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A Review A Review of of
Exposure and ToxicityExposure and Toxicity
The Need for Gloves and RespiratorsThe Need for Gloves and Respirators
A Brief Review of ExposureA Brief Review of Exposure
Pesticide Health HazardPesticide 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
ExposureExposure
How Pesticides Enter the Body
4 Routes of 4 Routes of ExposureExposure
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
EyesEyes
NoseNose
MouthMouth
SkinSkin
Dermal Dermal ExposureExposure 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
Dermal Dermal ExposureExposure Parts of the body absorb pesticides at different ratesParts of the body absorb pesticides at different rates
Area Rate *
forehead 4.2forearm 1.0abdomen 2.1 palm 1.3 scrotum 11.8ball of foot 1.8
*Absorption rate compared to forearm (1.0)
Dermal Dermal ExposureExposure 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
Inhalation Inhalation ExposureExposure
Typically occurs when using fine dusts and mists
Mixing and loading concentrates
Lung exposure is the fastest way to the bloodstream
Oral Oral ExposureExposure
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
Oral Route of Oral Route of ExposureExposure
Splashing during mixing or cleaning
Siphoning with the mouth
Eating Drinking Smoking Licking lips
Eye Eye ExposureExposure
Absorption through the eyes can be significant
Serious eye exposure can result from splash, spill, drift, or rubbing eyes with contaminated hands or clothing
PesticidePesticide ExposureExposure
Avoiding exposure is the key to safe pesticide use
Proper protective equipment worn correctly helps avoid exposure
The Need for Gloves and RespiratorsThe Need for Gloves and Respirators
A Brief Review of ToxicityA Brief Review of Toxicity
Hazard = Hazard = ToxicityToxicity x x ExposureExposure
Toxicity
Types of Types of ToxicityToxicity
Acute and
Chronic
Acute Acute ToxicityToxicity
single, short term exposure
the effects of acute pesticide poisoning usually occur within minutes or hours after exposure
Acute Acute ToxicityToxicity - Symptoms - 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
Acute Acute ToxicityToxicity
Acute toxicity is expressed as:
Lethal Concentration 50 (LC50)
Lethal Dose 50 (LD50)
Lethal Concentration (LC50)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)
Lethal Dose (LDLethal Dose (LD5050)) 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
Lethal Dose 50Lethal 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
Lethal Dose (LDLethal Dose (LD5050))
higher toxicity higher toxicity ==
HIGHERHIGHER LD50LD50 = =
lower toxicitylower toxicity LOWERLOWER LD50LD50
Chronic ToxicityChronic 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
Chronic Toxicity:Chronic Toxicity:
(repeated exposures)
x
Threshold concentrat ion
SYMPTOMS
TIME: Weeks, months, years
Blo
od
or
Tis
su
e
Co
nc
en
trat
ion
x
x
x
x
x
x
x
Chronic Toxicity Can CauseChronic Toxicity Can Cause
Cancer Tumors Birth defects Impotence Infertility or sterility
Blood Disorders Brain damage Paralysis Emphysema, asthma Kidney problems
REMEMBER:REMEMBER:
Repeated low-level exposure to chemicals can increase the possibility of future adverse health effects
Toxicity - 4 CategoriesToxicity - 4 Categories
Toxicity
Category
Signal
Word
Oral
LD50
(mg/kg)
Approx. Adult
Lethal Dose
(oral)
I
Highly Toxic Danger
Poison0-50
Few drops
to a teaspoon
II
Moderately Toxic
Warning 51-500
1 teaspoon
to
1 ounce
III
Slightly ToxicCaution 501-5,000 1 ounce to 1 pint
IV
Relatively nontoxic
Caution > 5,0001 pint
or more
Signal WordsSignal 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
Danger / PoisonDanger / 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
DangerDanger
Tells nothing about the toxicity of the pesticide
Indicates that the product has a high potential to irritate or damage the eyes and skin
WarningWarning
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”
CautionCaution 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 (>5,000 mg/kg) and those classified as “slightly toxic” (500 – 5,000 mg/kg)
Where do I find LD50 values?Where do I find LD50 values?
On the label? NO
On the product’s
MSDS
Relative Toxicity 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
SummarySummaryYou cannot control the toxicity of a
pesticide …BUT…You can control your exposure to a
pesticide
SummarySummaryToxicity is a given amount….not in
control of applicatorExposure 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%
The best way to avoid a The best way to avoid a pesticide poisoning is to protect pesticide poisoning is to protect
yourself by yourself by
Reading the labelReading the label andand
Wearing personal Wearing personal protective equipmentprotective equipment
SummarySummary
This presentation produced through a grant in cooperation withThis presentation produced through a grant in cooperation withThe Pennsylvania State University Pesticide Education ProgramThe Pennsylvania State University Pesticide Education Program
by the Southwestern Pennsylvania Pesticide Educators Committeeby the Southwestern Pennsylvania Pesticide Educators Committee
www.pested.psu.eduwww.pested.psu.edu