There is a well-established connection between chromium and cancer which has been documented in many studies going back as far as the 1930s. chromium is a metallic element which occurs naturally but is also produced by industrial processes and the latter are of concern due to the cancer connection. Chromium-6, in particular, is a known human carcinogen when inhaled and its presence in drinking water is also suspected of causing health problems.
Chromium is an essential mineral that helps insulin regulate blood sugar levels. Chromium 3, or trivalent chromium, is found naturally in fruits and vegetables, yeast, meats and grains and is a common addition to nutritional supplements. However, even though chromium from foods is considered to be of low toxicity, researchers still do not know what the safe limits are. It is advisable to avoid excessive use of dietary supplements containing the metal as the precise connection between this kind of chromium and cancer has not yet been established.
The chromium from foods is not the same as chromium which is produced industrially. The former is called chromium-3 and the latter involves chromium-0 and 6. Chromium O is used for making steel and other alloys and is not considered problematic. Chromium-6 (also called hexavalent chromium), however, has been labeled carcinogenic, particularly when inhaled. There is also increasing publicity about the safety levels of chromium-6 in drinking water. Used in the production of dyes and in leather tanning, chrome plating and wood preserving processes chromium can be found in the atmosphere due to being released during the manufacturing process. The use of chrome based products and their subsequent disposal leads to the presence of the metal in soil and water.
The first news of a connection between chromium and cancer emerged in the 1930s when workers at chemical producing company were found to have lung cancer at a much higher incidence than the general public. It is now well-established that breathing hexavalent chromium at high levels can result in breathing problems, nose damage such as ulcers and cancer. As it is an ingredient in tobacco smoke, smoking in enclosed areas and exposing others to second-hand smoke can lead to problems.
Ingestion of chromium can damage the stomach and intestines and may cause anemia. There is a lot of debate about whether the levels of chromium found in drinking water is cause for concern. There are health and safely guidelines stipulating that 0.1mg/L is the maximum concentration considered safe but there are moves to set an even lower standard.