Studies Of Environmental Exposures Research Articles

A European validation study of smoking and environmental tobacco smoke exposure in nonsmoking lung cancer cases and controls.

The purpose of this study was to validate, in a case-control study, the reporting by lung cancer cases and controls of their own lifetime smoking habits and of the smoking habit of the spouse. In a multicenter (Sweden, Spain, Italy) case-control study of environmental tobacco smoke (ETS) and lung cancer, subjects were screened by repeated probing to exclude regular smokers of one cigarette/day or more for one year or more, and to quantify any occasional smoking. We then performed a short validation interview with next-of-kin in three centers. Only five of 408 index subjects who had never smoked regularly (1.7 percent) were reported by next-of-kin to be former regular smokers. These subjects had a cumulative lifetime consumption of cigarettes below 1.1 pack years. Among 351 subjects with quantitative smoking information from both sources who reported ever smoking 400 cigarettes or less (the definition of never-smoker used in the multicenter ETS study), nine subjects (2.6 percent) had smoked more than this amount occasionally according to next-of-kin. Misclassification was not higher for cases than controls. Relative risks for lung cancer associated with indicators of ETS exposure were not substantially altered by excluding the nine possibly misclassified subjects. The reports from 223 pairs of index subjects and next-of kin regarding the cumulative amount smoked by the spouse agreed quite well (Spearman's rank correlation 0.75 for reported smokers, 0.92 for all subjects). Only one index subject failed to report a spouse who had smoked regularly (99 percent sensitivity). Smoking status and exposure to spousal ETS as reported by lung cancer cases and controls agreed strongly with reports by next-of-kin. Overall, our results suggest that bias from smoker misclassification is likely to be insignificant, and they contribute to the evidence linking exposure to ETS with an increased risk of lung cancer.

Epidemiological approaches to infertility.

There are a number of reasons why epidemiological approaches to infertility have not made a major contribution to research in Australia. They include the success of generic treatments, the high public profile of infertility and the consequent polarization of discussion over treatment versus prevention, some reluctance to draw attention to possible aetiologic factors which may be perceived negatively in public debates, and the lack of graduate training in reproductive and perinatal epidemiology. Voluntary infertility is now common for most of the fertile life span in developed countries, and intended family size is small. Many important conditions cannot be diagnosed without the use of invasive procedures or complex investigations, and the more widespread use of less invasive procedures has shown other conditions to be relatively common in healthy populations. If epidemiological approaches are to make a greater contribution towards an increased understanding and control of infertility, research should focus on retrospective and prospective cohort studies of the incidence and prevalence of infertility, nested case-control studies of occupational and environmental exposures, and an extension of the developing use of record-linkage across routinely collected data systems and registers.

The Keokuk County Rural Health Study

SUMMARY The Keokuk County Rural Health Study is a population-based, prospective study of environmental exposures and health status of a large randomly-selected sample of residents from each of three strata in one rural Iowa county. The study focuses on injury rates and respiratory disease; in addition, it monitors health care de-livery; geriatric, reproductive, and mental health; and other health outcomes. Injury and disease prevalence are investigated in relation to occupational, agricultural, and other environmental exposures. This paper describes the sampling method, the protocol, and the demographic profile of adult subjects of the first 400 households en-rolled in the study. Farmers were slightly younger than rural non-farmers and townspeople and more farmers had lived in the county all of their lives. Females were more highly educated than were males, and less than half as many female farmers had lived in the county all their lives than had male farmers. Net household income figures were complex and are shown in a graph in Table 1.

Multiple sclerosis in India: a case-control study of environmental exposures.

To compare the rate of prior environmental exposures between Indian multiple sclerosis (MS) patients and controls in order to identify potential disease triggering factors. A standard self-administered questionnaire regarding prior exposures was presented to 56 Indian MS patients and 147 other neural disease and healthy controls at two large medical centers in India. The rate of prior foreign travel, surgeries, blood transfusions, clinical chicken pox and mumps infections and exposure to cats and farm animals was not significantly different between MS patients and controls. However, clinical measles infection and dog exposure occurred significantly more often in the MS patients. These findings are consistent with but do not prove an association between prior measles infection, dog exposure and MS.

Brain cancer and leukemia and exposure to power-frequency (50- to 60-Hz) electric and magnetic fields.

Concern about a possible association between cancer and electric and magnetic fields created by the generation and use of electricity first surfaced in response to the study of childhood cancer in Denver, Colorado, by Wertheimer and Leeper (1). Since then, nearly 90 epidemiologic studies of both occupational and environmental exposure have been published, and numerous reviews (e.g., references 2-6) of this literature exist. Most of the existing reviews have not evaluated the published studies in depth (e.g., references 3 and 7-10). Some (e.g., references 4, 5, and 11) have included several noncancer outcomes, thus broadening their research base and inhibiting extensive review of individual papers. Most have uncritically accepted whatever means of exposure assessment may have been used, when exposure assessment is the most critical and least understood element of these studies of electric and magnetic fields. This review focuses specifically on published occupational and environmental epidemiologic studies of exposure to power-frequency (50to 60-Hz) electric and magnetic fields and brain cancer and leukemia. Although several study design issues are discussed, we emphasize techniques for assessing exposure to electric and magnetic fields. The large variation in study design and quality among the papers reviewed precludes any meaningful quantitative analysis (such as meta-analysis), but it is possible among studies of a given design to select those with exposure assessment methodology most likely to rank subjects by actual exposure to electric and magnetic fields and to concentrate on those results. This we have attempted to

Occupational and environmental radiation and cancer.

Epidemiologic evidence on the relation between occupational and environmental radiation and cancer is reviewed. Studies of pioneering radiation workers, underground miners, and radium dial painters revealed excess cancer deaths and contributed to the setting of radiation protection standards and to theories of carcinogenesis. Occupational exposures today are generally much lower than in the past, thus any associated increases in cancer will be difficult to detect. Pooling investigations of these more recently exposed workers, however, has the potential to validate current estimates of risk used in radiation protection. New information on the effects of chronic radiation exposure also may come from studies in the former Soviet Union of Chernobyl clean-up workers and of workers at the Mayak nuclear facilities. Studies of environmental radiation exposures, other than radon, are largely inconclusive, due mainly to the difficulties in detecting the low risks associated with low dose exposures. Thyroid cancer, however, has been linked to environmental radiation from the Chernobyl accident and from nuclear weapons tests. Low-level radiation released during normal operations at nuclear plants has not been found to increase cancer rates in surrounding populations. Radon, a human carcinogen, is the most ubiquitous exposure to human populations; remediating high residential-radon levels is recommended, recognizing that the exposure can never be removed completely because it occurs naturally.

Breath measurements as volatile organic compound biomarkers.

A brief review of the uses of breath analysis in studies of environmental exposure to volatile organic compounds (VOCs) is provided. The U.S. Environmental Protection Agency's large-scale Total Exposure Assessment Methodology Studies have measured concentrations of 32 target VOCs in the exhaled breath of about 800 residents of various U.S. cities. Since the previous 12-hr integrated personal air exposures to the same chemicals were also measured, the relation between exposure and body burden is illuminated. Another major use of the breath measurements has been to detect unmeasured pathways of exposure; the major impact of active smoking on exposure to benzene and styrene was detected in this way. Following the earlier field studies, a series of chamber studies have provided estimates of several important physiological parameters. Among these are the fraction, f, of the inhaled chemical that is exhaled under steady-state conditions and the residence times. tau i in several body compartments, which may be associated with the blood (or liver), organs, muscle, and fat. Most of the targeted VOCs appear to have similar residence times of a few minutes, 30 min, several hours, and several days in the respective tissue groups. Knowledge of these parameters can be helpful in estimating body burden from exposure or vice versa and in planning environmental studies, particularly in setting times to monitor breath in studies of the variation with time of body burden. Improvements in breath methods have made it possible to study short-term peak exposure situations such as filling a gas tank or taking a shower in contaminated water.

Microprobe study of diode corrosion

A few diodes from a production lot were discovered to have unacceptable current leak rates after about 5 years of storage. Inspection revealed the presence of copper sulfide deposits that bridged the external body of the diode and presumably provided a leakage path. Figure 1 shows the physical configuration of a diode. The function of this device is performed by a silicon-based semiconductor that is bonded between two cylinders of tungsten with copper headpins (Cu wire with a flat “nail-head” formed on one end) brazed to the opposite ends of the cylinders. A toroidal ring of glass protects the Si chip. All exposed metal parts are covered by an immersion plating of Ag. Then the entire assembly is coated with black epoxy and a band of green ink is applied to the cathode end. During storage, each diode was placed in a cardboard holder and secured in stacks of about ten with rubber bands.Analytical and environmental exposure studies were performed at Allied Signal and Sandia to determine the cause and potential long-term significance of this corrosion-related degradation problem. The objective of the analytical work was to characterize the corrosion product and help identify the corrosion mechanism. Tools included optical microscopy, scanning electron microscopy, electron microprobe analysis, SIMS, and x-ray diffraction.

COMBINING ENVIRONMENTAL INFORMATION. II: ENVIRONMENTAL EPIDEMIOLOGY AND TOXICOLOGY

An increasingly important concern in epidemiological and toxicological studies of environmental exposures is the need to combine information from diverse sources that relate to a common endpoint. This is clearly a statistical activity, but statistical techniques for data combination are still only developmental. Herein, we illustrate some current applications of combining information in environmental epidemiology and toxicology, with emphasis on the burgeoning use of meta-analyses for environmental settings. Our goal is to inform readers about modern statistical techniques useful for combining environmental information, with emphasis on more recently developed approaches.

Validity criteria for the use of biological markers of exposure to chemical agents in environmental epidemiology

Biomarkers may prove very useful in increasing the precision of exposure estimates during field epidemiological studies of environmental and occupational exposures. However, the determination of validity of exposure biomarkers is a laborious process. It is also a process that needs collaboration between laboratory and field scientists if biological markers of exposure are to be useful tools in environmental epidemiology.

Organic Halogens in the Environment: Studies of Environmental Biodegradability and Human Exposure

Organic Halogens in the Environment: Studies of Environmental Biodegradability and Human Exposure

Lessons learned from epidemiologic studies of environmental exposure and genetic disease

The induction of germ cell mutations with ionizing radiation and chemicals has been clearly demonstrated in experimental animal test systems. Less is known about the effects of environmental and other exposures on human germ cells. Epidemiologic studies of atomic bomb and childhood cancer survivors and their offspring have generally not indicated an excess risk for a variety of adverse reproductive outcomes and childhood diseases, including those due to germ cell mutations. Other epidemiologic studies, including the investigation of cancer among the offspring of fathers employed at the Sellafield nuclear facility in Great Britain and studies of paternal occupation and birth defects, have found associations. This paper reviews these studies and the methodologic problems inherent in the epidemiologic approach to evaluating environmentally induced germ cell mutagenesis in humans. Epidemiologic studies incorporating newly developed techniques for the detection of mutations and abnormalities in sperm may provide the sensitivity needed to determine precisely the magnitude of risk.

Reliability of environmental and occupational exposure data provided by surrogate respondents in a case-control study of Parkinson's disease

This study used data provided by 40 non-demented Parkinson's disease patients and 101 community controls, and by their 110 spouses and 31 adult children to assess the reliability of surrogate-provided rural environmental and occupational exposure information on the index subjects. The level of overall raw agreement between the index subjects and the spouse or adult child surrogates varied from 50.0 to 100.0% for the case-surrogate group and from 80.6 to 96.0% for the control-surrogate group. We did not detect significant differences in overall raw agreement between the case-surrogate and control-surrogate groups or between the spouse-surrogate and adult child-surrogate groups, for any of the variables studied. Considering all index subjects and their surrogates, the level of overall raw agreement was 80.3% for well water consumption, 82.3% for farm living, 85.8% for agricultural work, 87.1% for use of pesticides, 87.9% for field crop farming and 91.9% for use of fertilizers. However, the kappa estimates were lower, varying from 0.48 (SE = 0.20) for fertilizer use to 0.66 (SE = 0.11) for crop farming. The level of specific agreement was 52.2% for fertilizer use, 64.0% for pesticide use, 71.4% for agricultural work, 73.9% for crop farming, 80.9% for farm living, and 83.6% for well water consumption. The overall findings of this study support the use, if necessary, of spouses and adult children of index subjects as surrogate respondents in case-control studies of rural environmental and occupational exposures and Parkinson's disease and, possibly, other neurologic diseases. Specific agreement seems to be a better index of reliability than overall agreement in studies where exposure is rare.

An ecologic study of skin cancer and environmental arsenic exposure.

We conducted an epidemiologic study of skin cancer incidence rates for four counties in Montana. The two counties considered to be exposed to arsenic were Deer Lodge, containing the former Anaconda copper smelter, and Silver Bow, containing an open pit copper mine. Residents in these counties had potential exposure to arsenic and other heavy metals. Gallatin and Park counties served as controls. All histologically proven skin cancer cases during the period January 1980 through June 1986 were collected from pathology services and dermatologists in these four counties. In addition, all skin cancer cases from four dermatologists practicing in urban referral areas outside the counties were reviewed. Results were analyzed by individual as well as by two different definitions of anatomically distinct lesions: the National Cancer Institute (NCI) definition and the study definition. There were 1616 individuals with skin cancer in the four counties during the period under consideration, yielding 2252 (NCI definition) and 2451 (study definition) cases. The clinical features of the skin cancers in the exposed counties were not similar to those described for arsenic-related skin cancer. The age-adjusted annual skin cancer rates were higher for the two control counties as compared to either the county with the former smelter, Deer Lodge, or the county with the mine, Silver Bow. Our results cannot be explained by differences in ascertainment, latitude, or altitude. They can be partially explained by differences in both outdoor employment and medical practice. The overall skin cancer incidence rates for the exposed counties were well within the range of skin cancer rates observed for other locations in the United States.

(B8) Case control study of occupational and environmental exposure and myelodysplasia

(B8) Case control study of occupational and environmental exposure and myelodysplasia

Solvent exposure and cardiovascular disease

A review of cardiovascular disease (CVD) resulting from environmental exposures pointed out the lack of studies concerned with the cardiovascular effects of hazardous environmental exposures. A later Working Group report on CVD in the workplace recommended further occupational studies of CVD, and it identified carbon monoxide, nitrates, and organic solvents as exposures especially deserving of study. The literature lacks a detailed, critical epidemiologic overview of work on this last topic. Therefore, the following review focuses on the cardiovascular effects of solvent exposures. Some major difficulties inherent in studies of CVD and environmental exposures are brought out, and some suggested areas for future epidemiologic research are discussed.

What causes cryptogenic fibrosing alveolitis? A case-control study of environmental exposure to dust.

To investigate the role of occupational and domestic exposure to dust in the aetiology of cryptogenic fibrosing alveolitis. Matched case-control study. 40 Patients with cryptogenic fibrosing alveolitis and 106 community controls matched for age and sex who responded to a questionnaire. Responses to self administered questionnaire asking about lifetime exposure to dust, animals, and smoke at home and at work. The patients with cryptogenic fibrosing alveolitis were more likely to report occupational exposure to metal dust (matched odds ratio 10.97 (95% confidence interval 2.30 to 52.4), p less than 0.001) or wood dust (2.94 (0.87 to 9.90), p = 0.08), to have worked with cattle (10.89 (1.24 to 96.0), p = 0.01), and to have lived in a house heated by a wood fire (12.55 (1.04 to 114), p = 0.009). A history of smoking and social class based on occupation were not significantly related to disease state. Environmental exposure to dust may be an important factor in the aetiology of cryptogenic fibrosing alveolitis.

A Nordic data base on somatic chromosome damage in humans

Analyses of cytogenetic damage — chromosome aberrations (CA), micronuclei (MN), and sister-chromatid exchange (SCE) — are used to assess genotoxic exposure, on the supposition that higher levels of chromosome damage in peripheral lymphocytes reflect increased cancer risk. We attempt to test this hypothesis prospectively, by relating levels of cytogenetic damage to subsequent cancer morbidity in a cohort comprising 3190 subjects. All these subjects have been analyzed previously (1970–1988) for CA, MN, and/or SCE in studies of occupational and environmental exposure. The present paper describes the data base and assesses how the potential confounders smoking habits, sex, and age influence CA, MN, and SCE levels. Ten Nordic laboratories contributed data. In the present analyses, these data were treated separately to avoid the effects of interlaboratory differences. Point estimates from multiple regression analyses indicate that smoking may increase CA frequencies by up to 10–20% and SCE means by 5–8%, but that it has no effect on MN frequencies. Women had higher CA, MN, and SCE levels than men, but the sex effect was generally smaller than the effect of smoking. Age was positively associated with cytogenetic damage. Compared to the sex effect, the effect of a 10-year age increase was similar on CA, but less, 1–3%, on SCE. The amount of variation explained by the potential confounders taken together was generally low, often less than 20%. Thus, other still unknown factors must be the major sources of CA, MN, and SCE variability.

The corrosion protection behaviour of aluminum nitride and silicon dioxide coatings on magneto-optical media

Aluminum nitride (Al-N) thin films were used as protective overcoats for terbium-iron (Tb-Fe) magneto-optical media. Protective performance of the aluminum nitride overcoats was evaluated by electrochemical polarization, immersion tests and environmental exposure studies. The corrosion currents for Al-N coated Tb-Fe films were significantly lower than those of unprotected Tb-Fe films indicating that Al-N protected films have lower corrosion rates. Further, Al-N coatings were found to exhibit better corrosion resistance than silicon dioxide (SiO 2) overcoated Tb-Fe films. The corrosion resistance of the magneto-optical medium depends upon the architecture of the disk. Protective layers of Al-N both above and below the Tb-Fe layer yield greater corrosion resistance than a single overcoat of Al-N. The electrochemical corrosion results are consistent with the environmental exposure behaviour of these coatings and with the results of immersion tests.

Epidemiological studies of environmental exposure and specific diseases.

This paper includes many different epidemiological approaches to environmental health studies, and examples and discussion in terms of a limited number of exposures and diseases are provided. The methods described are not unfamiliar, but, by presenting a panorama in a linked context, it is intended to be constructive in developing ideas.