BASIC TERMS IN TOXICOLOGY

In toxicology, understanding units of measurement is crucial. Learn about parts per million, billion, and trillion through relatable examples. Dive into the world of toxicology with simple cube volumes and dimensions, making complex concepts easier to grasp. Explore how minuscule amounts can have significant impacts on the environment and human health, depicted in creative visuals. Gain insights into the magnitude of contamination levels using relatable comparisons like inches in miles, salt in tons of chips, and more.

• Toxicology
• Measurements
• Environment
• Units
• Chemicals

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1. BASIC TERMS IN TOXICOLOGY

2. Units Used to Measure Chemicals in the Environment PPM Parts per million PPB Parts per billion PPT Parts per trillion

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

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

5. One part per million is 1 inch (~2.5 cm) in 16 miles (~30 km) 1 minute in two years 1 cent in $10,000 (1 kuru in 10000 TRY) 1 ounce (~28.35 g) of salt in 31 tons of potato chips 1 bad apple in 2,000 barrels of apples 1 small ball in 1 million balls in a room

6. Divide each 1cc block 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 1ppb 1cm 1cm

7. One part per billion is 1 inch (~2.5 cm) in 16,000 miles (~30000 km) 1 second in 32 years 1 cent in $10,000,000 (1 kurus in 10,000,000 TRY) 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 1 small ball in 1 billion balls in a room

8. And divide each 0.1cc block into 1,000 blocks 0.01cm on a side 0.1cm 0.01cm x 0.01cm x 0.01cm = 0.000001cm3 0.1cm In 1 m3 block .000,000,001m3 = 0.000,001cc or 1ppt 0.1cm

9. One part per trillion is 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 1 small ball in 1 trillion balls in a room

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 1 liter of water = 1 kg 1 mg / kg = 1 ppm 1mm3/ liter = 1 ppm 1 mg / liter = 1 ppm

13. Measures of Toxicity Toxicity of chemicals is determined in the laboratory The normal procedure is to expose test animals By ingestion, application to the skin, by inhalation, gavage, or some other method which introduces the material into the body, or By placing the test material in the water or air of the test animals environment

14. Measures of Toxicity Toxicity is measured as clinical endpoints which include Mortality (death) Teratogenicity (ability to cause birth defects) Carcinogenicity (ability to cause cancer), and, Mutagenicity (ability to cause heritible change in the DNA) At this time we will discuss 2 measures of mortality the LD50 and the LC50

15. 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 (generally in 24 hours) mg/kg Normally expressed as milligrams of substance per kilogram of animal body weight

16. Measures of Toxicity: The Median 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 (generally 24 hours) mg/L Normally expressed as milligrams of substance per liter of air or water (or as ppm)

17. ED50 Effective dosage for 50 percent TD50 Toxic dosage for 50 percent TI=Therapeutic Index Ratio of LD50 or TD50 to ED50 LD50/ED50 or TD50/ED50 The larger value means the margin of safety between the effective dose and toxic dose is greater.

18. Marginal of safety (MOS) Estimated exposed dose to a human population and the highest non-toxic dose determined in experimental animals MOS = LD1/ED99

19. NOEL No Observed Effect Level (mg/kg/day) NOAEL No Observed Adverse Effect Level (mg/kg/day) LOAEL Low Observed Adverse Effect Level (mg/kg/day)

20. ADI Acceptable Daily Intake (mg/kg/day) QSAR Quantitative structure activity relationships Quantitative relationship between a biological activity (e.g. toxicity) and one or more descriptors that are used to predict the activity

21. RFD or RfD Reference dose An estimated dose based upon the amount of the contaminant to which a person may be exposed on a daily basis that is not anticipated to cause the adverse health effect over a person s lifetime

22. t1/2 Biological half-life The time required for some measure of the amount of a chemical in the body (for example, body burden, tissue concentration) to decrease to 1/2 its value at the beginning of the observational interval

26. TOXICOLOGICAL CLASSIFICATION OF PESTICIDES (EPA, active ingredients) Routes of Exposure Toxicity Cat. I Toxicity Cat. II Toxicity Cat. III Toxicity Cat. IV Oral LD50 Up to and including 50 mg/kg 50 500 mg/kg 500 5,000 mg/kg >5,000 mg/kg Inhalation LC50 Up to and including 0.2 mg/l 0.2 2 mg/l 2 20 mg/l >20 mg/l Dermal LD50 Up to and including 200 mg/kg 200 2,000 mg/kg 2,000 20,000 mg/kg >20,000 mg/kg Eye Effects Corrosive corneal opacity not reversible within 7 days Corneal opacity reversible within 7 days; irritation persisting for 7 days No corneal opacity; irritation reversible within 7 days No irritation Skin Effects Corrosive Severe irritation at 72 hours Moderate irritation at 72 hours Mild or slight irritation at 72 hours Signal Word DANGER POISON WARNING CAUTION CAUTION

27. TOXICOLOGICAL CLASSIFICATION OF PESTICIDES (WHO, active ingredients)