Providing answers to the questions you didn't know you wanted to ask
Dear AggieIn contrast to the usually more sober contributors to the Agrichemical and Environmental News, Dear Aggie deals light-heartedly with the peculiarities that cross our paths and helps decipher the enigmatic and clarify the obscure. Questions may be E-mailed to Dear Aggie at dearaggy@tricity.wsu.edu. Opinions are Aggie's and do not reflect those of WSU.
Last month you joked that women caused more pollution than men because estrogen has been found in treated municipal sewage effluents at levels that can affect normal endocrine physiology in fish. Aren't men just as "dangerous" because of potential effects on fish from excessive testosterone exposure?
Perhaps the reader thought Aggie was showing bias in picking on women, but the truth of the matter is that studies of testosterone concentrations in treated effluents have not been published. While any compound that would mimic testosterone would be considered today as a potentially endocrine disrupting chemical, most compounds studied have mimicked estrogen. One notable exception is DDE, the main breakdown product of DDT that is stored in fat tissue. DDE is now considered anti-androgenic, which is a fancy word for a chemical that blocks the normal action of testosterone (which is classified as an androgenic hormone). The testosterone receptor recognizes DDE as if it were testosterone, but instead of turning on its normal complement of genes, DDE just sits on the receptor blocking testosterone from attaching. Thus, excessive levels of DDE actually act as if a male has been given too much estrogen, causing the reproductive tissues to have female-like characteristics. We need not panic yet about the possible loss of males from our species. The levels of DDE required to cause the anti-androgenic effect are absurdly high. Whether testosterone is in the environment and can cause adverse physiological effects just has not been studied yet. However, Aggie proposes an experiment. On the day of the next SuperBowl, pregnant fish should be caged and placed in the effluent of municipal sewage treatment plants. Aggie's betting on a very high ratio of male fish among the offspring. (Information about DDE from Kelce et al., 1995, Nature v. 375, pp. 581-585)
Of all the bad heath effects attributed to chemicals, cancer has been at the top of the list. I continually read in the newspaper that cancer rates are increasing, especially among children. Where do these statistics come from and what do they really tell us?
Cancer is a hot button for good cause. An individual is estimated to have a 25-33% chance of contracting cancer in their lifetime. Thus, knowing someone with some type of cancer is very probable. Certain advocacy groups feel that synthetic chemicals, and especially pesticides, have contributed greatly to increasing incidence of cancer, but epidemiologists do not agree. Cancer statistics (incidence and mortality) are collected by the National Cancer Institute (NCI) Surveillance, Epidemiology, and End Results (SEER) program. The database represents about 9.5% of the U.S. population. During the spring of 1998, NCI in cooperation with The American Cancer Society and The Centers for Disease Control released a report about cancer incidence and mortality between 1973 and 1995. Aggie is pleased to bring some good news to our readers. Both the incidence and mortality rate for all cancers actually declined between the years 1990-1995. Sharp reductions in lung cancer rates were a major factor in the decline. However, the incident rate of other prevalent cancers like breast and prostate either showed no increase or declined slightly. Certain environmental health specialists had been hypothesizing that exposure to endocrine-disrupting chemicals may be a causal factor in the large increases in breast and prostate cancer recorded during the 1973-1995 period. An alternative hypothesis propounded by the NCI involves a jump in incidence of cancers when a new screening procedure is available. Thus, with the advent of mammography and the PSA (Prostate Specific Antigen) test, came higher rates of detection of non-malignant or slow growing cancers that were already at high levels but not detected previously. The good news even applied to children under 15 years old; their cancer incidence rate dropped 1.2% per year between 1990 and 1995. The cancer statistics will continue to be issued as an annual report card. Stay tuned. (Source: Wingo et al., 1998, Cancer, v. 82, pp. 1197-1207).
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