Lec 6

Question 1

What are the 2 approaches to human health risk assessment? What is the overall goal?

Answer 1

Non-carcinogenic endpoints - establish threshold dose (margin of safety)
Carcinogenic endpoints - no threshold dose. acceptable dose established (probability)

goal: establish the NOAEL (highest lvl of exposure in test animals in most sensitive test that causes no adverse effects)

Question 2

What safety factors are used from animal studies to humans? what is the equation for reference dose (RD) with safety factor?

Answer 2

10x safety factors (animal -> human + variations among humans) results in 100x total

RD = NOAEL / 100x safety factor

Question 3

what are 3 instances where additional safety factors are applied? what’s the range?

Answer 3

1. severity of toxic endpoint
2. sensitive sub-populations
3. concern or uncertainties of accuracy about toxicity and exposure

ranges from 3-10

RD = (NOAEL / 100x) / 3-10

Question 4

how can a calculated RD be evaluated if it has a sufficient safety factor?

Answer 4

if RD > potential exposure conc. then margin of safety is sufficient

potential exposure conc. at worst case scenario
- max application rate of pesticide
- max pesticide on skin absorbed
- ingested conc. from all routes of exposure (aggregate)

Question 5

what is ADI and ARfD?

Answer 5

ADI - acceptable daily intake dose
ARfD - acceptable maximum one-time-exposure dose

Question 6

what is the acceptable cancer risk of pesticide exposure from all sources?

Answer 6

1 in a million as it won’t add a sufficient increase in probability

Question 7

what safety factor is used for environmental risk?

Answer 7

no safety factor is used

Question 8

how is quantitative risk estimate calculated for environmental risks?

Answer 8

risk estimate = NOEC / EEC (most sensitive relevant species)

estimate > 1. pesticide can be approved
estimate < 1. environmental effects possible . needs risk management to lower EEC (environmental conc.) for approval