Cholinesterase Monitoring (WAC 296-307-148)
What are employers required to do?
The rule requires employers of agricultural pesticide handlers who use toxicity class I or II organophosphate or N-methyl-carbamate pesticides to take the following steps:
- Record the number of hours employees spend handling these pesticides.
- Implement a medical monitoring program for workers who could meet or exceed the handling threshold of 30 or more hours in any consecutive 30-day period.Identify a medical provider to provide medical monitoring services.
- Make baseline and periodic cholinesterase testing available to employees who could meet or exceed the handling threshold.
- Investigate work practices when a handler's red blood cell (RBC)or serum cholinesterase level drops more than 20 percent below the employee's personal baseline.
- Remove employees from handling and other exposures to organophosphate and N-methyl-carbamate pesticides when recommended by your health care provider.
- Provide training on cholinesterase monitoring to covered employees.
- Report employee handling hours to the medical provider with each periodic test.
- Maintain medical monitoring and other records for seven years.
Employer cost reimbursement
Employers may request reimbursement for the reasonable costs of training, recordkeeping, and medical expenses for cholinesterase monitoring by submitting the Cholinesterase Monitoring Reimbursement Request form along with required documentation.
Cholinesterase Monitoring Reimbursement Form (F413-062-000).
What is cholinesterase?
Cholinesterase (acetyl cholinesterase) is an enzyme that removes the chemical neurotransmitter acetylcholine from the junctions between nerves cells. Cholinesterase serves as the nervous system's "off switch" and is essential to the normal function of the nervous system.
Why monitor cholinesterase levels?
Exposure to organophosphate or N-methyl-carbamate pesticides may lower the level of available cholinesterase. Without the normal protective levels of cholinesterase, nerves in the body may be overstimulated to the point of exhaustion, leading to symptoms ranging from blurred vision, diarrhea and tremors to seizures, loss of consciousness and even death.
Monitoring cholinesterase levels in the blood through simple laboratory tests can detect cholinesterase depression prior to the onset of illness.When significant cholinesterase depression is identified employers are required to evaluate their pesticide worker protection program and make corrections to prevent further over-exposure.
What are the benefits of cholinesterase monitoring?
The cholinesterase monitoring Cost Benefit Determination and Small Business Impact Statement identified the following benefits of cholinesterase monitoring:
- Prevention of illness after over-exposure.
- Increase hazard awareness and improve overall workplace safety related to pesticide use.
- Improve pesticide illness diagnosis and reporting.
- Provide greater certainty about frequency of pesticide over-exposure.
- Decrease the risk of unintended exposures to workers families.
Background and purpose
The Cholinesterase Monitoring rule (WAC 296-307-148) requires agricultural employers to provide medical monitoring for workers who handle toxicity Category I or II organophosphate or N-methyl-carbamate cholinesterase-inhibiting pesticides. The rule has been amended to reflect current program requirements, including requiring the employer to obtain a written recommendation from the health care provider for each employee test (incl. baselines) and evaluation and ensuring that the employee receives a copy. The updated rule became effective Feb. 1, 2006.
Medical monitoring provides several benefits. It provides the primary benefit of preventing over-exposure to cholinesterase-inhibiting pesticides before illness occurs. In addition, it increases employer and worker awareness of pesticide hazards and reinforces appropriate work practices. If blood testing detects cholinesterase depression, the employer is directed by the medical provider to evaluate the worker's pesticide handling practices. If cholinesterase levels fall below specified removal levels, medical monitoring facilitates case management and the employer is directed by the medical provider to remove the worker from further exposure until cholinesterase levels regenerate and it is safe for the worker to return to working with cholinesterase-inhibiting pesticides.
Medical monitoring is a surveillance program that monitors agricultural workers who handle toxicity Category I or II organophosphate or N-methyl carbamate pesticides. It consists of periodic measurements of cholinesterase activity levels in workers that are compared to measurements of exposure-free baseline cholinesterase activity levels. Workers who handle cholinesterase-inhibiting pesticides for 30 or more hours in any consecutive 30-day period are covered by the medical monitoring requirements of the rule.
L&I along with the Department of Health, University of Washington Department of Environmental Health and the Pacific Northwest Agricultural Safety & Health Center (PNASH) has produced a clinical manual titled: Cholinesterase Testing: Guidelines for Health Care Providers, which explains and interprets the state program of cholinesterase monitoring.
There is significant variation among cholinesterase testing methods and among laboratories using the same testing method; it is misleading to compare test results from one method to another or from one laboratory to another. Because of this, a laboratory approved by L&I must be used for all cholinesterase tests. The only laboratory currently approved by L&I to provide cholinesterase testing under WAC 296-307-148 is Pathology Associates Medical Laboratories (PAML now part of LabCorp). For laboratories that would like to participate as an approved laboratory, please see our Approval Requirements and submit them to John.Stebbins@lni.wa.gov.
The handling hour threshold remains at 30 hours
Workers who handle organophosphate or carbamate pesticides, with the signal word “DANGER” or “WARNING” on the label, for 30 or more hours in any 30 day period must participate in the cholinesterase monitoring program, which includes:
- A discussion with a health care provider.
- A decision by the worker to have or not to have blood tests.
- An annual baseline blood test prior to exposure to these pesticides.
- Periodic blood tests to assess worker exposures to pesticides.
- Work practice evaluations for significantly depressed cholinesterase levels.
- Removal from handling of OP & CARB pesticides when recommended by the medical provider.
Employer reporting of handling hours is through the medical provider
Employers continue to report each employee’s handling hours for the above pesticides directly to the medical provider at the time of each periodic test. There is a spreadsheet and instructions to help with this on the Resources tab.
Pathology Associates Medical Laboratories (PAML now part of LabCorp), is the only current laboratory approved to provide cholinesterase testing services under the cholinesterase monitoring program. Employers must verify that their medical provider uses PAML for all cholinesterase laboratory testing. For laboratories that would like to participate as an approved laboratory, please see our Approval Requirements and submit them to John.Stebbins@lni.wa.gov.
Employee notification of health care provider recommendations
In 2006 the rule was amended to require employers to obtain a written recommendation from the health care provider for each employee test (incl. baselines) and evaluation and provide a copy of the recommendation to the employee, either directly or through the health care provider, within 5 days of receipt.
L&I Consultation & Compliance Services
Cholinesterase Depression (DD 33.27) sets policy for the provision of consultation and compliance services. Generally employers will be offered consultation services whenever an employee experiences a significant cholinesterase depression. A referral to compliance may be made when multiple employees experience significant cholinesterase depression and the employer declines consultation support, or circumstances indicate safety program deficiencies, e.g. cholinesterase depression clusters or ongoing employee cholinesterase depressions.
Requests for cholinesterase cost reimbursement
Employers may request reimbursement for the reasonable costs of training, recordkeeping, and medical expenses for cholinesterase monitoring by submitting the Cholinesterase Monitoring Reimbursement Request form (F413-062-000) along with required documentation. You will need to attach the Statewide Payee Registration form (F120-115-000) to be paid.
The Cholinesterase Monitoring program has an annual calendar and process that ensures a safe working environment for those working with these pesticides in the agriculture industry. This calendar aligns with the agriculture processes and growing cycle to maintain the consistency with and compliance to the Cholinesterase Monitoring rule (WAC 296-307-148).
|Last Day of October||Requests from laboratories seeking approval for program.||Cholinesterase Laboratory Approval Requirements|
|Mid-December||Department notification of Approved Laboratories||Email John.Stebbins@Lni.wa.gov|
|3rd Week of January||Testing begins|
|January through October||Employers Follow Requirements Employers Submit Reimbursements||Employer Information|
|Last Week of September||Testing concludes/ends||N/A|
|Last Day of October||Final QA/QC Reports||N/A|
- The Biology & Physiology of Cholinesterase: Running a Cholinesterase Program
- A PowerPoint presentation developed by Matthew Keifer MD MPH, Associate Professor, University of Washington.
- Cholinesterase monitoring clinical consultation services are available 24 hours a day through University of Washington Occupational Medicine Residency Program by calling 206-744-9393 or visit their website.
- Building Informed Consent for Pesticide Handlers in Washington
- A PowerPoint presentation developed by Karl F. Weyrauch MD MPH, Family Physician, Research Consultant UW PNASH Member, Western Institutional Review Board.
- Cholinesterase Monitoring, WAC 296-307-148
- A PowerPoint overview of the rule developed by John Furman, PhD, MN, CIC, COHN-S, Occupational Nurse Consultant, WISHA Policy & Technical Services.
- Cholinesterase Testing: Reporting Requirements and the Role of the Washington State Department of Health (DOH)
- A PowerPoint Presentation developed by Cheryl Hanks, RN, DOH Pesticide Surveillance Program.
Publications, Handouts, Checklists, Sample Programs
- Cholinesterase - Worker Protection Standard Checklist of Requirements
- Cholinesterase Handling Hours Spreadsheet
- Cholinesterase Handling Hours Spreadsheet Instructions
- Cholinesterase Informed Consent for Testing (English)
- Cholinesterase Laboratory Approval Requirements
- Cholinesterase Medical History Questionnaire (English)
- Cholinesterase Medical Monitoring Providers
- Cholinesterase Monitoring Fact Sheet for Employers - English
- Cholinesterase Monitoring of Pesticide Handlers in Agriculture - Final Report 2014
- Cholinesterase Monitoring of Pesticide Handlers in Agriculture - Final Report 2013
- Cholinesterase Monitoring of Pesticide Handlers in Agriculture - Final Report 2012
- Cholinesterase Monitoring: Health Care Provider Recommendations (SAMPLE) (English)
- Cholinesterase Monitoring Reimbursement Request Form (F413-062-000)
- Cholinesterase Start-Up Letter – from Approved Laboratories (Sample)
- Cholinesterase Testing: Guidelines for Health Care Providers
- Questions and Answers About the Cholinesterase Monitoring Rule
How can I get help from L&I?
The L&I office in your area has industrial hygienists who can assist with specific questions. Please call your local area L&I office and ask for a consultation supervisor.
Region 1: 425-290-1300
Island, San Juan, Skagit, Snohomish, and Whatcom counties.
Region 5: 509-454-3700 or 1-800-354-5423
Adams—west side, Asotin, Benton, Chelan, Columbia, Douglas, Franklin, Grant, Kittitas, Okanogan, Walla Walla and Yakima counties.
For questions about the cholinesterase monitoring rule and other program issues contact John Stebbins at 206-515-2870 or email him at John.Stebbins@Lni.wa.gov.