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EC number: 235-790-8 | CAS number: 12737-27-8
Endpoint summary
Administrative data
Key value for chemical safety assessment
Genetic toxicity in vitro
Endpoint conclusion
- Endpoint conclusion:
- no study available
Genetic toxicity in vivo
Endpoint conclusion
- Endpoint conclusion:
- no study available
Additional information
The in-vitro and in-vivo experiments described in the dataset are in very good agreement with regards to the negligible level of bioavailability of the elements Cr and Fe contained in the pigment, indicating a lack of any concern for genetic toxicity properties.
(1) no signs of local toxicity in an acute inhalation toxicity test at the limit dose of 5.01 mg/L. The study has been performed according to OECD TG 403 and which shows no signs of acute toxicity after inhalation exposure to the pigment chromium iron oxide, indicating a LC50 > 5.01 mg/L. No mortality occurred.
(2) In in-vitro dissolution experiments in five different artificial physiological media, dissolved Cr and Fe concentrations were below 18 µg/L even at the highest loading of 0.1g/L, corresponding to a solubility of 0.018 %.
(3) In a 28-day oral toxicity study with 1,000 mg/kg pigment no increase in Cr and Fe plasma and urine concentrations were observed when sampled at the end of the 28-day exposure period. From a final dose of 1,000 mg/kg of the pigment that the animals received on the last day of the study, only cumulated relative amounts of < 0.0025 % (m/f) were found in the terminal 24-h urine collection period.
(4) In a mass balance study with a single oral dose of 1,000 mg/kg of the pigment, 89.1% Cr, and 94.1% Fe of the dose were excreted via faeces within 3 days, with only <0.0024% of the dose being excreted via urine at the same time.
(5) In a relative bioavailability study, the relative bioavailability of orally administered pigment was calculated 0.07% (Cr) in relation to a soluble Cr3+compound (Cr3(OH)2(CH3COO)7)injected i.v..
Comparing the findings of in-vitro dissolution testing (1) with in-vivo results (2-4), the in-vivo data consistently demonstrates slightly lower bioavailability. This is in agreement with the general understanding that in-vitro experiments in simulated gastric juice provide a conservative estimate of actual (in-vivo) bioavailability.
In conclusion, the oral relative bioavailability of the pigment "Chromium iron oxide" can be assumed to be negligible, as demonstrated in three independent in-vivo studies in rats yielding very comparably results supported by an in-vitro dissolution experiment in five different artificial physiological media.
A rounded value of <0.01% for oral absorption can be taken forward from (i) terminal urine/plasma sampling in a study involving 28 repeated oral doses of 1,000 mg pigment/kg bw/d (<<0.008% for both metals) and (ii) a mass balance study involving a single dose of 1,000 mg pigment/kg bw (0.00009% for Cr, and <0.0024% for Fe).
It is concluded that the pigment was well tolerated and that no signs of systemic toxicity whatsoever were observed in rats when administered at a dose of 1000 mg/kg bw/day for up to 28 days. Either no or only marginal increases in Cr and Fe plasma concentrations were observed, and only a minor fraction (<0.002%) of the total administered dose of Cr and Fe was collected via urine, documenting the lack of bioavailability of this pigment. The no observed adverse effect level (NOAEL) in rats is 1000 mg/kg/day.
Justification for classification or non-classification
It is concluded that the pigment was well tolerated and that no signs of systemic toxicity whatsoever were observed in rats when administered at a dose of 1000 mg/kg bw/day for up to 28 days. Either no or only marginal increases in Cr and Fe plasma concentrations were observed, and only a minor fraction (<0.002%) of the total administered dose of Cr and Fe was collected via urine, documenting the lack of bioavailability of this pigment. The no observed adverse effect level (NOAEL) in rats is 1000 mg/kg/day.
No classification for genetic toxicity according to EC Regulation No. 1272/2008 is anticipated.
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