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K R Mahaffey

Publications and source records attributed to K R Mahaffey.

60 records · Page 4Linked to original sources
PubMed1974

Food exposures to lead.

Exposures to lead have emanated from various sources, including food, throughout human history. Occupational and environmental exposures (especially pica) appear to account for much of the identified human disease, however, food-borne exposures deserve further investigation. Lead residues in food can result from: biological uptake from soils into plants consumed by food animals or man, usage of lead arsenate pesticides, inadvertent addition during food processing, and by leaching them improperly glazed pottery used as food storage or dining utensils. Estimates of total dietary exposure should reflect frequency distribution data on lead levels in specific food commodities in relation to the quantities actually ingested by various sample populations to distinguish degrees of risk associated with particular dietary habits. Earlier estimates of average total dietary intake of lead by adults have been reported to range from above 500 mug/day downward with more recent estimates suggesting averages of 200 mug/day or lower. The strengths and weaknesses of these data are discussed along with analytical and sampling considerations. FDA programs related to food surveillance, epidemiology, and toxicological investigation are briefly described.

Animals↗
PubMedDate not supplied

Methylmercury: a new look at the risks.

In the US, exposure to methylmercury, a neurotoxin, occurs primarily through consumption of fish. Data from recent studies assessing the health impact of methylmercury exposure due to consumption of fish and other sources in the aquatic food web (shellfish, crustacea, and marine mammals) suggest adverse effects at levels previously considered safe. There is substantial variation in human methylmercury exposure based on differences in the frequency and amount of fish consumed and in the fish's mercury concentration. Although virtually all fish and other seafood contain at least trace amounts of methylmercury, large predatory fish species have the highest concentrations. Concerns have been expressed about mercury exposure levels in the US, particularly among sensitive populations, and discussions are underway about the standards used by various federal agencies to protect the public. In the 1997 Mercury Study Report to Congress, the US Environmental Protection Agency summarized the current state of knowledge on methylmercury's effects on the health of humans and wildlife; sources of mercury; and how mercury is distributed in the environment. This article summarizes some of the major findings in the Report to Congress and identifies issues of concern to the public health community.

Adolescent↗
PubMedDate not supplied

A rapid bioassay system for lead using young Japanese quail.

A rapid bioassay of lead was established in young japanese quail. Each group of 10 day-old birds received deionized water and a purified diet ad libitum for 2 wk. The diet contained 0.2 microgram lead/g. Lead acetate was added to give 14.8, 34.4, 51.2, 74.4, 234, 563, or 1223 microgram total lead/g by analysis. The duodenum, kidneys, liver and tibias were assayed for lead. Consumption of a diet containing either 563 or 1223 ppm lead caused a decrease (P less than or equal to 0.05) in body weight after 1 wk and an increase in free erythrocyte protoporphyrin after 2wk. Inhibition of red blood cell delta-aminolevulinic acid dehydratase (RBC-ALAD) activity occurred in birds consuming as little as 14.8 ppm lead. Packed cell volumes and hemoglobin concentrations were not affected by the dietary treatments. Lead concentrations in tissues from birds fed the lowest level of added lead were greater than those found in the corresponding tissues of control birds. The concentration of lead in the tibia showed the most distinguishable group means and the most nearly linear response; the highest slope was between 14.8 and 110 ppm dietary lead, using log-log transformations. The rapid bioassay is suitable for investigating high lead foods.

Animals↗