Organochlorine Residues and Risk of Breast Cancer

Epidemiological Studies and Effects of Environmental Estrogens

Increases in cancer of the testis, breast, and prostate have been noted recently, and these increases have often been attributed to a ubiquitous exposure to endocrine-modulating substances. In an effort to either prove or refute these associations, morbidities of (and mortalities from) certain hormonally responsive organs are reviewed. Cancer of the breast, ovary, uterus, cervix, prostate, and testis were selected for comparison and analysis of trends in incidence and mortality. The incidences of cryptorchidism and hypospadias were selected as birth defects representative of possible effects from in utero exposure to excessive estrogens. Sperm counts and endom etriosis were selected as other possible indicators of environmental estrogen effects. Wide, sometimes orders of magnitude, variability exists between incidences in some indicators between different geographical areas and between ethnic groups. Some explanations unrelated to environmental exposures are apparent, and some observations contradict a universal exposure to the same endocrine-modulating substance. In addition, wide differences in incidences exist among virtually adjacent geographical areas and between ethnic groups living in the same geographic area. The data available at present do not lead to the conclusion that endocrine-modulating substances account for worldwide trends in these epidem iological studies.

The Long Island Breast Cancer Study Project: description of a multi-institutional collaboration to identify environmental risk factors for breast cancer

The Long Island Breast Cancer Study Project is a federally mandated, population-based case-control study to determine whether breast cancer risk among women in the counties of Nassau and Suffolk, NY, is associated with selected environmental exposures, assessed by blood samples, self-reports, and environmental home samples. This report describes the collaborative project's background, rationale, methods, participation rates, and distributions of known risk factors for breast cancer by case-control status, by blood donation, and by availability of environmental home samples. Interview response rates among eligible cases and controls were 82.1% (n = 1,508) and 62.8% (n = 1,556), respectively. Among case and control respondents who completed the interviewer-administered questionnaire, 98.2 and 97.6% self-completed the food frequency questionnaire; 73.0 and 73.3% donated a blood sample; and 93.0 and 83.3% donated a urine sample. Among a random sample of case and control respondents who are long-term residents, samples of dust (83.6 and 83.0%); soil (93.5 and 89.7%); and water (94.3 and 93.9%) were collected. Established risk factors for breast cancer that were found to increase risk among Long Island women include lower parity, late age at first birth, little or no breast feeding, and family history of breast cancer. Factors that were found to be associated with a decreased likelihood that a respondent would donate blood include increasing age and past smoking; factors associated with an increased probability include white or other race, alcohol use, ever breastfed, ever use of hormone replacement therapy, ever use of oral contraceptives, and ever had a mammogram. Long-term residents (defined as 15+ years in the interview home) with environmental home samples did not differ from other long-term residents, although there were a number of differences in risk factor distributions between long-term residents and other participants, as anticipated.

Environmental endocrine modulators and human health: an assessment of the biological evidence

Recently, a great deal of attention and interest has been directed toward the hypothesis that exposure, particularly in utero exposure, to certain environmental chemicals might be capable of causing a spectrum of adverse effects as a result of endocrine modulation. In particular, the hypothesis has focused on the idea that certain organochlorine and other compounds acting as weak estrogens have the capability, either alone or in combination, to produce a variety of adverse effects, including breast, testicular and prostate cancer, adverse effects on male reproductive tract, endometriosis, fertility problems, alterations of sexual behavior, learning disability or delay, and adverse effects on immune and thyroid function. While hormones are potent modulators of biochemical and physiological function, the implication that exposure to environmental hormones (e.g., xenoestrogens) has this capability is uncertain. While it is reasonable to hypothesize that exposure to estrogen-like compounds, whatever their source, could adversely affect human health, biological plausibility alone is an insufficient basis for concluding that environmental endocrine modulators have adversely affected humans. Diethylstilbestrol (DES) is a potent, synthetic estrogen administered under a variety of dosing protocols to millions of women in the belief (now known to be mistaken) that it would prevent miscarriage. As a result of this use, substantial in utero exposure to large numbers of male and female offspring occurred. Numerous studies have been conducted on the health consequences of in utero DES exposure among the adult offspring of these women. There are also extensive animal data on the effects of DES and there is a high degree of concordance between effects observed in animals and humans. The extensive human data in DES-exposed cohorts provide a useful basis for assessing the biological plausibility that potential adverse effects might occur following in utero exposure to compounds identified as environmental estrogens. The effects observed in both animals and humans following in utero exposure to sufficient doses of DES are consistent with basic principles of dose response as well as the possibility of maternal dose levels below which potential non-cancer effects may not occur. Significant differences in estrogenic potency between DES and chemicals identified to date as environmental estrogens, as well as an even larger number of naturally occurring dietary phytoestrogens, must be taken into account when inferring potential effects from in utero exposure to any of these substances. The antiestrogenic properties of many of these same exogenous compounds might also diminish net estrogenic effects. Based on the extensive data on DES-exposed cohorts, it appears unlikely that in utero exposure to usual levels of environmental estrogenic substances, from whatever source, would be sufficient to produce many of the effects (i.e., endometriosis, adverse effects on the male reproductive tract, male and female fertility problems, alterations of sexual behavior, learning problems, immune system effects or thyroid effects) hypothesized as potentially resulting from exposure to chemicals identified to date as environmental estrogens.

Ethnicity and variation in breast cancer incidence

A breast cancer case-control study in Atlanta and 5 counties of central New Jersey involving interviews with 960 white and 281 black cases younger than 54 years of age enabled assessment of reasons for the varying incidence rates among these 2 ethnic groups. Of interest was why rates of breast cancer are higher among older white women, a trend that is reversed among very young women (<40 years). Calculation of the prevalence of exposure to classic and speculative risk factors and associated relative risks enabled derivation of population attributable risks (PARs) for the various combinations of age and ethnic groups. A higher PAR was derived for older (40-54 years) white (62%) than black (54%) women, which appeared to account for the observed difference in incidence between the 2 ethnic groups. Most of the difference in PARs between older whites and blacks was accounted for by whites having fewer births, later ages at first birth and slightly higher risks associated with reproductive and menstrual factors. Consideration of only well-established breast cancer risk factors showed a PAR among older whites of 57%, an estimate comparable to those previously published. Slightly higher overall PARs were derived when analyses considered several speculative but modifiable risk factors, including years of use of oral contraceptives, body size and alcohol consumption. Many of the analyses among younger women (20-39 years) were limited by available numbers, but it appeared that very little disease occurrence in young black women was associated with the factors studied.

Analytical methods for the determination of organochlorine compounds. Application to environmental samples in the Slovak Republic

The paper deals with the isolation of chlorinated phenols, benzenes and insecticides from water, soil and vegetable samples. A review of the current procedures is presented. Solid-phase extraction on Empore extraction discs was experimentally evaluated for isolation of the compounds from surface and ground waters. For the isolation of chlorophenols from soil and vegetable samples, a method of simultaneous steam distillation/extraction was elaborated which proved to be also applicable for waste waters and sludges. Chlorinated insecticides and benzenes were extracted from soil and vegetable samples with the Soxhlet procedure. Final determinations were carried out by GC-electron-capture detection. The recoveries of the methods were well over 70%, with relative standard deviations below 14%. Samples of surface and ground waters, soil and vegetables, mostly from the vicinity of chemical and municipal waste dumping sites, were analysed. The highest contamination levels were found for chlorinated phenols in surface water from the vicinity of a former chemical waste dumping place where the concentrations of 2,6-dichlorophenol and pentachlorophenol were 4.3 and 3.9 micrograms l-1, respectively.

Environmental estrogenic effects of alkylphenol ethoxylates

Alkylphenol ethoxylates (APEs) and related compounds recently have been reported to be estrogenic because it has been demonstrated in laboratory studies that they mimic the effects of estradiol both in vitro and in vivo. Chemicals referred to as "environmental estrogens" are suspected of causing health effects in both humans and wildlife through disruption of the endocrine system. In this review, the occurrence, environmental fate, and biological effects of APEs are presented. To provide understanding of the potential for endocrine disruption due to environmental estrogens, the physiology of estrogens in mammals and fish is also reviewed. The estrogenic potency of other environmental estrogens is compared to the potency of APE degradation products. The reproductive effects of estrogenic compounds are considered when evaluating the potential health effects of APEs. Given the reported environmental concentrations and bioconcentration factors of APE products, the potential for these compounds to produce estrogenic effects in the environment appears low. Although questions concerning the physiological effects of APEs and other environmental estrogens remain unanswered, there are indications that research is in progress that will lead to better understanding of the risks to humans and wildlife.