Aqueous eluates from a 24h extraction of pieces from sport grounds surfaces were analysed by HPLC with UV detection, When nitrificants and luminous bacteria were used as a test system for environmental toxicity all the eluates containing mercaptobenzothiazol (MET) were shown to be the source of toxicity. It is not known to us whether the MBT was used during the rubber-production or whether it appeared as a reaction product from the often applied vulcanisation accelerators of benzothiazolsulfenamide type, MTB was also detected in other rubber articles, for instance latex rubber glove eluates and in rubber tubes used for liquid food transfer. The luminous bacteria toxicity detected in some rubber tube eluates could not be traced back exclusively to the presence of MET. Therefore the presence of other toxic components must also be expected.