Establishing an occupational exposure limit for glyphosate in China

Background: Glyphosate is an efficient herbicide and has been widely used worldwide, resulting in high environmental dispersion and arousing extensive attention to its health effects. The occupational exposure limits (OELs) of glyphosate have not been clearly stipulated in China prior to this study. The study aims to establish OELs for glyphosate in China. Methods: To establish effective OELs for glyphosate, a total of 526 workers with varying degrees of occupational exposure and 442 controls from 5 manufacturing factories were chosen as subjects. Based on Guide for Establishing Occupational Health Standards-Part 1: Occupational Exposure Limits (OELs) for Airborne Chemicals in the Workplace (GBZ/T 210.1-2008), relevant literature on toxicology and epidemiology was also collected to determine the target organs of glyphosate, and liver function, kidney function as well as cholinesterase (ChE) activity were identified as the key effect indicators. The specific dose-response relationship was observed via the results of physical examinations and glyphosate levels in the air of workplace. Accordingly, the OEL was deduced based on the benchmark dose (BMD) method considering the dose-response relationship and the calculation method of EPA using no observed adverse effect level (NOAEL), along with the analogy analysis of OELs of other pesticides. Results: The results confirmed that 5 mg/m3 is the threshold at which adverse health effects occur more frequently among the exposed population. Conclusions: Finally, the permissible concentration-time weighted average (PC-TWA) of glyphosate was recommended to be set as 5 mg/m3. The proposal of OEL can help fill gaps in glyphosate limits in occupational hygiene standards and give reference to occupational health supervision and management.