Labour historians are now beginning to explore the history of occupational health and safety and its impact on workers and the community. An examination of past approaches to protecting workers’ health can inform current debates over such things as the relevance of the Precautionary Principle advocated by those who seek to remove from the workplace substances suspected of being harmful. In the United States from the 1920s-60s the employer body, the Lead Industries Association, funded much of the research into occupational lead poisoning. The results, which rejected the Precautionary Principle, understated the adverse effects of lead and placed workers’ lives in jeopardy. The politicisation of medical knowledge in the United States had a global impact that has not yet been fully examined. This article explores the influence of American research on the Australian medical community’s approach to occupational lead poisoning in the early twentieth century, with particular reference to the battery industry.