BACKGROUND: Lead exposure can cause adverse health effects and is a known occupational hazard in the shipyard industry. On March 28, 2016, the Minnesota Department of Health (MDH) and Wisconsin Department of Health Services (WDHS) learned of three workers with elevated blood lead levels (BLLs) >40 µg/dL. These workers had been retrofitting a 690-foot vessel – including lead-based paint removal in the ship’s engine room – at a Wisconsin shipyard beginning January 4, 2016. MDH and WDHS launched a joint investigation to determine the extent, severity, and risk factors for lead exposure.
METHODS: A case was defined as a BLL ≥5 µg/dL drawn after December 20, 2015, in a shipyard worker. We attempted contacting all workers by telephone to capture job tasks, symptoms, encourage blood lead testing, and relay exposure prevention messages. The maximum BLLs of the study population (i.e., interviewed, not excluded) (n=185) were compared by characteristics identified in the interviews. Significant differences between categories were evaluated using the Kruskal-Wallis test.
RESULTS: By August 31, 2016, of 357 identified workers, 233 (65.3%) had received ≥1 BLL test; 185 (51.8%) completed interviews. Of these 185 workers, 181 (97.8%) were male, and 144 (77.8%) were non-Hispanic white. Among 233 tested workers (median, 16.0 µg/dL; interquartile range, 4.4–30.6 µg/dL), 171 (73.4%) had BLLs ≥5 µg/dL and 33 (14.2%) had BLLs ≥40 µg/dL. Analysis of survey data indicated that several factors were related to significant differences in mean BLLs. For instance, interviewed workers who worked daily in the vessel engine room had higher BLLs than those who never did (103/185; 24.3 µg/dL versus 42/185; 13.9 µg /dL, P <0.05). Workers who exclusively worked day shifts had lower BLLs than their non-day shift counterparts (151/185; 18.8 µg/dL versus 33/185; 28.7 µg/dL, P <0.05). Stratified analyses were conducted to control for potential confounders. Shift work remained significantly associated even when stratifying on working exclusively on the contaminated vessel (n=86), daily engine room work (n=103), and frequent performance of metalwork tasks (n=151).
CONCLUSIONS: This investigation shows that lead remains an occupational hazard for shipyard workers and emphasizes the importance of periodic BLL monitoring, implementing engineering controls, and the provision of protective equipment for workers in high-risk lead-exposure situations. These steps can reduce – if not wholly prevent – lead poisoning among shipyard workers.