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Toxicity to soil macroorganisms except arthropods

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Description of key information

Aluminum zirconium chloride hydroxide is an inorganic substance which will rapidly dissociate into aluminum, zirconium, chloride and hydroxide ions upon dissolution in the environment. However, zirconium ions will not remain as such in solution, and the environmental toxicity (if any) will not be driven by zirconium. Therefore, full read-across to other aluminum substances considering a typical aluminum content of ca. 19.4%  would be justified. Soil toxicity data are available for soil macro-organisms. The lowest 14-d LC50 of 359 mg aluminum/kg dw soil for Eisenia andrei derived in artificial soil at pH 4.4 and recalculated for aluminum zirconium chloride hydroxide would yield an LC50 value of 1851 mg/kg dw soil whereas the recalculated 42-d NOEC also for E. andrei in artificial soil at pH 3.4 amounts to 515 mg/kg dw  for aluminum zirconium chloride hydroxide. However, Aluminum (Al) is the most commonly occurring metallic element, comprising eight percent of the earth's crust (Press and Siever, 1974) and is therefore found in great abundance in both the terrestrial and sediment environments. Concentrations of 3-8% (30,000-80,000 ppm) are not uncommon. The relative contributions of anthropogenic aluminium to the existing natural pools of aluminium in soils and sediments is very small and therefore not relevant either in terms of added amounts or in terms of toxicity. More information about exposure based waiving for aluminium in soil and sediments can be found in attached document (White Paper on exposure based waiving for iron and aluminium in soil and sediments.pdf. Final report. March 2010; section 6.3). Thus, considering the natural abundance of aluminum in soils, the formal derivation of a PNEC soil for aluminum zirconium chloride hydroxide is considered irrelevant for the hazard assessment.
Reference:
Press F. and Siever R. (1974) Earth.

Key value for chemical safety assessment

Short-term EC50 or LC50 for soil macroorganisms:
1 851 mg/kg soil dw
Long-term EC10, LC10 or NOEC for soil macroorganisms:
515 mg/kg soil dw

Additional information

Aluminum zirconium chloride hydroxide is an inorganic substance which will rapidly dissociate into aluminum, zirconium, chloride and hydroxide ions upon dissolution in the environment. However, zirconium ions will not remain as such in solution. Thus, regarding the environmental fate and toxicity of Aluminum zirconium chloride hydroxide, it can be assumed that environmental fate and toxicity (if any) will not be driven by zirconium. Therefore, full read-across to dialuminum chloride pentahydroxide (CAS #12042-91-0) and other aluminum substances considering a typical aluminum content of ca. 19.4% is justified.

Aluminum (Al) is the most commonly occurring metallic element, comprising eight percent of the earth's crust (Press and Siever, 1974) and is therefore found in great abundance in terrestrial environments. Concentrations of 3-8% (30,000-80,000 ppm) are not uncommon. The relative contributions of anthropogenic aluminium to the existing natural pools of aluminium in soils is very small and therefore not relevant either in terms of added amounts or in terms of toxicity. Based on these exposure considerations additional soil testing is not warranted. More information about exposure based waiving for aluminium in soil can be found in the attached document (White Paper on exposure based waiving for iron and aluminium in soil and sediments.pdf. Final report. March 2010; section 6.3).

One short-term and one long-term study with Eisenia andrei are available using soluble aluminium salts (Van Gestel and Hogerwerf, 2001). The studies are presented for completeness, but are not considered relevant for assessing the terrestrial toxicity of aluminum zirconium chloride hydroxide.

One short-term study with Eisenia andrei is available. Three aluminum salts were tested with an exposure period of 14 days. Three pH (KCl) levels were assessed, namely 3.3, 4.4 and 6.7. Aluminum chloride was most toxic and showed higher toxicity with lower pH levels. At pH (KCl) 4.4 the LC50 was 359 mg/kg dw (Al). Al2O3 did not affect survival at concentrations of 5000 mg/kg dw Al at pH levels of 2.4 and 7.1.

One long-term study is available with Eisenia andrei.This study was performed with Sulfuric acid, aluminium salt (3:2), octadecahydrate (CAS RN 7784-31-8). The effect on reproduction was assessed in artificial soil. In the main test, earthworms were exposed for 6 weeks to soils treated with Al2(SO4)3. As in the range-finding test, aluminium sulfate was most toxic at a pH of 3.4 with an LC50 of 589 mg/kg dw (Al). At this pH, growth and cocoon production of earthworms were significantly reduced at 320 mg/kg dw (Al), while at 1000 mg/kg dw (Al) all earthworms died. Survival was not affected by 1000 mg/kg dw (Al) at pH 4.3 and 7.3. At pH 4.3, growth was significantly reduced at 1000 mg/kg dw (Al) and cocoon production at 320 and 1000 mg/kg dw (Al). At pH 7.3, aluminium only affected cocoon production at the two highest exposure levels. At the highest two exposure levels at pH 7.3, growth was significantly increased, suggesting a trade-off between growth and reproduction.