| Research Abstract |
Powerful mutagenic and carcinogenic heterocyclic amines had been isolated from only food until now. Subsequently, these amines were also found in the general environment such as atmosphere and river water, etc. Therefore, it is very important to grasp the distribution and dynamic phase and biological effects of these amines for the hygiene chemistry viewpoint. However, it is unsolved how degree human and wildlife are exposed to the heterocydic amines, and whether the levels of these amines are safe. In this study, we measured heterocyclic amine contents in living environment, especially river water as supply source of drinking water and cooked foods in order to grasp heterocyclic amine pollution in the wildlife and human. From these results, an estimated intake of heterocyclic amine in Japanese was calculated based on the epidemiological technique. Furthermore, the heterocyclic amine-protein adduct as a biomarker for exposure evaluation was examined.
By Blue-rayon extraction, derivatiza
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tion and GC-NPD analysis, IQ, Trp-P-1, MeIQx and PhIP, etc, were identified in river water, and cooked fish and meat. Especially, PhIP was detected in the grilled fish at high concentration, and it was included in the part of skin than that of flesh at high content. In addition, daily individual intake level of heterocyclic amine in Japanese was estimated for Japanese from four geographic areas based on a self-reported food frequency questionnaire for meat and fish intake survey. Japanese mainly took PhIP, and the intake levels for the subjects in the mainland were higher than those for the subjects in Okinawa. It is considered that these results become an effective index for evaluating the relevance to eating habit and carcinogenic risk.
Next, we noticed the heterocyclic amine-protein adducts to directly estimate amount of the exposed heterocyclic amine. The method for measuring protein-adduct was established by extraction of protein fraction, acid hydrolysis and amount of adduct by the subsequent GC-NPD of the liberated amine, after it breeds the medaka in heterocyclic amine aqueous solution in selected time period. When the correlation between heterocychc amine exposure and the protein adduct formation was examined using this method, adduct formation increase in proportion to the exposure concentration and exposure period. The result suggest that heterocyclic amines are accumulated in the continually intake, and protein adduct is an effective index for exposure. On the other hand, it was proven that it could confirm protein-adduct formation in rat blood in the single administration of the high dose heterocyclic amine, but these adducts disappear short period. Furthermore, the accumulation of protein-adduct was not observed in low dose repetitive administration. From examination of organ distribution, the heterocyclic amine-protein adducts were mainly detected in liver, but not blood. From these results, it is difficult to be accumulated in the animal including the human who mainly takes the heterocyclic amine through the meal, though the protein adducts are accumulated in the fish continually exposed, if the heterocyclic amine always exists in the water. In the future, the development of measuring method of adducts except for sulfinamide which becomes original amine by acid hydrolysis, more sensitive detection method and samples concentration method, etc. seem to be necessary in order to use protein adducts in blood as biomarker for the heterocyclic amine exposure in human. Less
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