Chromium Trioxide, Sodium Chromate, Sodium Dichromate, Ammonium Dichromate and Potassium Dichromate
Environment
The environmental risk characterisation considers the production of the five chromium (VI) substances and their use in the following areas: pigment production; chromium oxide production; tanning salt production; wood preservation (formulation and use); metal treatment (formulation and use in electroplating, passivating, anodising and brightening); and mordant dyeing. The leaching of chromium from preservative-treated wood in direct contract with water is also included. A number of other uses were also considered and found to have negligible releases: chromium metal production; chromium dioxide production; Montan wax production. The use of chromium (VI) in the oxidation of sulphur dyes no longer occurs in Europe.
There are other sources of chromium release to the environment, both anthropogenic and natural, but there are not considered in this assessment. The assessment is based on the added local risk from the activities included. It is recognised that the wider background contribution may need to be considered when evaluating possible risk reduction measures.
For the aquatic compartment, including sediment, all the PEC/PNEC ratios are above one with the exception of two production sites and the use in mordant dyeing. Risk reduction measures are needed for surface water. The PNEC for sediment could be refined, but no work is proposed at present as the risk reduction measures for water will also reduce the risk to sediment organisms.
Risks are identified to micro-organisms in waste water treatment plants for all scenarios except production, wood preservative application and mordant dyeing.
For the terrestrial environment, risks are identified for all scenarios except production and mordant dyeing.
For indirect exposure through the food chain, the risk characterisation based on calculated concentrations in fish shows no risk from any of the scenarios. In contrast, the risk characterisation based on calculated concentrations in mussels shows a risk to all but there scenarios - production, wood preservative application and mordant dyeing. Further work could be carried out to refine this risk characterisation, but risk reduction measures for surface water will also lead to reduced risk for this endpoint and therefore no specific work is proposed. The terrestrial food chain risk characterisation shows no risk for any scenario.
Conclusion (i) There is a need for further information and/or testing.
This conclusion applies to sediment for all areas except for mordant dyeing. The effect concentration used in the risk characterisation is derived from data for aquatic organisms, and could be refined with data for sediment dwelling organisms. Although there may be value in trying to establish the relative sensitivity of sediment and aquatic organisms, measures to reduce water concentrations as a result of the assessment will also lead to reduced sediment levels. No further testing is proposed as the present.
This conclusion also applies to indirect exposure through the food chain for the mussel based food chain, for all areas except production, wood preservative application and mordant dyeing. Further work could be done to test whether the mussel-based food chain is of concern, for example through further investigation of the uptake of chromium into organisms other than fish, characterisation of the nature of the chromium in organisms and consideration of the toxicity of chromium in other forms to organisms consuming prey containing chromium.
However it should be noted that reductions in the emissions of chromium (VI) to water will reduce the estimated levels in biota as well. At present it is not proposed to carry out any further work, but to await the development of risk reduction measures.
Conclusion (ii): There is at present no need for further information and/or testing and for risk reduction measures beyond those which are being applied already. For the aquatic compartment this conclusion applies to the use in mordant dyeing and to production (two Bites only).
For sediment this conclusion applies to use in mordant dyeing.
For waste water treatment plants, this conclusion applies to production, wood preservative application, anodising and mordant dyeing.
For the terrestrial compartment, this conclusion applies to production and to mordant dyeing. This conclusion also applies to all areas for the air compartment and for indirect exposure though the fish-based food chain.
Conclusion (iii) There is a need for limning the risks; risk reduction measures which are already being applied shall be taken into account.
This conclusion applies to all areas for the aquatic, and terrestrial compartments, with the exception of mordant dyeing (both compartments) and production (terrestrial only, although the conclusion only applies to one production site for the aquatic). It also applies to waste water treatment plants for all areas, with the exception of production, wood preservative application, anodising and mordant dyeing.
Human health
Human health (toxicity)
Occupational exposure
Conclusion (i) There is a need for further information and/or testing.
Conclusion (i) is reached for repeated dose toxicity to the respiratory tract and the kidney. It is not possible to formally calculate an MOS for these effects since no NOAELs have been identified. Hence it is not possible to assess risk under contemporary working conditions. Further exposure-response information for respiratory tract and kidney effects is required.
Conclusion (ii) There is at present no need for further information and/or testing and no need for risk reduction measures beyond those which are being applied already.
Conclusion (ii) is reached for acute toxicity for full shift exposures since MOS values indicate there is no cause for concern.
Conclusion (iii) There is a need for limning the risks; risk reduction measures which are already being applied shall be taken into account.
In view of the genotoxic and carcinogenic properties of these Cr(VI) compounds, there are concerns for all exposure scenarios. In addition, there are concerns for acute toxicity as a result of short-term peak exposures, skin and eye irritation, respiratory tract sensory irritation, skin sensitisation, occupational asthma and reproductive toxicity (fertility and developmental toxicity). Conclusion (iii) is reached for these endpoints.
Consumer assessment
Conclusion (ii) There is at present no need for further information and/or testing and no need for risk reduction measures beyond those which are being applied already.
Conclusion (ii) is reached for all endpoints other than mutagenicity and carcinogenicity for the handling of CCA treated wood, both for adults and for children exposed via wooden playing structures.
Conclusion (iii) There is a need for limiting the risks; risk reduction measures which are already being applied shall be taken into account.
Conclusion (iii) is reached for mutagenicity and carcinogenicity because no threshold below which there would be no risk to human health can be identified for these endpoints. However, it is noted that exposure levels are very low.
No formal risk characterisation has been conducted for consumer exposure to wet CCA treated wood. In the UK, the supply of wood not fully dried following CCA treatment is prohibited as a condition of approval under the Control of Pesticides Regulations (1986). Similar controls may already exist in all other Member States. However, if specific controls were not available in each Member State, then there would be concerns for all relevant human health endpoints
Indirect exposure via the environment
Conclusions are presented for both local and regional scenarios together.
Conclusion (ii) There is at present no need for further information and/or testing and no need for risk reduction measures beyond those which are being applied already.
Conclusion (ii) is reached for all endpoints other than mutagenicity and carcinogenicity. Conclusion (iii) There is a need for limiting the risks; risk reduction measures which are already being applied shall be taken into account.
Conclusion (iii) is reached for mutagenicity and carcinogenicity because no threshold below which there would be no risk to human health can be identified for these endpoints. However, it is noted that exposure levels are very low.
Combined exposure
The combination of consumer exposure with indirect exposure via the environment does not produce significantly higher total exposures than those calculated for the separate individual contributions and therefore conclusion (ii) or, where appropriate, conclusion (iii) also applies to combined exposure.
Human Health (physico-chemical properties)
Given the level of control in manufacture and use the risks from physico-chemical properties are small.
Conclusion (ii) There is at present no need for further information and/or testing and no need for risk reduction measures beyond those which are being applied already.