Observation of general and specific adverse effects of organic solvents on Caenorhabditis elegans by toxicity testing using behavioral analysis

Novel chemical compounds are continuously being developed and are used in various industries as well as in our daily lives. Workers in industries estimate and avoid chemical hazardous risks based on published information on chemical toxicities. However, it is challenging to avoid hazards caused by chemicals with unknown toxicity. Therefore, it is necessary to understand the toxicities of chemicals in high-throughput and multifaceted ways. In this study, I develop a high-throughput method to assess chemical toxicities through the quantitative measurement of behavior in Caenorhabditis elegans. I determine the acute toxicity of 30 organic solvents that are widely used in industries with motility as an endpoint. The adverse effects of organic solvents on motility were proportional to the lipid solubility of chemicals, which is similar to the positive relationship between the anesthetic effects of volatile organic chemicals and their lipid solubility in organisms, including humans. In addition to the general toxicity on motility, organic solvents caused adverse effects on posture during locomotion in different ways depending on the chemicals functional group. Alcohols and cellosolves, both of which have a hydroxyl group, reduced the amplitude of body bending, whereas ketones and acetate esters, both of which have a ketone group, increased it during undulatory locomotion. Furthermore, organic solvents caused defects in behavioral plasticity based on the association of starvation and chemical signals at concentrations lower than those that affect locomotion, which suggests that sensory processing is more susceptible to organic solvents than motor function. This study provides a high-throughput method for acute chemical toxicity testing and new insights into the behavioral toxicity of organic solvents based on comprehensive behavioral analysis.