Effects of refining predicted chronic dietary intakes of pesticide residues: a case study using glyphosate

A chronic consumer risk assessment based on a worst-case scenario, conducted as part of the European Union review leading to Annex I inclusion for glyphosate, was evaluated and refined. An extensive database of information on the effects of processing on the levels of glyphosate residues in food is available. This database together with refined consumption data from the UK's surveys of adults and toddlers and extensive monitoring data of glyphosate residues in mainly cereal products conducted in the UK were combined to examine the potential overestimates of dietary intakes that are predicted using the current regulatory methodology developed by the Food and Agricultural Organization/World Health Organization and applied as part of the European Union regulatory process. Analysis focussed on the chronic exposure from treated cereals, the crop group contributing significantly to the dietary intake of glyphosate residues. A steep reduction of predicted intake was seen when progressively realistic measures of residues were incorporated into the models, giving a strong indication of the conservative nature of current regulatory procedures. Calculations using even the most unrefined methodology gave rise to intakes of up to 11% of the acceptable daily intake, this was reduced to 0.6% of the acceptable daily intake when justifiable refinements based on extensive monitoring data collected in the UK were made. Consumption data for processed foods abstracted from the UK Food Standard Agency's database were used to refine further the predicted dietary intakes as a result of residue reductions or concentration from processing. The current regulatory model used in the UK generally only has the potential to use a single value for consumption of a particular food. The Pesticides Safety Directorate model consistently predicted the highest intakes with the exception of intakes by adults using the supervised trials median residue and median monitoring data. This suggests that conservatism in the regulatory model exists particularly where specific processing factors cannot be applied to individual fractions of the diet.