Palladium dinitrate

Toxicological Summary

Workers - Hazard via inhalation route

Systemic effects

Long term exposure

Hazard assessment conclusion:

no hazard identified

DNEL related information

Explanation for the modification of the dose descriptor starting point:

See discussion section (Hazard via inhalation route: systemic effects following long-term exposure)

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)

Most sensitive endpoint:

skin irritation/corrosion

Acute/short term exposure

Hazard assessment conclusion:

medium hazard (no threshold derived)

Most sensitive endpoint:

skin irritation/corrosion

DNEL related information

Workers - Hazard via dermal route

Systemic effects

Long term exposure

Hazard assessment conclusion:

no hazard identified

DNEL related information

Explanation for the modification of the dose descriptor starting point:

See discussion section (Hazard via dermal route: systemic effects following long-term exposure)

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)

Most sensitive endpoint:

skin irritation/corrosion

Acute/short term exposure

Hazard assessment conclusion:

medium hazard (no threshold derived)

Most sensitive endpoint:

skin irritation/corrosion

Workers - Hazard for the eyes

Local effects

Hazard assessment conclusion:

medium hazard (no threshold derived)

Additional information - workers

Hazard via inhalation route: systemic effects following long-term exposure

Justification and comments

No relevant repeated dose toxicity data were identified for palladium dinitrate. However, good support for the conclusion that a repeated dose toxicity study can be waived comes from two sources. Firstly, a consideration of the known toxicity and physico-chemical properties of this compound. Palladium dinitrate is a strong acid (pH<2.0) and exhibits skin corrosivity in vitro. Secondly, there are good-quality endpoint-specific data on another palladium (II) species. In a combined repeated-dose and reproductive/developmental toxicity screening test, no adverse effects were observed at daily doses of palladium(II) dihydroxide up to 1000 mg/kg bw/day. This supports the hypothesis that, even if testing were possible, palladium dinitrate would not be expected to cause any significant systemic toxicity.

 

Hazard via inhalation route: systemic effects following acute exposure

Justification and comments

DNELs for acute toxicity should be calculated if an acute toxicity hazard, leading to classification and labelling (i.e. under EU CLP regulations) has been identified and there is a potential for high peak exposures (this is only usually relevant for inhalation exposures).

 

There are no data in relation to acute inhalation exposure to palladium dinitrate. In a guideline (OECD TG 423) acute oral toxicity study in rats with palladium dinitrate, the LD50 value was determined to lie between 200 and 2000 mg/kg bw (van Huygevoort, 2003a). The compound is classified in Category 4 according to CLP criteria. An oral N(L)OAEL (for sub-lethal effects) could be modified into an inhalation N(L)OAEC using route-to-route extrapolation. However, ECHA (2012a) guidance on DNEL calculation notes that this “procedure introduces significant uncertainties especially in relation to what inhalation time-frame this extrapolated N(L)OAEC would represent, and the procedure is therefore discouraged”. “A qualitative risk characterisation for this endpoint could be performed for substances of very high or high acute toxicity classified in Category 1, 2 and 3 according to CLP…. when the data are not sufficiently robust to allow the derivation of a DNEL” (ECHA, 2012b). However, palladium dinitrate is classified in Category 4, so a qualitative assessment is not required.

 

Further, as the substance is marketed or used in a non solid or granular form, inhalation is not considered to be a significant route of exposure.

 

Hazard via inhalation route: local effects following long-term exposure

Justification and comments

There are no data in relation to respiratory tract irritation or sensitisation in humans or laboratory animals. Consequently, no worker-DNELs for respiratory tract irritation/corrosion or sensitisation have been calculated.

 

Palladium dinitrate is not classified as a skin sensitiser.

 

Palladium nitrate is considered corrosive to the skin (Lehmeier, 2013a,b, 2014) and therefore serious damage to eyes is implicit. Despite the lack of respiratory tract irritation data, it would appear prudent to assume that palladium nitrate would also irritate the respiratory tract if inhaled at sufficient levels/durations. According to ECHA (2012b) guidance “substances classified for skin corrosion Category 1B/1C in CLP” or “Serious eye damage Category 1 in CLP “… “which relate to corrosive or severe irritant effects to the eye or irritant effects to the eyes, respiratory tract and skin simultaneously, are allocated to the moderate hazard band on the basis that exposure to such corrosives, eye damaging or irritant substances should be well-controlled”. Therefore, consider recommended Risk Management Measures/Operational Conditions (RMMs/OCs) in Table E.3-1 of ECHA (2012b).

 

 

 

Hazard via inhalation route: local effects following acute exposure

Justification and comments

There are no data in relation to respiratory tract irritation or sensitisation in humans or laboratory animals. Consequently, no worker-DNEL for acute local effects in the respiratory tract has been calculated.

 

Palladium dinitrate is not classified as a skin sensitiser.

 

Palladium nitrate is considered corrosive to the skin (Lehmeier, 2013a,b, 2014) and therefore serious damage to eyes is implicit. Despite the lack of respiratory tract irritation data, it would appear prudent to assume that palladium nitrate would also irritate the respiratory tract if inhaled at sufficient concentrations/durations. According to ECHA (2012b) guidance “substances classified for skin corrosion Category 1B/1C in CLP” or “Serious eye damage Category 1 in CLP “… “which relate to corrosive or severe irritant effects to the eye or irritant effects to the eyes, respiratory tract and skin simultaneously, are allocated to the moderate hazard band on the basis that exposure to such corrosives, eye damaging or irritant substances should be well-controlled”. Therefore, consider recommended RMMs/OCs in Table E.3-1 of ECHA (2012b).

 

 

 

Hazard via dermal route: systemic effects following long-term exposure

Justification and comments

No relevant repeated dose toxicity data were identified for palladium dinitrate. However, good support for the conclusion that a repeated dose toxicity study can be waived comes from two sources. Firstly, a consideration of the known toxicity and physico-chemical properties of this compound. Palladium dinitrate is a strong acid (pH<2.0) and exhibits skin corrosivity in vitro. Secondly, there are good-quality endpoint-specific data on another palladium (II) species. In a combined repeated-dose and reproductive/developmental toxicity screening test, no adverse effects were observed at daily doses of palladium(II) dihydroxide up to 1000 mg/kg bw/day. This supports the hypothesis that, even if testing were possible, palladium dinitrate would not be expected to cause any significant systemic toxicity.

 

Hazard via dermal route: systemic effects following acute exposure

Justification and comments

DNELs for acute toxicity should be calculated if an acute toxicity hazard, leading to classification and labelling (i.e. under EU CLP regulations) has been identified and there is a potential for high peak exposures (this is only usually relevant for inhalation exposures).

 

No acute dermal toxicity study was conducted. In a guideline (OECD TG 423) acute oral toxicity study in rats with palladium dinitrate, the LD50 value was determined to lie between 200 and 2000 mg/kg bw (van Huygevoort, 2003a). The compound is classified in Category 4 according to CLP criteria. However, as high peak exposures are not anticipated, a DNEL for acute toxicity is considered unnecessary (particularly via the dermal route). Long-term DNELs for systemic effects are expected to be sufficient to ensure that adverse effects do not occur.

 

“A qualitative risk characterisation for this endpoint could be performed for substances of very high or high acute toxicity classified in Category 1, 2 and 3 according to CLP…. when the data are not sufficiently robust to allow the derivation of a DNEL” (ECHA, 2012b). However, palladium dinitrate is classified in Category 4, so a qualitative assessment is not required.

 

 

 

Hazard via dermal route: local effects following long-term exposure

Justification and comments

In guideline (OECD TG 435) in vitro membrane barrier tests, palladium dinitrate (as palladium dinitrate hydrate (solid), palladium dinitrate solution type H and palladium dinitrate solution) was classified as corrosive sub-category 1B under GHS, on the basis of mean breakthrough times of about 14, 3 -6 and 4 minutes, respectively (Lehmeier, 2013a,b, 2014). Further, no dose-response data was available from which to derive a DNEL, therefore a qualitative assessment was considered appropriate. At worst this would be considered in the moderate hazard band according to ECHA (2012b) guidance.

 

In another guideline (OECD TG 406) study, palladium dinitrate hydrate failed to induce skin sensitisation in the guinea pig maximisation test (GPMT) (van Huygevoort, 2003b). The compound is not classified for skin sensitisation under CLP.

 

According to ECHA (2012b) guidance “substances classified for skin corrosion Category 1B/1C in CLP”… “which relate to corrosive or severe irritant effects to the eye or irritant effects to the eyes, respiratory tract and skin simultaneously, are allocated to the moderate hazard band on the basis that exposure to such corrosives, eye damaging or irritant substances should be well-controlled”.

 

Therefore, consider recommended RMMs/OCs in Table E.3-1 of ECHA (2012b).

 

 

 

Hazard via dermal route: local effects following acute exposure

Justification and comments

In guideline (OECD TG 435) in vitro membrane barrier tests, palladium dinitrate (as palladium dinitrate hydrate (solid), palladium dinitrate solution type H and palladium dinitrate solution) was classified as corrosive sub-category 1B under GHS, on the basis of mean breakthrough times of about 14, 3-6 and 4 minutes, respectively (Lehmeier, 2013a,b, 2014). Further, no dose-response data was available from which to derive a DNEL, therefore a qualitative assessment was considered appropriate. At worst this would be considered in the moderate hazard band according to ECHA (2012b) guidance.

 

In another guideline (OECD TG 406) study, palladium dinitrate hydrate failed to induce skin sensitisation in the GPMT (van Huygevoort, 2003b). The compound is not classified for skin sensitisation under CLP.

 

According to ECHA (2012b) guidance “substances classified for skin corrosion Category 1B/1C in CLP…which relate to corrosive or severe irritant effects to the eye or irritant effects to the eyes, respiratory tract and skin simultaneously, are allocated to the moderate hazard band on the basis that exposure to such corrosives, eye damaging or irritant substances should be well-controlled”.

 

Therefore, consider recommended RMMs/OCs in Table E.3-1 of ECHA (2012b).

 

 

 

Hazard for the eyes

Justification and comments

According to ECHA guidance on the application of CLP criteria (ECHA, 2015), “if a substance or mixture is classified as Skin corrosive Category 1 then serious damage to eyes is implicit and there is no need to proceed with classification for eye effects”. Palladium dinitrate is classified for skin effects as corrosive sub-category 1B. Consequently, the compound is classified for eye effects in Category 1 under EU CLP.

 

No dose-response data was available from which to derive a DNEL, therefore a qualitative assessment was considered appropriate. Substances classified for serious eye damage (Category 1 in CLP) should be allocated to the “moderate hazard band on the basis that exposure to such corrosives, eye damaging or irritant substances should be well-controlled”. Therefore, consider recommended RMMs/OCs in Table E.3-1 of ECHA (2012b).

General Population - Hazard via inhalation route

Systemic effects

Long term exposure

Hazard assessment conclusion:

hazard unknown but no further hazard information necessary as no exposure expected

Acute/short term exposure

Hazard assessment conclusion:

hazard unknown but no further hazard information necessary as no exposure expected

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

hazard unknown but no further hazard information necessary as no exposure expected

Acute/short term exposure

Hazard assessment conclusion:

hazard unknown but no further hazard information necessary as no exposure expected

DNEL related information

General Population - Hazard via dermal route

Systemic effects

Long term exposure

Hazard assessment conclusion:

hazard unknown but no further hazard information necessary as no exposure expected

Acute/short term exposure

Hazard assessment conclusion:

hazard unknown but no further hazard information necessary as no exposure expected

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

hazard unknown but no further hazard information necessary as no exposure expected

Acute/short term exposure

Hazard assessment conclusion:

hazard unknown but no further hazard information necessary as no exposure expected

General Population - Hazard via oral route

Systemic effects

Long term exposure

Hazard assessment conclusion:

hazard unknown but no further hazard information necessary as no exposure expected

Acute/short term exposure

Hazard assessment conclusion:

hazard unknown but no further hazard information necessary as no exposure expected

DNEL related information

General Population - Hazard for the eyes

Local effects

Hazard assessment conclusion:

hazard unknown but no further hazard information necessary as no exposure expected

Additional information - General Population

DNELs have been derived only for workers, not for consumers/general population. During assessment of the identified uses for palladium dinitrate, no uses have been identified in which consumers are exposed to palladium dinitrate. In all uses with potential consumer exposure due to service life of articles, palladium dinitrate is chemically transformed into another substance before reaching the consumers, and the subsequent lifecycle steps after this transformation of palladium dinitrate are appropriately included in the assessment of this newly formed substance. Regarding the general population, and following the criteria outlined in ECHA guidance R16 (2016), an assessment of indirect exposure of humans via the environment for palladium dinitrate has not been performed as the registered substance is manufactured/imported/marketed <100 tpa and is not classified as STOT-RE 1 or as CMR.