Hormonally Active Agents in the Environment (1999) / Chapter Skim
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3 Exposures: Sources and Dynamics of Hormonally Active Agents in the Environment
3 Exposures: Sources and Dynamics of Hormonally Active Agents in the Environment
Pages 54-81
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From page 54... ...
. Dose is based on exposure intake and body weight or surface area of the target organism (milligrams per kilogram of body weight per day or milligrams per square meter per hour)
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From page 55... ...
Humans and animals can be exposed involuntarily to synthetic HAAs as a result of drinking contaminated water, breathing contaminated air, ingesting food, or contacting contaminated soil. Humans can also be exposed voluntarily to many synthetic HAAs by using HAA-containing commercial products, such as cleaners, pesticides, and food additives (domesticated animals can also be exposed to these products, but such exposure is assumed to be involuntary)
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From page 56... ...
Concentrations of both isoflavones generally exceeded 200 ,ug/g in most samples (Reinli and Block 1996~. Synthetic HAAs Numerous synthetic chemicals have been implicated as HAAs.
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From page 57... ...
57 o ~ ~ ~ at ~ ~ ~ ~ ~ ~O ~O ~ i= ~O ~ ~I! i~:ie ~ ulcer ~ ~ _ _ ~ ~ ~ B _ a B c i, ~ ~ b ~ .
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From page 58... ...
In the United States, forest fires account for approximately 20 kg of dioxins per year, residential wood burning results in 20 kg/yr, agricultural burning releases 10 kg/yr, and incinerators contribute approximately 350 kg/yr for a total annual dioxin release of 400 kg (Spiro and Thomas 1994~. PERSISTENCE Global deposition of various persistent organic chemicals has been observed for years, even in areas thought to be pristine.
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From page 59... ...
Other persistent chemicals, such as PCBs, are also subject to recycling in the environment from sediments into the overlying water column. MONITORING HAAs have been detected in all environmental media as well as biologic tissue, but the concentrations can vary dramatically.
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From page 60... ...
HCHs showed higher ocean-air and surface-seawater concentrations in the northern hemisphere than in the southern hemisphere and higher concentrations closer to the poles than at more-central latitudes. Total DDT concentrations were highest near tropical Asia.
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From page 61... ...
(1996) and others have discussed the difficulty in comparing concentrations of PCBs reported in the 1970s or early 1980s (based on total PCB concentrations)
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From page 62... ...
Phthalate concentrations ranged from nondetectable in 1 sample to greater than 2,300,ug/kg of dry weight in another sample (South Platte River at Denver) ; 8 samples contained less than 100 ,ug/kg and 12 samples contained between 100 and 500 ,ug/kg.
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From page 63... ...
Concentrations were typically below the level of detection. Based on the annual Total Diet Study conducted between 1965 and 1984 by FDA, average daily intake of DDT by teenage males decreased from a high of 31 ,ug in 1965 to 2.5 ,ug in 1984, and PCB intake decreased from 1.4,ug in 1971 to 0.03,ug in 1984 (Tao and Bolger 1998~.
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From page 64... ...
The data in the table show ranges in the concentrations of total DDT usually measured as DDE (a persistent DDT metabolite) and either total PCBs or the sum of multiple PCB congeners.
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From page 66... ...
. Concentrations of total DDTs and total PCBs in baleen whales are greater in the northern hemisphere than they are in the southern oceans, apparently because of greater contamination of northern ecosystems (O'Shea and Brownell 1994~.
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From page 67... ...
must be considered separately to determine whether it poses a significant health risk, but the committee recognizes that wildlife and humans are exposed to complex mixtures of chemicals and that interactions between chemicals in mixtures cannot always be predicted by examining each chemical individually. Daily human exposures have been estimated for some chemicals that have been reported to have HAA activity (Table 3-3~.
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From page 68... ...
1996 DDT in total diet Oral 0.01 Gunderson 1995 PCBs in total diet Oral 0.002 Gunderson 1995 Phytoestrogen, 100 g of wheat Oral 200 Verdeal and Ryan with 2 ppm zearalenone 1979 Phytoestrogen, total Oral 1,000,000 Kuhnau 1976 bioflavonoids DDT, India, environmental Inhalation 0.0798 Kannan et al. 1995 Water 0.035 Kannan et al.
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From page 69... ...
Therefore, as endogenous steroid hormone concentrations increase, the pituitary feedback control signals the endocrine organ (the adrenal gland or gonads) , through pituitary hormones, to cease production or release of the endogenous steroid or to stimulate the release of opposing hormones.
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From page 70... ...
Exposure to PCBs from diet decreased from a high of 6.9 ,ug/d in 1971 to 0.05 ,ug/d in 1989. Combining dietary exposure with other routes of exposure yields a total daily exposure, on a body-weight basis, of 0.11 ,ug/kg of body weight per day for 1971 and 0.008,ug/kg of body weight per day in 1989, a decrease of 138fold (Delzell et al.
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From page 71... ...
Although the dose to the fetus is of critical importance in determining HAA effects, the dose is dependent on the exposure of the mother. An analysis of PCBs in umbilical cord blood of women who had and had not consumed Great Lakes fish, known to have high PCB concentrations, indicated that the average mean total PCB concentration in the cord blood was approximately 1.0 ppb for all women.
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From page 72... ...
Investigators have examined the dietary exposures of people living in polar regions, especially those who consume foods high in animal fat. It is reasonable to believe that such populations would receive high dietary exposures to organochlorines because of the higher concentrations of such chemicals in polar regions and because of accumulation of such chemicals through the food chain.
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From page 73... ...
Again, infants received approximately 3 mg/kg of body weight per day from the soy-based formula, but a single daily serving of infant cereal could increase the isoflavone intake by more than 25%. Dairy-based formula and human breast milk contained isoflavones below the limit of detection.
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From page 74... ...
Involuntary exposure can also occur as a result of aerial pesticide spray that drifts to nearby areas. Sources of the greatest consumer exposure to dietary pesticide residues have been listed by the U.S.
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From page 75... ...
The FDA Total Diet Study determined intake of selected pesticides, synthetic chemicals, and radionuclides from 1982 to 1991. The study focused on table-ready food rather than unwashed raw agricultural commodities or partially prepared fruits and vegetables (Gunderson 1995~.
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From page 76... ...
Estrogenic activity was detected in such cases. The authors reported no estrogenic activity in fresh vegetables used as controls; however, some activity might have been expected considering that many of the vegetables tested contain phytoestrogens (MAFF 1996a)
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From page 77... ...
After elimination of interference, average BPA residues from food cans dropped to 36 ppb, indicating that the analytic method used to determine the presence and concentration of HAAs in various environmental samples can be an important factor when assessing the exposure concentrations. SPI made a worst-case dietary exposure assessment, assuming that BPA residues were present at 5 ppb for beverages, even though none was detected, and present at 37 ppb for other foods.
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From page 78... ...
Therapeutic Agents Women of child-bearing age and postmenopausal women might have substantial voluntary exposure to estrogenic compounds. Current oral contraceptives contain a daily dose of 20-50 ,ug of a potent orally active estrogen, such as ethinyl estradiol or mestranol (Hardman et al.
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From page 79... ...
Although the study did not demonstrate changes from maternal exposures to oral contraceptives, such study designs illustrate the importance of evaluating this potential HAA exposure. Many women receive various forms of postmenopausal estrogen replacement.
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From page 80... ...
Some populations are known to have extremely high exposure to HAAs. In particular, some aboriginal groups, such as the 32 Inuits of northern Canada and the United States, have diets high in synthetic HAAs as a result of consumption of contaminated marine mammals and fish.
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From page 81... ...
Intake of phytoestrogens and synthetic HAAs by humans and other biota should be studied to establish a baseline for typical HAA exposure. Predominant routes of exposure, particularly diet and drinking water, should be assessed to determine background intake concentrations for all HAAs.
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