Chromium was discovered in 1797 by Vauquelin. Numerous industrial applications raised chromium to a very important economic element. At the same time, with the development of its uses, the adverse effects of chromium compounds in human health were being defined. Trivalent chromium is an essential trace element in humans and in animals. Chromium as pure metal has no adverse effect. Little toxic effect is attributed to trivalent chromium when present in very large quantities. Both acute and chronic toxicity of chromium are mainly caused by hexavalent compounds. The most important toxic effects, after contact, inhalation, or ingestion of hexavalent chromium compounds are the following: dermatitis, allergic and eczematous skin reactions, skin and mucous membrane ulcerations, perforation of the nasal septum, allergic asthmatic reactions, bronchial carcinomas, gastro-enteritis, hepatocellular deficiency, and renal oligo anuric deficiency. Prevention of occupational risks, biological monitoring of workers, and treatment of poisoning are also reported.

Twenty eight moderately water-soluble to insoluble chromium (VI) compounds, such as zinc and lead chromate, industrial and laboratory synthesized pigments, and the analytical reagents strontium, barium and calcium chromate, were physicochemically characterized and studied for cytotoxicity and morphological transformation in cultured Syrian hamster embryo (SHE) cells. In vivo validation of malignancy of transformed SHE cells was performed. A high physicochemical diversity among the complex chromium pigments was revealed. The solubility of the compounds was greatly increased after incubation in a complete medium and even higher under cell culture conditions. The cytotoxic effects appeared to be due principally to extracellular solubilized chromium because the most solubilized compounds. Zn, Ca and Sr chromates, were equitoxic at about the same Cr concentration treatment and 8-fold more cytotoxic than less soluble compounds such as some Pb chromates and Ba chromate. However, certain physicochemical properties of lead chromate pigments could also influence their cytotoxic activity. All test compounds were, in a dose-dependent manner, efficient in inducing morphological transformation of SHE cells. Many of the Cr pigments, although physicochemically different, were similarly effective in transformation induction. Nevertheless, compounds among Zn and Pb chromates had various transforming potencies. Ba chromate was the least active in inducing transformation. Certain physicochemical properties could mediate the transforming activity but no particular relationship could be established between any one of the physicochemical parameters and the transforming potency. Cloned morphologically-transformed colonies of SHE cells were grown in soft agar medium and showed true neoplastic behaviour by tumour formation in syngeneic animals. These results show that various chromate pigments containing either Zn or Pb, of medium to very low aqueous solubility, induced neoplastic transformation of SHE cells.

Objective-To conduct a field study to obtain information on the urinary concentrations of aluminium (Al) and fluoride (F-) depending on the different compounds exposed to in the aluminium industry. Methods-16 workers from one plant that produced aluminium fluoride (AIF,), and from two plants that produced alnium electrolytically by two different processes participated in the study for one working week. Pollutants were monitored by eight hour personal sampling every day, and urine samples were collected during the week. Al and F-were analysed in both atmospheric and urine samples by atomic absorption spectrometry and an ion selective electrode. Results-The principal results show different characteristics of kinetic curves of Al and F-excretion in workers with different exposures. Some characteristics of excretory peaks were linked to specific exposures-for instance, after exposure to AlF3 there was one delayed Al peak associated with one delayed F-peak about eight hours after the end of the daily shift, and after mixed exposure to HF and AIF3, two F-peaks were noted, one fast peak at the end of the shift and another delayed peak at 10 hours synchronised with an Al peak. In one of the electrolysis plants, the exposure to Al and F-compounds led to the simultaneous excretion of Al and Fpeaks, either as a single peak or two individual ones depending on the type of technology used on site (open or enclosed potlines). The average estimated half life of Al was 7 5 hours, and of F-about nine hours. Quantitative relations between excretion and exposure showed an association between the F-atmospheric limit value of 2-5 mg/m3 with a urinary F-concentration of 6-4 mg/g creatinine at the end of the shift, a peak of 7*4 mglg creatinine, and 7-4 mg excreted a day. For Al, the exposure to 136 mglm' during the shift Conclusion-Particular differences in the behaviour of Al and F-in urine depended upon the original molecular form in the pollutant. These results reinforce the principle that, in biological monitoring, the sampling strategy and the choice of limit value should be dependent on kinetic data that take the exposure compound of the element in question into account.(Occup Environ Med 1995;52:396-403)

A cross sectional study was conducted on 513 employees at three hard metal plants: 425 exposed workers (351 men, 74 women) and 88 controls (69 men, 19 women). Cough and sputum were more frequent in workers engaged in "soft powder" and presintering workshops compared with controls (12-5% and 16X5% v 3 5%). Spirometric abnormalities were more frequent among women in sintering and finishing workshops compared with control women (56-8% v 23-8%) and abnormalities of carbon monoxide test were more frequent in exposed groups than in controls; this difference was more pronounced in women (31[4% v 5-6%) than in men (18-5% v 13%). No significant correlation was observed between duration ofexposure and age adjusted lung function tests. Slight abnormalities of chest radiographs (0/1, 1/1 according to ILO classification) were more frequent in exposed men than controls (12-8% v 1-9%) and mostly in soft powder workers. In subjects with abnormal chest radiographs FVC, FEV1 and carbon monoxide indices (fractional uptake of CO or CO transfer index or both) were lower compared with those with normal chest radiographs. Although relatively mild, the clinical, radiological, and functional abnormalities uncovered call for a regular supervision of workers exposed to hard metal dust.The industrial use of hard metal tools began in Germany in 1922. Owing to their hardness and resistance to wear and high temperatures they are used to make cutting tools, drill tips, and armament components. Their qualities are due mainly to tungsten carbide which, with cobalt (Co), constitutes the essential part of this alloy. They are produced according to the powder metallurgy technique in specialised factories in relatively large quantities (in France 300 tons a year at present).About 20 years later, hard metals were suspected of being responsible for bronchopulmonary disorders, first in Germany, then in the other industrialised countries. Despite a certain heterogeneity of the symptoms and signs, the condition progresses towards a diffuse pulmonary fibrosis and leads to severe respiratory insufficiency. Except for sporadic case reports, the frequency and intensity of clinical and functional respiratory disorders which can be observed among a group of workers exposed to hard metal dust are not well known. Thus a cross sectional survey was conducted among a group of 425 workers exposed to hard metal dusts and of 88 controls who worked in three factories.

Chromium(VI) compounds--Ca, Sr, Zn and Pb chromates--were studied for cytotoxicity and morphological transformation in Syrian hamster embryo (SHE) cells in relation to their solubilization in cell culture conditions and intracellular Cr concentration. Ca, Sr and Zn chromates were completely solubilized after 1 day of incubation in cell cultures; for Pb chromate, 20-36% Cr was solubilized only after 7 days. In two parallel transformation assays, the SHE cells were treated with suspensions or with corresponding supernatants (containing only solubilized Cr) of these compounds. A statistically significant relationship was observed between the Cr treatment concentration and the amount of Cr per cell, irrespective of the compound (except suspensions of Pb chromate). The cytotoxicity was due to extracellular solubilized chromium because treatments with either supernatants or suspensions of Ca, Sr and Zn chromates gave the same LC50 of 0.31 +/- 0.01 microgram Cr/ml. A clear dose-response relationship was observed for the induction of morphological transformation for each compound, either previously solubilized or in suspension. The expression of the transformation frequencies as a function of the Cr concentration/cell revealed that (i) the transformation frequency is dependent on the Cr concentration/cell irrespective of the Cr compound Ca, Sr or Zn chromate, (ii) the transformation frequency induced by solubilized Pb chromate is higher than that induced by the other compounds at the same concentration of Cr/cell. A double treatment with solutions of Cr and Pb at corresponding concentrations induced the same transformation frequency as the solubilized Pb chromate. The results show that the solubilization of particulate Cr(VI) compounds is a critical step for their cytotoxic and transforming activities; the intracellular soluble Cr is the sole causative agent of the transforming activity of Ca, Sr and Zn chromates, while Pb appears to act synergistically with Cr in inducing the transformation by Pb chromate.