Cholinesterase Monitoring 

of Pesticide Handlers 

in Agriculture: 2009 Report 

Division of Occupational Safety and Health (DOSH)

NOVEMBER 20, 2009

If you have questions about this report please contact John Furman PhD, MSN, CIC, 

COHN-S, at 360-902-5666 or furk235@lni.wa.gov
1

Executive Summary

The Division of Occupational Safety and Health (DOSH) administers the agriculture 

cholinesterase monitoring program under WAC 296-307-1481, Cholinesterase Monitoring (the 

rule). During the 2009 cholinesterase monitoring season (January 12 – September 17), ~217 

growing operations and 2060 pesticide handlers participated in baseline cholinesterase testing. 

Two hundred and forty nine of these pesticide handlers were tested again (periodic testing) at 

least once during the application season. The great majority of handlers submitting periodic tests

met the testing requirement threshold of handling toxicity class I or II organophosphate or Nmethyl-carbamate pesticides for >30 hours in any consecutive 30 day period. However, in some 

cases employers scheduled testing regardless of number of handling hours.

Of these 249 handlers, 22 (8.8%) received at least one test with a serum cholinesterase activity 

depression of >20% (action level) requiring the employer to evaluate pesticide handling 

practices, there were no red blood cell cholinesterase action level depressions. Seven (2.8%) of 

the 22 handlers were temporarily removed from exposure to covered pesticides because of a 

serum cholinesterase depression of >40%. All action level cholinesterase depressions occurred 

in Labor & Industries (L&I) Region 52. Twelve growing operations accounted for the 22 action 

level cholinesterase depressions.

The number of pesticide handlers undergoing blood cholinesterase testing in 2009 rose slightly 

from 2008 (2013), while the number of participating growing operations remained unchanged.

However the number of handlers undergoing periodic testing decreased from 314. This is 

believed to be affected by actions such as; a) changes in pest control strategies, b) reductions in 

Guthion use, and c) employer actions resulting in limiting handler exposure (e.g., employee 

rotation).

All handlers with cholinesterase depression to the action level were employed in the tree fruit 

industry (DOSH is not aware of any field crop operations participating in the cholinesterase 

monitoring program) and all operations applied pesticides through the air blast method. DOSH 

consultation and compliance field evaluations identified common potential over-exposure 

scenarios involving respiratory protection, personal protective equipment and decontamination. 

Toxicity class I and II cholinesterase inhibiting pesticides handled within the 30 days prior to 

periodic testing included Lorsban, Guthion, Imidan, Phosmet, Carbaryl, and Carzol (Sevin 4F 

and Diazinon 50W Class III pesticides were also used). 

Pathology Associates Medical Laboratories (PAML) continues to conduct all laboratory analysis. 

Quality control indicators were well within limits and customer satisfaction remains high. 

PAML will continue to serve as the sole laboratory approved by DOSH in 2010.

In conclusion, the 2009 cholinesterase monitoring program functioned well. The information 

gleaned from field evaluations is used by DOSH and WSDA in developing pesticide handler 

training curriculum. The program continues to provide value by maintaining awareness of 

hazardous chemicals and worker protections, and bolsters DOSH’s ability to work directly with 

agriculture employers to solidify pesticide worker protection programs.

 

1

http://www.lni.wa.gov/WISHA/Rules/agriculture/HTML/part-j-1.htm

2

http://www.lni.wa.gov/Safety/Basics/Assistance/Consultation/consultants.asp
2

Background

Acetylcholinesterase (AChE) is an enzyme that removes the chemical neurotransmitter

acetylcholine from the junctions between nerves cells. AChE effectively serves as the nerve

cell “off switch” and is essential to normal nervous system function. Certain pesticides, known

as cholinesterase inhibitors, bind with AChE resulting in over-excitement of nervous system

pathways.

Exposure to organophosphate or N-methyl-carbamate pesticides may lower the level of available 

cholinesterase in the nervous system. Depressed cholinesterase activity may lead to symptoms 

ranging from malaise, blurred vision, and diarrhea to, in extreme cases, coma and death. 

Laboratory monitoring of cholinesterase levels in the blood (both serum and red blood cell 

[RBC] cholinesterase) detects reductions in cholinesterase activity prior to the onset of related 

symptoms, as well as provides information regarding pesticide exposure and the effectiveness of 

exposure control measures. While cholinesterase levels may be affected by such factors as liver 

and blood disease, and certain medications in the absence of such factors cholinesterase 

depression is most likely caused by over-exposure to the cholinesterase inhibiting pesticides 

handled by the these workers. Previous reports provide detailed background and describe 

cholinesterase monitoring experiences during the years 2004 – 083.

WAC 296-307-148, Cholinesterase Monitoring (the rule), was adopted in December 2003 and 

remains unchanged since amendments were made in 2005. The rule requires agriculture 

employers to: a) record hours employees handle4toxicity class I and II organophosphate and Nmethyl-carbamate pesticides (covered pesticides); b) provide cholinesterase blood testing to 

employees who handle covered pesticides for 30 or more hours in any consecutive 30 day 

period; and c) follow health care provider recommendations for pesticide handlers regarding 

pesticide handling practices and medical evaluation. A copy of the licensed health care 

provider’s (LHCP) written recommendation is provided to the handler by the employer. Health 

care provider recommendations include cholinesterase percent change from baseline, direction 

regarding actions to be taken based on cholinesterase activity, and any additional direction 

regarding further medical evaluation.

DOSH offers consultation services to agriculture employers with pesticide handlers who

experience a cholinesterase depression >20% from individual baseline (action level

cholinesterase depression). In addition to assisting with an evaluation of the employer’s

pesticide worker protection program and the pesticide handler’s work practices, information on

pesticide handling practices and equipment is gathered. DOSH compliance inspections are

opened in certain circumstances such as clusters of action level cholinesterase depressions, and 

employer refusal to accept consultation services5.

Reimbursement to employers for testing services and related administrative program costs

 

3

Previous reports can be found at http://www.lni.wa.gov/Safety/Topics/AtoZ/Cholinesterase/default.asp

4

Pesticide handling is defined in WAC 296-307-11005

5 DOSH Directive 33.27 Cholinesterase Depression 

http://www.lni.wa.gov/Safety/Rules/Policies/PDFs/WRD3327.pdf
3

continued in 2009. Sixty-one employers requested and were granted reimbursements totaling

$129,000.00.

The following table outlines participation and monitoring outcomes from the inception of the 

cholinesterase monitoring program.

Washington State Agriculture Cholinesterase (ChE) Monitoring 2004-09

2004 2005 2006 2007 2008 2009

# Employers 380 316 244 226 218 217

# Handlers submitting 

baseline tests

2630 2263 1889 1857 2013 2060

# Handlers declining 

testing*

Data not 

collected

232 184 167 192 229

# Working baselines Data not 

collected

165 48 120 71 29

# Handlers with >1 

periodic test

580 611 471 386 314 249

# Periodic tests 911 970 692 532 495 286

# Handlers with ChE 

depression to work 

evaluation level

97(16.7%) 49(8.0%) 50(10.6%) 49(12.6%) 21(6.7%) 15(6.1%)

# Handlers with ChE 

depression to 

exposure removal 

level

22(3.8%) 10(1.6%) 7(1.5% 18(4.6% 1(0.1%) 7(2.8%)

Total # handlers with 

AL ChE depression 

119(20.5%) 59(9.6%) 57(12.1%) 67(17.3%) 22(7.0%) 22(8.8%)

# Handlers reporting 

pesticide illness 

symptoms

0 0 0 0 0 0

Avg. days from 

referral to DOSH field 

visit**

34 13 20 12 7 5

*Declinations are reported through polling of medical clinics are mid-season

 ** Includes 9 consultation and 4 compliance visits

Medical Services

Fifteen medical clinics provided blood collection and medical evaluation services. Twelve clinics 

are located in Region 5, two in Region1, and one in Region 46. In preparation for the 2009 

monitoring season the DOSH Occupational Nurse Consultant (ONC) contacted all participating 

 

6

http://www.lni.wa.gov/Main/FindAJob/regions.asp?WT.svl=3
4

clinics. The ONC reviewed the rule and cholinesterase medical monitoring guidelines7 with each 

clinic, onsite training to 6 high volume clinics. All clinics reported satisfaction with the 

laboratory services and support provided by DOSH.

Pathology Associates Medical Laboratories (PAML) is the sole laboratory approved to provide

testing services. There were no changes in Standard Operating Procedures8from 2008 to 2009. 

Blood samples are packed in ice and picked up at the clinic using same-day courier services.

Samples are analyzed within 24 hours of collection and reported that same day.

The DOSH Industrial Hygiene Laboratory worked directly with PAML to track quality control

indicators. These activities entailed weekly reviews of the internal quality control samples,

charting of all internal quality control samples and monthly site visits to discuss QC review and

status update. DOSH staff also participated in a limited QC program where DOSH staff was

drawn on a monthly basis and the results were compared to other Quality Control date. All 

quality control indicators demonstrated good precision throughout the season. Dr. Barry 

Wilson’s Laboratory at the University of California at Davis continued to provide consultation 

services.

Monitoring Summary

As in previous years, the vast majority of employers participating in the medical

monitoring program had operations located in Central Washington (West Adams, Benton,

Chelan, Columbia, Douglas, Franklin, Grant, Kittitas, Okanogan, Walla Walla, and Yakima

counties). North and Southwest counties accounted for the remainder of the samples submitted. 

During the 2009 cholinesterase testing season (January 21 – October 11), ~217 growing 

operations participated in testing and 2,060 handlers submitted cholinesterase baseline tests. 

Baseline submissions increased slightly from 2008. This appears to be related to clinics 

encouraging baseline testing as a risk management strategy and employers incorporating baseline 

testing into hiring practices.

Of the 249 handlers who received at least one periodic test, 22 (8.8%) received at least one

periodic test result with a >20 percent cholinesterase depression from baseline (action level 

cholinesterase depression) requiring the employer to evaluate pesticide handling practices for 

possible deficiencies. Of those same 22 handlers, 7 (2.8%) were temporarily removed 9from 

handling covered pesticides. The 22 pesticide handlers (all serum action level cholinesterase 

depressions) worked for 12 different employers, two employers accounted for 12 of the action 

level cholinesterase depressions. One of the handlers also experienced an action level 

cholinesterase depression in 2008. No handlers were identified with pesticide illness related 

symptoms. (see Pesticide Incident Review Tracking Panel reports for data on pesticide illness in 

Washington State http://www.doh.wa.gov/ehp/PIRT/default.htm)

 

7

http://www.lni.wa.gov/Safety/Topics/AtoZ/Cholinesterase/files/ProvidersGuidelines1.pdf 

8 Available upon request

9 Employees may return to handling covered pesticides when cholinesterase levels return to within 20% of baseline. 

While medically removed from exposure to covered pesticides employee pay, seniority and other benefits are 

maintained at the pesticide handler level for a maximum of 3 months. 
5

The rule allows employees to either choose to participate or decline participation in the 

employer’s cholinesterase testing program. The option is consistent with other WISHA rules 

that contain medical surveillance provisions. As an additional protection against potential 

coercion regarding the handler’s decision to participate in the program the rule includes the 

requirement that this decision is made in conversation with the health care provider. All clinics 

were asked to report handler declinations; 229 handler declinations were reported from 42

growing operations. DOSH opened compliance inspections with 12 growing operations which 

had >3 handlers decline testing. Thirty seven handlers were interviewed with no instances of 

employer coercion found. Reasons given for declining included; a) pain and fear of needles, b) 

limited to no handling of covered pesticides (e.g. organic operations), c) not receiving test results 

in previous years, d) never experiencing illness, and e) in one case handlers were sent in for 

periodic testing on a Friday. Since samples are not collected on Friday they were asked to come 

back on Monday, however the desk clerk also mistakenly had the handlers sign declination 

forms. Unfortunately this set of periodic tests was never done. 

DOSH contacted the 3 employers who had >3 pesticide handlers with working baselines. All 3 

were organic operations with either no use or limited use of cholinesterase inhibiting pesticides. 

The employers were educated as to the correct application of the rule.

Handler receipt of LHCP written recommendations has been an ongoing stakeholder concern. 

Of the 22 handlers with action level cholinesterase depressions DOSH did find that in one 

instance the employer did not provide a copy of the LHCP written recommendation to the 

handler. There where two additional instances where handlers had not been provided a copy of 

the LHCP written recommendation however the employers had not yet received the written 

recommendations from the health care providers. In addition, DOSH conducted 40 inspections 

in which compliance with the cholinesterase monitoring rule was evaluated. Four growing 

operations were cited for not providing copies of LHCP written recommendations (these 

operations did not have handlers with action level cholinesterase depression). 

L&I Consultation and Compliance Findings

All 12 growing operations with handlers who had experienced action level cholinesterase 

depression received site visits by DOSH consultation or compliance services. The average 

number of days between a referral for consultation or compliance action was 5, with a low of 3 

and high of 15. 

In some cases the employer removed the handler from handling cholinesterase in habiting

pesticides, even though medical removal was not required, while waiting for DOSH to aid in the 

handling practice evaluation

Note: Upon interview 10 of the 22 handlers with action level cholinesterase depression reported 

that they had attended the WSDA hands-on pesticide training. Only 1 of these handlers could be 

matched by name and employer in the training attendance data base (2006-2009). Two additional 

handlers were identified by name but not matched by employer. As part of next year’s 

interviews handlers will be asked if they can provide their training certification card.
6

Consultation Visit Summaries

Growing Operation 1: This consultation is in relation to a mixer, applicator that experienced a 

25.74% serum cholinesterase depression. The handling hours reported in the 30 days prior to 

testing was 30.5. Covered pesticides handled in the 30 days prior to testing were Lorsban 4E and 

Carbaryl (Seven 4F a class III cholinesterase inhibitor was also applied). 

Rule Violations:

WAC 296-307-61205: The handler when interviewed had a beard and indicated that he had been 

spraying while wearing his beard and a North half face respirator.

WAC 296-307-13045(6)(g)(iii): There was no written change schedule for the filters used on 

the North half face respirator.

WAC 296-307-14835: There was no completed written record of the findings of the work

practice evaluation done after the company was notified of the action level cholinesterase

depression.

WAC 296-307-60405: The handler’s duties include wearing a fitted respirator to apply

organophosphate containing pesticides. The handler has not undergone a respirator use medical 

evaluation.

WAC 296-307-13050(4): Emergency flushing water to carry or to be on the tractor while 

applying pesticides is not provided.

WAC 296-307-13025(3)(a): Written material or audiovisual training aids were not used to 

provide required WPS training. 

Potential Over-Exposure Scenarios:

The handler reported that he had mixed covered pesticides while wearing ripped gloves.

Growing Operation 2: This consultation is in relation to an applicator that experienced a 28.82% 

serum cholinesterase depression. The handling hours reported in the 30 days prior to testing was 

30.0 . Covered pesticides handled in the 30 days prior to testing were Lorsban 4E. 

Rule Violations:

WAC 296-307-13025(3)(d)(viii): Pesticide handler found to be removing chemical resistant 

hood in order to look back at spray boom while conducting application and making turns. The

handler also mentioned taking gloves off while unclogging plugged nozzles on the spray

equipment.

Potential Over-Exposure Scenarios:

Removing hood while applying and removing gloves to unplug spray nozzles
7

Growing Operation 3: This consultation is in relation to a mixer, loader, applicator that 

experienced a 30.11% serum cholinesterase depression. The handling hours reported in the 30 

days prior to testing was 38.0. Covered pesticides handled in the 30 days prior to testing were 

Lorsban 4E (Sevin 4F a class III product was also handled). 

Rule Violations:

WAC 296-307-13045(6)(i)(ii): The area in front of the employees' lockers is used by pesticide 

handler/applicators to change into personal protective equipment. This is a concrete floor 

covered with dirt and gravel. The area is not clean and has no place for workers to sit if needed 

to put on or take off boots.

WAC 296-307-14835: There was no completed written record of the findings of the work 

practice evaluation done after notification of the handler’s action level cholinesterase

depression.

Potential Over-Exposure Scenarios:

The handler reports removing gloves when cleaning spray nozzles and smoking while on lunch 

and bathroom breaks. Also reports an incident where he felt feeling spray on his face when 

cleaning nozzles even though he was wearing full PPE.

Growing Operation 4: This consultation is in relation to a loader, mixer, applicator that 

experienced a 20.92% serum cholinesterase depression. The handling hours reported in the 30 

days prior to testing was 30.0. Covered pesticides handled in the 30 days prior to testing were 

Lorsban 4E (Seven 4F a class III product was also handled). 

Rule Violations:

WAC 296-307-61205: The handler was found to have a beard and was a designated respirator

user. The beard may interfere with the proper fit and seal of the half face respirator rendering 

it less effective.

WAC 296-307-13025(3)(a): The training provided the handler did not include written material 

or audiovisual training aids. 

WAC 296-307-12025(3)(f)(iii): The designated sign prohibiting entry into an orchard was 

posted on an orchard that had not been sprayed for quite some time. The foreman indicated that

the sign was kept up to keep kids going home from school out of the orchard.

WAC 296-307-14835: There was no written record of the findings of the work practice

evaluation done after the company was notified of the cholinesterase depression. 

Potential Over-Exposure Scenarios:

Poor fitting respirator and facial hair inhibiting respirator seal.

Growing Operation 5: This consultation is in relation to a loader, mixer, applicator that 

experienced a 37.30% serum cholinesterase depression. The handling hours reported in the 30 
8

days prior to testing was 70.0. Covered pesticides handled in the 30 days prior to testing were 

Lorsban 4E and Carzol SP. 

Rule Violations:

WAC 296-307-14835: There was no written record of the findings of the work practice 

evaluation done after the company was notified of the action level cholinesterase depression. 

WAC 296-307-13025(3)(a): No written material or audiovisual training aids were used to 

provide WPS required training. 

WAC 296-307-13045(6)(g)(iii): There was no written change schedule for the filters used on the 

Kasco K80S helmet Respirator.

Potential Over-Exposure Scenarios:

Handler reports that he was sprayed in the face when while performing spray nozzle 

maintenance. 

Growing Operation 6: This consultation is in relation to 4 loader, mixer, applicators that 

experienced 43.72%, 23.91%, 25.39%, and 64.12% serum cholinesterase depressions. The 

handling hours reported in the 30 days prior to testing were 41.5, 38.0, 47.5, and 40.5 

respectively. Covered pesticides handled in the 30 days prior to testing were Lorsban 4E for 3 of 

the handlers, and Lorsban 4E and Carzol SP for the remaining handler. (43.72% cholinesterase 

depression).

Rule Violations: 

WAC 296-307-14835: There was no written record of the findings of the work practice

evaluation done after the company was notified of the cholinesterase depressions.

WAC 296-307-61205: One handler was found to have a beard and was a designated respirator

user.

WAC 296-307-13025(3)(b): The WPS training was not conducted by a qualified individual but 

by co workers who did not use written materials. 

Potential Over-Exposure Scenarios:

Handlers reported that they do not always have time to perform complete decontamination of 

PPE and equipment, “tractors are washed about every 3 days”.

One handler had facial hair interfering with respirator seal.

Growing Operation 7: This consultation is in relation to 7 applicators that experienced 46.14%, 

67.86%, 20.69%, 26.01%, 43.8%, 47.39%, and 53.29% serum cholinesterase depressions. The 

handling hours reported in the 30 days prior to testing were 36.0 for all of the handlers. 

Covered pesticides handled in the 30 days prior to testing were Lorsban 4E. 
9

Rule Violations:

WAC 296-307-13045(6)(a): All handlers indicated that they only used soap occasionally when 

washing their chemical resistant rain gear. They further indicated that on many occasions they do 

not wash the PPE at the end of the day due to being hurried. 

WAC 296-307-61205: One handler (47.39% cholinesterase depression) was found to have a 

beard and was a designated respirator user. The beard may interfere with the proper fit and seal 

of the full face respirator rendering it less effective.

WAC 296-307-60605: Both North half and full face respirators are used. The handlers had only 

been fit tested to the full face respirator. 

WAC 296-307-13045(6)(i)(ii): The area used by pesticide handler/applicators to change into 

personal protective equipment was maintained but the floor was wet. The water extended to most 

of the floor in front of the employees lockers.

WAC 296-307-14835: There was no completed written record of the findings of the work

practice evaluation done after the company was notified of the Cholinesterase depressions. 

WAC 296-307-14830: The medically removed handlers were paid a dollar less per hour than 

when they were applying. 

Potential Over-Exposure Scenarios:

Wearing respirators that were not fit tested and one respirator user with facial hair.

Handlers reported that they do not always have time to perform complete decontamination of 

PPE and equipment.

Wearing contaminated PPE

Growing Operation 8: This consultation is in relation to a loader, mixer that experienced a 

38.72% serum cholinesterase depression. The handling hours reported in the 30 days prior to 

testing was 32.5. Covered pesticides handled in the 30 days prior to testing were Lorsban 4E.

Rule Violations:

WAC 296-307-13045(6)(g)(iii): Handler exceeded eight hours use without replacing cartridges.

WAC 296-307-13050(6): Insufficient water at decontamination site. Employees hauling water in 

buckets from approximately 100 feet away.

WAC 296-307-13045(6)(a): Respirators found to be dirty and stored with cartridges and filters 

attached. Chemical resistant suits were found in similar conditions.

WAC 296-307-12030(3): The required notice of applications was not displayed at the Central 

Notification Board.
10

Potential Over-Exposure Scenarios:

Use of expired respirator cartridges.

Insufficient decontamination and use of contaminated PPE. 

Growing Operation 9: This consultation is in relation to a mixer, loader, applicator that 

experienced a 27.31% serum cholinesterase depression. The handling hours reported in the 30 

days prior to testing was 28.0. Covered pesticides handled in the 30 days prior to testing were 

Lorsban 4E.

Rule Violations:

WAC 296-307-13025(1): The handler was not trained in accordance with the pesticide safety 

training requirements for handlers.

WAC 296-307-60405: Employer failed to provide medical evaluations for employees required to 

use respirators as part of their duties.

WAC 296-307-62015: The handler failed to properly clean and disinfect respirator, storing it 

with organic vapor removing cartridges and pre filters attached. Two other respirators were 

found in the same condition.

WAC 296-307-13045(6)(f)(iv): Respirator cartridges were not changed out during a 28 hour 

application period. 

WAC 296-307-13045(6)(g)(iii): The handler used a TC23C North half-face respirators with 

vapor removing cartridges and exceeded eight hour's of use without replacing cartridges.

WAC 296-307-30006(2): The employer's Massey Tractor model 135, had power takeoff driven 

equipment attached which had a damaged shaft cover.

WAC 296-307-018(5): Employer did not have a current OSHA 300 log, still using the 200 

version.

Potential Over-Exposure Scenarios:

Inadequate respirator cartridge change-out schedule.

Failure to adequately decontaminate PPE

Lack of WPS compliant training.
11

Compliance Visit Summaries

Growing operation 10: This inspection is in relation to an applicator that experienced a 20.46% 

serum cholinesterase depression. The handling hours reported in the 30 days prior to testing was

2.5. Only Diazinon 50W a class II cholinesterase inhibitor was applied. The inspection was 

assigned to compliance after consultation first contacted the employer by telephone and the 

employer failed to schedule a consultation visit. 

Proposed Citations:

None found. 

Potential Over-Exposure Scenarios:

The handler does not shower after applying (spray blast method).

Growing Operation 11: This inspection is in relation to a mixer, loader, applicator that 

experienced a 31.41% serum cholinesterase depression. The handling hours reported in the 30 

days prior to testing was 35.0. Covered pesticides handled in the 30 days prior to testing were

Lorsban 4E and Phosmet (Sevin 4F a class III cholinesterase inhibitor was also handled). The 

inspection was conducted by compliance due to the fact that compliance was already on site 

following up on declinations when this handler experienced an action level cholinesterase 

depression. The employer agreed to the compliance inspection.

Proposed Citations:

None found. 

Potential Over-Exposure Scenarios:

Not showering after application. 

Growing operation 6: This inspection is in relation to an applicator that experienced a 26.82% 

serum cholinesterase depression. The handling hours reported in the 30 days prior to testing was 

41.0. Covered pesticides handled in the 30 days prior to testing were Guthion and Imidan. 

The inspection was assigned to compliance after consultation had provided services to this 

operation earlier in the year due to 4 handlers experiencing action level cholinesterase 

depression.

Rule Violations:

None found.

Potential Over-Exposure Scenarios:

None found
12

Growing Operation 12: This inspection is in relation to a mixer, loader, applicator that 

experienced a 23.75% serum cholinesterase depression. The handling hours reported in the 30 

days prior to testing was 39.5. Covered pesticides handled in the 30 days prior to testing were 

Lorsban 4E (Sevin 4F a class III product was also handled). The inspection was assigned to 

compliance after the employer declined a consultation visit. 

Rule Violations

WAC 296-307-28016(2)(a): Two instances of unguarded PTO shafts were found.

WAC 296-307-14815: The handler had not been provided a copy of the LHCP written

recommendation. However, had been notified by the employer of the action level 

cholinesterase depression. 

Potential Over-Exposure Scenarios:

The handler reports that the respirator sometimes slips.

Conclusion

In conclusion, the 2009 cholinesterase monitoring program functioned well. DOSH continues to 

work with all stakeholders to make improvements where indicated, e.g., ensuring pesticide 

handlers receive copies of the health care provider’s written recommendations. Information 

gleaned from field evaluations continues to prove useful. For example, the information gleaned 

from field evaluations is used by DOSH and WSDA in developing pesticide handler training 

curriculum

Laboratory services have been solidified and are monitored to identify and limit potential areas 

of bias and analytical variability. Dr. Barry Wilson’s laboratory and the DOSH Industrial 

Hygiene Laboratory have worked closely with PAML to maintain strong services.

DOSH would like to thank all of those individuals, stakeholders and entities involved in 

supporting the L&I Cholinesterase Monitoring Program, with particular appreciation to: 

Pathology Associates Medical Laboratories (PAML); the University of California Davis - Dr. 

Barry Wilson, Mr. Jack Henderson; the DOSH field consultation and compliance staff; and all 

participating health care providers.