Establishing a threshold dose for peanut allergen

The team at the Food Allergy Research & Resource Program (FARRP) in Nebraska have screened existing publications for lowest- and no-observed adverse effect levels (LOAELs and NOAELs) obtained from blinded, low-dose oral challenges. Their aim was to establish both what these levels were and how many peanut-allergic individuals these data represented. They found 12 publications relating to studies on 185 peanut-allergic individuals. However, three different methods had been employed to deduce the LOAELs and NOAELs across the range of publications: diagnostic series, threshold studies, and immunotherapy trials.

Using mathematical analyses, three probability distribution models were fitted to the published data to estimate the ED(10) (the estimated dose corresponding to an increase of 0.10 in the probability of the specified response, relative to the probability of that same response at dose zero). The three models provided ED(10)'s in close agreement: 17.6, 17.0, and 14.6 mg of whole peanut. The 95% lower confidence interval for the ED(10)'s were 9.2, 8.1, and 6.0 mg of whole peanut.

The modeling of Individual NOAELs and LOAELs identified from three different types of published studies yielded significantly different whole peanut ED(10)'s of 11.9 mg for threshold studies, 18.0 mg for diagnostic series and 65.5 mg for immunotherapy trials. It was acknowledged that patient selection and other biases may have influenced the estimates.

The authors concluded that these data and risk assessment models provide the type of information that is necessary to establish regulatory thresholds for peanut.

Reference: Taylor et al 2009. Food Chemistry and Toxicology Feb 18. [Epub ahead of print]