Toxicity

1
A Review of Exposure and Toxicity
2
The Need for Gloves and Respirators
A Brief Review of Exposure
3
Pesticide Health Hazard

• Pesticide health hazard is determined by the
  toxicity of the pesticide and the amount of
  exposure to the pesticide
• Hazard Exposure x Toxicity

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Exposure

• How Pesticides Enter the Body

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4 Routes of Exposure

• Dermal - any covered or uncovered skin
• Eyes direct splash or contact with hands
• Inhalation carried in with air
• Oral taken into mouth or on lips

Skin
Eyes
Nose
Mouth
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Dermal Exposure

• 97 of all pesticide exposures are dermal
• The most common route is through the hands and
  forearms
• Dermatitis is most
• common reported
• symptom associated
• with exposure

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Dermal Exposure Parts of the body absorb
pesticides at different rates
Area Rate forehead 4.2 forearm
1.0 abdomen 2.1 palm 1.3 scrotum
11.8 ball of foot 1.8
Absorption rate compared to forearm (1.0)
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Dermal Exposure

• Formulations vary in their ability to be absorbed
  through the skin. Emulsifiable concentrates are
  more readily absorbed than other formulations
• All formulations can be absorbed in clothing,
  thereby becoming a path to skin exposure

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Inhalation Exposure

• Typically occurs when using fine dusts and mists
• Mixing and loading concentrates
• Lung exposure is the fastest way to the
  bloodstream

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Oral Exposure

• Poisoning occurs most often when pesticides have
  been taken from original container and put in
  unlabeled bottle or food container
• Children are most common victims

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Oral Route of Exposure

• Splashing during mixing or cleaning
• Siphoning with the mouth
• Eating
• Drinking
• Smoking
• Licking lips

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Eye Exposure

• Absorption through the eyes can be significant
• Serious eye exposure can result from splash,
  spill, drift, or rubbing eyes with contaminated
  hands or clothing

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Pesticide Exposure

• Avoiding exposure is the key to safe pesticide
  use
• Proper protective equipment worn correctly helps
  avoid exposure

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The Need for Gloves and Respirators
A Brief Review of Toxicity
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Hazard Toxicity x Exposure

• Toxicity

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Types of Toxicity

• Acute
• and
• Chronic

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Acute Toxicity

• single, short term exposure
• the effects of acute pesticide poisoning usually
  occur within minutes or hours after exposure

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Acute Toxicity - Symptoms

• Dermal - skin irritation, itching, reddening
• Oral - nausea, muscle twitching, sweating,
  weakness

• Inhalation - burning of throat and lungs,
  coughing
• Eye - temporary or permanent irritation or
  blindness

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Acute Toxicity

• Acute toxicity is expressed as
• Lethal Concentration 50 (LC50)
• Lethal Dose 50 (LD50)

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Lethal Concentration (LC50)

• The concentration of a chemical in an environment
  (generally air or water) which produces death in
  50 of an exposed population of test animals in a
  specified time frame
• mg/L
• Normally expressed as milligrams of substance per
  liter of air or water (ppm)

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Lethal Dose (LD50)

• Subject test members to different dosages of the
  active ingredient and each of its formulated
  products
• Amount of a chemical that it takes to kill 50 of
  the test population
• mg/kg
• Expressed in milligrams of chemical per kilogram
  of body weight of the test animal

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Lethal Dose 50

• The less you need to cause a toxic effect the
  more toxic the substance is
• Thus an LD50 of 25 mg/kg is more toxic than is an
  LD50 of 6,000 mg/kg

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Lethal Dose (LD50)
HIGHER LD50
higher toxicity
LOWER LD50
lower toxicity
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Chronic Toxicity

• Potential of a pesticide to cause injury from
  repeated or prolonged exposure to small doses of
  pesticides.
• Delayed - time lapses between exposure and
  effects

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Chronic Toxicity

• (repeated exposures)

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Chronic Toxicity Can Cause

• Cancer
• Tumors
• Birth defects
• Impotence
• Infertility or sterility

• Blood Disorders
• Brain damage
• Paralysis
• Emphysema, asthma
• Kidney problems

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REMEMBER

• Repeated low-level exposure to chemicals can
  increase the possibility of future adverse health
  effects

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Toxicity - 4 Categories
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Signal Words

• Warning signs on the label that indicate the
  toxicity of the pesticide to both humans and
  animals
• Signal words measure acute toxicity for skin,
  mouth, lung and eye exposure

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Danger / Poison

• The oral LD50 is from a trace amount up to 50
  mg/kg of body weight
• Label must have the signal word DANGER/PELIGRO
  plus the word POISON
• Label also must display the skull and crossbones
  icon
• Human Exposure trace to teaspoon is fatal to
  150lb. person

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Danger

• Tells nothing about the toxicity of the pesticide
• Indicates that the product has a high potential
  to irritate or damage the eyes and skin

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Warning

• The oral LD50 is between 50 and 500 mg/kg of body
  weight
• Pesticides in this category are classed as
  moderately toxic
• Human Exposure - two teaspoons is fatal to 150lb.
  Person
• WARNING/AVISO

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Caution

• All pesticides with an LD50 of greater than 500
  mg/kg must display this word on their label
• Actually includes two groups of pesticides
  those classed by the EPA as Relatively nontoxic
  (gt5,000 mg/kg) and those classified as slightly
  toxic (500 5,000 mg/kg)

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Where do I find LD50 values?

• On the label? NO
• On the products
• MSDS

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Relative Toxicity

• Are all substances toxic?
• YES!
• All are toxic to some quantifiable degree
• Sugar has an LD50 of 30,000 mg/kg
• 4.5 pounds
• Even water has a recognized LD50 of slightly
  greater than 80,000 mg/kg
• 1.5 gallons

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Summary

• You cannot control the toxicity of a pesticide
  BUT
• You can control your exposure to a pesticide

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Summary

• Toxicity is a given amount.not in control of
  applicator
• Exposure is determined by applicator therefore,
  if exposure is low or zero (0) then health hazard
  is also low or zero
• Using the equation
• Toxicity x Exposure Hazard
• 90 x 100 (1.0) 90
• 90 x 0.0 (0.0) 0

38

Summary
The best way to avoid a pesticide poisoning is to
protect yourself by Reading the label and
Wearing personal protective equipment
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This presentation produced through a grant in
cooperation withThe Pennsylvania State
University Pesticide Education Programby the
Southwestern Pennsylvania Pesticide Educators
Committee

• www.pested.psu.edu