The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has re‐evaluated the carcinogenicity and developmental toxicity of di‐n‐butyl phthalate. The literature has been checked for new studies relevant to the evaluation considering all toxicological endpoints.
The assumption made in the documentation from 2010 that the squamous metaplasia in the larynx of rats in the 29‐day inhalation study will not increase over time is supported by the results of inhalation studies with glycerine and butynediol. The maximum concentration at the workplace (MAK value) of 0,05 ml/m3 and the assignment to peak limitation category I with an excursion factor of 2 have therefore been retained.
In the previous documentation, merely sporadic Leydig cell adenomas were reported in the offspring of rats exposed in utero. From a study in B6C3F1 mice with numerous shortcomings and co‐exposure to other substances, a carcinogenic potential of di‐n‐butyl phthalate cannot be derived. Di‐n‐butyl phthalate, like Di(2‐ethylhexyl) phthalate, activates various receptors, which are assumed to be involved in carcinogenicity. Therefore, di‐n‐butyl phthalate is suspected to be a non‐genotoxic carcinogen and is classified in Carcinogen category 3B. No classification as germ cell mutagen as well as assignment to Pregnancy Risk Group C are confirmed.
Skin absorption does not contribute significantly to systemic toxicity. The substance is not sensitising to skin or airways.