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Thursday, May 13, 2004 - Page updated at 12:00 A.M.
Chemical exposure of farmworkers studied
By Hal Bernton
The incidence of possible overexposures to organophosphate or carbamate chemicals is higher than some expected when the new monitoring program was launched earlier this year in response to a state Supreme Court ruling on a farmworker lawsuit.
"I was surprised by the frequency," said David Kalman, a University of Washington professor of environmental health who chairs a state science advisory group that helps evaluate the blood test data.
The Washington Farm Bureau, in a labor advisory, cautioned that the numbers are still preliminary. But the group noted concern over the possibility of "substantial numbers of workplace exposures." The advisory reminded members to provide information and training to pesticide handlers, and demand that these workers comply with protection rules.
Organophosphate and carbamates are nerve poisons widely used to combat insect pests in Washington state orchards and on some cropland. They can also affect humans by lowering blood levels of a critical enzyme known as cholinesterase that helps to regulate the nervous system.
The new program targets workers of highest concern: more than 2,600 people who mix, spray or otherwise handle the pesticides. These workers are supposed to don gloves, respirators and other protective equipment, but still may be exposed during long hours in the field.
The initial laboratory results track 345 of these workers, with more test results expected as the growing season progresses. Blood tests indicated that 82 of those workers nearly 24 percent had significantly reduced cholinesterase compared to blood tests taken before the spring spray season, according to state Department of Labor and Industries statistics.
Under the new rules, more than 5 percent of the workers had levels of the enzyme low enough to trigger immediate removal from pesticide handling to allow levels time to rebuild. But it still is unclear just how quickly those workers have been contacted and removed from exposure.
Another 62 workers about 18 percent had less severe reductions in the enzyme that require workplace investigations by the Department of Labor and Industries.
"The new test results prove that monitoring is very much needed," said Erik Nicholson, with the United Farm Workers.
"I think this reveals a very serious public health problem," said Carol Dansereau, of the Seattle-based Farm Worker Pesticide Project.
For more than a decade, the UFW and other farmworker advocates have been pressing for the monitoring of workers involved in mixing and spraying pesticides.
In 2002, after lengthy litigation, the state Supreme Court ruled that "denial of the pesticide handlers' request for rulemaking was unreasonable," and ordered the state to establish rules for a monitoring program.
Before the spray season begins, workers give blood samples to establish baseline information about their cholinesterase levels. Then they offer follow-up samples after they have worked for 50 hours in any consecutive 30-day period with organophosphates or carbamates, another group of chemicals that can affect cholinesterase.
When the cholinesterase level sinks too low, the nervous system can get overstimulated. That can lead to symptoms such as dizziness, breathing problems, involuntary muscle twitching and, in severe cases, paralysis, according to Matthew Keifer, a UW environmental and occupational-health-sciences professor.
Industry officials have been concerned that the monitoring be done with sound scientific protocols, so that they don't end up with inaccurate results that exaggerate worker risk. They are concerned that other factors beside pesticides, such as a medication taken by a worker, might be lowering the enzyme levels.
Industry officials also have asked the state to do "blind testing" that would examine blood levels of another group, such as office workers.
Times staff reporter Andrew Garber contributed to this report.
Hal Bernton: 206-464-2581 or email@example.com
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