consumption of restaurant chicken or beef, eating two or more "fast" food meals in a week, and overseas travel. Comparing exposures for the 0- to 4-year and 5-year and older age groups allowed detection of additional risk factors. Eating restaurant-prepared red meat and swimming were significantly associated with Campylobacter illness in the older group only. These findings demonstrate age-specific differences in risk factors for campylobacteriosis.     

Occupational differences in ischemic heart disease mortality and risk factors in Australia

Mortality rates from ischemic heart disease in Australia declined by about 25% over the period 1969-1978. The greatest declines were experienced by the professional occupations, while lower socioeconomic groups had higher mortality rates at the beginning of the period and experienced smaller declines. From a national survey in 1980, significantly and consistently lower risk levels of blood pressure, triglyceride, cigarette smoking, body mass and exercise were found among higher status occupation groups. This suggests that there is a pattern of coronary prevention behavior spanning multiple risk factors that is associated with a reduction in ischemic heart disease.