Chromium trichloride

Endpoint summary

Description of key information

acute oral toxicity to rats: LD50 1568 mg/kg bw
acute dermal toxicity to rats: LD50 >2000 mg/kg bw

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

1 568 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Additional information

Acute oral toxicity

Four studies for chromium(III) compounds were identified addressing acute oral toxicity. Smyth et al. (1969) investigated chromium trinitrate nonahydrate upon acute exposure to rats and found a LD50 value of 3250 mg/kg bw (equivalent to 422 mg Cr/kg bw) but also chromium acetate monohydrate (LD50 value of 11620 mg/kg bw, equivalent to 2365 mg Cr/kg bw). Vernot et al. (1977) found in an equivalent experiment to Smyth et al. a LD50 value of 1465 mg/kg bw (equivalent to 190 mg Cr/kg bw) for chromium trinitrate nonahydrate. Shara et al. (2005) investigate chromium(III) nicotinate for acute toxicity to rats and found no oral toxicity at 5000 mg/kg bw (> 621.5 mg Cr/kg bw). Smyth et al. (1969) also tested the acute toxicity of chromous chloride (CrCl2), a chromium(II) compound which readily gets oxidized to chromium(III) in aqueous systems and reported a LD50 of 1870 mg/kg bw (equivalent to 791 mg Cr/kg bw).

It was reported by several authors that toxicity of chromium (III) compounds increases with water solubility and thus the results found with chromium trinitrate nonahydrate are more relevant for chromium trichloride as both substances are very well soluble in water. Thus, the acute oral LD50 of chromium trichloride may be based on the two findings on chromium trinitrate nonahydrate with an average LD50 of 306 mg Cr/kg bw which equates to 932 mg CrCl3/kg bw or more appropriately 1568 mg CrCl3.6H2O/kg bw.

This value is taken forward for hazard and risk assessment.

Acute inhalation toxicity

No acute inhalation studies with chromium(III) chloride are available. However, in a 90 day inhalation repeated dose study, reported by Derelanko et al. (1999) - see section on repeated dose toxicity - no systemic toxicity was noted upon exposure to chromium(III) hydroxysulfate, also a soluble chromium(III) compound, but local effects in the respiratory tract were observed. Similar effects can be expected for chromium trichloride hexahydrate upon inhalation exposure.

Acute dermal toxicity

No acute dermal study with chromium(III) chloride is available but a dermal study with chromium(III) nicotinate in which no mortality and no adverse symptoms were seen in rats at 2000 mg/kg bw. Considering, that no skin irritation effects were observed for chromium(III) chloride - see section on skin corrosion/irritation - in vitro and in vivo, one can assume that although chromium trichloride is acidic the skin barrier remains intact and no enhanced skin penetration is expected upon exposure to chromium trichloride. Thus, the acute dermal finding for chromium(III) nicotinate is considered representative for chromium trichloride too and acute dermal toxicity is not expected.

Acute toxicity by other routes

Bryson et al. (1983) had investigated toxicity to mice by intraperitoneal injection- the aqueous solution had a pH of approx. 2.5. The LD50 found was 42.2 and 49.2 mg/kg bw for female and male mice respectively. In comparison to the other acute study results by oral and dermal application this finding supports the result from toxicokinetic reviews indicating that chromium(III) absorption by oral, dermal and inhalation exposure is low and this is mainly responsible for the low toxicity of chromium(III) compounds.

Justification for classification or non-classification

No data is available for inhalation exposure to chromium trichloride. Results from dermal studies to chromium(III) indicate no significant toxicity. However, based on acute toxicity studies chromium trichloride shall be classified as harmful (Xn, R22) according to DSD (Directive 67/548/EEC) or Acute Toxic Category 4, H302 according to CLP (Regulation EC No 127272008).