Assessing indoor concentrations of termiticides and their risk to humans

Termiticides are widely used to protect wooden houses from termites. Dieldrin, chlordane, heptachlor, and chlorpyrifos, which are effective termiticides, have been banned because of their high toxicity. Neonicotinoids, pyrethroids, phenyl pyrazoles, and triazoles have been used as alternatives to termiticides in indoor environments. However, despite numerous studies showing that farm-applied pesticides contaminate house dust, the health risks to humans from indoor termiticides remain unclear. We collected house dust and indoor air samples from 37 and 7 houses, respectively, to investigate the indoor termiticide contamination levels. The minimum margin of exposure to fipronil was 173, indicating that fipronil posed the highest risk among the targeted 28 compounds in indoor environment. The mean concentrations of alternative termiticides in house dust and air samples ranged from 1,126 ng g^− 1 (cyproconazole) to 5,356 ng g^− 1 (MGK-264) in thirty-seven houses and 0.08 ng m^− 3 (acetamiprid) to 34 ng m^− 3 (MGK-264) in seven houses, respectively. These results are comparable to the pesticide concentrations in houses close to farms where pesticides were applied, and are higher than atmospheric pesticide concentrations in oceans. Therefore, houses sprayed with termiticides may be as contaminated as agricultural environments where farmers apply substantial quantities of pesticides. The main route of exposure was air inhalation for fipronil, and both air inhalation and house dust ingestion for triazoles and potentiators. Establishment of regulations and development of decontamination methods are needed for indoor contamination of termiticides. Floor cleaning may be effective to remove termiticides that are ingested mainly through the house dust pathway.