Relationship between personal‐sampled air lead and blood lead in low‐lead‐exposure workers in Japan to apply multiple regression models determining permissible air lead concentration

OBJECTIVES: We investigated the relationship between lead in air (Pb‐A) measured by personal sampling and blood lead (Pb‐B) in workers with relatively low lead exposure to estimate the permissible air concentration of lead corresponding to the biological tolerance value of Pb‐B of 15 µg/dL. METHODS: We collected air samples at a lead‐acid battery factory in Japan by personal sampling devices attached to 32 workers (19 males and 13 females) and measured Pb‐A by a graphite furnace atomic absorption spectrophotometer in 2017‐2020. In addition, we collected information on age, smoking habits, Pb‐B, and urinary δ‐aminolevulinic acid from the records of medical examinations for lead poisoning. Samples were collected two times from four workers, resulting in 36 data sets. RESULTS: Before analyses, we excluded four inappropriate data sets. The levels of Pb‐A in the factory and Pb‐B in the workers were almost under the current permissible limits. Multiple regression models showed significant correlations between Pb‐B and Pb‐A, and sex, and borderline significance between Pb‐B and age. Based on them, we calculated Pb‐A corresponding to Pb‐B 15 μg/dL, and obtained similar values to the current occupational exposure limit (OEL) of 30 μg/m(3), with slight variation between sex and age. CONCLUSION: These results validate OEL, although supplementary conditions in terms of sex and age may be necessary.