Cholinesterase is a necessary enzyme in the blood, but each year many people are reportedly exposed to toxic chemicals which inhibit this vital enzyme.  The function of the blood enzyme cholinesterase is to convert acetylcholine back to choline and acetic acid.  Acetylcholine is the substance which is released from our nerves to activate muscles.  When cholinesterase is blocked, acetylcholine level continues to increase, causing a build-up in the muscles.  This overabundance of acetylcholine, in turn, causes the muscle coordination to become jerky and irregular to the point of muscle fibrillation.  Simply put, cholinesterase is necessary to ensure proper muscle function.

Cholinesterase inhibition should be suspected if there has been a possible exposure to any carbamates or organophosphates - chemicals most commonly found in herbicides and pesticides.  Although the potential for toxic cholinesterase inhibition may affect anyone from the avid homeowner who desires an impeccable lawn or the weekend gardener, the highest incidence is in the herbicide / pesticide industry.

There are over 100 herbicides/pesticides presently known to contain carbamates and/or organophosphates which may inhibit cholinesterase.  The chemical names of some of the more common herbicides/pesticides used today are Ronnel, Malathion, Diazinon, Dursban and Parathion.  If the names sound somewhat familiar, it is probably because they are found as main ingredients in many over-the-counter preparations used by the general public across the country to kill unwanted weeds in the driveway, on the patio, and in the lawn.

The verification of suspected cholinesterase inhibition is accomplished by measuring the plasma and red blood cell levels of the enzyme.  If either or both of the tests indicate a decreased level of cholinesterase, inhibition has been validated.  The lower the cholinesterase level, the larger the intensity of the inhibition and the greater the degree of toxicity.

The treatment is simply to remove the person from further exposure.  Bi-weekly blood tests should be done to monitor the gradual increase to normal levels which takes 4-6 weeks.  On rare occasions, usually after severe inhalation, return to normal levels is slower than expected.  Chest x-rays or pulmonary function testing may be ordered to rule out pulmonary complications.

Awareness of the possible health hazard is the first step in a preventive program. If the potential for exposure is higher and more constant as in most of the herbicide/pesticide industry, blood tests for cholinesterase inhibition should be routinely performed to denote pre-symptom early stages and to prevent cumulative effects of repetitive low-level exposures.  The typical company runs blood tests on all employees in the early spring before any contact is made with the chemicals in question.  This baseline is important because some people have genetically low cholinesterase levels which might prove deceptive when comparing future test levels usually taken in mid-season and post-season.  Some companies test for cholinesterase levels every three to four weeks due to the amount of chemical contact of their employees.  Other companies, whose use of these chemicals is not seasonal but rather year round, provide ongoing cholinesterase testing for all their employees.  Each program must be individual to that company's needs and chemical usage.

The cost of cholinesterase testing varies greatly with the laboratory chosen.  Due to the expense of the materials required to perform the specialty test, most local labs either do not have the necessary materials or find the specialty of the test worth a higher charge.  For most needs, a specialty lab serves the company much better.  The blood samples can be drawn locally, prepared and sent to the specialty lab for testing.  The turn-around is usually one to two days with the employer receiving a computer print-out of all the blood samples tested and the cholinesterase levels of each.  Because of the volume of tests processed, specialty labs prepared to test for cholinesterase usually charge between 60% to 65% less than the local lab which may receive few requests for the tests.