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Carcinogenicity

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Description of key information

 In accordance with column 2 of REACH Annex X, the carcinogenicity study (required in section 8.9.1) does not need to be conducted as the substance does not have a widespread dispersive use; the human exposure is low; the substance is not classified as mutagen category 3, and there is no evidence from the repeated dose studies that the substance is able to induce hyperplasia and/or preneoplastic lesions. 

Key value for chemical safety assessment

Additional information

Results from a 90-day toxicity study indicate that the toxicity of dibenzyltoluene is limited to liver (hypertrophy of hepatocytes) and increased kidney weights in male and female rats after prolonged exposure at the mid and high dose exposure (100 and 500 mg/kg bw). In a 120-day toxicity study, the compound induced hypertrophy of centrilobular (and sometimes mediolobular) hepatocytes in most animals associated with a slight increase in liver weights in both sexes and a slight increase in cholesterol levels in males at 500 mg/kg bw, whereas the animals of the mid dose exposure (50 mg/kg bw) were unaffected.

Hypertrophy of hepatocytes in the 100 and 500 mg/kg bw exposures of the studies is isolated and not a specific histological sign of pre-carcinogenic effect. Moreover the consistently negative results from the series of in vitro and in vivo genotoxicity tests assessing gene mutation and chromosomal damage do not suggest any cause for concern with respect to carcinogenicity. In addition, the studies performed to assess the enzymatic induction and peroxisome proliferation show that dibenzyltoluene is only a slight inducer. Therefore there is presumption on absence of a carcinogenic potential for dibenzyltoluene.

Justification for classification or non-classification

From a 90-day and a 120-day toxicity study, the toxicity of dibenzyltoluene is known to be limited to liver (in particular hypertrophy of hepatocytes) and slight kidney effects after prolonged exposure at dose levels of 100 and 500 mg/kg bw. No carcinogenic or pre-carcinogenic effects were observed after 90 days or 120 days oral exposure.

In addition, negative results were obtained from a series of in vitro and in vivo genotoxicity tests assessing gene mutation and chromosomal damage. Moreover, the studies performed to assess the enzymatic induction and peroxisome proliferation show that dibenzyltoluene is only a slight inducer.

Therefore, no carcinogenic classification is required for dibenzyltoluene.