Copper iodide

Endpoint summary

Additional information

COPPER IODIDE

Copper iodide will dissociate following exposure via the inhalation, oral or dermal routes, giving rise to cuprous copper ions (Cu+) and iodide ions (I-) that will be more bioavailable than the parent compound. These ionic species will be independently responsible for any effects seen in the event that organisms are exposed to copper iodide as a result of its production and/or use.

With regard to copper, there was no evidence of mutagenic activity in Salmonella typhimurium strains when tested with copper sulphate pentahydrate. In vivo studies conducted with copper sulphate pentahydrate did not induce micronuclei in the polychromatic erythrocytes of mouse bone marrow. Copper sulphate pentahydrate also did not induce DNA damage in the rat hepatocyte UDS assay. It was concluded that copper compounds are not genotoxic.

With regard to the genetic toxicity of iodine, although positive results are available from in vitro cytogenetic assays, results obtained in vivo in both somatic (micronucleus and chromosome aberrations tests) and germ cells (dominant lethal test) indicate that iodine can be regarded as non-genotoxic.

In view of the above it is concluded that copper iodide does not have mutagenic potential.

Summary information on the genetic toxicity of copper and iodine is presented below.

COPPER

Short description of key information:

There was no evidence of mutagenic activity in Salmonella typhimurium strains in the presence or absence of the metabolic activation system when tested with copper sulphate pentahydrate. In vivo studies conducted with copper sulphate pentahydrate did not induce micronuclei in the polychromatic erythrocytes of the bone marrow of mice treated with 447 mg/kg (x2). Copper sulphate pentahydrate did not induce DNA damage according to rat hepatocyte UDS assay. From the results above, copper and copper compounds are not considered genotoxic.

Administrative Data:

Endpoint conclusion: No adverse effect observed (negative).

Discussion:

Non-human information

In vitro data

Method	Results	Remarks	Reference
bacterial reverse mutation assay (e.g. Ames test) (gene mutation) Salmonella typhimurium Strains TA98, TA100, TA1535, TA1537, TA102 (met. act.: with and without) Doses: 1.6, 8, 40, 200, 1000 µg/plate and 50, 100, 200, 400, 800 µg/plate in mutation experiments 1 and 2, respectively. OECD Guideline 471 (Bacterial Reverse Mutation Assay)	Evaluation of results: negative Test results: negative for Salmonella typhimurium Strains TA98, TA100, TA1535, TA1537, TA102(all strains/cell types tested); met. act.: with and without; cytotoxicity: yes (See additional information on results.)	1 (reliable without restriction) key study experimental result Test material (common name): Cu2+ as copper sulphate pentahydrate	Ballantyne, M. (1994)

 

The existence of two negative in vivo studies (summarised below) negates the need for in vitro mammalian cell assays.

Under normal physiological conditions, the concentration of free copper is extremely low in vivo and the majority of the copper is bound to ceruplasmin and albumin (See Section 5.1). In addition, cells contain high concentrations of potent antioxidants (e.g. glutathione). Therefore, the biological relevance of any in vitro observations would be uncertain where high concentration of the free ion would be available in cell culture growth medium. From reviews of public domain data (WHO, 1998; VRAR, 2008), there is conflicting evidence regarding the activity of copper in cell based assays for genotoxicity, however, due to the relevance of such studies in determining the genotoxicity potential of copper it is considered not appropriate or applicable to use these studies for copper and copper compounds.

In addition, due to the inappropriate level of free cupric ion present in any in vitro assays, the results of such studies will also be affected by the toxicity of the cupric ion to the mammalian cell lines.

Therefore it was considered more appropriate to review the genotoxic potential of copper and copper compounds using in vivo studies.

In vivo

Method	Results	Remarks	Reference
unscheduled DNA synthesis (DNA damage and/or repair) rat (Wistar) male oral: gavage 632.5 or 2000 mg/kg (actual ingested) equivalent or similar to OECD Guideline 486 (Unscheduled DNA Synthesis (UDS) Test with Mammalian Liver Cells in vivo)	Evaluation of results: negative Test results: Genotoxicity: negative (male); toxicity: not examined	1 (reliable without restriction) key study experimental result Test material (common name):Cu2+ as copper sulphate pentahydrate	Ward, P.J. (1994)
micronucleus assay mouse (CD-1) male/female oral: gavage 447 mg/kg EU Method B.12 (Mutagenicity - In Vivo Mammalian Erythrocyte Micronucleus Test) (Cited as Directive 2000/32/EC, B.12)	Evaluation of results: negative Test results: Genotoxicity: negative (male/female)	1 (reliable without restriction) key study experimental result Test material (common name):Cu2+ as copper sulphate pentahydrate	Riley, S.E. (1994)

 

There are additional equivocal in vivo genotoxicity studies in the public domain. However these studies do not adhere fully to OECD guidelines, have unreliable routes of administration (i.v) and are not conducted to GLP. When toxicity studies are conducted with either i.p. and i.v. routes of administration, they bypass the normal uptake and distribution mechanism that is specifically designed to protect the animal from the toxic/reactive Cu2+ ion. This invalidates these studies from regulatory decision-making procedures where the normal production and use of the chemical would not result in direct i.v. or i.p. exposure.

Therefore, 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.

From the results above, copper sulphate pentahydrate, copper and other copper compounds are not considered genotoxic.

IODINE:

Short description of key information:

In vitro gene mutation in bacteria: Equivocal

In vitro cytogenicity studies in mammalian cells: Positive

In vitro gene mutation in mammalian cells: Negative

In vivo test, germ cells: Negative

In vivo tests, somatic cells: Negative

 

Administrative Data:

Endpoint conclusion: No adverse effect observed (negative).

 

Discussion:

Iodine is a well-known micronutrient that is essential for the synthesis of thyroid hormones in all vertebrates, as well as a promoter of metamorphosis or transformation of life stages in several invertebrates. Iodine and iodide compounds have been reported to be non genotoxic by authorities reviews (EVM, 2002; WHO, 2009). Hincal (2009), in addition, has reported that severe iodine deficiency may impair thyroid hormone synthesis and cause a compensatory increase in hydrogen peroxide concentration in thyrocytes. This increase may result in a more prolonged exposure to oxygen-free radicals, which in turn may lead to DNA damage and induce mutations.

Iodine and chemically related compounds have been tested for genotoxicity in a variety of systems both in vitro and in vivo (Table 1). For this end-point, data from iodine, iodine tincture and polyvinylpyrrolidone-iodine complex (PVP-I) has been assessed. PVP-I is a complex of polyvinylpyrrolidone (povidone) and iodine, designed to be a stable form of complexed iodine. 9-12 % available iodine is present in standard United States Pharmacopoeia (USP) preparations. PVP-I is used in surface disinfection but is also used extensively in antiseptic preparations of iodine as well as in drug and other applications leading to direct human contact/intake. No consistent or relevant toxic effects in humans have been reported with PVP-I. Iodine tincture is a mixture containing 2 % iodine and 2.0 % sodium iodide in 50% alcohol and is also available as strong iodine tincture (7 % iodine and 5 % KI in 83 % ethanol). There are no reports on the genotoxicity of potassium iodide and on the classification of ethanol under the criteria applied for classification and labelling of chemicals. Both PVP-I and iodine tincture act by releasing iodine to the surrounding medium, thus the potential genotoxic activity may result from the available iodine.

Table 1: Summary of available genotoxicity studies for iodine and chemically related compounds

Refererence (Reliability)	Assay/Condition	Result/Test compound
Wlodowski et al., 1975. (3)	Gene mutation bacteria/In vitro	Equivocal/PVP-I
Hori et al., 2007. (2)	Chromosome aberrations/In vitro	Positive/Iodine tincture
Hori et al., 2007. (2)	Chromosome aberrations/In vitro	Negative/PVP-I
Hikiba et al., 2005. (2)	Chromosome aberrations/In vitro	Positive/Iodine
Miyachi and Tsutsui, 2005. (2)	Sister chromatid exchanges/In vitro	Positive/Iodine
Yamamoto and Tsutsui, 2005. (2)	Unscheduled DNA synthesis/In vitro	Negative/Iodine
Kessler et al., 1980. (2)	Gene mutation in mamm. cells/In vitro	Negative/PVP-I
Kessler et al., 1980. (2)	Gene mutation in mamm. cells/In vitro	Negative/Iodine
Merkle and Zeller, 1979. (2)	Dominant Lethal Assay/In vivo	Negative/PVP-I
Merkle and Zeller, 1979. (2)	Bone marrow micronucleus test/In vivo	Negative/PVP-I
Merkle and Zeller, 1979. (2)	Bone marrow chromosome aberrations test/In vivo	Negative/PVP-I

Wlodowski et al. (1975) reported that povidone-iodine (PVP-I) was mutagenic in the TA1530 but not in the TA1538 tester strains of Salmonella typhimurium. The positive findings, however, were encountered under unusual temperature conditions (at 4 °C, and not the usual 37 °C in current standards). Also, the applicability of a bacterial system to evaluate the mutagenicity of a bactericide agent remains questionable. Povidone-iodine and iodine were negative in the L5178Y mouse lymphoma assay in the absence of metabolic activation and in the presence of metabolic activation, povidone-iodine showed only marginal activity.

Cytogenicity assays in vitro are consistent with a potential positive effect of iodine, however, it is suggested that iodine may induce chromosome damage by secondary mechanisms associated to cytotoxicity, but not as a result of DNA damage. In vitro mammalian tests have raised concern for the high rate of false positive results obtained with cytotoxic chemicals (Kirkland et al., 2007; Pfuhler et al., 2010). Iodine is in fact a high oxidizing agent which can react with proteins leading to high cytotoxicity in vitro. This hypothesis could be proven by the lack of cytogenotoxicity of PVP-I.

Doses of 72 mg/kg be povidone iodine (given by i.p. injection) were not mutagenic in the mouse dominant lethal assay (Merkle and Zeller, 1979). Povidone-iodine was also tested in mouse micronucleus assay and was negative at doses of 35 mg/kg bw (i.p) and did not produce chromosome aberrations in the in the bone marrow of Chinese hamsters given i.p. doses of 38.3 and 82.5 mg/kg bw, one quarter and one half of the LD50 respectively.

Although positive results are available for iodine on in vitro cytogenetic assays, results in vivo in both somatic (micronucleus and chromosome aberrations tests) and germ cells (dominant lethal test) indicate that iodine can be regarded as a non genotoxic substance. Based on the overall package provided and the fact that in vivo studies are more biologically relevant to humans, no additional studies are considered necessary.

References (not summarized in this section of the IUCLID File):

- Expert Group on Vitamins and Minerals (EVM). Revised review of iodine. 2002.

- Hincal, F. Oxidative damage in iodine deficiency. In: “Comprehensive handbook of iodine: nutritional, biochemical, pathological and therapeutic aspects”. USA, 2009.

- Kirkland, D., Pfuhler, S., Tweats, D., Aardema, M., Corvi, R., Darroudi, F., Elhajouji, A., Glatt, H., Hastwell, P., Hayashi, M., Kasper, P., Kirchner, S., Lynch, A., Marzin, D., Maurici, D., Meunier, J-R., Muller, L., Nohynek, G., Parry, J., Parry, E., Thybaud, V., Tice, R., van Benthem, J., Vanparys, P., White, P. 2007. How to reduce false positive results when undertaking in vitro genotoxicity testing and thus avoid unnecesary follow-up animal tests: Report of an ECVAM Workshop. Mutat. Res. 628: 31 -55.

- Pfuhler, S., Kirst, A., Aardema, M., Banduhn, N., Goebel, C., Araki, D., Costabel-Farkas, Dufour, E., Fautz, R., Harvey, J., Hewitt, N., Hibatallah, J., Carmichael, P., Macfarlane, M., Reisinger, K., Rowland, J., Schellauf, F., Schepky, A., Scheel, J. 2010. A tiered approach to the use of alternatives to animal testing for the safety assessment of cosmetics: Genotoxicity. A COLIPA analysis. Regul. Toxicol. Pharmacol. 57: 315 -324.

- World Health Organization (WHO). Iodine and inorganic iodides: human health aspects. Concise international chemical assessment document: 72. 2009.

Justification for classification or non-classification

IODINE:

Iodine is not classified as a germ cell mutagenic substance based on the lack of genotoxic activity of a chemically related compound (polyvinylpirrolidone iodine complex) in both germinal and somatic cells in vivo.