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Administrative data

Key value for chemical safety assessment

Effects on fertility

Effect on fertility: via oral route
Endpoint conclusion:
no study available
Effect on fertility: via inhalation route
Endpoint conclusion:
no study available
Effect on fertility: via dermal route
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 Zr, Si and Pr contained in the pigment, indicating a lack of any concern for toxicity to reproduction properties.

(1)  No signs of local toxicity in an acute inhalation toxicity test at the limit dose of 5.5 mg/L and no signs of mutagenic or clastogenic potential in three different genetic toxicity test systems could be observed.

The inhalation study has been performed according to OECD TG 403 and which shows no signs of acute toxicity after inhalation exposure to the pigment, indicating a LC50 > 5.5 mg/L. No mortality occurred.

(2) In in-vitro dissolution experiments in five different artificial physiological media, dissolved Zr, Si and Pr concentrations from this pigment were very low, corresponding to a solubility of less than 0.4%.

(3) In a 28-day oral toxicity study with 1,000 mg/kg pigment no increase in Pr 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 < 0.00001 % (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, 102% Pr of the dose and 74.3% Zr were excreted via faeces within 3 days, with only <0.00001% Pr and < 0.002% Zr of the dose being excreted via urine at the same time.

(5)   In a bioavailability study, the absolute (0.000055% (Pr)) and relative (0.000011% (Pr)) bioavailability of orally administered pigment was calculated in relation to a soluble Pr3+compound (PrCl3), injected i.v..

Comparing the findings ofin-vitrodissolution testing (2) within-vivoresults (1,3-5), thein-vivodata consistently demonstrates slightly lower bioavailability. This is in agreement with the general understanding thatin-vitroexperiments in simulated gastric juice provide a conservative estimate of actual (in-vivo) bioavailability.

In conclusion, the oral absolute and relative bioavailability of the pigment "Zirconium praseodymium yellow zircon" can be assumed to be negligible, as demonstrated in three independent in-vivo studies in rats yielding very comparable results, supported by in-vitro dissolution experiments 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 (<<0.00001%)and (ii) a mass balance study involving a single dose of 1,000 mg pigment/kg bw (0.00003% for Pr and <<0.00001% for Zr).

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 Pr plasma concentrations were observed, and only a minor fraction (<<0.001%) of the total administered dose of Pr 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.

Effects on developmental toxicity

Effect on developmental toxicity: via oral route
Endpoint conclusion:
no study available
Effect on developmental toxicity: via inhalation route
Endpoint conclusion:
no study available
Effect on developmental toxicity: via dermal route
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 Zr, Si and Pr contained in the pigment, indicating a lack of any concern for toxicity to reproduction properties.

(1)  No signs of local toxicity in an acute inhalation toxicity test at the limit dose of 5.5 mg/L and no signs of mutagenic or clastogenic potential in three different genetic toxicity test systems could be observed.

The inhalation study has been performed according to OECD TG 403 and which shows no signs of acute toxicity after inhalation exposure to the pigment, indicating a LC50 > 5.5 mg/L. No mortality occurred.

(2) In in-vitro dissolution experiments in five different artificial physiological media, dissolved Zr, Si and Pr concentrations from this pigment were very low, corresponding to a solubility of less than 0.4%.

(3) In a 28-day oral toxicity study with 1,000 mg/kg pigment no increase in Pr 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 < 0.00001 % (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, 102% Pr of the dose and 74.3% Zr were excreted via faeces within 3 days, with only <0.00001% Pr and < 0.002% Zr of the dose being excreted via urine at the same time.

(5)   In a bioavailability study, the absolute (0.000055% (Pr)) and relative (0.000011% (Pr)) bioavailability of orally administered pigment was calculated in relation to a soluble Pr3+compound (PrCl3), injected i.v..

Comparing the findings ofin-vitrodissolution testing (2) within-vivoresults (1,3-5), thein-vivodata consistently demonstrates slightly lower bioavailability. This is in agreement with the general understanding thatin-vitroexperiments in simulated gastric juice provide a conservative estimate of actual (in-vivo) bioavailability.

In conclusion, the oral absolute and relative bioavailability of the pigment "Zirconium praseodymium yellow zircon" can be assumed to be negligible, as demonstrated in three independent in-vivo studies in rats yielding very comparable results, supported by in-vitro dissolution experiments 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 (<<0.00001%)and (ii) a mass balance study involving a single dose of 1,000 mg pigment/kg bw (0.00003% for Pr and <<0.00001% for Zr).

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 Pr plasma concentrations were observed, and only a minor fraction (<<0.001%) of the total administered dose of Pr 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 Pr plasma concentrations were observed, and only a minor fraction (<<0.001%) of the total administered dose of Pr 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 toxicity to reproduction according to EC Regulation No. 1272/2008 is anticipated.