The significance of the subchronic toxicity in the dietary risk assessment of pesticides.

Based on 289 public pesticide evaluations, geometric means of subchronic/chronic No Observed Adverse Effect Level (NOAEL) ratios of 2.6, 2.5 and 1.6 in mice, rats and dogs were calculated. The 75th percentiles are 5.5, 5.1 and 3.2. Higher ratios correlate with increased dose spacing in chronic studies and may be mainly explained therewith. In rats fed at constant pesticide concentrations in feed, the mean chronic dose decreases by 1.7- and 2.7-fold compared to the subchronic and subacute phase. These dose decreases match the subchronic/chronic NOAEL ratios. The ratio of predicted rat chronic NOAEL (dose decrement adjusted subchronic NOAEL) to experimental chronic NOAEL is 1.5 and the 75th percentile is 3.0. In dietary risk assessment, the Acute Reference Dose and the Acceptable Daily Intake (derived from acute and chronic NOAEL) are compared to acute (IESTI) or mean (TMDI) exposure estimates. Because IESTI and TMDI base on acute or mean food consumption they differ by orders of magnitude for certain commodities. As subchronic and chronic NOAEL are similar, it remains to be shown whether pesticide intake estimates based on mean food consumption are adequate measures to compare against the ADI if repeated daily exposures considerably higher than mean exposures may occur.

Levels of polychlorinated dibenzo-p-dioxins and dibenzofurans in food of animal origin. The Swiss dioxin monitoring program.

Between 1997 and 1999, several cases of dioxin contaminations in foodstuffs of animal origin occurred in Europe due to feed contaminated by several independent sources: citrus pulp pellets, fat containing polychlorinated biphenyls (PCB), and kaolinitic clay as anti-caking agent in feedingstuffs. As a consequence of the latter, a survey on polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) in food of animal origin was initiated by the Swiss authorities to assess the extent of PCDD/F contamination and to document the efficiency of the measures taken to ensure the decontamination of the food supply. Investigation of a total of 128 samples of cow's milk, poultry, eggs, and meat revealed several cases of residue levels distinctly above the background exposure limit of approximately 2.5 ng of I-TEQ/kg (fat basis). Particularly, elevated concentrations were found in eggs (maximum 13 ng of I-TEQ/kg), poultry (maximum 3.9 ng of I-TEQ/kg), and pork (maximum 7.5 ng of I-TEQ/kg). On the basis of the observed PCDD/F congener pattern, the contamination could be attributed to PCDD/F-contaminated kaolin that was used as an anti-caking agent in particular feedstuffs.