• Most insecticides affect the nervous system of animals (insects and humans)
• DOSE is the primary factor as to why insects are most susceptible, but with increased doses (exposure) humans are susceptible

• Nerve to nerve transmission
• Nerve to muscle transmission
• Nerve to organ transmission

• Cell body
• Dendrite - receives the message
• Axon - sends the message
• Synapse - chemical transmitter released, cleansing enzyme shuts off transmission

• Axon to dendrite
• Axon to muscle
• Synapse
  • chemical transmitter = acetylcholine
  • cleansing enzyme = cholinesterase

• Baseline in off season (30-day exposure free)
• Red blood cell
  • drop 30% or more from baseline
• Plasma
  • drop 40% or more from baseline
• You can return to handling when levels return to within 20% of baseline

• These two classes of insecticides actually TRAP the cholinesterase (cholinesterase inhibition)
• Once inhibited, there is NO free cholinesterase enzyme to cleanse the synapse
• Thus, acetylcholine (transmitter) continually stimulates the nerves, muscles, glands
• Muscles and glands remain overexcited (this is poisoning).
• Poisoning can be mild, moderate, severe, or deadly.

• Too much neural transmitter
• Not enough cholinesterase (50% decreased)
• Headache, dizzy, nauseous, diarrhea
• Muscle aches, clumsy, cramps, out of breath breath
• Pin point pupils, blurred vision
• Convulsions, coma
• Death

• An enzyme that is critical for “cleaning out” the synapse and stopping the ongoing transmission of neural messages to muscles and glands.
• Cholinesterase is found in the blood system and nervous system (“equally ”), so measuring levels in the blood is a great indicator of the bodies’ supply of cholinesterase in nerves.

• Your body continually makes more cholinesterase enzyme (Liver and bone marrow)
• Keep exposure low so that you do not deplete your body’s reserves of cholinesterase to a harmful level, especially organophosphates
• The body does not recognize the depletion, and only builds so much a day (1% per day for red blood cells)
• It may take a month or two for your body to build back to a safe level

• Amount of exposure needed to cause harm
• Levels are predetermined
• Risk of pesticide use and symptoms vary
  • Frequency of exposure – Concentration of the pesticide
• Toxicity can be cumulative
  • Rate of depletion, rate of generation

• Genetic Trait
• Liver disease
• Certain medications

• Become familiar with pesticides used
• Save labels!
• Wear appropriate equipment
• Clothing should provide an effective barrier to pesticide sprays and dusts!
• Respirators should be chemical specific

• Use unlined rubber or plastic gloves
• Never wear leather!
• Not too tight
• Not too big
• Wear on the outside of the sleeve
• Wash gloves after use
• Dispose of old gloves

• Wear Neoprene or nitrile boots
• Do not wear leather
• Wear pant legs outside of boots

Closed Systems

Used closed systems. When using closed systems, you do not add those hours handling to the total exposure period prior to testing.



Disclaimer and Reproduction Information: Information in NASD does not represent NIOSH policy. Information included in NASD appears by permission of the author and/or copyright holder. More

NASD Review: 06/2006