Science and industry: Conflict-of-interests in the field of toxicology David A. Groneberg, Journal of Occupational Medicine and Toxicology 24 August 2009 In this report by Heller et al., two companies which are involved in the exploration, mining, and processing of nickel, sponsored a study that questions soluble nickel as a carcinogenic substance. Although the editors agreed to publish this hypothesis, we feel that some clarifying words should be stated: 1) The editors-in-chief and the publisher questioned the integrity of the article on first sight. The first impression was to reject the article due to the magnitude of the conflict of interest. This conflict of interest arises from the nature of the sponsoring companies: The companies are Vale Inco and Falconbridge Ltd. Vale Inco is the second largest mining company in the world, with a market capitalization of more than US$ 125 billion and over 12,000 employees worldwide with net sales last year of over US$8 billion last year . The second company Falconbridge Limited was a Canadian natural sources company that was absorbed in 2006. 2) After reviewing the article, the editors-in-chief decided to publish the article because: a) the conflict of interest is clearly stated: “Drs. Heller and Conard received financial support from Vale Inco Ltd. for the preparation of this paper. Dr. Heller also received financial support previously from Falconbridge Ltd. to conduct the underlying research in this paper. Mr. Thornhill has received no financial support.” b) the article reviews a large amount of studies and data – although partly onesided – that should be discussed by other non-biased scientists and c) it can be regarded as a typical example of the approach of private companies towards the scientific discussion of compound toxicity and carcinogenity. The authors hypothesize that the true causes of historical lung cancer risk at certain nickel refineries may lie in other exposures, including insoluble nickel compounds, arsenic, sulphuric acid mists and smoking. This hypothesis is based by their failure to accurately identify the source(s) of observed lung cancer risk in one nickel refinery (KNR). Freedom of speech is an important issue in science but also, the integrity of arguments represents a keystone when it comes to the discussion of toxic and carcinogenic effects. Ideally, scientists that are involved in research on nickel toxicity should now discuss the different points raised by Heller et al. in order to substantiate the knowledge on nickel toxicity. David A. Groneberg, MD Editor-in-Chief, Journal of Occupational Medicine and Toxicology Professor of Medicine/Occupational Medicine Axel Fischer, MD Editor-in-Chief, Journal of Occupational Medicine and Toxicology Professor of Medicine/Allergy  http://www.inco.com/  http://www.xstrata.com/ Competing interests No competing interests.