Determination of the No-Observed-Death Level for Inhalable Ingredients in Household Chemical Products

Household chemical products are frequently used in daily life, and some ingredients are used across different products, suggesting potential duplicate exposure. Given that the respiratory system is a primary route of exposure to these products, we aimed to determine the nontoxic level (no-observed-death level [NODL]) for ingredients in household chemical products. We first selected 34 chemicals, focusing on ingredients in biocidal products approved by the US EPA and the Korean Ministry of Environment. We then single-dosed them to mice via oropharyngeal aspiration and observed them for up to 14 days. Considering uncertainties arising from sample preparation and dilution, the NODL for seven chemicals was 5000 ± 800 μg/mouse. Meanwhile, the NODL for three chemicals (CPC, DDAC, and BKC) was less than 5.0 ± 0.8 μg/mouse, and a significant decrease in body weight gain was observed in mice exposed to linalool. Furthermore, we examined lung tissues from all surviving mice and found that some chemicals cause pathological changes at the NODL, including granulomatous inflammation and fibrosis. Herein, we believe that the suggestion of the NODL, accompanied by a pathological examination, would serve as a minimum measure for the safe use of household chemical products. Given that household chemical products are formulated to maximize their effects, we also suggest that the synergistic toxicity of the mixtures should be evaluated utilizing the NODL.