高感度・高精度バイオマーカー分析法の開発による殺虫剤の安全性評価

抄録

Recently, the use of neonicotinoid pesticides (NNs) has been increasing in place of organophosphorus pesticides, because NNs have very low toxicity to humans, and their toxicity is considered negligible in daily life, as long as it is below a certain standard. In Japan, however, food residue limits for fruits, vegetables, and tea leaves are set several to several dozen times higher than in other countries.

In this study, to clarify the exposure to NNs in Japan, we collected urine samples from newborns and infants and measured the amount of NNs in the urine to assess the exposure.

On the other hand, NNs have been reported to have effects on experimental animals even at lower exposure levels than NOAEL. For example, Hirano et al. reported that NNs induced anxiety behavior in mice at a dose level of 5 mg/kg, which is lower than the NOAEL of 9.7 mg/kg for clothianidin. Therefore, we sought to develop sensitive biomarkers to conduct appropriate toxicity assessment. Monoamine neurotransmitters (MAs) such as dopamine (DA) and serotonin (5-HT) regulate brain functions such as behavior, memory, and learning, and their abnormalities are said to be involved in the development of neurological diseases such as depression and Parkinson's disease. In order to clarify the distribution and concentration of MA in the brain, we developed a comprehensive, highly sensitive, and accurate analytical method using mass spectrometry, and attempted to clarify the effects of NN administration on MA in the brain.

As a result of quantification of MAs in various brain regions, no change in DA concentration in the striatum was observed after IMI administration, but decreases in 3-MT and DA in the olfactory bulb, and decreases in 5-HT and histamine in the striatum were observed.

Considering the fact that NNs disrupt neurotransmitters in the brain and that infants are exposed to multiple NNs, the exposure level of infants and newborns is not negligible, and it is necessary to elucidate the toxicity mechanism in more detail.