RP14 Ecological Fate and Effects of Explosives and Related Compounds
Thursday, 17 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(RIC-1117-835444) Human exposure to perchlorate in milk depends on its concentrations in dairy feed.

Rice, C.¹, Abbott, L.², Hapeman, C.¹, McCarty, G.¹, Baldwin, R.³, Capuco, A.³, Hare, W.⁴, Paape, M.³, McConnell, L.¹, Van Tassell, C.³, ¹ U.S. Department of Agriculture, Environmental Quality Lab, Beltsville, MD, USA² USDA, Office of Risk Assessment and Cost Benefit Analysis, Washington D.C., D.C., USA³ USDA, Bovine Functional Genomics Laboratory, Beltsville, MD, USA⁴ USDA, Veterinary Service, Beltsville, MD, USA

ABSTRACT- The concern for human exposures to perchlorate has been a subject of intense debate for several years. Adding to this debate are recent discoveries of low levels of perchlorate in milk. Determining the extent to which perchlorate in feed is transferred to milk will aid in managing human exposure. We conducted an experiment where 16 lactating dairy cows were dosed with ruminally-infused perchlorate. From these data, a dose-response relationship was established. The concentrations in the milk was directly related to the levels in the feed; however, especially important was the discovery that the efficiency of transfer to the milk diminished in a regular and predictable pattern as the concentration in the food increased. Using USDA Food and Nutrition Survey data and USDA Nutritional Information data, potential perchlorate exposures from milk were determined. The findings emphasize the need to better understand how perchlorate cycles through the environment and ends up in dairy feed.

Key words: perchlorate, milk, exposure assessment, dairy feed