Role of cobalt, iron, lead, manganese, mercury, platinum, selenium, and titanium in carcinogenesis.

Abstract

The possible carcinogenicity of cobalt, iron, lead, manganese, mercury, platinum, selenium, and titanium is reviewed, taking into account epidemiological data, the results of animal experimental studies, data on mutagenic effects and on other in vitro test systems. Of the great variety of occupations where exposure to one of these metals may occur, only haematite mining has been clearly shown to involve an increased human cancer risk. While the possibility that haematite might in some way act as a carcinogen has to be taken into consideration it is more likely that other carcinogens are responsible. Certain platinum coordination complexes are used in cancer chemotherapy, are mutagenic, and likely to be carcinogenic. Cobalt, its oxide and sulfide, certain lead salts, one organomanganese, and one organotitanium compound have been shown to have a limited carcinogenic effect in experimental animal studies, and except for titanium appear to be mutagenic. Certain mercury compounds are mutagenic but none have been shown to be carcinogenic. The presently available data are inadequate to assess the possible carcinogenicity of selenium compounds, but a few observations suggest that selenium may suppress the effect of other carcinogens administered to experimental animals and may even be associated with lower cancer mortality rates in man. Epidemiological observations are essential for the assessment of a human cancer risk, but the difficulty in collecting past exposure data in occupational groups and the complexity of multiple occupational exposures with changes over time, limits the usefulness of retrospective epidemiological studies.

Cancer risk from inorganics

“…Reports of respiratory tumors in iron and steel foundry workers from England and Finland, show definite cancer excesses but values are not corrected for smoking and other factors [117].…”

“…Enhanced B(a)P toxicity is not accompanied by an increase in DNA strand breaks [44] or by inhibition of metabolic cooperation [45]. 117 …”

“…The reports generally fail to stand up to critical evaluation [117]. Nevertheless selenium sulfide is listed by the EPA carcinogenesis assessment group as a chemical having substantial evidence for carcinogenicity bascd on a National Cancer Institute carcinogenesis testing program report, in which selenium sulfide induced carcinomas of the liver in F344 rats and female B6C3, F~ mice, and carcinomas and adenomas of the lung in female mice [134].…”

“…There have been no reported studies on occupational exposure to titanium dusts in industry [49,117].…”

“…Although such devices have not been associated with an increased cancer risk [117], their wide use is relatively recent. Life time follow ups on patients with these devices seems advisable.…”