111. Risk assessment, management, and communication

• Risk assessment
  • = assessing the health risk of a policy, action, or intervention
  • Involves:
  • Identification of the hazard
  • Evaluation of the dose-response relationship
    • Compounds can follow a deterministic dose-response relationship or a stochastic dose-response relationship
    • Deterministic dose-response relationship
      • = means that as the dose is increased past a certain threshold (LOAEL), the severity of the effect increases
      • Most compounds have this type of relationship
      • The highest dose at which there is no observed effect is the NOAEL (no observed adverse effect level)
      • The lowest dose at which there is an observed effect is the LOAEL (lowest observed adverse effect level)
    • Stochastic dose-response relationship
      • = means that there is no safe dose threshold, and as the dose increases the probability (not the severity) of the effect increases
      • Even at an exposure of 1 molecule, the adverse effect can occur (albeit with extremely low probability)
      • Carcinogenic compounds have this type of relationship
      • There is no upper limit of safe dose, so instead we use the ALARA principle (as low as reasonably achievable)
  • Evaluation of human exposure
    • Estimate concentration in the environment
    • Perform measurements of the environment and biological samples
      • Many chemicals have biomarkers which can be measured in the urine
  • Characterization of the risk
    • The unit of risk is microrisk (µR)
      • 1 µR refers to one case of adverse effect per 1 million people
    • The highest acceptable risk for the general population is 1 µR/life
    • The highest acceptable risk for the working population is 10 µR/year
      • Because the working population is overall healthier than the general population
    • Reference dose (RfD) = (NOAEL or LOAEL) / (UF1 x UF2 x … x MF)
      • RfD is the maximum acceptable dose to be exposed to
      • This formula allows for extrapolation of results from animal studies to humans
      • UF and MF are uncertainty factors
• Risk management
  • = planning and implementation of actions to reduce or eliminate health risk
  • Preventative measures (in sequence)
    • Improve manufacturing practice
      • For example, change the manufacturing process to one with less risk
    • Use better working tools
    • Use less hazardous chemicals
    • Collective safety
    • Rearrange work
      • Decrease working hours
    • Use personal safety equipment
      • This should only be used is all other measures fail
      • This is because workers tend to not use safety equipment correctly (because they’re uncomfortable), so it’s not an effective way of preventing risk
• Risk communication
  • = communicating the risk to the exposed people