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9 HAAS and Carcinogenesis in Humans
Pages 243-273

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From page 243...
... . There are some 209 PCB congeners, but only a few recent epidemiologic studies have distinguished among them.
From page 244...
... If HAAs operate in humans, the activity should be most evident in tissues that are known targets for endogenous and exogenous sex steroid hormones. Thus, breast and endometrial cancers in women and prostate and testicular cancers in men were selected.
From page 245...
... 1997~. Breast-cancer mortality rates stayed fairly constant during the 1970s and 1980s (Miller et al.
From page 246...
... The studies have been varied: They include case-control studies, in which the chemical dose is measured in body adipose tissue or serum; occupational studies of highly exposed individuals, and ecologic analyses. Case-control studies are most likely to provide valid data because of the greater accuracy of the exposure measurement.
From page 248...
... (1990) analyzed adipose tissue from the breast tissue of 44 living cases and 33 postmortem controls for several organochlorines.
From page 249...
... Higher serum concentrations of PCBs and DDE were observed in cases than were found in controls. Using conditional multiple-logistic regression analysis and retention of first-degree family history, months of lactation, and age at first full-term pregnancy in the model, the odds ratio (OR)
From page 250...
... Conditional logistic regression allowed for matching of age and sex, adjustment for body mass index, age at first full-term pregnancy, and alcohol consumption. ORs were calculated by quartiles of the controls' DDE distribution, with the lowest quartile being the reference group.
From page 252...
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From page 254...
... 254 a' ·_4 o al o .5 ca o o Hi - +1 o ~ +1 a a ca a - o To to o ~ ~ ca o .
From page 255...
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From page 256...
... (1998) concluded that "there is no correlation between concentrations of these substances in the human body and breast cancer." Studies based on serum concentrations of various compounds include the Charleston Heart Study cohort of 405 white and black women who had blood drawn and analyzed for DDE in 1974-1975 (Sutherland et al.
From page 257...
... There were no associations between any of the specific DDT isomers or metabolites or any of the individual PCB congeners and breast cancer. Of the 46 compounds analyzed, however, only dieldrin showed a positive association with breast cancer risk: odds ratios of 1.96 and 2.05 in the top two quartiles of the distribution of values.
From page 258...
... Occupational studies are sometimes designed to use retrospective cohorts of employees working at a plant or in another occupational setting who are identified from employment records and characterized for likely exposure to the agent of interest. Exposure measurement is usually based on job title, industrial hygiene surveys of the ambient environment, measurements of air concentrations of chemicals, and, occasionally, sampling of blood concentrations.
From page 259...
... receptor and regulating the induction of specific forms of cytochrome P450, specifically aryl hydrocarbon hydroxylase (Skene et al.1989~. Ah receptor agonists, including TCDD, inhibit E2-induced responses in rodent models and in human mammary cell lines, suggesting antiestrogenic rather than estrogen agonist effects.
From page 260...
... Cause-specific national death rates and cancer-incidence rates were used as the referents. Exposure classification was based on job history; no blood concentrations of any chemicals were available for women.
From page 261...
... 1993~. As with the mortality study, relative risks and 95% confidence intervals were reported separately for each of the three exposure zones.
From page 262...
... 1995~. Ecologic Data Overall, existing epidemiologic data provide little support for a positive association between the HAAs discussed in this chapter and the risk of breast cancer (Longnecker et al.
From page 263...
... Specifically, after age 40, breast-cancer incidence rates are consistently higher in whites than they are in blacks, and the disparity increases with age. Conversely, serum concentrations of p,p'-DDE and PCBs are consistently reported to be higher in blacks than in whites (Krieger et al.
From page 264...
... to HAAs in the environment is not known. Although exposure to HAAs could be continuous, analogous to the administration of hormonal drugs, the potency of the HAAs is orders of magnitude lower than that of the endogenous steroid hormones present in premenopausal women or of exogenous HRT exposure in postmenopausal women (Adam)
From page 265...
... In California, the decline in endometrial cancer incidence was almost concurrent with the decline in prescribing estrogen for replacement therapy (Austin and Roe 1982~. After the estrogen-induced epidemic of the 1970s, age-adjusted incidence rates for endometrial cancer declined from 28.4 per 100,000 women in 1973 to 21.6 per 100,000 in 1992 (Kosary et al.1995~.
From page 266...
... The peak incidence rates are in the 25- to 39-yr age groups: for whites ages 30-34, 16.7 per 100,000; for blacks ages 25-29, 1.9 per 100,000, and for blacks ages 34-39, 1.9 per 100,000. Testicular canceris unlike most major cancers with respect to its rarity (particularly in blacks)
From page 267...
... HAAs AND CARCINOGENESIS IN HUMANS 267 cn O ,, , , , , , it ~>< / ~ V: Cry ~ ~ ~;; m ~ 0~ ~ ~O O ,, ~ Jilt} ~ lYc ~ ~.
From page 268...
... 1984~. Incidence rates for testicular cancer are available from cancer registries in ten northern European countries for the past 3-4 decades.
From page 269...
... Testicular cancer mortality rates were averaged for each 5-yr interval from 1971 to 1990. The coefficients from the regression analysis were negative in five of the six models, indicating no positive association between DDE and testicular cancer mortality some 2 to 22 yr later.
From page 270...
... Of the studies reviewed, none provided data on prostate cancer deaths (Bertazzi et al.1987; Brown and CDC 1987; Sinks et al.
From page 271...
... also evaluated prostate cancer mortality rates for the 22 states from which the U.S. EPA's Human Monitoring Program had human adipose tissue.
From page 272...
... There are no analytic epidemiologic studies that examine a connection between exposure to HAAs and testicular cancer. Increasing testicular cancer incidence rates in northern European countries and in North America are unlikely to be related to environmental DDT because exposure, as measured by concentrations of DDT metabolites in both serum and breast milk, has declined significantly over the past 40 yr.
From page 273...
... However, several studies show small increases in prostate cancer mortality in relation to TCDD exposure, although none of the risk estimates was statistically significant. The antiestrogenic activity of TCDD could alter the functional balance between estrogen and androgen in the prostate resulting in a hormonal environment conducive to cancer formation.


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