Zirconium dichloride oxide

Toxicological Summary

Workers - Hazard via inhalation route

Systemic effects

Long term exposure

Hazard assessment conclusion:

no hazard identified

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

no hazard identified

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

DNEL related information

Workers - Hazard via dermal route

Systemic effects

Long term exposure

Hazard assessment conclusion:

no hazard identified

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

medium hazard (no threshold derived)

Acute/short term exposure

Hazard assessment conclusion:

medium hazard (no threshold derived)

Workers - Hazard for the eyes

Local effects

Hazard assessment conclusion:

medium hazard (no threshold derived)

Additional information - workers

Acute / short-term exposure - systemic and local effects

- Inhalation: no experimental data are available after acute inhalation exposure. In addition, an acute inhalation study does not need to be conducted as the substance is corrosive to the skin, according to REACH Annex VIII section 8.5, column 2. Therefore no DNEL acute/short-term exposure (systemic effects) after inhalation exposure can be derived.

However as the substance is considered corrosive to skin, the possibility of hazard after inhalation needs to be considered. Nevertheless, values for particle size distribution reported in this dossier (Butler, 2010) indicate that the formation of respirable particulate matter is unlikely and therefore no respiratory exposure is expected. Consequently, no DNEL needs to be derived.

- Dermal: no acute dermal toxicity study is available for zirconium dichloride oxide and the study is waived based on Column 2 adaptation (REACH Regulation, Annex VIII, section 8.5) as the substance is corrosive to the skin. Due to the lack of acute dermal toxicity data, no acute/short-term DNEL (systemic effects) can be derived. However the substance is classified as corrosive to skin (category 1B, H314). Therefore, and according to ECHA's Guidance on Information Requirements and Chemical Safety Assessment, Part E, Table E.3-1, zirconium dichloride oxide should be considered to cause medium hazard (qualitative assessment) for dermal local effects.

Long-term exposure (systemic effects)

- Inhalation: the key study from Spiegl et al. (1956) provides a NOAEC for zirconium dichloride oxide >= 11.3 mg/m3 after 60 days of exposure. Although only one dose was tested in this study, no adverse effects were observed up to and including this dose. Therefore it can be concluded from the results of this study that the NOAEC will be higher than (or equal to) the dose tested. As no hazard has been identified based on the available data, no DNEL is required to be derived. In addition, there is sufficient evidence available indicating that zirconium is barely absorbed after exposure via inhalation (see section 7.1) and is therefore of low bioavailability, supporting the fact that a DNEL long-term (systemic) effects does not need to be derived for zirconium dichloride oxide.

National exposure limits for zirconium compounds were defined in Europe by 15 national authorities and set at 5 mg/m3 (expressed as Zr). In the USA, NIOSH, ACGIH, and OSHA have evaluated toxicity and defined long-term and short-term exposure limits for zirconium dioxide. The 8-h Time Weighted Average (TWA) was set at 5 mg Zr/m3 whereas the Short Term Exposure Limit (STEL) was set at 10 mg Zr/m3. These values were based on the results of Spiegl et al. (1956) with zirconium dioxide as well as on the results of the study from Hodge (1955). The study of Hodge (1955), is a 1-year experiment performed on rats with zirconium oxide dust at a a low dose of 3.5 mg/m3. Unfortunately the unpublished study was not accessible.

Although no DNEL needs to be derived for zirconium dichloride oxide, it is advised to respect, when relevant, the generic standards for zirconium compounds mentioned above.

- Dermal: no long-term dermal toxicity studies are available for zirconium dichloride oxide and this test is also waived based on the following information: a key study is available for both the oral and inhalation route of exposure and, according to the REACH Regulation, only one route of exposure should be tested for repeated dose toxicity (column 2, annex VIII, section 8.6.1). Therefore, it was not necessary to perform a repeated dose toxicity study via the dermal route of exposure. As there is no adequate data, no DNEL dermal exposure (systemic effects) is derived. Although experimental data from an oral combined repeated dose toxicity study with reproduction/developmental toxicity screening performed with the read across substance zirconium acetate are available (Rossiello, 2013), no systemic hazard was identified up to and including the highest dose tested (limit dose as per OECD 422 guideline) that could be used to derive a DNEL using 'route-to-route extrapolation'. Based on all abovementioned considerations and the fact that there is sufficient evidence available indicating that zirconium is barely absorbed after dermal exposure (see section 7.1), no DNEL long-term (systemic effects) needs to be derived.

Long-term exposure (local effects)

- Inhalation: no adverse local effects were reported after repeated inhalation exposure to zirconium dichloride oxide (Spiegl et al., 1956). Therefore, a DNEL long-term exposure, local effects is not required. In addition, values for particle size distribution reported in this dossier (Butler, 2010) indicate that the formation of respirable particulate matter is unlikely and therefore no respiratory exposure is expected.

- Dermal: there is no reliable dose descriptor to derive this DNEL. However, zirconium dichloride oxide is corrosive to the skin (Skin corrosive category 1B (H314)) according to the criteria of the CLP Regulation. Therefore, and according to ECHA's Guidance on Information Requirements and Chemical Safety Assessment, Part E, Table E.3-1, the substance should be considered to cause medium hazard (qualitative assessment).

Hazard for the eyes

According to the criteria of the CLP Regulation, zirconium dichloride oxide is classified as Eye damage category 1 (H318). Therefore, and according to ECHA's Guidance on Information Requirements and Chemical Safety Assessment, Part E, Table E.3-1, the substance should be considered to cause medium hazard (qualitative assesment).

General Population - Hazard via inhalation route

Systemic effects

Long term exposure

Hazard assessment conclusion:

no hazard identified

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

no hazard identified

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

DNEL related information

General Population - Hazard via dermal route

Systemic effects

Long term exposure

Hazard assessment conclusion:

no hazard identified

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

no hazard identified

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

General Population - Hazard via oral route

Systemic effects

Long term exposure

Hazard assessment conclusion:

no hazard identified

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

DNEL related information

General Population - Hazard for the eyes

Local effects

Hazard assessment conclusion:

medium hazard (no threshold derived)

Additional information - General Population

Acute / short-term exposure - systemic and local effects

- Inhalation: no experimental data are available on acute toxicity after inhalation exposure. In addition, an acute inhalation study does not need to be conducted as the substance is corrosive to the skin (REACH Annex VIII section 8.5, column 2). Therefore no DNEL acute/short-term exposure (systemic effects) after inhalation exposure can be derived.

However as the substance is considered corrosive to the skin, the possibility of hazard after inhalation needs to be considered. Nevertheless, values for particle size distribution reported in this dossier (Butler, 2010) indicate that the formation of respirable particulate matter is unlikely and therefore no respiratory exposure is expected. Consequently, no DNEL needs to be derived.

- Dermal: no acute dermal toxicity study is available for zirconium dichloride oxide and the study is waived based on Column 2 adaptation (REACH Regulation, Annex VIII, section 8.5) as the substance is corrosive to skin. Due to the lack of acute dermal toxicity data, no acute/short-term DNEL (systemic effects) can be derived. However the substance is classified as corrosive to skin (category 1B, H314). Therefore, and according to ECHA's Guidance on Information Requirements and Chemical Safety Assessment, Part E, Table E.3-1, zirconium dichloride oxide should be considered to cause medium hazard (qualitative assessment) for dermal local effects.

- Oral: one reliable study is available for zirconium dichloride oxide (Cochran et al., 1950). In this study the oral LD50 was derived to be 3500 mg/kg bw. As no acute toxic effects leading to classification and labeling were identified, no acute/short-term DNEL needs to be derived.

Long-term exposure (systemic effects); oral, inhalation and dermal exposure

- Oral: an oral combined repeated dose toxicity study with reproduction/developmental toxicity screening (OECD 422) has been performed with the read across substance zirconium acetate, which is a 'water soluble' zirconium compound with similar behaviour as zirconium dichloride oxide (Rossiello, 2013). The test solution was administered daily, by gavage. Parental Sprague-Dawley rats (10 per sex and per dose) were treated, starting at 6-7 weeks old and ending when the animals were euthanized, at dose levels of 100, 300 and 1000 mg/kg bw/day of zirconium acetate. A control group of 10 males and 10 females was dosed with vehicle alone (deionized water). The No Observed Adverse Effect Level (NOAEL) was considered to be >= 1000 mg/kg bw/day. No systemic hazard was identified up to and including the highest dose tested (limit dose as per OECD 422 guideline) that could be used to derive a DNEL. Based on all abovementioned considerations and the fact that there is sufficient evidence available indicating that zirconium is barely absorbed after oral exposure (see section 7.1), no DNEL long-term (systemic effects) needs to be derived.

- Inhalation: the study from Spiegl et al. (1956) provides a NOAEC for zirconium dichloride oxide >= 11.3 mg/m3 after 60 days of exposure. Although only one dose was tested in this study, no adverse effects were observed up to and including this dose. Therefore it can be concluded from the results of this study that the NOAEC will be higher than (or equal to) the dose tested. As no hazard has been identified based on the available data, no DNEL is required to be derived. In addition, there is sufficient evidence available indicating that zirconium is barely absorbed after exposure via inhalation (see section 7.1) and is therefore of low bioavailability, supporting the fact that a DNEL long-term (systemic) effects does not need to be derived for zirconium dichloride oxide.

- Dermal: no long-term dermal toxicity studies are available for zirconium dichloride oxide and this test is also waived based on the following information: a key study is available for both the oral and inhalation route of exposure and, according to the REACH Regulation, only one route of exposure should be tested for repeated dose toxicity (column 2, annex VIII, section 8.6.1). Therefore, it was not necessary to perform a repeated dose toxicity study via the dermal route of exposure. As there is no adequate data, no DNEL dermal exposure (systemic effects) is derived. Although experimental data from an oral combined repeated dose toxicity study with reproduction/developmental toxicity screening performed with the read across substance zirconium acetate are available (Rossiello, 2013), no systemic hazard was identified up to and including the highest dose tested (limit dose as per OECD 422 guideline) that could be used to derive a DNEL using 'route-to-route extrapolation'. Based on all abovementioned considerations and the fact that there is sufficient evidence available indicating that zirconium is barely absorbed after dermal exposure (see section 7.1), no DNEL long-term (systemic effects) needs to be derived.

Long-term exposure (local effects): inhalation and dermal exposure

- Inhalation: no adverse local effects were reported after repeated inhalation exposure to zirconium dichloride oxide (Spiegl et al., 1956). Therefore, a DNEL long-term exposure, local effects is not required. In addition, values for particle size distribution reported in this dossier (Butler, 2010) indicate that the formation of respirable particulate matter is unlikely and therefore no respiratory exposure is expected.

- Dermal: there is no reliable dose descriptor to derive this DNEL. However the substance is corrosive to the skin according to the criteria of the CLP Regulation (Skin corrosive category 1B, H314). Therefore, and according to ECHA's Guidance on Information Requirements and Chemical Safety Assessment, Part E, Table E.3-1, the substance should be considered to cause medium hazard (qualitative assessment).

Hazard for the eyes

According to the criteria of the CLP Regulation, zirconium dichloride oxide is classified as Eye damage category 1 (H318). Therefore, and according to ECHA's Guidance on Information Requirements and Chemical Safety Assessment, Part E, Table E.3-1, the substance should be considered to cause medium hazard (qualitative assesment).