The in vivo mutagenicity of hexavalent chromium in the small intestine, the target organ of tumorgenicity, was examined by means of a transgenic mouse gene mutation assay. Sodium dichromate dihydrate was administered orally in drinking water to male gpt delta mice at a dose of 85.7 or 257.4 mg/L for 28 days or at a dose of 8.6, 28.6 or 85.7 mg/L for 90 days. No significant increase in gpt mutant frequency relative to that in control mice was observed in the small intestine in either the 28- or 90-day study, whereas 28-day oral administration of potassium bromate, a positive control substance, increased mutant frequency.
Flies play a key role as vectors in transmitting various bacteria and pose bacterial contamination risk to food. To evaluate the time- and concentration-related bacterial contamination of food by houseflies based on their attraction to the food, we determined the number of fed antimicrobial-resistant Escherichia coli transferred from houseflies to foods, sugar and milk mixture, apple, and castella (such as sponge cake). Houseflies contaminated the foods with the fed E. coli within 5 min, and the bacteria were present in high numbers on apple and castella (3.3 × 103 and 3.5 × 104 CFU/g of food, respectively). Furthermore, the number of fed E. coli on the foods increased with time, rising to 3.6 × 104–1.7 × 105 CFU/g. We show that the food contamination level caused by houseflies depends on the concentration of bacteria that the houseflies carry, the contact time with the food, and the attraction of the flies to the food.
The Food Safety Commission of Japan (FSCJ) conducted a risk assessment of flubendiamide (CAS No. 272451-65-7), an iodophthalimide insecticide for the setting of an acceptable daily intake (ADI) in 2006. FSCJ now has assessed this insecticide for the setting of an acute reference dose (ARfD). Data including fate in animals (rats and mice) and residues in crops (burdock roots, pumpkins and others) were newly submitted. Major adverse effects of flubendiamide include hepatocellular hypertrophy, fatty changes in hepatocytes, follicular epithelial cell hypertrophy in thyroid and ocular enlarged eye in rats. No neurotoxicity, carcinogenicity, reproductive toxicity, teratogenicity, neurodevelopmental toxicity and genotoxicity were observed. The lowest no-observed-adverse-effect level (NOAEL) in the toxicological studies was 1.70 mg/kg body weight/day in a two-year carcinogenicity study in rats. FSCJ confirmed an ADI of 0.017 mg/kg bw/day after applying a safety factor of 100 to the NOAEL. Adverse effects elicited by a single oral administration of flubendiamide would be abnormalities in eyes such as ocular hypertrophy and iris adhesion in offspring, which were obtained in a two-generation reproductive toxicity study, a one-generation reproductive toxicity study and a neurodevelopmental toxicity study in rats. FSCJ judged that these studies may be applicable to set the ARfD for lactating women in relation to the exposure of flubendiamide to offspring after the birth through breast milk. By taking into account the overall evaluations of the two-generation reproductive toxicity study, one-generation reproductive toxicity study and neurodevelopmental toxicity study in rats, FSCJ judged NOAEL of 15.0 mg/kg bw/day as for an overall NOAEL, and consequently specified an ARfD of 0.15 mg/kg bw/day for lactating women by applying a safety factor of 100 to the NOAEL.