Food safety (Tokyo, Japan)最新文献

Bovine spongiform encephalopathy (BSE) is a fatal neurodegenerative disease that belongs to transmissible spongiform encephalopathy (TSE). Since the first case was identified in the UK in 1986, BSE spread to other countries including Japan. Its incidence peaked in 1992 in the UK and from 2001 to 2006 in many other countries, but a feed ban aimed at eliminating the recycling of the BSE agent and other control measures aimed at preventing food and feed contamination with the agent were highly effective at reducing the spread of BSE. In 2004, two types of atypical BSE, H-type BSE (H-BSE) and L-type BSE (L-BSE), which differ from classical BSE (C-BSE), were found in France and Italy. Atypical BSE, which is assumed to occur spontaneously, has also been detected among cattle in other countries including Japan. The BSE agent including atypical BSE agent is a unique food-safety hazard with different chemical and biological properties from the microbial pathogens and toxic chemicals that contaminate food. In this review, we summarize the reported findings on the tissue distribution of BSE prions in infected cattle and other aspects of BSE, as well as the control measures against the disease employed in Japan. Topics that require further studies are discussed based on the summarized findings from the perspective of food safety.

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.

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.

The Food Safety Commission of Japan (FSCJ) conducted a self-tasking assessment of mycotoxins, fumonisin B1 (FB1 CAS No. 116355-83-0), fumonisin B2 (FB2 CAS No. 116355-84-1), and fumonisin B3 (FB3 CAS No. 136379-59-4). Hepatotoxicity and/or nephrotoxicity were commonly observed in experimental animals given orally purified FB1, and the sex-related differences were observed in rats and mice. Species differences were also identified: Increased incidences of liver tumors in female mice and of kidney tumors in male rats were observed in chronic toxicity/carcinogenicity studies. Fumonisins did not show appreciable genotoxicity both the in vivo and in vitro tests. FSCJ judged fumonisins as non-genotoxic carcinogens from the results of various toxicological studies on fumonisins, and thus specified a tolerable daily intake (TDI) of 2 μg/mg bw/day for fumonisins (FB1, FB2 and FB3, alone or by combination), after applying an uncertainty factor of 100 to the lowest no-observed-adverse-effect level (NOAEL) of 0.21 mg/kg bw/day in subacute toxicity study in rats. The estimated exposure levels of fumonisins among high consumers such as toddlers are still below the TDI. Therefore, FSCJ concluded that adverse effect of fumonisin on human health through food are unlikely under the current situation in Japan.

In this study, a method using a recombinant phage for detection of E. coli O157:H7 in fresh vegetables was investigated. Four kinds of fresh vegetables, i.e. lettuce (Lactuca sativa), mustard greens (Brassica juncea), coriander (Coriandrum sativum), and soybean sprouts were selected since they are commonly used in meals in Vietnam. Firstly, a phage-based method was investigated for detection of E. coli O157:H7 in the four types of vegetables. To support the detection by suppressing growth of background bacteria in vegetables, selective antibiotics, i.e. novobiocin (N) and vancomycin (V) in combination with BHI medium were examined. Secondly, quality of the method was evaluated in terms of sensitivity, specificity, and rapidity. The method enabled the detection of E. coli O157:H7 inoculated at 10³, 10², or 10¹ CFU/ 10 mL of sterile 0.8% NaCl containing 5 g of vegetable and in the presence of several Gram-positive and Gram-negative bacteria inoculated at 10⁷ CFU/10 mL. The time for detection was approximately 16.5 hours for E. coli O157:H7 inoculated at 10 CFU/10 mL of sterile 0.8% NaCl containing 5 g of vegetable. The limit of detection was considered to be 2 CFU g^-1 vegetable.

Fluoroquinolone is widely used for the treatment of bacterial diseases, and the emergence of quinolone resistance has become a serious concern in recent years, owing to an increase and inappropriate use of antimicrobials. Here, we attempted to understand the differences in the emergence frequency of quinolone-resistant bacterial variants in three Salmonella serotypes S. Infantis, S. Schwarzengrund, and S. Manhattan-which are mainly found in broiler industries in Japan. Emergence frequency tests for quinolone-resistant variants using enrofloxacin-containing agar plates and sequence analysis in the quinolone resistance-determining region (QRDR) of gyrA in DNA gyrase were performed. The results showed no significant difference in the emergence frequency among the three serotypes, and most of the resistant variants had mutations in the QRDR region. These findings suggest that differences in the serotypes tested are not associated with the emergence frequency of quinolone-resistant variants.