Occupational and environmental risks of spontaneous abortions around a smelter

Ambient temperature and stillbirth risks in northern Sweden, 1880-1950

Background

Climate vulnerability of the unborn can contribute to adverse birth outcomes, in particular, but it is still not well understood. We investigated the association between ambient temperature and stillbirth risk among a historical population in northern Sweden (1880-1950).

Methods

We used digitized parish records and daily temperature data from the study region covering coastal and inland communities some 600 km north of Stockholm, Sweden. The data included 141,880 births, and 3,217 stillbirths, corresponding to a stillbirth rate of 22.7 (1880-1950). The association between lagged temperature (0-7 days before birth) and stillbirths was estimated using a time-stratified case-crossover design. Incidence risk ratios (IRR) with 95% confidence intervals were computed, and stratified by season and sex.

Results

We observed that the stillbirth risk increased both at low and high temperatures during the extended summer season (April to September), at -10°C, and the IRR was 2.3 (CI 1.28, 4.00) compared to the minimum mortality temperature of +15°C. No clear effect of temperature during the extended winter season (October to March) was found. Climate vulnerability was greater among the male fetus compared to the female counterparts.

Conclusion

In this subarctic setting before and during industrialization, both heat and cold during the warmer season increased the stillbirth risk. Urbanization and socio-economic development might have contributed to an uneven decline in climate vulnerability of the unborn.

Reproductive outcomes among male and female workers at an aluminum smelter

OBJECTIVES

Several adverse pregnancy outcomes were reported among female laboratory workers in a North American aluminum smelter. To determine whether these outcomes were associated with any occupational exposure at the plant, a cross-sectional survey was undertaken.

METHODS

Rates of miscarriage, premature singleton birth, and major congenital anomaly occurring during employment were compared with a reference group comprised of all pregnancies that occurred before employment.

RESULTS

Among female workers, the excess of congenital anomalies among female laboratory workers that defined the initial cluster was observed, but no specific pattern was found.

CONCLUSIONS

On the basis of these analyses, the increase in congenital anomalies could not be attributed to occupational exposures at the smelter nor could potential exposure likely explain the diverse anomalies described.

Epidemiologic evidence of relationships between reproductive and child health outcomes and environmental chemical contaminants

This review summarizes the level of epidemiologic evidence for relationships between prenatal and/or early life exposure to environmental chemical contaminants and fetal, child, and adult health. Discussion focuses on fetal loss, intrauterine growth restriction, preterm birth, birth defects, respiratory and other childhood diseases, neuropsychological deficits, premature or delayed sexual maturation, and certain adult cancers linked to fetal or childhood exposures. Environmental exposures considered here include chemical toxicants in air, water, soil/house dust and foods (including human breast milk), and consumer products. Reports reviewed here included original epidemiologic studies (with at least basic descriptions of methods and results), literature reviews, expert group reports, meta-analyses, and pooled analyses. Levels of evidence for causal relationships were categorized as sufficient, limited, or inadequate according to predefined criteria. There was sufficient epidemiological evidence for causal relationships between several adverse pregnancy or child health outcomes and prenatal or childhood exposure to environmental chemical contaminants. These included prenatal high-level methylmercury (CH(3)Hg) exposure (delayed developmental milestones and cognitive, motor, auditory, and visual deficits), high-level prenatal exposure to polychlorinated biphenyls (PCBs), polychlorinated dibenzofurans (PCDFs), and related toxicants (neonatal tooth abnormalities, cognitive and motor deficits), maternal active smoking (delayed conception, preterm birth, fetal growth deficit [FGD] and sudden infant death syndrome [SIDS]) and prenatal environmental tobacco smoke (ETS) exposure (preterm birth), low-level childhood lead exposure (cognitive deficits and renal tubular damage), high-level childhood CH(3)Hg exposure (visual deficits), high-level childhood exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (chloracne), childhood ETS exposure (SIDS, new-onset asthma, increased asthma severity, lung and middle ear infections, and adult breast and lung cancer), childhood exposure to biomass smoke (lung infections), and childhood exposure to outdoor air pollutants (increased asthma severity). Evidence for some proven relationships came from investigation of relatively small numbers of children with high-dose prenatal or early childhood exposures, e.g., CH(3)Hg poisoning episodes in Japan and Iraq. In contrast, consensus on a causal relationship between incident asthma and ETS exposure came only recently after many studies and prolonged debate. There were many relationships supported by limited epidemiologic evidence, ranging from several studies with fairly consistent findings and evidence of dose-response relationships to those where 20 or more studies provided inconsistent or otherwise less than convincing evidence of an association. The latter included childhood cancer and parental or childhood exposures to pesticides. In most cases, relationships supported by inadequate epidemiologic evidence reflect scarcity of evidence as opposed to strong evidence of no effect. This summary points to three main needs: (1) Where relationships between child health and environmental exposures are supported by sufficient evidence of causal relationships, there is a need for (a) policies and programs to minimize population exposures and (b) population-based biomonitoring to track exposure levels, i.e., through ongoing or periodic surveys with measurements of contaminant levels in blood, urine and other samples. (2) For relationships supported by limited evidence, there is a need for targeted research and policy options ranging from ongoing evaluation of evidence to proactive actions. (3) There is a great need for population-based, multidisciplinary and collaborative research on the many relationships supported by inadequate evidence, as these represent major knowledge gaps. Expert groups faced with evaluating epidemiologic evidence of potential causal relationships repeatedly encounter problems in summarizing the available data. A major driver for undertaking such summaries is the need to compensate for the limited sample sizes of individual epidemiologic studies. Sample size limitations are major obstacles to exploration of prenatal, paternal, and childhood exposures during specific time windows, exposure intensity, exposure-exposure or exposure-gene interactions, and relatively rare health outcomes such as childhood cancer. Such research needs call for investments in research infrastructure, including human resources and methods development (standardized protocols, biomarker research, validated exposure metrics, reference analytic laboratories). These are needed to generate research findings that can be compared and subjected to pooled analyses aimed at knowledge synthesis.

Science linking environmental contaminant exposures with fertility and reproductive health impacts in the adult female

STUDY OBJECTIVE

To broadly review the recent literature linking environmental factors and adult female reproductive health for the UCSF-CHE Summit on Environmental Challenges to Reproductive Health and Fertility.

DESIGN

Reviewed articles indexed in PubMed from 1999-2007 addressing environment and puberty, menstrual and ovarian function, fertility, and menopause.

RESULT(S)

The strongest evidence of environmental contaminant exposures interfering with healthy reproductive function in adult females is for heavy metals, particularly lead. Compounds that can influence hormone function, including pesticides and persistent pollutants, are also associated with risk. The pattern of effects for these endocrine-active compounds is often complex, with no clear dose response, but alterations in function and poor reproductive health outcomes are observed. From a clinical perspective, most modifiable risk appears to be associated with exposures in unique populations (contaminated fish consumers) or occupational groups (farmworkers). Many compounds have demonstrated increased risks for reproductive health impairment in women, but the literature is largely cross-sectional in nature and too sparse or inconclusive to support causal inference.

CONCLUSION(S)

Reproductive function in adult females is impaired by lead exposure. Pesticides and persistent pollutants can alter hormone function resulting in adverse reproductive health effects. Coordinated research is needed to address contaminant effects across the life span.

The influence of the environment and other exogenous agents on spontaneous abortion risk

It is estimated that close to 30% of all pregnancies end in spontaneous abortion. Although about 60% of spontaneous abortions are thought to be due to genetic, infectious, hormonal, and immunological factors, the role of the environment remains poorly understood. Pregnancy involves a delicate balance of hormonal and immunological functions, which may be affected by environmental substances. Many toxic substances that are persistent in the environment and accumulate in the fatty tissues may disrupt this equilibrium. This overview addresses known risk factors for spontaneous abortions and examines the role, if any, that environmental factors (chemical and physical) may play in the etiology of this adverse health outcome.

Comparative analysis of gynaecological status of workers from textile and metal industry

Introduction Female workers in textile and metal industry are exposed to various physical and chemical hazards that can lead to the occurrence of gynaecological diseases. Objective The aim of this study was to estimate the frequency of gynaecological diseases among workers of textile and metal industries. METHOD The investigation comprised 197 female workers, 148 from textile and 49 from metal industry, aged from 26 to 57 years. All subjects were hospitalized based on non-gynaecological diagnoses. Gynaecological diagnoses included: tumours of the genital organs and breasts, cervical ectopy and lacerations, inflammatory diseases, disturbances of static of genital organs, cysts, and irregularities of menstrual cycle. Results Textile workers were significantly younger than metal workers, but the groups were comparable according to total and exposure work-time, qualifications and diagnosis on hospital admission. Gynaecological diseases were diagnosed among all investigated subjects. About 80% were diagnosed with tumours and inflammatory diseases. A highly statistically significant difference was observed among groups according to the presence of cervical ectopy and lacerations, which were more frequent among textile workers. Conclusion Comparison of gynaecological status of workers revealed that, among textile workers, cervical ectopy and lacerations were more frequent than among workers in metal industry. .

Acute intermittent porphyria in women: clinical expression, use and experience of exogenous sex hormones. A population-based study in northern Sweden

OBJECTIVE

To describe the clinical expression of acute intermittent porphyria (AIP) in women, their use of exogenous sex hormones, and the effects on AIP.

DESIGN

A retrospective population-based study.

SUBJECTS

All women aged > or =18 years (n = 190) with DNA-diagnosed AIP in northern Sweden.

RESULTS

A total of 166 women (87%) participated; 91 (55%) had manifest AIP. Severe attacks were reported by 82%; 39% reported recurrent premenstrual AIP attacks and 22% reported chronic AIP symptoms. Oral hormonal contraceptives had been used by 58% of all these women and by 50 with manifest AIP (57%). Twelve women (24%) associated oral contraceptives as precipitating AIP attacks; in nine cases their first attack. One woman experienced relief from AIP symptoms. On commencing their treatment, 72% of the women with manifest AIP had not yet suffered their first attack. Twenty-two women (25%) aged > or =45 years had used hormonal replacement therapy (HRT) at menopause to remedy climacteric symptoms (the percutaneous route was most frequently used); no AIP attack was precipitated. HRT to remedy vaginal dryness was used by 26 women (28%) aged > or =45 years without triggering an AIP attack. Miscarriages were more frequent in women with manifest AIP (50%) than in the latent group (30%, P = 0.014).

CONCLUSIONS

About half of the women with AIP had used oral hormonal contraceptives. As 25% of women with manifest AIP reported attacks associated with such drugs, caution must still be recommended. Menopausal HRT only rarely affected the disorder. Miscarriage was more common amongst women with manifest AIP.