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What's your baseline number?

When Phil Jahde entered his farm shop eight years ago, he didn't realize that his brother-in-law was calibrating the SmartBoxes filled with corn insecticide.

A few hours later, he was having trouble breathing, and his wife called 911. Jahde spent the next three days in the hospital intensive care.

Shortly afterwards, the Alta, Iowa, producer quit farming. “For years, we were careless about chemical exposures,” he says.

Today, he owns a tree-moving business and is cautious around all chemicals. “I carry a respirator in case the lawns have been sprayed,” he says.

“It sounds as though he may have what's called multiple chemical sensitivity,” says Kelley Donham, director, Iowa Center for Agricultural Safety and Health. “It's difficult to diagnose.”

Jahde's acute episode was triggered by an organophosphate. Organophosphates and carbamates inhibit cholinesterase, an enzyme vital to the nervous system.


Cholinesterase is an enzyme necessary for normal nerve transmission. Exposures to organophosphates and carbamates can inhibit this enzyme with potentially serious consequences. Exposure can occur from inhalation, ingestion, or eye or skin contacts. Watch out for these symptoms:

• Blurred Vision • Headaches

• Breathing Difficulties • Nausea

• Cramps • Sweating

• Dizziness • Vomiting

• Fatigue • Weakness

A normal range of baseline cholinesterase varies widely among individuals. About 3% of the population have abnormally low levels, due to genetics, liver disease, pregnancy, or certain medications.

Repeated exposure may cause cholinesterase to decline over time, or it may drop dramatically in a single fatal exposure.

Individuals with an extremely low baseline should avoid pesticides with cholinesterase inhibitors. A baseline value is key for diagnosis and treatment if symptoms develop after exposure.

“Not everyone needs a test,” says Carolyn Sheridan, director, AgriSafe Clinic, Spencer (Iowa) Hospital, and clinical director of AgriSafe Network.

Testing is advisable for:

• Individuals who mix, load, apply, or come into contact with moderate to highly toxic organophosphates and carbamates. This includes servicing equipment.

• Individuals in contact with these chemicals for more than 30 hours at a time within a 30-day period.

A baseline test should be conducted during the off-season. The test requires a blood sample but no fasting. It's about a $20 charge at Spencer's AgriSafe Clinic.

“If your hospital has to send it out for analysis, it will cost more,” Sheridan says. “A baseline test isn't covered by insurance. If you have symptoms of exposure, a test for diagnosis would be covered.”

If additional pesticide exposure is avoided, cholinesterase levels will eventually rebuild to normal levels.

“If you have a baseline test and later have an exposure that requires testing, it's important to send your blood to the lab that did the baseline,” Sheridan says.


Understanding the pesticides you work with and doing safe handling help prevent pesticide poisoning from these products:

• Abate • Furadan

• Advantage • Landrin

• Aztec • Lannate

• Baygon • Larvin

• Bidrin • Lorsban

• Bolstar • Nudrin

• Carbamates • Organophosphates

• Counter • Primor

• Curacron • Prolate

• De-Fend • Sevin

• Dursban • Thimet

• Ficam • Vydate

• Fortress • Zectran

Best offense is a good defense

Donham says a 20% decrease in cholinesterase levels is an action level for improving management practices, including personal protective equipment (PPE).(A 50% drop in levels triggers symptoms.)

“Skin is a major source of absorption,” Donham says. “Clothing must protect the skin.” PPE includes goggles and chemical-specific respirators, unlined rubber or plastic gloves, and neoprene or nitrile boots.

“Cholinesterase-inhibiting insecticides are being replaced by less toxic products,” Donham says. “The use of Bt corn also is significantly reducing use of these compounds. Producers need to read and be familiar with label directions.”

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