New analysis indicates that earlier studies into lead absorption levels of workers in the battery industry “likely overestimated” the rates of absorption.
The Battery Council International (BCI) said the new study, which it sponsored, found the airborne lead particle size observed in lead battery manufacturing and secondary smelter facilities “significantly changes previously-held assumptions about lead absorption rates”.
The BCI said while previous studies have been conducted to investigate occupational lead exposure, the latest findings are from the “first modern study to analyse actual workplace lead-in-air data collected in the US”.
“It finds that the lead-in-air at lead battery manufacturing facilities (BMFs) and secondary smelter facilities (SSFs) has a larger particle size than was previously assumed, which could dramatically reduce the rate at which workers absorb lead into the body,” said the BCI.
“As prior studies have shown, the size of the airborne lead particle plays a significant role in absorption rates, because particle size determines where and how much airborne lead is deposited into the respiratory tract and stomach and then subsequently is absorbed into the body,” the BCI said. “The study posits this means prior modelling efforts likely over-estimate the rate at which airborne lead would be absorbed by workers’ bodies.”
The study is based on monitoring at nine BMFs and five SSFs across the US. “The data showed the presence of predominantly larger-sized particles in the work environments evaluated, with average mass median aerodynamic diameters (MMADs) ranging from 21 to 32 micrometres (µm) at BMFs and from 15 to 25 µm at SSF,” the BCI said.
“Data concluded that the presence of submicron range lead mass measured at these facilities was generally small, from 0.8-3.3% at BMFs and 0.44-6.1% at SSFs,” the BCI said.
BCI’s executive president Mark Thorsby said the study’s findings introduce “a new variable to consider when determining safety standards at battery manufacturing facilities and other facilities dealing with lead”.
“Data collection of this kind is crucial to properly setting occupational exposure limits for lead,” Thorsby said.
The study has been published in the Journal of Occupational and Environmental Hygiene.
Earlier this year, BCI and EUROBAT said they would be working with the International Lead Association to reduce worker blood lead levels to below 20mcg/dL (microgrammes per decilitre).
The organisations said they would work with the International Lead Association to hit the new voluntary target by the end of 2025— and established an interim target of 25mcg/dL by the end of 2019. The ILA said its members are committed to achieving the target of 20mcg/dl as soon as reasonably practicable.