Sanchez hopes to expand this preliminary survey into a more comprehensive, statistically rigorous, geo-referenced study across a wider range of leafy vegetables over the next couple of seasons. Initial funding came from the Arizona Iceberg Lettuce Research Council and a cooperative agreement with the USDA-ARS (Agricultural Research Service).
Sanchez is continuing his work funded by the Arizona Iceberg Lettuce Research Council during 2003-2004 by looking at some of the factors affecting uptake of perchlorate by plants. There is considerable variation in the perchlorate accumulation within lettuce despite the fact that all of Yuma's lettuce is irrigated with the same water.
"Perhaps fertilization practices, water management practices, or genetic variation are important," Sanchez says. "We are also concerned with potential sources of perchlorate in addition to irrigation water." Sanchez added that recent EPA and USGS studies have identified certain fertilizers and agricultural amendments as sources of perchlorate.
Other important research issues Sanchez plans to pursue include evaluation of the extent to which perchlorate has accumulated in soils and to what extent it has tainted local groundwater sources. He has recently teamed up with a toxicologist from the University of California at Riverside where this data will be used for preliminary exposure and risk assessment research.
The debate over the suitable standard of perchlorate in water and how much is safe for human consumption has been turned over to the National Academy of Sciences, Sanchez says.
"With conclusions possibly by mid-2004, the Food and Drug Administration can develop recommendations based on how much salad people consume daily, and what the relative source contribution is, both from water that's tainted with perchlorate
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Contact: Charles Sanchez
sanchez@ag.arizona.edu
928-782-3836
University of Arizona
29-Jan-2004