Reaction mass of potassium;sodium;2-[bis[2-[bis(carboxymethyl)amino]ethyl]amino]acetate;copper and potassium;sodium;2-[2-[bis(carboxymethyl)amino]ethyl-(2-hydroxyethyl)amino]acetate;copper

Endpoint summary

Description of key information

The substance is a reaction mixture of Copper (Cu), DTPA and HEEDTA. None of these constituents are classified as skin sensitisers according to the ECHA dissemenation website. To support that both copper and the two chelating agents (DTPA and HEEDTA) are non-sensitizers, selected lines of evidence are provided.

The voluntary risk assessment of copper (2008) reviewed all available information to conclude that copper should not be classified for skin sensitisation. QSAR predictions for CuDTPA and CuHEEDTA indicate that these substances have no skin sensitisation potential.

Because none of the constituens has known skin sensitisation properties, the reaction mixture of CuDTPA and CuHEEDTA is also regarded as a non-sensitiser.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Reference 1

Endpoint:

skin sensitisation, other

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with limited documentation / justification

Justification for type of information:

1. SOFTWARE
ToxTree 2.6.13

2. MODEL (incl. version number)
Skin sensitisation reactivity domain (Identification of mechanisms of toxic action for skin sensitisation using a SMARTS pattern based approach)

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
CuHEEDTA: C1(=O)CN(CC(=O)O[Na])CCN(CCO[Na])CC(=O)O[Cu]O1
CuDTPA: C(=O)(CN(CC(=O)O[Na])CCN1CC(=O)O[Cu]OC(=O)CN(CC(=O)O[Na])CC1)O[Na]

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
[Explain how the model fulfils the OECD principles for (Q)SAR model validation. Consider attaching the QMRF or providing a link]
A QMRF is not available for this substance, but see Enoch et al. 2008 for more information on used algorithm, training dataset and applicability domain.

5. APPLICABILITY DOMAIN
See attached report of the QSAR predictions.

6. ADEQUACY OF THE RESULT
The absence of  skin sensitisation reactivity domains alerts supports the claim that CuHEEDTA and CuDTPA are non-sensitizers.

Qualifier:

according to guideline

Guideline:

other: REACH Guidance on QSARs R.6

Principles of method if other than guideline:

http://toxtree.sourceforge.net

Specific details on test material used for the study:

CuHEEDTA: C1(=O)CN(CC(=O)O[Na])CCN(CCO[Na])CC(=O)O[Cu]O1
CuDTPA: C(=O)(CN(CC(=O)O[Na])CCN1CC(=O)O[Cu]OC(=O)CN(CC(=O)O[Na])CC1)O[Na]

Run / experiment:

other: CuHEEDTA

Parameter:

other: QSAR prediction

Remarks on result:

other: Skin Sensitisation Reactivity Domain

Remarks:

 No skin sensitisation reactivity domains alerts identified.

Run / experiment:

other: CuDTPA

Parameter:

other: QSAR Prediction

Remarks on result:

other: Skin Sensitisation Reactivity Domain

Remarks:

 No skin sensitisation reactivity domains alerts identified.

CuHEEDTA

 QSNAR.SNAr-Nucleophilic Aromatic Substitution No   O=C1CN(CC(=O)O[Na])CCN(CC(=O)O[Na])CC(=O)O[Mg]O1
 QSB.Schiff Base Formation No   O=C1CN(CC(=O)O[Na])CCN(CC(=O)O[Na])CC(=O)O[Mg]O1
 QMA.Michael Acceptor No   O=C1CN(CC(=O)O[Na])CCN(CC(=O)O[Na])CC(=O)O[Mg]O1
 Qacyl.Acyl Transfer Agents No   O=C1CN(CC(=O)O[Na])CCN(CC(=O)O[Na])CC(=O)O[Mg]O1
 QSN2.SN2-Nucleophilic Aliphatic Substitution No   O=C1CN(CC(=O)O[Na])CCN(CC(=O)O[Na])CC(=O)O[Mg]O1
 Q6.At least one alert for skin sensitisation? No Class No skin sensitisation reactivity domains alerts identified. C1(=O)CN(CC(=O)O[Na])CCN(CCO[Na])CC(=O)O[Cu]O1

CuDTPA

 QSNAR.SNAr-Nucleophilic Aromatic Substitution No   O=C1CN(CC(=O)O[Na])CCN(CC(=O)O[Na])CC(=O)O[Mg]O1
 QSB.Schiff Base Formation No   O=C1CN(CC(=O)O[Na])CCN(CC(=O)O[Na])CC(=O)O[Mg]O1
 QMA.Michael Acceptor No   O=C1CN(CC(=O)O[Na])CCN(CC(=O)O[Na])CC(=O)O[Mg]O1
 Qacyl.Acyl Transfer Agents No   O=C1CN(CC(=O)O[Na])CCN(CC(=O)O[Na])CC(=O)O[Mg]O1
 QSN2.SN2-Nucleophilic Aliphatic Substitution No   O=C1CN(CC(=O)O[Na])CCN(CC(=O)O[Na])CC(=O)O[Mg]O1
 Q6.At least one alert for skin sensitisation? No Class No skin sensitisation reactivity domains alerts identified. C(=O)(CN(CC(=O)O[Na])CCN1CC(=O)O[Cu]OC(=O)CN(CC(=O)O[Na])CC1)O[Na]

Interpretation of results:

other:

Conclusions:

Based on the predictions of the ToxTree Skin Sensitisation QSAR (using SMARTS pattern based approach), no skin sensitisation reactivity domains alerts were identified for CuDTPA and CuHEEDTA.

Reference 2

Endpoint:

skin sensitisation, other

Remarks:

Review of all available information on skin sensitisation of copper compounds

Type of information:

other: review (voluntary risk assessment)

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Justification for type of information:

This voluntary risk assessment report of copper and copper compounds has been submitted to the European Chemicals Agency by the European Copper Institute. This report is based on the industry initiative to perform a voluntary risk assessment on a substance according to the mechanisms of the implementation of the Existing Substance Regulation (EEC) No 793/93 (ESR). The procedure was agreed by the 11 Joint Meeting of the Competent Authorities for the Implementation of Directive 67/548/EEC and ESR Regulation.
Italy has been acting as a reviewing Member State for the substance and the risk assessment report has been reviewed by the Technical Committee on New and Existing Substances (TC NES) according to standard operational procedures of the Committee.

Qualifier:

no guideline followed

Principles of method if other than guideline:

This voluntary risk assessment report of copper and copper compounds gives an overview of all available test results for copper (compounds) relevant to assess skin sensitisation.

Type of study:

other: Review

Remarks on result:

no indication of skin sensitisation

Remarks:

See any other information on results for an overview of available studies

Remarks on result:

no indication of skin sensitisation

Remarks:

See any other information on results for an overview of available studies

Remarks on result:

no indication of skin sensitisation based on QSAR/QSPR prediction

Remarks:

See any other information on results for an overview of available studies

4.1.1.1.1                        Studies in animals

Skin

No published studies are available which report on the potential of copper or its compounds to cause skin sensitisation in animals. However, a number of unpublished reports of skin sensitisation tests have been made available[1]. These unpublished studies provide good quality data on the skin sensitising potential of copper and some copper compounds, and are reviewed here. In most of these studies, the test method used was the guinea pig maximisation test (GPMT) of Magnusson and Kligman. In one study, the Buehler test was used (Walker 1990). In most cases, tests were conducted according to EU Annex V (method B.6) and OECD (No. 406) guidelines. 

Copper (I) oxide

Current classification for sensitisation: none

Skin sensitising potential of copper (I) oxide was investigated using 20 test animals and 20 controls (Bien 1993– unpublished). Concentrations of test substance used for induction and challenge appear to have been based on results of a pilot study. The induction phase of the test involved intradermal injection on day 0 with cuprous oxide at 0.25% concentration in CMC or FCA[2]) It is noted that this concentration (0.25%) caused no skin reaction in the pilot study and it is uncertain why a higher, slightly irritating, concentration was not used. The second phase of induction involved topical application of copper (I) oxide (50% concentration in vaseline) for 48 hours on day 7. This concentration of copper (I) oxide used (50%) appears to have been the highest achievable concentration but was also non-irritating in the pilot study.

Consequently pre-treatment of skin with 10% sodium lauryl sulphate was used for topical induction in the main study. Skin irritation scores at both stages of induction were not reported in the main study. On day 21, animals were challenged with copper (I) oxide (50% concentration in vaseline) for 24 hours. The challenge concentration of copper (I) oxide (50%) was reported to be the maximum non-irritating concentration. Skin response was assessed at 24 and 48 hours after challenge. No skin reaction was seen in treated or control animals at either time-point. Whilst this study deviated from Annex V guidelines by using a non-irritating concentration of test material for intradermal induction, the results show no indication that copper (I) oxide is a skin sensitiser.

In another GPMT test, copper (I) oxide (Nordox agro-grade) similarly failed to induce skin sensitisation in guinea pigs (Driscoll 1999e- unpublished). Concentrations of test substance selected for induction and challenge were based on the results of a preliminary screening test. Intradermal injection of 0.05% and topical application of 75% (w/w in distilled water) caused slight to moderate skin irritation and were selected for induction. 25% (w/w in distilled water) by topical application was the highest non-irritating concentration and was selected, together with a lower concentration, for challenge. In the induction phase, 20 test animals received an intradermal injection of test substance (0.05% w/w in distilled water and/or FCA), followed by topical application of test substance (75% w/w in distilled water) on day 7 for 48 hours. Ten control animals received intradermal injections of FCA and/or distilled water, followed by topical application of distilled water. On day 21, animals were challenged with a topical application of copper (I) oxide (10 and 25% w/w in water) for 24 hours. No skin reaction was recorded in test or control animals 24 or 48 hours after challenge with either 10% or 25% copper (I) oxide.

Skin sensitisation properties of copper (I) oxide were investigated by Smith (1986 –unpublished) in a modified Buehler test. A pilot study was carried out to determine appropriate concentrations of test substance for induction and challenge; no skin reactions were observed at concentrations up to and including 100% in propylene glycol. In the induction phase, 10 guinea pigs were treated topically with 500 mg of test substance (100%; moistened with propylene glycol), three times a week for three weeks. No skin reaction occurred at first induction, although skin irritation increased at subsequent applications. Two weeks following induction, animals were challenged with 500 mg test substance (100%; moistened with propylene glycol). Very slight erythema was reported in 3/10 animals at 24 hours after challenge, and in 1/10 animal at 48 hours.  However, very slight erythema was also reported in 2/10 negative control animals, raising questions regarding the quality of this study.

Copper (II) oxide

Current classification for sensitisation: none

Copper (II) oxide similarly failed to induce skin sensitisation in a guinea pig maximisation test (Sanders 2002e –unpublished). Induction treatment involved intradermal injection of copper (II) oxide (0.1% w/w in arachis oil) on day 0 and topical application of copper (II) oxide (75% w/w in arachis oil) on day 7 for 48 hours. Animals were challenged on day 21 with copper (II) oxide (10% and 5% w/w in arachis oil on right and left flanks, respectively). Concentrations of the test substance selected were based on results of a sighting study; 0.1% (intradermal injection) and 75% (topical application under occlusive dressing for 48 hours) caused mild to moderate irritation and were selected for induction; 10% (topical application for 24 hours) was the highest non-irritant concentration tested and was selected for challenge. Skin response was assessed in animals (10 treated and 5 controls) at 24 and 48 hours after challenge. With 10% copper (II) oxide, discrete or patchy erythema occurred at challenge sites in 4/10 treated animals at 24 hours; no skin reaction was seen at 48 hours. With 5% copper (II) oxide, discrete or patchy erythema occurred at challenge sites in 2/10 treated animals; no skin reaction occurred at 48 hours. No skin response was observed in control animals at either time-point. In summary, copper (II) oxide produced a 0% sensitisation rate in this test and is therefore considered to have no skin sensitising potential in guinea pigs.

Copper sulphate

Current classification for sensitisation: none

Copper sulphate pentahydrate failed to induce skin sensitisation in a GPMT (Mercier 1994 a– unpublished). Concentrations of test substance selected for induction and challenge were based on results of a sighting study. Induction involved intradermal injection of test substance (0.1% in water) on day 0, a concentration which produced weak to moderate irritation in the sighting study. This was followed by topical application of test substance (10% in water) on day 7 for 48 hours. Sodium lauryl sulphate (10%) was also applied at topical induction, prior to the test substance, as the test substance alone at a concentration of 10% failed to provoke signs of irritation in the sighting study. The skin response at topical induction in the main study was not reported. After an 11-day treatment-free period, animals were challenged by topical application of the test substance (10% in water) under an occlusive dressing for 24 hours. Skin response was assessed in animals (20 treated and 9 controls) at 24 and 48 hours after challenge. Slight erythema was observed in one treated animals at 24 hours, but not at 48 hours. No skin reactions occurred other treated animals or in controls at either time-point. In conclusion, copper sulphate pentahydrate produced a 0% sensitisation rate under the conditions of this test and is therefore considered to have no skin sensitising potential in guinea pigs. 

Copper oxychloride

Current classification for sensitisation: none

Copper oxychloride failed to induce skin sensitisation in guinea pigs in a Buehler test (Walker 1990 –unpublished). Concentrations selected for induction and challenge were based on results of a preliminary screening test. Topical application of 50% (w/w in distilled water) produced slight irritation and was selected for induction. Topical application of 25% (w/w in distilled water) was the highest non-irritant concentration and was selected for challenge. The test involved three topical applications of copper oxychloride (50% w/w in distilled water), each of 6 hours duration, at 7-day intervals for induction. This was followed, 14 days later, by a topical challenge application of copper oxychloride (25% w/w in distilled water) for 6 hours. 20 test animals and 20 control animals were used in the study. No skin reaction occurred in test or control animals 24 or 48 hours after challenge. Positive skin reactions were recorded in the positive control group (10 animals) induced and challenged with DNCB.   

Copper powder

Current classification for sensitisation: none

Copper powder was investigated for skin sensitising potential in a GPMT (Sanders 2001d– unpublished). Induction involved intradermal injection of copper powder (0.1% in arachis oil) on day 0, followed by topical application of copper powder (50% in arachis oil, occluded) on day 7 for 48 hours. On day 21, animals were challenged by topical application of the test substance (50% and 25% in arachis oil on each flank, occluded) for 24 hours. Concentrations of the test substance selected were based on results of a sighting study: 0.1% (intradermal) caused mild to moderate irritation and was well-tolerated systemically; 50% (topical application for 48 hours) produced mild to moderate irritation; 50% (topical application for 24 hours) was reported to be the highest non-irritant concentration tested. In the main test, skin response was assessed in 10 test and 5 control animals at 24 and 48 hours after challenge. No skin reaction was observed at challenge sites in any test or control animals at 24 or 48 hours. In conclusion, in this test copper powder produced a 0% sensitisation rate in this test and is therefore considered to have no skin sensitising potential in guinea pigs. 

4.1.1.1.1                        Studies in humans

Skin

The few cases of skin sensitisation from exposure to copper or its compounds reported in the literature are restricted to clinical case reports involving small numbers of patients, and in evaluation of a case-series of patients from dermatology clinics. 

Allergic dermatitis with positive patch tests

Barranco (1972) reviewed the literature and noted that only six cases of allergic contact dermatitis to copper have been reported by then – 3 cases occurred as a result of contact with brass (copper and zinc alloy). The other cases were due in each case to CuSO₄, copper metal, and copper in jewellery respectively. To evaluate the prevalence of skin sensitisation to a range of metals encountered in the ceramics industry, Motolese and co-workers (1993) assessed 190 enamellers and decorators by patch tests. While the patch tests showed several cases positive to other metals, there was only a single case of a positive patch test to red copper oxide in the group. 

Sterry and Schmoll (1985) described contact urticaria with a positive patch test in a patient exposed to copper (II)-acetyl acetonate used in self-adhesive disinfection pads applied to the skin. 

Cross-reactivity

Metal objects such as spectacle frames have caused dermatitis (Gaul, 1958), but the role of copper in these cases is uncertain, as there is often concomitant exposure to other known sensitisers such as nickel compounds. Cross-reactivity between copper and other metal sensitisers have been documented. Hackel and co-workers (1991) described a patient with palladium sensitisation who also reacted positively to patch tests using nickel sulphate and CuSO₄(1% petrolatum preparation). Nordlind (1992) showed cross reactivity between CuSO₄and mercuric chloride in patients with oral lesions associated with mercury amalgam restorations.

Skin reactions following use of copper IUD

Barkoff (1976) reported a case of a woman who developed urticaria a month after insertion of a copper-based intra-uterine contraceptive device (IUD). Skin patch tests using 1% CuSO₄ solution were negative, but scratch tests using the same test material resulted in an erythematous flare reaction. 

Romaguera and Grimalt (1981) described four women who developed papulo-erythematous skin lesions between 1 and 4 months after insertion of a copper-containing IUD. Patch tests were positive for 2% CuSO₄in all four cases, although one of the patients also tested positive to nickel sulphate. All four patients improved after removal of the IUDs and provision of topical treatment. 

The first report of IUD-induced copper sensitisation was by Barranco (1972) who obtained a positive patch test with 5% CuSO₄solution. Other subsequent similar reports include those by Frenz and Teilum (1980) and Rongiolettiet al(1985) who demonstrated a positive patch test reaction to 1% CuSO₄in water in a housewife with a 2-month history of dermatitis, and a copper-containing IUD inserted a few weeks before the onset of symptoms. Removal of the IUD resulted in abatement of the symptoms. Pujolet al(1998) reported a case of a woman with a 2-year history of recurrent non-pruritic skin eruption and abdominal pain. It was reported that the woman had had a copper-containing IUD “placed 12 years earlier”. Whilst not clearly stated, this suggests that the same IUD remained in place for the whole period and therefore represents misuse. Patch tests were positive for CuSO₄(2%) and for nickel and cobalt salts. Symptoms resolved after removal of the IUD. The authors suggest the copper-containing IUD as a cause for the dermatitis. However, it is possible that the other substances to which the patient reacted with a positive patch test may be the causative factor.

In an assessment of 37 female patients with side-effects following usage of a copper impregnated IUD, Joupillaet al(1979) showed that skin tests to copper were negative despite a history of skin rashes experienced by ten of the patients after insertion of the IUD. Allergy to copper was therefore not thought responsible for the skin and other side effects.

Prevalence of allergic dermatitis from copper salts

To establish the prevalence of irritant and allergic contact dermatitis from pesticides, Lisiet al(1987) patch tested 652 outpatients with pre-existing skin disorders. 564 subjects were tested with 1% CuSO₄, of which 4 cases (<1%) demonstrated an allergic reaction, with none of the cases deemed to have an irritant reaction to CuSO₄. The inclusion of 2% CuSO₄in a routine patch test series assessing 1190 eczema patients over a three-year period showed a positive reaction to CuSO₄in only 13 patients. Copper salts are not common as skin sensitiers (Karlberg, 1983).

These findings indicate the relative rarity of copper compounds in comparison to other metals as a cause of allergic contact dermatitis.

4.1.1.1.1                        Summary of sensitisation

No published studies are available which report on the potential of copper or its compounds to cause skin sensitisation in animals. 

Several unpublished studies have been made available, using the guinea pig maximisation test of Magnusson and Kligman or the Buehler test and all conducted according to EU Annex V or OECD guidelines.  These studies have investigated the skin sensitising potential of copper (I) oxide, copper (II) oxide, copper sulphate pentahydrate, copper oxychloride and copper powder. In these tests, none of the substances investigated have demonstrated potential to cause skin sensitisation in guinea pigs.

There have been several reports in humans of skin reactions to copper either as the metal, principally from jewellery and IUDs, or in copper salts, principally from the use of copper sulphate as a pesticide. Positive reactions from patch tests have been reported following challenge with 1-5% solutions of copper sulphate and, in a single case, with copper oxide. The possibility of cross-reactivity to salts of potent sensitisers exists. The prevalence of sensitisation to copper sulphate among patients with pre-existing skin conditions are reported to be of the order of 1% but is unknown among asymptomatic individuals. The largest investigation of women using copper containing IUDs (n=37) who reported side effects including skin reactions (n=10) found that none reacted positively to copper in patch tests. This finding suggests that copper was not responsible for their symptoms.

The following clinical criteria should be satisfied to accept a reported case of skin sensitisation as likely to be caused by copper or its compounds:

a clear history of significant dermal exposure to the copper species, followed by experience of skin rashes, and a positive reaction on patch testing. Using the above criteria resulted in very few documented cases of copper and/or its compounds as a cause of skin sensitisation in humans in the medical and scientific literature. Given the extensive use of copper, and the potential for continuous and/or intermittent skin contact, human case-reports of skin sensitisation due to copper or its compounds are rare.

Classification for sensitisation

Current classification of copper (I) oxide, copper (II) oxide, copper sulphate, copper oxychloride and copper powder for sensitisation: none

Available animal and human data on the skin sensitisation properties of copper (I) oxide, copper (II) oxide, copper carbonate, copper sulphate, copper oxychloride and copper powder have been considered against EU classification criteria as contained in Annex VI of Directive 67/548/EEC.  The available animal data donotmeet the criteria requiring these substances to be classified for skin sensitisation. Human data on skin sensitisation properties of copper or its compounds are insufficient to require classification for skin sensitisation.

Interpretation of results:

GHS criteria not met

Conclusions:

Available animal and human data on the skin sensitisation properties of copper (I) oxide, copper (II) oxide, copper carbonate, copper sulphate, copper oxychloride and copper powder have been considered against EU classification criteria as contained in Annex VI of Directive 67/548/EEC. The available animal data do not meet the criteria requiring these substances to be classified for skin sensitisation. Human data on skin sensitisation properties of copper or its compounds are insufficient to require classification for skin sensitisation.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)