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Risk Assessment II

Risk Assessment II. Dec 3, 2008. Carcinogens : There exists a “measurable” risk from any exposure, eg 4.1 x 10 -6 cancer risk for exposure to 1 μ g/m 3 of CH 2 Cl 2 for a lifetime Non-carcinogens : A “safe” dose can be determined Pathogens : An “infectious dose” can be determined

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Risk Assessment II

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  1. Risk Assessment II Dec 3, 2008

  2. Carcinogens: There exists a “measurable” risk from any exposure, eg 4.1 x 10 -6 cancer risk for exposure to 1 μg/m3 of CH2Cl2 for a lifetime Non-carcinogens: A “safe” dose can be determined Pathogens: An “infectious dose” can be determined - ID50, , - Dose that produces 1 in 104 risk of infection Each is considered in isolation

  3. 1996 Food Quality Protection Act • Amendment to FDCA, removes application of Delaney Clause to pesticides and pesticide residues • The “Risk Cup”

  4. The Risk Cup • Food Quality Protection Act (1996) • “Assess the risk of the pesticide chemical residue [to infants and children] based on…available information concerning the cumulative effects of infants and children of such residues and other substances that have a common mechanism of toxicity”

  5. Interactions • Additivity • Synergism • Potentiation • Antagonism

  6. Interactions can be expected between chemicals that • Act by binding to the same receptor • Act through the same mechanism • Require the same enzyme for activation/detoxication

  7. Combinations • Binary mixtures • Ternary mixtures • Four- , five-component mixtures • Six, seven, eight…. • ... • Complex mixtures

  8. Competing risks Drinking water disinfectant by-products ↔ infectious diseases

  9. “Acceptable” risks • Carcinogens: 1 in 106 over lifetime • Occupational exposures: 1 in 103 – 1 in 104 over working lifetime • Enteric diseases: 1 in 104 per year

  10. Comparison of Risks Disability Adjusted Life Years One DALY = 1 lost year of healthy life Disability is weighted by a factor that reflects the severity of the disease on a scale from 0 (perfect health) to 1 (equivalent to death). WHO Global Burden of Disease analysis http://www.who.int/healthinfo/global_burden_disease/en/index.html

  11. Some examples of weighing factors • Asthma -- 0.043 • Blindness – 0.600 • Cancer: Liver – 0.20 • Cancer: Trachea, bronchus and lung 0.15 • Metastatic 0.75 • Cirrhosis of the liver - 0.330 • Cleft palate - Cases 0.103 • Diarrheal diseases - 0.105 • Malaria - 0.191

  12. USA, National Center for Health Statistics

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