Zinc neodecanoate

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

Species:

other: animal and human data

Additional information

Introductionto read-across matrix

A comprehensive data gap analysis was conducted for the entire substance portfolio of the Metal carboxylates REACH Consortium (MCRC), covering 10 metal carboxylates in total. This literature screening effort included:

 

• all available proprietary studies from the Metal carboxylates REACH Consortium (MCRC)
• detailed literature searches in online databases
• screening of human health review articles
• rigorous quality and reliability screening according to Klimisch criteria, where those criteria apply

 

During the literature search and data gap analysis it became obvious that the overall database on substance-specific human health hazard data for the metal carboxylates is too scant to cover all REACH endpoints. Therefore, the remaining data gaps had to be covered by either experimental testing or read-across from similar substances.

 

Selected endpoints for the human health hazard assessment are addressed by read-across, using a combination of data on the organic acid counterion and the metal (or one of its readily soluble salts). This way forward is acceptable, since metal carboxylates dissociate to the organic anion and the metal cation upon dissolution in aqueous media. No indications of complexation or masking of the metal ion through the organic acid were apparent during the water solubility tests (please refer to the water solubility data in section of the IUCLID and chapter of the CSR). Once the individual constituents of the metal carboxylate become bioavailable (i.e. in the acidic environment in the gastric passage or after phagocytosis by pulmonary macrophages), the “overall” toxicity of the dissociated metal carboxylate can be described by the toxicity of the “individual” constituents. Since synergistic effects are not expected for this group of metal carboxylates, the human health hazard assessment consists of an individual assessment of the metal cation and the organic anion.

 

The hazard information of the individual constituents was obtained from existing REACH registration dossiers via a license-to-use obtained by the lead registrant. These registration dossiers were submitted to ECHA in 2010 as full registration dossiers, and are thus considered to contain relevant and reliable information for all human health endpoints. All lead-registrant dossiers were checked for completeness and accepted by ECHA, i.e. a registration number was assigned.

 

Zinc neodecanoate is the zinc metal salt of neodecanoic acid, which readily dissociates to the corresponding divalent zinc cation and neodecanoic acid anions. The zinc cation and the neodecanoic acid anion are considered to represent the overall toxicity of the zinc neodecanoate in a manner proportionate to the free acid and the metal (represented by one of its readily soluble salts). Based on the above information, unrestricted read-across is considered feasible and justified.

 

Introduction to the neoacids hazard assessment

The carboxylic acids “neodecanoic acid” and “fatty acid C9 to C13 neo” are considered similar in their toxicological profile and are therefore grouped together. Both neoacids originate from the same production process in which a branched olefin is reacted with carbon monoxide and water at elevated temperature and pressure in th1e presence of an acid as catalytic component. The dossiers for neodecanoic acid and fatty acid C9 to C13 neo contain human health hazard information on both substances indicating that the toxicological profile is similar. This approach was also used and accepted in the US EPA HPV programme, even for a wider range of neo-acid substances (US EPA, April 2009: http://www.epa.gov/chemrtk/pubs/summaries/neoc528/c13335tc.htm).

Based on the above information “neodecanoic acid” and “fatty acid C9 to C13 neo” will be assessed for their hazardous properties, using the same dataset for both substances.

 

Although the term „constituent“ within the REACH context is defined as substance (also being part of a mixture), the term constituent within this hazard assessment is meant to describe either part of the metal carboxylate salt, i.e. anion or cation.

Toxicity for reproduction– effects on fertility

No toxicity data on adverse effects on sexual function and fertility with zinc neodecanoate are available, thus the reproductive toxicity will be addressed with existing data on the dissociation products as detailed in the table below. Further details on the reproductive toxicity of the individual constituents are given below.

 

Table: Summary of toxicity data on adverse effects on sexual function and fertility of the zinc neodecanoate and the individual constituents.

	(slightly soluble) zinc substances	Neodecanoic acid (CAS# 26896-20-8)	Zinc neodecanoate (CAS# 27253-29-8)
Two-generation reproductive toxicity study	NOAEL (human data) =20 mg/kg bw/day   not classified	NOAEL(3-gen;rat, P, F1 and F2)= 75 mg/kg bw/day*   no classified	no data   not classified

* Identified as most sensitive endpoint in the registration dossier for neodecanoic acid, thus has been used for the DNEL derivation of this substance.

 

Zinc

The reproductive toxicity of zinc compounds has been investigated in one- and two-generation reproductive toxicity studies in which rats or mice were dosed by gavage or via diet with soluble zinc compounds (i.e., zinc chloride, zinc sulphate) at exposure levels up to 14 mg Zn/kg bw/day (gavage) or 200 mg Zn/kg bw/day (diet) (Khanet al., 2001, 2003, 2007). Further information on potential effects of zinc compounds on male or female reproductive organs could be retrieved from subchronic toxicity studies as conducted by Maitaet al.(1981) and Edwards and Buckley (1995).

 

The available information suggests that high oral doses of zinc (i.e., exposure levels greater than 20 mg Zn/kg bw/day) may adversely affect spermatogenesis and result in impaired fertility indicated by decreased number of implantation sites and increased number of resorptions (US EPA, 2005). However, these effects were only observed in the presence of maternal toxicity as seen in the one- or two-generation studies conducted by Khanet al. (2001, 2003, 2007) or, in case of the study conducted by Kumaret al. (1976), when other study non-zinc relevant study specificities could have impacted the study outcome. In a large number of controlled trials, dietary supplementation with zinc rate of 20 mg/day and 30 mg/day did not result in any adverse reproductive effects in healthy pregnant women as summarised in WHO (2001) and ATSDR (2005).

 

Neodecanoic acid

In a modified three-generation reproductive toxicity study, male and female Sprague-Dawley rats were administered neodecanoic acid at 0, 100, 500 and 1500 ppm (approximately 0, 5, 25 and 75 mg/kg-bw/day, respectively) in the diet. No adverse effects were observed on survival, appearance, behaviour, body-weight gain and food consumption in the parental, F1 or F2 generations. The reproductive performance of the parents was not affected. No treatment-related gross or microscopic pathological findings were observed at any of the dietary levels.

 

 

Zinc neodecanoate

Zinc neodecanoate is not expected to show adverse effects on sexual function and fertility, since the two constituents zinc and neodecanoic acid have not shown effects in a range of test systems. Thus, zinc neodecanoate is not to be classified according to regulation (EC) 1272/2008 for reproductive toxicity: adverse effects on sexual function and fertility. Further testing is not required. For further information on the toxicity of the individual constituents, please refer to the relevant sections in the IUCLID and CSR.

 

Information on the individual constituents zinc and neodecanoic acid will be used for the hazard assessment and, when applicable, for the risk characterisation of zinc neodecanoate. For the purpose of hazard assessment of zinc neodecanoate, the point of departure for the most sensitive endpoint of each constituent will be used for the DNEL derivation. In case of neodecanoic acid in zinc neodecanoate, the NOAEL of 75 mg/kg bw/day for the reproductive toxicity will be used.

Short description of key information:
Zinc neodecanoate is not expected to be toxic for reproduction.

Justification for selection of Effect on fertility via oral route:
Information from read-across substances:
human data for zinc: NOAEL=20mg/kg bw/day
animal data for neodecanoic acid: NOAEL(rat, P)=75mg/kg bw/day

Effects on developmental toxicity

Description of key information

Zinc neodecanoate is not expected to be a developmental toxicant.

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

Species:

other: animal and human data

Additional information

Introduction to read-across matrix

A comprehensive data gap analysis was conducted for the entire substance portfolio of the Metal carboxylates REACH Consortium (MCRC), covering 10 metal carboxylates in total. This literature screening effort included:

 

• all available proprietary studies from the Metal carboxylates REACH Consortium (MCRC)
• detailed literature searches in online databases
• screening of human health review articles
• rigorous quality and reliability screening according to Klimisch criteria, where those criteria apply

 

During the literature search and data gap analysis it became obvious that the overall database on substance-specific human health hazard data for the metal carboxylates is too scant to cover all REACH endpoints. Therefore, the remaining data gaps had to be covered by either experimental testing or read-across from similar substances.

 

Selected endpoints for the human health hazard assessment are addressed by read-across, using a combination of data on the organic acid counterion and the metal (or one of its readily soluble salts). This way forward is acceptable, since metal carboxylates dissociate to the organic anion and the metal cation upon dissolution in aqueous media. No indications of complexation or masking of the metal ion through the organic acid were apparent during the water solubility tests (please refer to the water solubility data in section of the IUCLID and chapter of the CSR). Once the individual constituents of the metal carboxylate become bioavailable (i.e. in the acidic environment in the gastric passage or after phagocytosis by pulmonary macrophages), the “overall” toxicity of the dissociated metal carboxylate can be described by the toxicity of the “individual” constituents. Since synergistic effects are not expected for this group of metal carboxylates, the human health hazard assessment consists of an individual assessment of the metal cation and the organic anion.

 

The hazard information of the individual constituents was obtained from existing REACH registration dossiers via a license-to-use obtained by the lead registrant. These registration dossiers were submitted to ECHA in 2010 as full registration dossiers, and are thus considered to contain relevant and reliable information for all human health endpoints. All lead-registrant dossiers were checked for completeness and accepted by ECHA, i.e. a registration number was assigned.

 

Zinc neodecanoate is the zinc metal salt of neodecanoic acid, which readily dissociates to the corresponding divalent zinc cation and neodecanoic acid anions. The zinc cation and the neodecanoic acid anion are considered to represent the overall toxicity of the zinc neodecanoate in a manner proportionate to the free acid and the metal (represented by one of its readily soluble salts). Based on the above information, unrestricted read-across is considered feasible and justified.

 

Introduction to the neo acids hazard assessment

The carboxylic acids “neodecanoic acid” and “fatty acid C9 to C13 neo” are considered similar in their toxicological profile and are therefore grouped together. Both neo acids originate from the same production process in which a branched olefin is reacted with carbon monoxide and water at elevated temperature and pressure in th1e presence of an acid as catalytic component. The dossiers for neodecanoic acid and fatty acid C9 to C13 neo contain human health hazard information on both substances indicating that the toxicological profile is similar. This approach was also used and accepted in the US EPA HPV programme, even for a wider range of neo-acid substances (US EPA, April 2009: http://www.epa.gov/chemrtk/pubs/summaries/neoc528/c13335tc.htm).

Based on the above information “neodecanoic acid” and “fatty acid C9 to C13 neo” will be assessed for their hazardous properties, using the same dataset for both substances.

Although the term „constituent“ within the REACH context is defined as substance (also being part of a mixture), the term constituent within this hazard assessment is meant to describe either part of the metal carboxylate salt, i.e. anion or cation.

Toxicity for reproduction – developmental toxicity

No toxicity data on adverse effects on development of the offspring with zinc neodecanoate is available, thus the reproductive toxicity will be addressed with existing data on the dissociation products as detailed in the table below. Further details on the reproductive toxicity of the individual constituents are given below.

 

Table: Summary of toxicity data on adverse effects on development of the offspring of zinc neodecanoate and the individual constituents.

	(slightly soluble) zinc substances	Neodecanoic acid (CAS# 26896-20-8)	Zinc neodecanoate (CAS# 27253-29-8)
Pre-natal developmental toxicity study	NOAEL (human data) =20 mg/kg bw/day   not classified	NOAEL(rat)=250mg/kg bw/day (read-across from carboxylic acids, C6-8-neo-, CAS# 95823-36-2 (neoheptanoic acid))   not classified	no data   no classified
Two-generation reproductive toxicity study		NOAEL(3-gen;rat, P, F1 and F2)= 75 mg/kg bw/day*   no classified	no data   not classified

* Identified as most sensitive endpoint in the registration dossier for neodecanoic acid, thus has been used for the DNEL derivation of this substance.

 

Zinc

The reproductive toxicity of zinc compounds has been investigated in one- and two-generation reproductive toxicity studies in which rats or mice were dosed by gavage or via diet with soluble zinc compounds (i.e., zinc chloride, zinc sulphate) at exposure levels up to 14 mg Zn/kg bw/day (gavage) or 200 mg Zn/kg bw/day (diet) (Khanet al., 2001, 2003, 2007). Further information on potential effects of zinc compounds on male or female reproductive organs could be retrieved from subchronic toxicity studies as conducted by Maitaet al.(1981) and Edwards and Buckley (1995).

 

The available information suggests that high oral doses of zinc (i.e., exposure levels greater than 20 mg Zn/kg bw/day) may adversely affect spermatogenesis and result in impaired fertility indicated by decreased number of implantation sites and increased number of resorptions (US EPA, 2005). However, these effects were only observed in the presence of maternal toxicity as seen in the one- or two-generation studies conducted by Khanet al. (2001, 2003, 2007) or, in case of the study conducted by Kumaret al. (1976), when other study non-zinc relevant study specificities could have impacted the study outcome. In a large number of controlled trials, dietary supplementation with zinc rate of 20 mg/day and 30 mg/day did not result in any adverse reproductive effects in healthy pregnant women as summarised in WHO (2001) and ATSDR (2005).

 

Neodecanoic acid

In a modified three-generation reproductive toxicity study, male and female Sprague-Dawley rats were administered neodecanoic acid at 0, 100, 500 and 1500 ppm (approximately 0, 5, 25 and 75 mg/kg bw/day, respectively) in the diet. No adverse effects were observed on survival, appearance, behaviour, body-weight gain and food consumption in the parental, F1 or F2 generations. The reproductive performance of the parents was not affected. No treatment-related gross or microscopic pathological findings were observed at any of the dietary levels.

In a developmental toxicity study, pregnant rats, n=22 per dose, were treated by oral gavage to 50, 250, 600 or 800 mg/kg bw/day neoheptanoic acid, a substance similar in structure to neodecanoic acid, during gestation days 6-15. On gestation day 21, the dams were euthanized and the pups were examined for signs of developmental toxicity. Under the conditions of the experimental methods, the test material produced maternal toxicity at dose levels of 600 and 800 mg/kg with maternal lethality at 800 mg/kg. The test material was severely embryotoxic at 800 mg/kg with less than 20% of embryos surviving. Offspring of the 800 mg/kg group had reduced body weight, reduced crown-rump distance, displayed variations signifying delayed development, and a significant percentage (25%) were malformed. In the 600 mg/kg group, there was an increase number of dams with 3 or more resorptions. Offspring of the 600 mg/kg group displayed significant incidences of major (hydrocephalus) and minor (knobby or angular ribs, extra lumbar vertebrae) malformations but showed few signs of delayed development and were not runted. There was no statistically significant evidence of maternal toxicity at dose levels of 50 or 250 mg/kg. There was a slight, but not statistically significant, increase in embryonic resorption noted for the 250 mg/kg group. There was no statistically significant evidence of developmental toxicity at doses for 50 or 250 mg/kg. The NOAEL for maternal toxicity is 250 mg/kg and the NOAEL for developmental toxicity is 250 mg/kg. 

 

Zinc neodecanoate

Zinc neodecanoate is not expected to show effects on development of the offspring, since the two constituents zinc and neodecanoic acid have not shown developmental toxicity in a range of test systems. Thus, zinc neodecanoate is not to be classified according to regulation (EC) 1272/2008 for reproductive toxicity. Further testing is not required. For further information on the toxicity of the individual constituents, please refer to the relevant sections in the IUCLID and CSR.

 

Information on the individual constituents zinc and neodecanoic acid will be used for the hazard assessment and, when applicable, for the risk characterisation of zinc neodecanoate. For the purpose of hazard assessment of zinc neodecanoate, the point of departure for the most sensitive endpoint of each constituent will be used for the DNEL derivation. In case of neodecanoic acid in zinc neodecanoate, the NOAEL of 75 mg/kg bw/day for the reproductive toxicity will be used.

Justification for selection of Effect on developmental toxicity: via oral route:
Information from read-across substances:
human data for zinc: NOAEL=20mg/kg bw/day
animal data for neodecanoic acid: NOAEL(rat)=250mg/kg bw/day

Justification for classification or non-classification

Zinc neodecanoate is not expected to show adverse effects on sexual function and fertility, since the two constituents zinc and neodecanoic acid have not shown effects in a range of test systems. Thus, zinc neodecanoate is not to be classified according to regulation (EC) 1272/2008 for reproductive toxicity: adverse effects on sexual function and fertility.

Zinc neodecanoate is not expected to show effects on development of the offspring, since the two constituents zinc and neodecanoic acid have not shown developmental toxicity in a range of test systems. Thus, zinc neodecanoate is not to be classified according to regulation (EC) 1272/2008 for reproductive toxicity: effects on development.

Furthermore, zinc neodecanoate has not to be classified according to Directive 67/548 EC for reproductive toxicity: adverse effects on sexual function and fertility and effects on development.