Recommended
More Related Content
What's hot
What's hot (20)
Viewers also liked
Viewers also liked (20)
Similar to toxicity-of-pesticides
Similar to toxicity-of-pesticides (20)
More from Ghassan Hadi
More from Ghassan Hadi (20)
Recently uploaded
Recently uploaded (20)
toxicity-of-pesticides
- 2. HAZARD = EXPOSURE x TOXICITY Toxicity - how poisonous the pesticide is Exposure - how pesticides enter the body
- 3. 4 Methods of Exposure • Dermal (skin) • Oral (mouth) • Inhalation (lungs) • Eyes
- 4. Dermal exposure • rinse with water • remove contaminated clothing • wash with plenty of soap and water
- 5. • Parts of the body absorb pesticides at different rates. • The head is 4 times more absorbent then the hand • and the genital area is 11 times more absorbent.
- 6. Oral Exposure • rinse mouth with water • Do not induce vomiting if – victim is unconscious – having convulsions – petroleum based product – corrosive pesticide – label specifies NOT to induce vomiting PESTICIDE
- 7. Pesticides removed from their original containers are the highest cause of pesticide poisonings in adults and children.
- 8. Inhalation Exposure • remove to fresh air • loosen tight clothing • keep air passages clear • perform artificial respiration if necessary
- 9. Eye exposure • wash eye with a gentle stream of clean water for 15+ minutes • get medical attention if there is pain or reddening of the eye
- 10. First Aid • Act immediately! • Stop exposure • Rinse with clean water • Read and follow label directions! • See a doctor and bring the pesticide label.
- 11. HAZARD = EXPOSURE x TOXICITY Toxicity = the pesticide’s ability to cause damage
- 12. Acute Toxicity • immediate harm caused by pesticide exposure (within 24 hours) • signal words measure acute toxicity for skin, mouth, lung and eye exposure
- 13. Acute Toxicity is measured in LD50 and LC50 lethal dose lethal concentration PESTICIDE
- 14. What this means higher LD50/LC50 = less toxic lower LD50/LC50 = more toxic
- 15. Toxicity - 4 Categories TOXICITY CATEGORY ORAL LD50 (mg/kg) SIGNAL WORD APPROX. ADULT LETHAL DOSE (ORAL) I 0-50 DANGER/ POISON Few drops to 1 teaspoon II 50-500 WARNING 1 teaspoon to 1 ounce III 500-5,000 CAUTION 1 ounce to 1 pint or pound IV >5,000 CAUTION More than 1 pint or pound
- 16. Putting it all together….. = Category I = DANGER/POISON = low LD50/LC50 = small amount of pesticide can kill or harm you
- 17. Acute Toxicity - symptoms • Dermal - skin irritation, reddening, itching • Oral - nausea, muscle twitching, sweating, weakness • Inhalation - burning of throat and lungs, coughing • Eye - temporary or permanent irritation or blindness
- 18. Chronic Toxicity • delayed - time lapse between exposure and effects (don’t appear immediately) • result of repeated exposure to same pesticide or one with similar mode of action • or from a single exposure • effects are not seen until much later
- 19. Chronic toxicity can cause • cancer • tumors • birth defects • infertility or sterility • impotence • blood disorders (anemia, inability to clot) • brain damage • paralysis • emphysema, asthma • kidney problems
- 20. REMEMBER: Low-level exposure to chemicals that have potential to cause long- term effects may not cause immediate injury, but repeated exposures can greatly increase the risk of chronic adverse effects.
- 21. Allergens • anything that causes allergies • need more than 1 exposure to product • after the 1st exposure the body develops a negative response • when exposed again, the body responses negatively = allergic reaction
- 22. Allergies can cause • trigger an asthma attack • shock • rashes, blisters, contact dermatitis • itchy, watery eyes • sneezing
- 23. The nervous system of insects and humans have some common characteristics. Why are some pesticides a health risk?
- 24. Nervous System • Nerves communicate with electrical signals. • Special proteins called “transmitters” carry the electrical signal across the gap between 2 nerves. • Other proteins called enzymes, clean out the gap so the nerve is ready for the next signal • Insects and humans have some of the same transmitters and enzymes.
- 25. Organophosphates (OP) • widespread use and high toxicity • interferes with an important nervous system enzyme, cholinesterase • nerves continuously send messages to the muscles • causing twitching, convulsions, seizures and death
- 26. Organophosphates (OP) • Large exposures can cause acute poisoning. • Small exposures over time “add up” in the body leading to poisoning.
- 27. Carbamates • also interferes with cholinesterase • broken down by the body • acute poisoning
- 28. Symptoms of OP and Carbamate poisoning • Mild - headache, fatigue, dizziness • Moderate - muscle twitching, unable to walk, pinpoint pupils • Severe - unconscious, seizures, death
- 29. Cholinesterase Test Program • Consult your doctor. • off season base line test (January or February) • periodic testing during the season • monitor changes in chlolinesterase levels
- 30. The signs and symptoms of a pesticide poisoning are similar to
- 31. Heat Stress symptoms • exhaustion, headache, nausea, chills, dizzy • thirsty and dry mouth • clammy skin or hot, dry skin • heavy sweating or not sweating • confused, slurred speech, irrational • death
- 32. Pupils of a heat stress victim are normal. Pupils of an OP pesticide poisoning victim are pinpoint.
- 33. Heat Stress • move to shade • rapidly cool victim - splash or sponge cool water on skin • drink as much water as possible • stay calm and call for help
- 34. HAZARD = EXPOSURE x TOXICITY The best way to avoid a pesticide poisoning is to protect yourself by reading the label and wearing personal protective equipment.
Editor's Notes
- Pesticides are designed to kill or harm pests. But pesticides can also harm or kill people. This is chapter 6 of the Pesticide Applicator Core Training Manual, Pesticides and Human Health.
- Pesticides vary in how poisonous or toxic they are. This simple formula helps determine the risk of handling a particular pesticide. Hazard = Exposure x Toxicity Hazard is the risk of the pesticide to cause injury and is a function of both exposure and toxicity. Toxicity is how poisonous the pesticide is. Exposure is how the pesticide enters the body.
- There are 4 ways pesticides can enter the body. The pesticide comes into contact with 1. the skin. Dermal Exposure 2. the mouth or is swallowed. Oral Exposure 3. the lungs. Pesticide vapors or dust are inhaled. Inhalation 4. the eyes.
- The most common way pesticides enter the body is through the skin. To help reduce dermal exposure wear the correct personal protective equipment (PPE) and always wash your hands after handling pesticides or contaminated items. If skin comes into contact with a pesticide -rinse with water - remove contaminated clothing - and wash with plenty of soap and water
- Different parts of the body absorb pesticides at different rates. For example, your hands are not very absorbent compared with other parts of the body. The head is 4 times more absorbent and the genital area is 11 times more absorbent than your hands. Remember to always wash your hands before using the bathroom.
- Pesticide poisoning from oral exposure is very dangerous. Oral exposure can occur from splashing, putting contaminated items and hands in or near mouth, such as food or cigarettes, or accidentally ingesting the pesticide. If a pesticide is splashed on to the mouth or swallowed - rinse mouth with water - and induce vomiting unless - the victim is unconscious, - the victim is having convulsions, - the pesticide is petroleum based, - the pesticide is corrosive, - or the label says DO NOT INDUCE VOMITING.
- Most pesticide poisonings of children occur because pesticides were removed from their original containers and stored in an unlabeled common container such as milk jugs and soda bottles. Keep pesticides in their original labeled containers.
- Pesticides can damage your nose, mouth, throat and lungs when you breathe in pesticide dusts and vapors. If pesticides are inhaled -get victim to fresh air and loosen any tight clothing that might restrict breathing. -keep all air passages (nose and mouth) open and free from obstructions. -perform artificial respiration if necessary.
- Your eyes also easily absorb pesticides. Eye exposure can cause temporary or permanent blindness. If pesticides contact your eyes, wash with pure, clean water for 15 or more minutes and seek medical attention.
- First aid treatments are different for each pesticide and method of exposure. Always read the pesticide label BEFORE using the product so you know what to do in case of a poisoning.
- The other half of the risk equation is toxicity. The pesticide label gives a quick indication of how poisonous the pesticide is - the signal word.
- The signal word is determined by measuring acute toxicity. Acute toxicity is the ability of a pesticide to cause damage within 24 hours after a single exposure. Tests are done to measure the acute toxicity of all 4 methods of exposure.
- Acute toxicity is expressed as “ lethal dose 50 percent” and “lethal concentration 50 percent”, or the LD50 or LC50. This is the single dose of pesticide that kills 1/2 or 50% of the test animals it is given to.
- Another way to think about the LD50/LC50 is the higher the LD50, the less toxic the pesticide-it takes more to kill. The lower the LD50, the more toxic - it takes less to kill.
- Based on the LD50, pesticides are separated into 4 categories. Category I is the most toxic and category IV is the least toxic. For example, a moderately toxic pesticide(which has an adult lethal dose of 1 teaspoon to 1 ounce) would be placed in category II and given the signal word WARNING.
- Pesticides with high acute toxicity are placed in category I, the signal word DANGER appears on the label, they have a low LD50/LC50, and they can kill or harm you in very small amounts such as droplets.
- The symptoms for acute pesticide poisoning vary with the type of pesticide and the method of exposure. Symptoms may appear immediately after exposure, or in a few hours. Some symptoms of acute pesticide poisoning are itching, nausea, weakness, burning lungs, and eye irritation.
- The long-term effects of pesticide exposure are referred to as chronic toxicity. These effects don’t appear immediately after exposure but can take months to years of repeated exposure to develop.
- Illnesses caused by repeated pesticide exposure are cancer, birth defects, blood disorders, brain damage, and kidney problems.
- It is difficult to determine the delayed effects of pesticide exposure because low-level exposures may have no immediate injury but repeated exposure increases the risk of health problems.
- Pesticides can also cause allergies. Anything that causes an allergy is called an allergen. An allergy develops after more than 1 exposure. The first time you are exposed to the pesticide the body develops a negative response, such as a rash. When you are exposed to the pesticide for a 2nd time, the body displays a more severe negative response. You can see the rash. This response is called an allergic reaction.
- Unlike acute or chronic toxicity, allergies are different for everyone. Allergies to pesticides, like those to flowers, milk and chocolate, affect some people and not others. Some common allergic reactions are asthma, a rash, watery eyes, or contact dermatitis.
- Some insecticides interact with the nervous system. The nervous system of insects and humans have some common characteristics. Therefore, pesticides targeted at the insect nervous system can affect humans in the same way.
- The nervous system of insects and humans is made of special cells called nerves. Nerves communicate with each other, organs, and muscles by using electrical signals. Nerves send an electrical signal to a muscle. For the signal to reach the muscle it has to cross a gap. Special proteins called neurotransmitters carry it across the gap. Nerves act like spark plugs. They send an electrical signal to start an action. If something happens so that the nerve or spark plug ‘misfires,’ the muscle or engine does not work.
- One of the most common and most toxic insecticides for both insects and humans are the organophosphates. OP’s interfere with the enzyme cholinesterase, which “cleans” the nerve gap between signals. OP’s stop cholinesterase from working, which allows the nerves to continuously ‘fire,’ send electrical signals. The body responds by twitching, convulsing,and seizing. High exposure can kill.
- OP’s can result in acute poisoning from a single large exposure or several small exposures over time can lead to chronic pesticide poisoning.
- Like OP’s, carbamates interfere with the enzyme cholinesterase in the nervous system and can lead to acute poisoning. But, carbamates do not “add up” in the body. Eventually, the body will break down and expel the carbamates.
- Some symptoms of OP and/or carbamate poisoning are a mild poisoning - headache, fatigue, dizziness a moderate poisoning - muscle twitching, inability to walk, and pinpoint pupils a severe poisoning - unconscious, seizures or even death.
- To help avoid OP poisonings, have a cholinesterase blood test during the winter before you are exposed to pesticides. This establishes your base line level of cholinesterase. Then during the season, have periodic tests to see if the cholinesterase level has changed. Your doctor may then instruct you to not use OP or carbamates for a period of time to avoid a pesticide poisoning if your cholinesterase levels are very low. Consult your doctor for more information.
- The signs and symptoms of pesticide poisoning are similar to those for heat stress. It is important to know the difference.
- The symptoms of heat stress are exhaustion, nausea, dizziness, clammy or hot, dry skin, heavy sweating or not sweating, and confused irrational behavior.
- One way to determine if a persons behavior is the result of heat stress or a pesticide poisoning is to look at the victim’s eyes. The pupils of a heat stress victim are normal. But the pupils of an OP poison victim are constricted.
- If a person is suffering from heat stress move them to a shady, cooler area and splash or sponge cool, clean water on their skin. Drink as much water as possible and call for help.
- To review - The health risk of using a pesticide is a function of how poisonous the pesticide is and the amount of exposure. If exposure is low or “0”, then the hazard is also low or “0”. In other words, even if the toxicity of a pesticide is very high, hazard can be low if exposure is low. Exposure can be reduced by wearing the proper personal protective equipment, and following the label directions.