4-(dimethylbutylamino)diphenylamin
Definition of 4-(dimethylbutylamino)diphenylamine (6PPD):
4-(dimethylbutylamino)diphenylamine is an aromatic amine and is used in high production volumes
as a protective agent (anti-ozonant and antioxidant) in the rubber industry. The main area of application is the tyre sector. As such, the main entry pathway of 6PPD to the environment is through tyre abrasion. [1]This is the common definition for 4-(dimethylbutylamino)diphenylamine (6PPD), other definitions can be discussed in the article
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Although the main area of use of 6PPD is the tyre sector, the chemical is also found in other consumer products, such as seals of pressure cookers. Production in 2001 was estimated at 130.000 tonnes per year of which 25.000 tonnes was produced in Europe (Germany). 6PPD enters the environment mainly from the use and disposal of rubber products, but also in wastewater from manufacturing, cleaning and recycling. From the surface of rubber products, 6PPD might enter rivers through rain and despite its low volatility, it might evaporate to the atmosphere. Until the 1990s tyres were deposited in dumps, which resulted in mass 6PPD leakage. Since then, tyres are increasingly recycled or incinerated, which reduces 6PDD emissions.
6PPD is not a persistent substance. It is expected to be rapidly photodegraded in air and to be degraded in water by biotic and abiotic processes. There is no information available on the stability of 6PPD in sediment but there is indication of a strong tendency of 6PPD to absorb to organic matter. Therefore, 6PPD might persist in the sediments. Due to the low stability of 6PPD in aqueous media, it's expected to have a low potential for bioaccumultation and biomagnification.
Acute toxicity is caused by both 6PPD and, at a lower level, by degradation products. Exposure of 6PPD to the environment and transport to the sea is anticipated to be low, and therefore risks to marine organisms are expected to be negligible. Nevertheless, 6PPD is a high production volume chemical. This justifies a continuous attention towards this substance and its metabolites. 6PPD is included in the list of existing substances produced within or imported to the European Community in quantities exceeding 1000 tonnes/year (Council Regulation (EEC)
No. 793/93) and is subject to ongoing evaluation by the OECD Existing Chemicals Programme.
