Bio not provided
It's not just industry that relies on discrediting low dose effects.
A report by the New York City Dept of Environmental Protection (www.nyc.gov/html/dep/pdf/quality/nyc_dep_2010_ppcpreport.pdf) found low levels of many pesticides, drugs, and personal care products in the city's drinking water. Table 11 is entitled, "Number of Glasses of Water Required to Exceed Derived Drinking Water Guideline." For example, DEET, which was found at 9 parts per trillion (nanograms per liter), we are told, is not problematic unless one drinks 3,290,000 8-oz glasses of water a day. However, many prescription drugs (albuterol, Synthroid, birth control pills) function therapeutically at parts per billion concentrations. It is not difficult to imagine that the brew of low doses in the parts per billion and parts per trillion range of a mixture of ibuprofen, nicotine, caffeine, Atrazine, and so forth has effects on our bodies (not to mention on the fish!).
One of the most important lessons that we are learning in endocrine disruption is that "the timing makes the poison." In particular, exposures in utero during critical periods of development can have not only lifelong effects but also, through epigenetic pathways, transgenerational effects. Although regulators claim that their "margin of safety" should account for these differences in susceptibility, we are finding that they are inadequately protective.
Another example of "the timing makes the poison" is Lupron (gonadotropin-releasing hormone). When naturally released in hourly pulses it initiates puberty, but monthly injections of Lupron, a GnRH analog delay puberty.
We are starting to find, also, that even the time of day that an exposure occurs affects the outcome. Circadian rhythms appear to affect not only our immune system but also our vulnerability to chemical insults.
We certainly do not know enough to call any level of exposure to endocrine disrupting compounds safe. Thank you, Beth, for calling attention to this.
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