Copper oxide

Dermal absorption

Administrative data

Endpoint:

dermal absorption in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Already evaluated by the Competent Authorities for Biocides and Existing Substance Regulations.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2003

Report date:

2003

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 428 (Skin Absorption: In Vitro Method)

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Kocide PM-E (containing Cu 2+ as cupric hydroxide)

IUPAC Name:

Kocide PM-E (containing Cu 2+ as cupric hydroxide)

Constituent 2

Reference substance name:

MACC 80 (Bordeaux Mixture 20 % WP)

IUPAC Name:

MACC 80 (Bordeaux Mixture 20 % WP)

Constituent 3

Reference substance name:

Nordox Super 75 WP (containing: Cu 2+ as copper oxide)

IUPAC Name:

Nordox Super 75 WP (containing: Cu 2+ as copper oxide)

Constituent 4

Reference substance name:

Copper Oxychloride 50 WP (containing: Cu 2+ as Dicopper chloride trihydroxide)

IUPAC Name:

Copper Oxychloride 50 WP (containing: Cu 2+ as Dicopper chloride trihydroxide)

Constituent 5

Reference substance name:

Cuproxat Flowable (containing: Cu2+ Tribasic copper sulphate)

IUPAC Name:

Cuproxat Flowable (containing: Cu2+ Tribasic copper sulphate)

Details on test material:

Lot/Batch number:
Kocide PM-E (containing cupric hydroxide): 1020105705
MACC 80 (Bordeaux Mixture 20 % WP): 1/155
Nordox Super 75 WP (containing: copper oxide): 200601
Copper Oxychloride 50 WP (containing: Dicopper chloride trihydroxide): 11313B
Cuproxat Flowable (containing: Tribasic copper sulphate): 141/2001

Purity:
Kocide PM-E (containing cupric hydroxide): 76.1 % cupric hydroxide (metallic copper equivalent 49.6 % w/w)
MACC 80 (Bordeaux Mixture 20 % WP): 19.55 % copper w/w
Nordox Super 75 WP (containing: copper oxide): 75 % copper w/w
Copper Oxychloride 50 WP (containing: Dicopper chloride trihydroxide): 49.64 % copper w/w
Cuproxat Flowable (containing: Tribasic copper sulphate): 18.8 % copper w/v

Description:
Kocide PM-E (containing cupric hydroxide): solid powder at ambient temperature
MACC 80 (Bordeaux Mixture 20 % WP): not specified
Nordox Super 75 WP (containing: copper oxide): not specified
Copper Oxychloride 50 WP (containing: Dicopper chloride trihydroxide): not specified
Cuproxat Flowable (containing: Tribasic copper sulphate): not specified

Stability:
Kocide PM-E (containing cupric hydroxide): stable for at least 2 years from date of analysis
MACC 80 (Bordeaux Mixture 20 % WP): not specified
Nordox Super 75 WP (containing: copper oxide): not specified
Copper Oxychloride 50 WP (containing: Dicopper chloride trihydroxide): not specified
Cuproxat Flowable (containing: Tribasic copper sulphate): not specified

Radiolabelling:

no

Test animals

Species:

human

Strain:

not specified

Sex:

not specified

Administration / exposure

Vehicle:

water

Duration of exposure:

6 hours. At the end of the 6 hour exposure period, the exposed skin surface was washed with ca. 10 mL soap solution (ca. 2 %).

Doses:

Concentration of test substances:

Phase 1: (10 replicates/group)
The following substances were tested in a single moist slurry (representing the formulation prior to mixing with water, but sticking to skin):
3.34 mg/cm2 copper oxychloride;
2.26 mg/cm2 copper hydroxide;
5.40 mg/cm2 copper oxide;
1.25 mg/cm2 Bordeaux mixture.

The following substance was tested as supplied (suspension concentrate):
1.88 mg/cm2 tribasic copper sulphate.

Phase 2: (10 replicates/group)
200.6 µg/cm2 copper hydroxide (tested as concentrated suspension).
12.6µg/cm2 copper hydroxide (tested as dilute suspension).

Details on study design:

Analysis: Measurements of copper concentrations (including method validation) were performed by ICP-MS.

Details on in vitro test system (if applicable):

Skin samples: Full thickness human breast skin samples.

Source: Patients (22 to 66 years old), who gave informed consent for their skin to be taken for scientific research purposes, prior to undergoing routine surgery at the Plastic Surgery Unit, St. Johns Hospital NHS Trust, Livingston, UK.

Preparation: Split-thickness skin membranes were prepared.

Application: The 5 test preparations were topically applied to human split-thickness skin membranes mounted in flow through diffusion cells in vitro.

Exposure parameters:
Surface area of exposed skin: 0.64 cm2
Receptor chamber volume: 0.25 mL
Flow rate: ca. 1.5 mL/h
Receptor fluid: phosphate buffered saline containing bovine serum albumin (ca. 5 % w/v) and streptomycin and penicillin G with the pH changed to pH 7.4 using 0.2 M sodium hydroxide.

Volume applied: 10 µl/cm2

Sampling time: Receptor fluid was collected in a single 0-24 hour sample.

Results and discussion

Signs and symptoms of toxicity:

not examined

Dermal irritation:

not examined

Absorption in different matrices:

Following topical application of copper oxychloride (ca. 250 g/kg), copper hydroxide (188 g/kg), copper oxide (375 g/kg), Bordeaux mixture (100 g/kg) and tribasic copper sulphate (190 g/L) to human skin, absorption of copper was < 0.01, < 0.01, <0.01, 0.01 and 0.01 % of the applied dose, respectively. Following topical application of copper in form of copper hydroxide at two states of dilution (1.25 and 20 g/L), absorption of copper was 0.12 and < 0.01 % of the applied dose, respectively.

The results are summarised in Table 1 and Table 2.

Any other information on results incl. tables

Table 1. Summary of results of Phase 1.

Copper form	Applied dose	Absorbed dose
		ng/cm^2		% of applied dose
	mg/cm^2	Mean	SD	Mean	SD
Copper oxychloride	3.34	82.98	316.07	0.00	0.01
Copper hydroxide	2.26	16.05	699.74	0.00	0.03
Copper oxide	5.40	55.56	397.70	0.00	0.01
Bordeaux mixture	1.25	140.92	274.02	0.01	0.02
Tribasic copper sulphate	1.88	116.54	670.76	0.01	0.03

Table 2. Summary of results of Phase 2.

Copper form	Applied dose	Absorbed dose
		ng/cm^2		% of applied dose
	µg/cm^2(g/L)	Mean	SD	Mean	SD
Copper hydroxide	12.6 (1.25)	14.50	302.07	0.12	2.40
Copper hydroxide	200.6 (20)	2.93	285.44	0.00	0.14

Applicant's summary and conclusion

Conclusions:

The absorption of copper through human skin was negligible, with a worst case of 0.12 % of the applied dose.

Executive summary:

In vitro percutaneous absorption of copper from various formulations through human split-thickness skin membranes was tested in flow-through diffusion cells. The study was conducted according to OECD 428 (Draft, 2002) and OECD Draft guidance document No. 28 (2002). The absorption of copper through human skin was negligible, with a worst case of 0.12 % of the applied dose.