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Cholinesterase Basics button pdf version  
 

 

 

 


Patricia Boiko
Pacific Northwest Agricultural Safety and Health Center

Goal: To provide information and resources to growers and managers.

Schedule Growers/Manager Breakout

1:30- 2:00 Cholinesterase basics Patricia Boiko
2:00- 2:30 Cholinesterase monitoring rules John Furman
2:30- 3:00 Cholinesterase testing and informed consent/dissent John Furman
3:00- 3:15 Break- Handlers interact with growers and health care providers
3:15- 3:35 Practicalities of the rule Dr. Todd Denny
3:35- 4:00 Grower experiences a monitoring programs

The Rule

Employers must provide cholinesterase monitoring
  • Baseline plasma and rbc cholinesterase
  • Follow-up plasma and rbc level
  • To OP and Carbamate pesticide handlers
    • Who handle for 50 hours or more in a thirty day period for 2004, 30 hours in 2005
Medical Providers Role

According to WAC 296-307-148 Licensed Health Care Providers must:
  • Discuss the risks and benefits of handler participation in cholinesterase monitoring
  • Obtain a signed declination if the handler chooses not to participate
  • Provide and interpret baseline and periodic testing of blood cholinesterase levels
  • Provide other written occupational health recommendations as indicated.
Cholinesterase Basics: >20% Depression From Baseline

Understand
  • Basic science of cholinesterase and cholinesterase inhibiting pesticides
  • Everything about monitoring
    • Testing methods
    • Responses to a positive test: Cholinesterase depression false positives
  • Quality assurance evaluation
The Rule
  • Listen for
    • Which pesticides
      • OP, carbamates
    • Which workers
      • handlers
    • What is the responsibility of growers/managers
Handler Consent
  • Rule says the handler must sign a written declination statement of which a copy goes to the grower
  • WHAT DOES THIS MEAN FOR YOU??
Reporting Requirements and Poisoning

  • Pesticide-related illness
    • Reportable condition to the Washington State Department of Health (WAC 246-10)
    • All types pesticide-related cases must be reported
      • Including skin, eye injuries, systemic poisonings, suicides, homicides,
      • Home and occupational exposures.
Why is ChE Testing Useful?

  • ChE reflects the substance on its target
  • Integrates exposure over time
  • The test is available
  • Blood tests are available
  • BUT!
    • Baseline is needed
    • Good lab methods needed
    • Interpretation and timing important
    • Sample handling important
Objective

To understand the basic biology of cholinesterase and cholinesterase inhibiting pesticides.

Biology of Cholinesterase
  • Present from paramecia to sapiens
  • Very Fast enzyme Ubiquitous in the human body
  • Critical for many nervous system functions


Cholinesterase Enzyme
  • Produced in tissues and blood
  • Hydrolyzes acetylcholine: A key neurotransmitter
  • Present in the autonomic, central and peripheral nervous systems


Two Different Kinds of ChE enzymes
Some behaviors in common
  • Plasma Cholinesterase
    • Butyrylcholinesterase, pseudocholinesterase, PChE, or just cholinesterase and ChE
  • RBC Cholinesterase
    • True cholinesterase, acetylcholinesterase, or AChE
Plasma ChE
  • Floats freely in plasma
  • Made by liver
  • Rapid recovery from depression
  • Rapid replacement by new synthesis
  • Liver disease may affect levels
  • Sensitive to most ChE inhibitor pesticide exposures
Red Blood Cell Cholinesterase
  • Bound to red blood cells
  • Made at the same time as the Rbc's
  • Recovery from depression 0.8%/day
  • Slower to depress, slower to recover
  • Low RBC count may cause lower levels
  • Identical to neuronal ChE
What Cholinesterase Does: Physiologically

  • Autonomic Nervous System
    • Parasympathetic
    • Presynaptic Sympathetic l
  • PNS
    • Skeletal muscle
  • CNS
    • Memory & others


Cholinesterase
  • Found at the synapse
  • It turns off the chemical messenger
  • When inhibited the messenger builds
  • Over stimulation results


Pesticides That Inhibit Cholinesterase
  • Organophosphates
    • Inhibit irreversibly "aging of complex"
    • ChE must be replaced by the body
  • Carbamates
    • Inhibit temporarily
    • No "aging"
    • Reversal is rapid and level related
    • ChE reactivates and is ready to go
Toxicity of ChE Inhibitors

Mild cases: tiredness, weakness, dizziness, nausea and blurred vision

Moderate cases: headache, sweating, tearing, drooling, vomiting, tunnel vision, and twitching

Severe cases: abdominal cramps, urinating, diarrhea, muscular tremors, staggering gait, pinpoint pupils, hypotension (abnormally low blood pressure), slow heartbeat, breathing difficulty, and possibly death

Extoxnet http://ace.ace.orst.edu/info/extoxnet/



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NASD Review: 06/2006