Traces of insecticides detected in rainwater in Japan

Free Malaysia Today

12-06-2025

Japanese researchers say certain insecticides are also present in rainwater. (Envato Elements pic)
PARIS : Pesticides don't just contaminate the air humans breathe or the food they eat. According to recent research conducted in Japan, certain insecticides are also present in rainwater.
Scientists at Japan's University of Tokyo recently made a worrying discovery. Residues of several insecticides belonging to the well-known neonicotinoid family have been detected in rainwater.
In Japan, neonicotinoids were introduced on a large scale in the 1990s, particularly in rice fields and pine forests.
To reach this conclusion, the scientists collected and analysed rainwater samples from the cities of Tsukuba and Kashiwa, both located northeast of Tokyo.
Their analyses were carried out between April 2023 and September 2024. They reveal that 91% of samples contained several insecticides from the neonicotinoid family.
The highest total concentration was detected in August 2024, the study authors note.
Acetamiprid is the predominant insecticide, having been identified in 82% of samples, followed by thiacloprid (73%) and dinotefuran (45%), two other insecticides from the neonicotinoid family.
'This research is the first report on neonicotinoid presence in precipitation, suggesting that neonicotinoids, as low volatile matter, can still be dispersed to the environment via precipitation,' warned the researchers, whose work is published in the journal Environmental Monitoring and Contaminants Research.
Potential effects on human health
In 2019, another study (also conducted by researchers at the University of Tokyo), published in the journal Science, explained in detail how the large-scale use of neonicotinoids contributed to the destruction of several species of fish, crustaceans, and zooplankton in Lake Shinji (southwestern Japan).
Starting in 1993, several rice farmers began spraying imidacloprid on their fields. According to the study, the introduction of this insecticide in areas geographically close to the lake coincided with an 83% decrease in the average zooplankton biomass.
While the harmful effects of neonicotinoids on insects (particularly bees) and several other animal species are increasingly well documented, doubts remain about their impact on human health.
Given that neonicotinoids target the nervous system, scientists fear (among other things) that exposure to these substances may be linked to neurological disorders.
However, these risks remain uncertain at present due to a lack of large-scale studies on the subject.