This paper tackles the medicine vs. science debate through an exemplary controversy on the potential hazards of copper mining in the late nineteenth century. In my analysis I will focus on the nature of the relationship between chemical and traditional medical expertise in risk assessment, for the case of the Humos de Huelva, in the Riotinto mines.

In 1873 the pyrite mines of Riotinto (Huelva) were bought from the Spanish state by The Rio Tinto Company, an international venture of British and German origin. The extraction of copper and sulphur from the mines was then highly intensified and soon became very profitable for the Company. But this increase in activity was very controversial among several local stakeholders.

The Mines included vast territories and would soon become the main international source for copper. However, the ores extracted were not very rich in copper, and in order to obtain a competitive product, big piles of mineral were slowly burnt, producing the so-called Humos de Huelva. This method was effective enough to isolate the copper from other components but, at the same time, the fumes involved occupational and public health hazards, as well as destruction of local agriculture.

The controversy confronted local and national political representatives, miners’ unions, farmers’ organisations, citizens, medical and chemical experts coming from the country’s capital, and several international companies involved in the management of the Rio Tinto mines. The effects of this smoke were considered in their multiple dimensions in numerous reports, articles, books and public debates.

In this paper I will focus on the reports drafted by contemporary experts, including engineers as well as members of the main Spanish intellectual authority in health matters: the Real Academia de Medicina. The involvement of this academy was especially important, with several of its members travelling to the mines and drafting reports that subsequently were subjected to in-depth debate. In these works, the discussion of the respective values of chemical and medical proofs was one of the main issues at stake. The paper analyses these discussions and evaluates their influence on contemporary accounts by other medical and non-medical experts.