1 / 25

Toxicology Basics

Toxicology Basics. An Introduction to the Concepts of Toxicology Used in APES (Building off your knowledge of pesticides to lead into environmental hazardous chemicals as a whole). Units Used to Measure Chemicals in the Environment.

bree
Download Presentation

Toxicology Basics

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Toxicology Basics An Introduction to the Concepts of Toxicology Used in APES (Building off your knowledge of pesticides to lead into environmental hazardous chemicals as a whole)

  2. Units Used to Measure Chemicals in the Environment PPM – Parts per million (1 in per 1,000,000 , 10-6 ) PPB – Parts per billion (1 part in 1,000,000,000 , 10-9 ) PPT – Parts per trillion (1 in 1,000,000,000,000 , 10-12 ) Since parts-per notations are quantity-per-quantity measures, they are known as dimensionless quantities; that is, they are pure numbers with no associated units of measurement.

  3. Consider A simple cube 1 cubic meter in volume 1m 1m 1m

  4. formed of 1,000,000 cubes, 1 cubic centimeter each 100cm 100cm x 100cm x 100cm = 1,000,000 cc 100cm In 1 m3 block 1cc = 1ppm 100cm

  5. One part per million is 1 inch in 16 miles 1 minute in two years 1 cent in $10,000 1 ounce of salt in 31 tons of potato chips 1 bad apple in 2,000 barrels of apples

  6. NOW…Divide each 1CCblock into 1,000 blocks 0.1cM on a side 1cm 0.1cm x 0.1cm x 0.1cm = 0.001cm3 In 1 m3 block 0.001cm3 = 0.001cc or 1/1000 of a cc = 1ppb 1cm 1cm

  7. One part per billion is 1 inch in 16,000 miles 1 second in 32 years 1 cent in $10,000,000 1 pinch of salt in 10 tons of potato chips 1 lob in 1,200,000 tennis matches 1 bad apple in 2,000,000 barrels of apples

  8. Next, divide each 0.1cc block into 1,000 blocks0.01cm on a side 0.1cm 0.01cm x 0.01cm x 0.01cm = 0.000001cm3 In 1 m3 block .000,000,001m3 = 0.000,001cc or 1/1,000,000 of a cc = 1ppt 0.1cm 0.1cm

  9. One part per trillion is 1 postage stamp in the area of the city of Dallas 1 inch in 16 million miles (more than 600 times around the earth) 1 second in 320 centuries 1 flea on 360 million elephants 1 grain of sugar in an Olympic sized pool 1 bad apple in 2 billion barrels

  10. Important Concept • On the left side of the decimal point ( . ) • 1 trillion is bigger than 1 billion • 1 billion is bigger than 1 million • 1 million is bigger than 1 thousand… • On the right side of the decimal point ( . ) • 1 part per trillion is smaller than 1 part per billion • 1 part per billion is smaller than 1 part per million • 1 part per million is smaller than 1 part per thousand

  11. Important Relationship For water at STP (standard temperature [23oC] and pressure [15 psi]) 1 cc = 1ml = 1g

  12. …Which means that (1000 ml or cc )  1 liter of water = 1 kg  (1000 g) (1/1000 g)  1 mg / kg  (1000 g) = 1 ppm (1/1000 cm3 )  1 mm3 / liter (1000 cm3 ) = 1 ppm (1/1000 g)  1 mg / liter  (1000 g) = 1 ppm

  13. Measures of Toxicity: The Median Lethal Dose LD50 The amount (dose) of a chemical which produces death in 50% of a population of test animals to which it is administered by any of a variety of methods Substance (1/1000 g)  mg/kg  (1000 g) body weight Normally expressed as milligrams of substance per kilogram of animal body weight (same as ppm)

  14. Your Turn! PPM Visualization Worksheet

  15. Primary Routes of Exposure to Pesticides There are three primary routes by which organisms are exposed to pesticides Oral Dermal Inhalation

  16. Primary Routes of Exposure: Oral Exposure Any exposure to pesticide which occurs when the chemical is taken in through the mouth and passes through the gastrointestinal tract During oral exposure, although carried within the body, the pesticide is still outside of the body proper until it passes through epithelial cellular membranes.

  17. Primary Routes of Exposure: Dermal Exposure Exposure of the skin to a pesticide Most common route of human exposure With proper hygiene this type of exposure is generally not serious unless there is a specific, rapid toxicological effect (often eye effects) which is of concern

  18. Primary Routes of Exposure:Inhalation Exposure Occurs when a pesticide is breathed into the lungs through the nose or mouth Significant route of exposure for aquatic organisms Not of toxicological concern until it crosses from the lung into the body (unless the chemical is corrosive)

  19. Remember – • For pesticides – less is more when dealing with toxicity • 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 one of 7,000 mg/kg

  20. Signal Words The relative acute toxicity of a pesticide is reflected on the label in the form of a “signal word” The (toxicologically) appropriate signal word MUST appear on every pesticide label The three possible signal words are CAUTION WARNING DANGER

  21. Signal Words:CAUTION “Caution” reflects the lowestdegree of relative toxicity 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 classed as “Slightly toxic” (500 – 5,000 mg/kg)

  22. Signal Words:WARNING “Warning” reflects an intermediate degree of relative toxicity All pesticides with an LD50 of greater than 50 and less than 500 mg/kg must display this word on their label Pesticides in this category are classed as “Moderately toxic” (>50 but <500 mg/kg)

  23. Signal Words:DANGER “Danger” reflects the highest degree of relative toxicity All pesticides with an LD50 of less than 50 mg/kg must display this word on their label Pesticides here are classed as “Highly toxic” (< 50 mg/kg)

  24. POISON!!! Legally defined term – not just anything you don’t like Any pesticide with an LD50 of 50 mg/kg or less Labels must reflect this classification Label must have the signal word “DANGER” plus the word “POISON” Label also must display the skull and crossbones icon

  25. Relative Toxicity: Are all substances toxic? YES! • All are toxic to some quantifiable degree • Sugar has an LD50 of 30,000 mg/kg • Ethanol, a party favorite, has an LD50 of only 13,700 mg/kg • Water has a recognized LD50 of slightly greater than 80,000 mg/kg

More Related