15 risk assessment for pest control products Flashcards
what is the data source for human health risk assessment?
animal (mammalian) toxicological studies (NOAEL establishment). Test animals considered good surrogates
what are the two approaches of human health risk assessment”
- non-carcinogenic (non-mutagenic) compounds:
-a threshold dose is established (margin of safety approach)
-threshold dose=dose below which no adverse effects are expected - carcinogenic compounds (or mutagenic):
-no threshold dose used
-acceptable dose established using quantitative risk estimate
goal=establish the NOAEL (the highest level of exposure in test animals in the most sensitive test that caused no adverse effect)
what are the two graphs of human health risk assessment approaches?
what are safety factors used for human health risk?
safety factors (extrapolations):
1. from test animals to humans:
-10x safety factor
-accounts for interspecies variation (e.g. test animals to humans)
-can be changed if new evidence comes up
2. variation within human population
-10x safety factor
-accounts for intraspecies variation (between humans)
what are additional safety factors for human health risk?
applied to RD (reference dose) when there is a need to:
1) address the severity of toxicological endpoints
2) account for sensitive sub-populations
3) address concerns/uncertainties about accuracy of toxicity and exposure estimates
-usually ranges from 3 to 10x
what does RD tell us in human health risk?
to evaluate whether the RD seems reasonable, it has to be compared to estimated human exposure (the RD is basically the same as the ADI (acceptable daily intake))
-the RD (ADI) cannot be lower than the estimated human exposure
-estimates exposure < RD=considered to provide a sufficient margin of safety
exposure estimates are kept conservative (worst case assumptions):
-100% of food crop treated at maximum application rate
-100% of pesticide deposited on the skin is absorbed
-exposure is summed from all sources (aggregate exposure)
what is ADI and ARfD?
ADI (acceptable daily intake): (chronic)
-the amount of a pesticide that is considered safe for humans to consume each day for an entire lifetime
ARfD (acceptable reference dose): acute
-the dose to which an individual could be exposed on any given day and expects no adverse health effects
what is cancer risk assessment?
-uses sophisticated statistical models and data from carcinogenicity studies to estimate the probability of cancer caused by an average daily lifetime exposure
-a lifetime risk less than one in a million is considered acceptable for the general population through exposure to pesticide residues in food or via bystander exposure
why 1 in a million?
-because of all of our exposures combined from all chemicals (adds up quickly)
what else gives us a 1 in a million odds?
lots of things that you experience every day have a greater than one in a million chance of giving you cancer
what is the assessment of environmental risk?
based on a direct comparison of estimated exposure (air, water, soil, sediment, food sources) and measured effects (hazard) on indicator organisms (standard test species)
-no safety factors (just for comparisons)
what is assessment of exposure in environmental risk?
-estimated based largely on modelling of expected environmental concentrations (EECs)
-EECs based on: application rates and frequency, crop, climate, environmental chemistry and fate
-requires a detailed understanding of chemical properties, environmental chemodynamics and use pattern (other parts of the data package)
what is the current approach to assessment of environmental risks?
quantitative risk estimate=ratio of the NOEC to the appropriate EEC (expected environmental concentration), for the most sensitive test species from relevant environmental toxicology studies for that environmental compartment (risk quotient (RQ)= EEC/NOEC)
-no use of safety factors, cancer no considered
what does the risk quotient mean?
-for ratios <1, the risk is considered negligible for that compartment
ratios >1, environmental effects are considered possible
-in such a case, PMRA can request risk management options needed to ensure the EEC does not reach the NOEC (e.g., buffer zones, reduced application rates, crop use restrictions)
-if risk management options cannot be adequately reduce risk, the product will not be registered
