Transcript Problem-Based Learning Activity: Occupational Herbicide Poisoning

Paraquat
Toxicity and Treatment
Pesticide Health Effects Medical Education Database
(PHEMED)
Paraquat
Paraquat: is very toxic to the skin and mucous membranes (inside of mouth, nose, eyes).
Particles are considered too large for respiratory absorption, but once paraquat in the system
(through broken skin or mucous membranes) it migrates to the lungs because of its oxygen
seeking properties. If ingested it is very lethal, survival rates are generally poor.
Skin:
1. dryness, cracks
2. erythema (redness)
3. blistering
4. ulcerations
Nails:
1. discoloration
2. splitting nails
3. loss of nails
Respiratory
1. cough
2. nosebleeds
3. sore throat
Eyes:
1. conjunctivitis (irritation)
2. ulceration, scarring, blindness
Ingestion:
1. pulmonary fibrosis
2. multi-system organ failure, specifically
• respiratory failure
• kidney failure
Pesticide Health Effects Medical Education Database
(PHEMED)
Toxicology
• Ingestion- life threatening effects on GI, kidney,
liver and heart
• LD50 3-5mg/kg or 10-15ml in 20% solution
• Most lethal in lungs – but toxicity from inhalation rare
• Mechanism – generation of free radicals with
oxidative damage to lung tissue
• Pulmonary fibrosis w/in 7-10 day causes death
Pesticide Health Effects Medical Education Database
(PHEMED)
Source: Richards, Kerry Penn State University Extension Service
Pesticide Health Effects Medical Education Database
(PHEMED)
LD50
Lethal Dose = Amount of
chemical it takes to kill 50% of
an experimental population
Pesticide Health Effects Medical Education Database
(PHEMED)
Source: Richards, Kerry Penn State University Extension Service
Pesticide Health Effects Medical Education Database
(PHEMED)
Source: Richards, Kerry Penn State University Extension Service
Pesticide Health Effects Medical Education Database
(PHEMED)
Adverse effects of Exposure
• GI: mucous membrane swelling, edema,
ulcerations
• Renal –proximal renal tubule damage –reversible
• Cardiac – focal necrosis myocardium
• Cerebral – edema and brain damage
• Smoking paraquat contaminated marijuana:
pyrolyzed to non toxic dipyridyl
Pesticide Health Effects Medical Education Database
(PHEMED)
Toxicology (Skin)
• Local skin damage  contact dermatitis
• Prolonged contact  blisters, abrasion,
ulcerations, finger nail changes
• Slow absorption via intact skin
• Abraded or eroded skin absorption efficient
Pesticide Health Effects Medical Education Database
(PHEMED)
Treatment of Contact
Dermatitis from Paraquat
• Upon contact, flush the skin with copious
amounts of water
• Mild skin reactions are usually self limiting as
long as there is no more contact
• More severe reaction should be treated by a
dermatologist
Pesticide Health Effects Medical Education Database
(PHEMED)
Factors Leading to Illness Event
• What the product used for its intended purpose?
– Is it registered?
– Is it registered for use on wheat & alfalfa?
– Is it restricted?
• What the product used correctly?
• What factors could have lead the worker not to
take action to mitigate the effects?
Pesticide Health Effects Medical Education Database
(PHEMED)