Diphosphoric acid, copper salt

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Description of key information

A two-generation study using copper sulphate (Mylchreest, 2005) in the rat indicates that under the conditions of this study, the no-observed-adverse-effect level (NOAEL) for reproductive toxicity was 1500 ppm, the highest concentration tested. The NOAEL for P1 and F1 rats and F1 and F2 offspring during lactation was 1000 ppm, based on reduced spleen weight in P1 adult females, and F1 and F2 male and female weanlings at 1500 ppm however the transient reduced spleen weights are not considered a reproductive endpoint as it did not affect growth or fertility.  As the results of this study do not indicate specific reproductive toxicity at the highest dose level tested, it is proposed that copper sulphate and therefore also the test substance are not classified for reproductive and developmental toxicity.

Link to relevant study records

Reference

Endpoint:

two-generation reproductive toxicity

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH
For further information please refer to read across justification in IUCLID section13.

Reason / purpose for cross-reference:

read-across source

Key result

Dose descriptor:

NOAEL

Effect level:

1 500 ppm

Based on:

test mat.

Remarks:

Equivalent to 23.6 mg Cu/kg bw/day for P1 males during premating.

Sex:

male

Basis for effect level:

other: No adverse effect observed [general toxicity]

Key result

Dose descriptor:

NOAEL

Effect level:

1 000 ppm

Based on:

test mat.

Remarks:

Equivalent to 19.1, 17.0 and 33.8 mg Cu/kg bw/day for P1 females during premating, gestation and the first 2 weeks of lactation, respectively.

Sex:

female

Basis for effect level:

organ weights and organ / body weight ratios

Key result

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

1 000 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

organ weights and organ / body weight ratios

Remarks on result:

other: Equivalent to 23.5 mg Cu/kg bw/day for adults

Key result

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

1 500 ppm

Based on:

element

Remarks:

Cu

Sex:

male

Basis for effect level:

other: No adverse effects observed [reproductive toxicity]

Remarks on result:

other: Equivalent to 26.7, 17.1, 35.2 mg Cu/kg bw/day for F1 females during pre-mating, gestation and the first two weeks of lactation, respectively.

Key result

Dose descriptor:

NOAEL

Generation:

F2

Effect level:

1 500 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No adverse effects observed [reproductive toxicity]

Key result

Dose descriptor:

NOAEL

Generation:

F2

Effect level:

1 000 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

organ weights and organ / body weight ratios

Key result

Reproductive effects observed:

no

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

17 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

The quality of the study is considered sufficient for assessment.

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

Non human information

 

Available public domain studies on the fertility of copper, taken in isolation are of limited value to ascertain the reprotoxic potential copper compounds over multi-generations. These studies have been given lower quality criteria than those summarised above and should not be used for either risk assessment purposes or to classify copper compounds. However, the VRAR, 2008 provides a full review of these studies and the discussion on the unsuitability/unacceptability of these studies.

 

The results of Mylchreest, 2005 indicate that under the conditions of this study, the no-observed-adverse-effect level (NOAEL) for reproductive toxicity was 1500 ppm, the highest concentration tested. The NOAEL for P1 and F1 rats and F1 and F2 offspring during lactation was 1000 ppm, based on reduced spleen weight in P1 adult females, and F1 and F2 male and female weanlings at 1500 ppm however the transient reduced spleen weights are not considered a reproductive endpoint as it did not affect growth or fertility. In compliance with the “Definition of reproductive toxicity”, OECD document ENV/JM/MONO(2001)6 the spleen effect cannot be considered a reproductive effect as this must include:

Adverse effects on sexual function and fertility in adult males and females

Developmental toxicity in the offspring

For a compound to be considered to be a reproductive toxin “data for animal studies ideally should provide clear evidence of specific reproductive toxicity in the absence of other, systemic, toxic effects”. Therefore as the results of this study do not indicate specific reproductive toxicity at the highest dose level tested, it is proposed that copper sulphate and copper are not classified as toxic to reproduction.

 

The lowest no-observed-adverse-effect-level (NOAEL) of 17 mg Cu/kg bw/day (1000 ppm) was observed for female animals of the P generation.

Effects on developmental toxicity

Description of key information

The available study (Munley, 2003) demonstrated maternal toxicity (initial weight loss and reduced food intake) and effects on the fetus (increased incidence of a common skeletal abnormality) following oral exposure of rabbits to copper hydroxide at 9 mg Cu/kg/bw/day and above during pregnancy. There were no indications of fetal abnormalities associated with treatment at up to maternally toxic levels. The NOAEL for maternal toxicity and developmental effects in rabbits in this study was 6 mg Cu/kg/bw/day. Effects on the fetus were considered to be secondary to maternal toxicity and consequently not a specific effect of copper on reproduction.

The existing data base is sufficient to adequately evaluate the developmental toxicity of copper.

Link to relevant study records

Reference

Endpoint:

developmental toxicity

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH
For further information please refer to read across justification in IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Key result

Dose descriptor:

NOAEL

Effect level:

6 mg/kg bw/day

Based on:

element

Basis for effect level:

other: No adverse effects observed.

Key result

Dose descriptor:

LOAEL

Effect level:

9 mg/kg bw/day

Based on:

element

Basis for effect level:

body weight and weight gain

food consumption and compound intake

Key result

Dose descriptor:

NOAEL

Effect level:

6 mg/kg bw/day

Based on:

element

Sex:

not specified

Basis for effect level:

other: No effects at this concentration (NOAEL).

Key result

Dose descriptor:

LOAEL

Effect level:

9 mg/kg bw/day

Based on:

element

Sex:

not specified

Basis for effect level:

skeletal malformations

Key result

Developmental effects observed:

yes

Lowest effective dose / conc.:

9 mg/kg bw/day (nominal)

Treatment related:

yes

Relation to maternal toxicity:

developmental effects occurring together with maternal toxicity effects, but not as a secondary non-specific consequence of maternal toxicity effects

Effect on developmental toxicity: via oral route

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

6 mg/kg bw/day

Study duration:

subacute

Species:

rabbit

Quality of whole database:

The quality of the studies is considered sufficient for assessment.

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

Non-human information

 

In the developmental toxicity study (Munley, 2003), groups of 22 female NZW rabbits were treated orally by gavage on days 7 to 28 of pregnancy with copper hydroxide (0, 6, 9 or 18 mg Cu/kg/bw/day). A preliminary range-finding test, conducted in non-pregnant rabbits, indicated there were no marked differences between several copper compounds (including copper hydroxide, copper (I) oxide and copper oxychloride) in terms of maternal toxicity. In the main study, maternal toxicity was evident at 9 and 18 mg Cu/kg/bw/day. Initial weight loss and reduced food intake occurred at 9 and 18 mg/kg bw/day, followed by partial recovery during the middle/late pregnancy. At the end of the study, bodyweight gain in these two groups was 31% and 72% lower than controls and total food consumption 17% and 30% lower than controls, respectively. Three deaths and two abortions occurred at 18 mg/kg bw/day which appeared to be related to treatment; necropsy of decedents and one aborted animal showed haemorrhagic and/or ulcerative changes in the stomach lining. No deaths occurred at 9 or 6 mg/kg/bw/day. At 9 mg/kg/bw/day, there were no abortions. At 6 mg/kg/bw/day, there was a single abortion on day 27. This abortion was not considered to be treatment-related in view of the absence of abortions at the higher dose level and earlier occurrence of abortions at 18 mg/kg/bw/day. At 6 mg/kg/bw/day, and bodyweight gain and food intake were only marginally lower than controls. There was no difference between treatment groups and controls in the number of pregnant females, or the number of females showing total resorption or with live offspring. There was no difference between treatment and control groups in the number of corpora lutea, implantations, embryonic deaths, live young or percentage of males in litter. At 18 mg/kg/bw/day, mean fetal weight was slightly lower than in controls (9% less). Four malformed fetuses occurred in the study: one with fused ribs (control group); one with ectopic kidney (6 mg/kg/bw/day); two with hemivertebra (18 mg/kg/bw/day). These malformations were all considered to be unrelated to treatment. With regard to fetal skeletal abnormalities, retarded ossification of pelvis and skull showed a slightly increased incidence at 18 mg/kg/bw/day and occurrence of extra ribs was increased at 9 and 18 mg/kg/bw/day compared to controls. It was noted that the occurrence of extra ribs was a common finding in all treatment groups, including the control group (64%, 67%, 80% and 87% incidence at 0, 6, 9 and 18 mg/kg/bw/day, respectively). With regard to fetal visceral abnormalities, none were recorded for any treatment or control group.  In conclusion, this study demonstrated maternal toxicity (initial weight loss and reduced food intake) and effects on the fetus (increased incidence of a common skeletal abnormality) following oral exposure of rabbits to copper hydroxide at 9 mg Cu/kg/bw/day and above during pregnancy. There were no indications of fetal abnormalities associated with treatment at up to maternally toxic levels. The NOAEL for maternal toxicity and developmental effects in rabbits in this study was 6 mg Cu/kg/bw/day. Effects on the fetus were considered to be secondary to maternal toxicity and consequently not a specific effect of copper on reproduction.

 

Maternal toxicity, reported in this study at 9 mg/kg/bw/day, was represented by initial weight loss. These effects are considered to be local effects on the stomach in rabbits which result from gavage administration of copper hydroxide. Consequently, it is considered inappropriate to use data on maternal toxicity from this study as the basis of a repeat-dose NOAEL for copper.

 

With the addition of the multi generation study to the existing toxicology data base it is considered that sufficient information is available to adequately evaluate the developmental toxicity potential of copper. The two generation study (Mychreest, 2005) is particularly relevant as the rat is considered the best animal model for evaluating the potential hazard effects on human populations.

Although the principal aim of this study was to investigate toxicity to reproduction it also provides important information on the developmental toxicity potential of the test substance. Notably, investigation of F1 and F2 litters showed no test substance related effects on the following parameters:

pups survival, sex ratio, and survival indices during the lactation period, body weights and clinical observations during lactation,

macroscopic examination of pups that died during the lactation period, of weanlings with external abnormalities or clinical signs and of randomly selected weanlings,

microscopic observations of any gross findings and of liver and brain from randomly selected high-dose and control weanlings.

 

It is therefore considered that all major manifestations of developmental toxicity (including mortality, structural abnormality, altered growth and functional deficiency) are adequately investigated in this study.

 

The results of the two generation study should also be interpreted in conjunction with the rest of the toxicology data base for copper. The following findings are considered relevant when evaluating the reproductive and developmental toxicity potential of the test substance:

·        Subchronic and chronic studies show no adverse effects on reproductive organs or endocrine functions,

·        Copper salts show no indication of genotoxicity

 

It is also important to consider that copper is an essential element and many countries recommend an increased dietary intake of copper during pregnancy. This increased recommendation is because a foetus requires copper levels up to 10 times adult levels. The copper is absorbed across the placenta and is required for healthy growth and development, especially in blood maturation, bone development, heart development and function, brain development and function and the function of 20 key enzymes (Ralph & McArdle, 2001).

 

The existing toxicology data package therefore supports the conclusion that copper has no reproductive or developmental toxicity potential.

Justification for classification or non-classification

The studies do not indicate specific reproductive toxicity at the highest dose level tested, it is proposed that inorganic soluble copper materials are not classified as toxic to development or reproductive function.