Unless specifically included in the schedule wording, listing in Schedules 7 or 10 implies that the entries would capture products that contain the chemicals as an impurity or residual reaction product. What regulatory impact would such listing impose on products with residual contaminants if the ACCS recommends listing of the individual aromatic amines? Is there any basis for recommending scheduling cut-offs below which the restrictive scheduling would not apply?
The critical concern for this group of chemicals relates to potential carcinogenic effects following exposure. The data from the structurally-related chemicals and aromatic amines azo cleavage products , the p -aminoazobenzene; o -anisidine; o -toluidine; 4-toluenediamine; o -aminoazotoluene; 5-nitro- o -toluidine; 4-chloro- o -toluidine; and p -chloroaniline are also included. Based on the limited data available, it is not possible to draw a definite conclusion regarding the genotoxicity of the chemicals in this group.
Although available data are neither sufficient nor adequately comprehensive for classification, a genotoxic mode of action cannot be ruled out. The chemicals identified by CAS No. No experimental data are available to evaluate or to support an amendment to this classification. Limited data are available on the chemicals in this group. The strongest evidence for carcinogenicity was reported for Orange Oil SS. The chemical was found to be carcinogenic in mice, with intestinal and local tumours identified following oral and subcutaneous administration, respectively.
The chemical also produced tumours in the mouse urinary bladders following bladder implantation. Studies in rats were inadequate for evaluation. Whilst both positive and negative results have been observed for other chemicals in this group, studies generally were considered inadequate for evaluation IARC, ; Government of Canada, ; Government of Canada, a.
The aromatic amine o -toluidine that could be formed following azo bond reductive cleavage in some of the chemicals in this group, is recommended for classification as a category 1 carcinogenic substance based on the evidence for carcinogenicity in humans. Seven of these aromatic amines p -aminoazobenzene; o -anisidine; o -toluidine; toluenediamine; o -aminoazotoluene; 4-chloro- o -toluidine; and p -chloroaniline are classified as hazardous Category 2 carcinogenic substance with the risk phrase 'May cause cancer' T; R45 in the HSIS Safework Australia.
The chemical 5-Nitro- o -toluidine is classified as hazardous Category 3 carcinogenic substance with the risk phrase 'Limited evidence of carcinogenic effect' Xn; R40 Safe work Australia. The available experimental data animal studies for these aromatic amines identifies a number of chemically-induced multi-organ tumours.
These include benign and malignant tumours in the urinary bladder, spleen, subcutaneous tissues, kidneys, adrenal gland, liver, mammary glands, skin, blood and blood vessels, thyroid, lungs, gallbladder and renal pelvis. Findings from several cohort studies involving factory workers have provided strong evidence for an increased risk of urinary bladder cancer associated with long-term occupational exposure to o -toluidine.
The mechanism of action underlying the carcinogenicity of these aromatic amines is still not fully understood. However, metabolic activation to produce nitrenium ion metabolites, which cause DNA adduct formation and induction of DNA damaging effects, has been suggested. A genotoxic mode of action cannot be dismissed. Overall, based on the potential for the chemicals to be metabolised to form classified carcinogens, classification is considered appropriate.
Some of the potential cleavage products or impurities of the chemicals in this group aromatic amines such as o -toluidine; p -aminoazobenzene; o -aminoazotoluene; and p -chloroaniline have been detected in a number of cosmetic products. The chemical o -toluidine was detected in permanent hair dyes and commercial henna samples colours not specified.
Hence, the public could potentially be exposed to classified carcinogens as an impurity in, or through the release of, these aromatic amines derived from the chemicals in this group. In addition, o -aminoazotoluene in decorative colouring alta used by Asian women on their feet has been reported.
Based on the available data, widespread domestic use is not expected; however, the introduction of these dyes for home use cannot be excluded. In the above directives, the chemical is specified as 'not to be used in products applied to mucus membranes'; purity criteria also apply. In , the SCCNFP concluded that several of the dyes cannot be considered safe for hair dyeing purposes, unless they are regarded as such on the basis of an adequate safety dossier.
These include:. However, this opinion did not directly consider the release of o-anisidine from reductive cleavage of the azo linkage. Whilst quantitative risk calculations conducted by the Government of Canada estimated a margin of exposure of for cancer effects for the use of Solvent Red 1 in hair conditioner concentration 0.
Azodyes which, by reductive cleavage of one or more azo groups, may release one or more of the aromatic amines listed in Appendix 8, in detectable concentrations,. Furthermore, the textile and leather articles referred to in paragraph 1 above shall not be placed on the market unless they conform to the requirements set out in that paragraph.
The chemicals proposed for scheduling consideration are not currently specifically scheduled. However, other azo dyes that have the potential to be metabolised to known carcinogens have previously been considered for scheduling and listed in Schedule 7. These other azo dyes include:. The delegate also noted that some of the dyes may have use as laboratory and analytical reagents. While there are stringent existing controls under Model Work Health and Safety legislation, and industry advises that they have been largely phased out of many uses, their carcinogenic potential, via conversion to benzidine a known human carcinogen , indicates they should not be used in products available in the domestic market.
The delegate confirmed a proposed implementation date of 1 June for the following benzidine-based dyes:. Acid Black 29 to the existing list. One public submission was received. The submission stated concern for the sheer number of compounds being considered for scheduling and that there is a lack of resources for a thorough consideration of each. Scheduling is posed to be delayed to enable more time for this. These dyes, and any others that may also be permitted in any degree, be exempt from Appendix C listing.
The public submissions are available at Public submissions on scheduling matters. The committee recommended a new Schedule 7 be created for azodyes that are derivatives by diazotisation from the substances listed in the resolution.
The matters under subsection 52E 1 of the Therapeutic Goods Act considered relevant by the Committee included: a the risks and benefits of the use of a substance; and c the toxicity of a substance.
For an interpretation of the toxicological results, cell-specific transport systems and osmotic effects of the commercial azo dye which contains several inorganic and organic additives has to be considered.
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