Exposure to Organophosphate _amp; Carbamate Insecticides

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Exposure to Organophosphate _amp; Carbamate Insecticides Powered By Docstoc
					Exposure to Organophosphate
& Carbamate Insecticides

Monitoring for Over Exposure
Principles of Monitoring

n   Detect organophosphate [OP] or
    carbamate [Carb] exposures before
    employees get sick
n   Based on OP/Carb inhibitory effects of the
    enzyme- cholinesterase
n   OPs effects are long term - “irreversible”
n   Carbs effects are shorter term -
    Mechanism of Action

                                    Nerve Ending
n   Inhibits Cholinesterase
    – enzyme responsible for
      hydrolyzing acetylcholine
      to choline
    – choline reabsorbed and
      acetylated ( +     =    )
n   Enzyme inhibition     leads
    to excess accumulation of
    acetylcholine at nerve
    synapse or neuromuscular
    receptor                      Neuromuscular Junction
    Health Effects from
n   Cholinergic stimulation
     – SST: salivation, sweating, tearing
     – blurred vision (miosis)
     – nausea/vomiting, abdominal pains,
     – chest tightness, wheezing
n   Nicotinic stimulation
     – muscle twitching, tremors
     – weakness
     – anxiety, irritability
How is Biological Monitoring
n   Presence of cholinesterase enzymes in
    RBCs and Plasma
    – reflect what may be happening in nervous
      system and muscles
n   Lab methodologies prevalent
n   “Simple” blood test (but it’s not too
Factors for Adequate Monitoring
n   Great variability between individuals & within
    the same individual
n   Use two unexposed specimens to average
    baseline (1-2 weeks apart)
n   Generally ignore Laboratory “Normal Range”
    – Individual serves as own baseline b/o great
n   Using same lab, same methodology
n   Cooling down specimens quickly &
    expeditious processing
    – inhibition of enzymes can be reversible, esp.
      Carbs, resulting in false negatives
Plasma vs. RBC Cholinesterase
n   Plasma Cholinesterase        n   RBC Cholinesterase
    – aka serum, pseudo- or          – aka acetylcholinesterase
      butyrylcholinesterase          – slower to fall and recover
    – quick fall and quick             post-exposure
      recovery after exposure        – no known genetic
    – 0.03-3.0% genetic                deficiency
      deficiency in population       – good for non-acute
       • False “low” reading           exposure monitoring
       • can cause panic
       • not at > risk from
         exposure however
Using Cholinesterase Activity
to Assess Toxicity
n   Correlation between
    depression of
    activity and health
n   At > 25% inhibition,
    occurrence of
    adverse effects rises
    quickly - “slippery
        Cholinesterase Biological Monitoring for OP/Carb Exposure

                Clinical Component                                Safety/ Industrial Hygiene
            Does employee have potential for
             exposure to organophosphates               Obtain Safety / Industrial Hygiene input
              (OP) or carbamates (CARB)?                 before proceeding. See partial list of
                                                          commonly used OPs and CARBs
No                      Yes            Don't Know

                                                         Does employee have potential for
Stop!                                                     exposure to organophosphates
           Establish Baseline Levels:                      (OP) or carbamates (CARB)?
          • Before job assignment or reassignment
            to job with potential for exposure
          • In lieu of this, make sure employee is      Yes                             No
            free from potential exposure for > 4
          • Obtain first set of RBC and Plasma
            Cholinesterase levels
          • Approximately one week later, obtain
            second set of RBC and Plasma
            Cholinesterase levels
          • Average both sets – this establishes
            employees baseline.
          • Baseline data should be readily available
            to employee and supervisory personnel
            in the event of an acute exposure.
   Cholinesterase Biological Monitoring for OP/Carb Exposure

             Clinical Component                                   Safety/ Industrial Hygiene

   Monitor Periodically:
   • Frequency Dependent Upon Exposure (for
   • Pesticide Applicators – monthly
   • Seasonally, Biannually or Annually for others
   • Assessment requires Safety input
   • For most instances, RBC cholinesterase levels
     only need to be obtained
   • Exceptions: Phosdrin (mevinphos); chlorpyrifos:
     require plasma cholinesterase levels

      Drop in cholinesterase levels > 25% baseline?
                                                          Notify Safety / IH office to
                                                          investigate work site and assess
      No                              Yes
                                                          potential for excessive exposure

Continue monitoring         • Remove from Exposure
                            • Notify Safety / IH Office
                            • Repeat levels in 1-2
                              weeks, under guidance
                              of Occupational
                              Medicine Professional
                            • Return to duties once
                              employee recovers and
                              Doctor/Safety deems
                Spill, Leak, Breakdown in Engineering, Personal Protective
               Equipment, or other sudden event which leads to unequivocal
                                    employee exposure

                   Does employee have any symptoms or did
                     employee require any decontamination
                  procedures (shower, partial wash, eye wash,
                 etc.)? [See below for list of symptoms of acute

       Yes to either                                                  No to each

Transport immediately to                                      Counsel employee to seek
Emergency/Urgent Care                                         medical attention immediately
Center:                                                       if any symptoms develop
• Evaluation by health                                        (review symptoms with
  professional                                                employee)
• Draw RBC and Plasma
                                                              Arrange for testing for RBC
  cholinesterase levels
                                                              and Plasma cholinesterase
• Treatment as needed
                                                              levels within 24 hours

n   Establish adequate baselines
    – RBC and Plasma Levels
n   Identify genetically “low” plasma
    cholinesterase levels
n   Use similar lab/methodologies
n   Process and Cool Specimen quickly
    Conclusions (cont’d)

n   Look for >25% Depression
     – only when employee works with
       organophosphate or carbamate
     – use RBC only, with notable exceptions
       (mevinphos; chlorpyrifos)
n   Check plasma cholinesterase under
    acute exposure circumstances

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