CORDIS provides links to public deliverables and publications of HORIZON projects.
Links to deliverables and publications from FP7 projects, as well as links to some specific result types such as dataset and software, are dynamically retrieved from OpenAIRE .
Exploitable results
General Information : The toxicity and bioavailablity of trivalent and hexavalent chromium species have been a matter of public health concern for some time. The deleterious effect on living systems of Cr(VI) in effluents is very well documented and asks for strict control. In occupational health the OEL (occupational exposure limits) for water soluble and certain water insoluble compounds in indoor air is limited to 0.5 mg/m3 for Cr(VI), to 0.5 mg/m3 for Cr(III) compounds as Cr and to 0.05 mg/m3 for Cr(VI) as Cr whereas the maximum level of total Cr in drinking water has been set at 50 mg/L (Directive 80/774/EEC). Cr (VI) is such a potent carcinogenic agent for the respiratory tract that continuous monitoring of the amount of Cr (VI) inhaled by workers has been imposed, as described in the Directive 90/3941/EEC on exposure to carcinogenic substances.
At present the reliability of Cr(III) and Cr(VI) determinations appears very unsatisfactory. The lack of agreement between the results produced by different laboratories of the member states clearly points to deficiencies in the methodologies for separation and measurement of the Cr(III) and Cr(VI) species. There is an urgent need to improve the accuracy of the results to ensure that a population never becomes subject to harmful amounts of Cr species in water and air. Furthermore there is the requirement to harmonize the results between the different member states to allow unequivocal economical and political decisions.
Achievements : A certified reference material, representative for drinking water with Cr(III) and Cr(VI) contents of approximately 25 micro g.L-1 was envisages. A major obstacle in speculation analyses is to preserve the original species present in the sample. Preliminary studies were therefore carried out to investigate the stability of Cr(III) and Cr(VI) as a function of time, temperature, matrix, container material, etc. The best results were obtained with a HCO3/H2CO3 buffer at pH 6.4. Doing so, a matrix close to that of real water was achieved. Next the product was freeze-dried, guaranteeing a presumably unlimited shelf life. The methodology to produce a batch of filters with a homogeneous and stable distribution of Cr(VI) and a load of Cr(VI) corresponding to what is usually found on occupationally charged filters had to be developed. Also the particle size distribution had to be representative for the inhaled fraction of welding dust. The candidate reference materials were also checked for their homogeneity. An intercomparison on European scale was organized to detect possible pitfalls and sources of error. Twenty two laboratories participated in the final certification campaign. They used different analytical techniques for the separation and final detection of the Cr species to avoid an overall systematic error on the final certified value.
The certified reference materials for Cr specification (CRM 544) and (CRM 545) will be a very useful tool for (National, International, etc) institutes involved in monitoring the quality of drinking, natural or surface water and occupational exposure respectively. It can also be used by industries or private laboratories to check and improve their skills in Cr specification analyses. A challenge for the future could be the development of a waste water material certified for the Cr species which would be useful for industries dealing with Cr plating, leather tanning etc.
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