5.3 Measures of ‘safety’: ADI, ArFD, OELs, etc.

A pesticide can only be approved for use if the risk to consumers, based on potential exposure, is acceptable. The limit set for a pesticidal active ingredient (AI), the ADI, is an estimate of the amount that can be consumed daily, for a lifetime, without harm to the person. 

The term “acceptable” is considered to involve a 100-fold safety factor from a measure called the No Observed Effect Level (NOEL) obtained in laboratory studies, which is 10 times lower than the Lowest Observable Effect Level (LOEL).

Data from laboratory studies is expressed as a dose (usually mg/kg bodyweight) and it is necessary to extrapolate these data for human exposure (be it dermal toxicity for AOEL or ADI for dietary safety). 

Dietary intake is often based on the National Estimated Dietary Intake (NEDI), estimate of a given foodstuff using surveys by national food standards agencies. 

Ideally, judgements would be carried out on Theoretical Maximum Daily Intake (TDMI), but there may be substantial variations between infants, children and adults even after adjusting for body weight. Another often quoted parameter, the Acute Reference Dose (ARfD), which is similar to the ADI, refers to short- term intake of an AI.