Hamilton began her long career in public health and workplace safety in 1910, when Illinois governor Charles S. Deneen appointed her as a medical investor to the newly-formed Illinois Commission on Occupational Diseases. Hamilton lead the commission's investigations, which focused on industrial poisons such as lead and other toxins. She also authored the "Illinois Survey," the commission's report that documented its findings of industrial processes that exposed workers to lead poisoning and other illnesses. The commission's efforts resulted in the passage of the first workers' compensation laws in Illinois in 1911, in Indiana in 1915, and occupational disease laws in other states. The new laws required employers to take safety precautions to protect workers.  By 1916 Hamilton had become America's leading authority on lead poisoning. For the next decade she investigated a range of issues for a variety of state and federal health committees. Hamilton focused her explorations on occupational toxic disorders, examining the effects of substances such as aniline dyes, carbon monoxide, mercury, tetraethyl lead, radium, benzene, carbon disulfide and hydrogen sulfide gases. In 1925, at a Public Health Service conference on the use of lead in gasoline, she testified against the use of lead and warned of the danger it posed to people and the environment. Nevertheless, leaded gasoline was allowed. The EPA in 1988 estimated that over the previous 60 years that 68 million children suffered high toxic exposure to lead from leaded fuels. Her work on the manufacture of white lead and lead oxide, as a special investigator for the U.S. Bureau of Labor Statistics, is considered a "landmark study". Relying primarily on "shoe leather epidemiology" (her process of making personal visits to factories, conducting interviews with workers, and compiling details of diagnosed poisoning cases) and the emerging laboratory science of toxicology, Hamilton pioneered occupational epidemiology and industrial hygiene. She also created the specialized field of industrial medicine in the United States. Her findings were scientifically persuasive and influenced sweeping health reforms that changed laws and general practice to improve the health of workers.  During World War I, the US Army tasked her with solving a mysterious ailment striking workers at a munitions plant in New Jersey. She led a team that included George Minot, a Professor at Harvard Medical School. She deduced that the workers were being sickened through contact with the explosive trinitrotoluene (TNT). Her recommendations that workers wear protective clothing that should be removed and washed at the end of each shift solved the problem.  Hamilton's best-known research included her studies on carbon monoxide poisoning among American steelworkers, mercury poisoning of hatters, and "a debilitating hand condition developed by workers using jackhammers." At the request of the U.S. Department of Labor, she also investigated industries involved in developing high explosives, "spastic anemia known as 'dead fingers'" among Bedford, Indiana, limestone cutters, and the "unusually high incidence of pulmonary tuberculosis" among tombstone carvers working in the granite mills of Quincy, Massachusetts, and Barre, Vermont. Hamilton was also a member of the Committee for the Scientific Investigation of the Mortality from Tuberculosis in Dusty Trades, whose efforts "laid the groundwork for further studies and eventual widespread reform in the industry."

Answer this question "what did she know about lead poisoning?" by extracting the answer from the text above.
Hamilton focused her explorations on occupational toxic disorders, examining the effects of substances such as aniline dyes, carbon monoxide, mercury, tetraethyl lead, radium, benzene, carbon disulfide and hydrogen sulfide gases.