Two-year follow-up of exposure, engineering controls, respiratory protection and respiratory health among workers at an indium-tin oxide (ITO) production and reclamation facility

Abstract

ObjectivesTo determine whether engineering controls and respiratory protection had measurable short-term impact on indium exposure and respiratory health among current indium-tin oxide production and reclamation facility workers.MethodsWe documented engineering controls implemented following our 2012 evaluation and recorded respirator use in 2012 and 2014. We measured respirable indium (Inresp) and plasma indium (InP) in 2012 and 2014, and calculated change in Inresp (∆Inresp) and InP (∆InP) by the 13 departments. We assessed symptoms, lung function, serum biomarkers of interstitial lung disease (Krebs von den Lungen (KL)-6 and surfactant protein (SP)-D) and chest high-resolution CT at both time points and evaluated workers who participated in both 2012 and 2014 for changes in health outcomes (new, worsened or improved).ResultsEngineering controls included installation of local exhaust ventilation in both grinding departments (Rotary and Planar) and isolation of the Reclaim department. Respiratory protection increased in most (77%) departments. ∆InP and ∆Inresp often changed in parallel by department. Among 62 workers participating in both 2012 and 2014, 18 (29%) had new or worsening chest symptoms and 2 (3%) had functional decline in lung function or radiographic progression, but average KL-6 and SP-D concentrations decreased, and no cases of clinical indium lung disease were recognised.ConclusionsIncreased engineering controls and respiratory protection can lead to decreased Inresp, InP and biomarkers of interstitial lung disease among workers in 2 years. Ongoing medical monitoring of indium-exposed workers to confirm the longer-term effectiveness of preventive measures is warranted.

Elevated exposures to respirable crystalline silica among engineered stone fabrication workers in California, January 2019–February 2020

“…Employers in the stone fabrication industry should comply with applicable state or federal OSHA standards, including measuring employee RCS exposure levels and implementing effective controls as needed to bring levels below the AL and PEL or lower. To achieve this goal, comprehensive preventive programs that include educational efforts and workplace interventions are needed [28][29][30]. More research concerning types of work activities that pose the highest risk for RCS exposure and types of engineering controls that effectively decrease this exposure would inform employer guidance on how to best protect workers.…”