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Aluminium trilactate is very soluble in water and dissociates to Lactate and Aluminium in form of its cation.Thus, the read-across approach to Lactic acid and Aluminium is justified in accordance with REACH Regulation (Annex XI, 1.5) by chemical structure and common physiological activity of the dissociation products.

Lactic acid is present in most organisms and as metabolic intermediate a key substance in several physiological processes. No concern arises from Lactic acid or the Lactate ion.

US EPA (U.S. Environmental Protection Agency) (2003) has assessed the toxicity of Aluminium to the terrestrial compartment:

“Aluminum (Al) is the most commonly occurring metallic element comprising eight percent of the earth's crust (Press and Siever, 1974). It is a major component of almost all common inorganic soil particles with the exceptions of quartz sand, chert fragments, and ferromanganiferous concretions. The typical range of aluminum in soils is from 1% to 30% (10,000 to 300,000 mg Al kg-1) (Lindsay, 1979 and Dragun, 1988) with naturally occurring concentrations variable over several orders of magnitude.

EPA recognizes that due to the ubiquitous nature of aluminum, the natural variability of aluminum soil concentrations and the availability of conservative soil screening benchmarks (Efroymson, 1997b), aluminum is often identified as a contaminant of potential concern (COPC) for ecological risk assessments. The commonly used soil screening benchmarks (Efroymson, 1997b) are based on laboratory toxicity testing using aluminum solution amendments to test soils. Comparisons of total aluminum soil concentrations to solution based screening values are deemed by EPA to be inappropriate.

The standard analytical measurement of aluminum in soils under CERCLA contract laboratory procedures (CLP) is total recoverable metal. The available data on the environmental chemistry and toxicity of aluminum in soil to plants and soil invertebrates as discussed in the preceding chapters supports the following conclusions:

• Total aluminum in soil is not correlated with toxicity to the tested plants and soil invertebrates.

• Aluminum toxicity is associated with soluble aluminum.

• Soluble aluminum and not total aluminum is associated with the uptake and bioaccumulation of aluminum from soils into plants.


Measurement of Soluble Aluminum in Soils

Chemical and toxicological information suggests that aluminum must be in a soluble form in order to be toxic to biota. It is, however, difficult to measure accurately or with precision the concentration of soluble aluminum in pore water or in soil extracts. The difficulties associated with the measurement of soluble aluminum are discussed in detail in the previous chapters and include the following:

• Contamination problems. Aluminum is ubiquitous and the possibility of contamination of pore water or soil extract samples with aluminum from other sources is high. Sampling requires special handling to minimize background contamination.

• Forms of soluble aluminum which may be toxic are poorly understood

• Techniques for measurement of soluble aluminum are not well developed and would equire refinement in order to consistently provide reproducible results that could be used with confidence.

Based on the available information, it is not possible at this time to recommend the direct measurement of soluble aluminum as the method for prediction of toxicity of aluminum in soils. It is possible to recommend as an alternative the measurement of soil pH. The presence of soluble aluminum forms is pH dependent. Thus, the measurement of soil pH provides an indirect but reliable approach for assessing if soluble aluminum could be present. The use of a pH screening level of 5.5 is considered environmentally protective .


Alternative Screening Procedure for Aluminum

Potential ecological risks associated with aluminum in soils is identified based on the measured soil pH.

Aluminum is identified as a COPC only for those soils with a soil pH less than 5.5.

The technical basis for this procedure is that the soluble and toxic forms of aluminum are only present in soil under soil pH values of less than 5.5. Site-specific considerations could, however warrant inclusion of aluminum as a COPC.”



US EPA (U.S. Environmental Protection Agency) 2003, Ecological Soil Screening Level for Aluminum Interim Final. Available via internet: