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Chapter XIV: Toward Phosphorus Target Loadings
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although the 1978 Great Lakes Water Quality Agreement had stated that the parties, within eighteen months, would confirm the future phosphorus loadings stated in the agreement and, based on these, establish loading allocations and compliance schedules, these tasks were not accomplished until October 1983, when the parties added a supplement on phosphorus reduction to Annex 3 of the agreement.1 Only then did the parties begin to develop and implement additional phosphorus loading reduction plans. In the meantime, in an important development, it had become possible from 1980 for U.S. manufacturers to incorporate NTA as a builder in laundry detergents, as their Canadian counterparts had been doing since the late 1960s. In a related later development, in 1988 Ohio and Pennsylvania finally joined the other states of the Lake Erie Basin in restricting phosphorus in detergents to a maximum of 0.5 percent. As recounted earlier, the IJC’s Great Lakes Water Quality Board’s July 1976 recommendation that the phosphate content of detergents used in the Great Lakes Basin be reduced had found support not only from the IJC but also from EPA’s Region V and the United States Senate. The board’s recommendation appears also to have influenced the IJC’s Research Advisory Board to create the Task Force on the Health Implications of NTA, 23 Toward Phosphorus Target Loadings C H A P T E R X I V which met for the first time in September 1976. The task force’s terms of reference noted that current data strongly suggested that the concentration of phosphorus in municipal wastewater treatment plant effluent should be reduced as much as possible because other sources, particularly land runoff, were less controllable.2 Furthermore, at some plants the amount of phosphorus being removed was less than expected, while significant sludge problems were being encountered. Given these considerations , replacing phosphates in detergents appeared a desirable means of reducing effluent phosphorus concentrations. The Research Advisory Board directed the task force to assemble in an encapsulated form the research data on NTA in relation to human health; advise the board on the adequacy and validity of the data; identify the implications of the findings for health; and “Recommend a course of action for the International Joint Commission to take regarding the United States and Canadian policies on NTA.” The task force reported in May 1977, but presented no recommendation , only conclusions. Its comprehensive review of the literature and current research on NTA in regard to health revealed no evidence of teratogenic or mutagenic potential.3 Its only concern—in regard to the safety of workers in the manufacture of NTA and of people in general whose principal exposure to NTA would be from drinking water—stemmed from findings of carcinogenesis of the urinary tracts of rats and mice given large doses of NTA over their lifetimes. The task force had available to it the progress report of the Canadian program monitoring NTA in the environment ,4 from which it estimated that a person drinking two liters of water a day would ingest fifty micrograms of NTA a day.5 Using a statistical analysis of data on rodents fed NTA, the task force estimated the maximum probability of tumor formation in rodents consuming that amount of NTA per day and found it to be within an order of magnitude of one in two million.6 Regarding what this might mean for humans, the task force did not exactly say; but it did note that “rodent probabilities incorporate a large measure of conservative exaggeration” and that humans absorbed NTA from food and water to about one-fifth the degree that rats did. The implication was that the probability of humans developing tumors was considerably less than within an order of magnitude of one in two million. 240 Toward Phosphorus Target Loadings [3.95.233.107] Project MUSE (2024-03-19 02:43 GMT) The Canadian program monitoring NTA in the environment, begun in late 1971, published its findings to date in 1977.7 Rapid disappearance of NTA in wastewater treatment plants and in receiving waters had prevented a “build-up” of its concentration in the environment despite its expanded use. Only a very few instances had been encountered in which the concentration of NTA in drinking water deriving from surface sources had exceeded ten parts per billion. These instances occurred where the raw water was polluted with wastewaters containing NTA and reused before degradation and dilution had reduced the concentration. Although shallow...