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Carol Ramsay
Pacific Northwest Agricultural Safety and Health Center
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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
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- Nerve to nerve transmission
- Nerve to muscle transmission
- Nerve to organ transmission
Nerve Cells (neurons)
- Cell body
- Dendrite - receives the message
- Axon - sends the message
- Synapse - chemical transmitter released, cleansing enzyme shuts off transmission
Sensory stimulation evokes a motor
Neural Transmission
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Axon to dendrite
- Axon to muscle
- Synapse
- chemical transmitter = acetylcholine
- cleansing enzyme = cholinesterase
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Cholinesterase stops the continual transmission. Nerves then are back to normal resting state, awaiting next stimulation
- 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.
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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.
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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
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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
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Genetic Trait
- Liver disease
- Certain medications
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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
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Wear Neoprene or nitrile boots
- Do not wear leather
- Wear pant legs outside of boots
Used closed systems. When using closed systems, you do not add those hours handling to the total exposure period prior to testing.
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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
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