Contentious worker testing.

Washington State farmworkers who mix, Load, or apply organophosphate or N-methyl carbamate pesticides must now receive cholinesterase blood tests as part of a controversial new state rule. The goal of the new rule, which took effect in February 2004, is to identify workers who are at increased risk for gradual cumulative overexposure and subsequent poisoning. But the rule faces heated opposition from scientists and agricultural interests over questions of cost and effectiveness, and raises questions of environmental justice as well.

About 400,000 pounds of organophosphate and N-methyl carbamate pesticides were sprayed on Washington apple orchards in 2001, according to the National Agricultural Statistics Service. These pesticides bind to acetylcholinesterase, an enzyme that modulates nerve signals. As acetylcholinesterase activity is inhibited, nerves continue to fire uncontrollably. In humans, this can produce symptoms such as fatigue, nausea, headache, and seizures. Long-term effects may include weakness or paralysis of the extremities and impairments in concentration, memory, language, and personality.

Each year, says Washington Department of Labor and Industries (L&I) occupational nurse consultant John Furman, the state Department of Health receives about a dozen reports of acute poisoning from cholinesterase-inhibiting insecticides among farmworkers, mostly from when a pesticide is splashed on a worker. The new monitoring does not target these kinds of illnesses or exposures; instead, it aims to prevent the poisonings that result from gradual exposure. Although many U.S. employers have adopted voluntary cholinesterase monitoring as a precaution to protect workers, California is the only other state with mandatory testing, which has been in effect since 1974.

The Washington rule requires that workers provide a baseline blood sample before they begin handling pesticides during the spraying season. Follow-up tests are required if workers handle the pesticides for a total of 50 hours in any period of 30 consecutive days. If a worker's cholinesterase level drops by 21-29%, an inspector will visit the workplace to determine the cause of the exposure and recommend how to prevent it in the future. Workers must temporarily stop handling pesticides if acetylcholinesterase tests show a drop of 30% or more or if plasma cholinesterase drops by 40% or more. These action thresholds are lower than the amounts of cholinesterase inhibition that would likely cause symptoms, says Furman.

Workers may not handle the pesticides until the difference between their test result falls to within 20% of their baseline. But their pay and seniority are guaranteed by the rule for up to three months--a reasonable amount of time for workers to recover, says University of Washington pesticide and health expert Matthew Keifer.

To ensure test reliability and valid comparison between baseline and subsequent test results, all tests are being done initially through the Washington State Public Health Laboratory near Seattle. Eventually the state plans to certify commercial labs for the analyses, Furman says. An advisory panel of scientists and physicians will track the test results and report periodically to L&I.

For some farmworkers, the rule is a mixed blessing. Some are reluctant to be tested for fear of missing work, being fired, or other reprisal. The 1 December 2003 Seattle Times quotes one worker as saying, "[We] don't have the liberty to think about health in the short term because there are long-term consequences for the family." Workers can opt out of testing, but this decision must be discussed between workers and their health care providers, a requirement aimed at stopping employers from coercing workers to avoid testing, says lawyer Dan Ford, who represented the farmworkers whose legal action spurred the L&I rule making.

In March 2004, the state legislature passed a measure that reduces the financial burden on growers by reimbursing them for testing and medical provider costs. The source of funding will likely be the state's workers compensation funds, says L&I spokeswoman Elaine Fischer, which shifts more of the costs to employers in industries besides agriculture who pay into the state system. Further, based on their experience with voluntary cholinesterase testing, agricultural interests have consistently argued that the tests are unlikely to provide any new information and hence are not worth the cost, according to Mike Gempler, executive director of the Yakima-based Washington Growers League.

Environmental toxicologist Allan Felsot, of the Food and Environmental Quality Laboratory at Washington State University Tri-Cities, believes it's important to limit workers' exposure, but says monitoring is the wrong way to do it. "Why waste time monitoring?" he says. "We should be focusing on prevention by finding and replacing faulty equipment and providing more worker education."