Strontium chromate

Endpoint summary

Description of key information

A valid test on acute inhalation toxicity of strontium chromate exists. In acute oral toxicity, a poorly described study on strontium chromate is notified but the LD50 is based on read-across from a sparingly water soluble chromate. There is no non-human information on acute dermal toxicity of strontium chromate. Human information on strontium chromate is also lacking. 

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Dose descriptor:

LD50

Value:

327 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Dose descriptor:

LC50

Value:

270 mg/m³ air

Acute toxicity: via dermal route

Endpoint conclusion

Value:

mg/kg bw

Additional information

According to REACH guidelines with>1,000 t/a substances, two toxicity tests are required (oral and inhalation or dermal acute toxicity tests) for showing acute toxicity of a substance. Based on the assumptions made in the toxicokinetics of the bioavailability, exposure via inhalation route is relevant for chromates. In a well-performed acute inhalation toxicity test, the LC₅₀of strontium chromate was between 0.27 and 0.51 mg/L air, suggesting category 2 in classification. There are two other studies on acute toxicity of strontium chromate which are giving substance-specific evidence. In these, the substance was orally or intratracheally administered in rats, giving a LD₅₀value of 3,118 mg/kg bw (795 mg Cr/kg) and 16.6 mg/kg (4.2 mg Cr/kg), respectively. According to this acute oral toxicity study, there would not be classification for strontium chromate. There is no non-human information on acute dermal toxicity of strontium chromate. Human information on strontium chromate is also lacking.

Read-across from other sparingly soluble hexavalent chromium compounds - which would be the most potential in the case of strontium chromate - can be used only partially. Data with highly water soluble chromates exist, but this data can be regarded as worst case scenario. This is because both the well-documented inhalation study (LC₅₀0.27-0.51 mg/L) and the supporting oral toxicity study (LD₅₀3,118 mg/kg bw) with strontium chromate give evidence on the lower acute toxicity of strontium chromate compared to the results received in studies with highly water soluble hexavalent chromium compounds (e.g. in Gad et al. 1986: LC₅₀for acute inhalation toxicity 0.094-0.158 mg/L, and LD₅₀for acute oral toxicity 51.1-57.2 mg/kg bw). For acute inhalation toxicity, classification of strontium chromate into category 2 is justified. Furthermore, it is reasonable to judge acute oral toxicity of strontium chromate to category 4 as a study with sparingly soluble calcium chromate suggest. This is milder classification than with highly water soluble chromates but tighter than in the poorly described study with strontium chromate.

Justification for classification or non-classification

Conclusion: Strontium chromate is classified for acute oral toxicity as 'harmful if swallowed' (category 4), and for acute inhalation toxicity 'fatal if inhaled' (category 2). No further testing is suggested.