Partial report on the German Federal Biological Research Centre for the Umweltbundesamt (German Federal Environmental Agency), UFOPLAN-No. 207 01 036
To which extent (1) surfactants (not anionic), (2) polycarboxylates and (3) agricultural cleaning and disinfecting agents being in the dung and sewage sludge are to find in the agricultural soil where they could accumulate to phytotoxic concentrations? Compared to 1990 the concentrations of nonionic NPEO and cationic DSDMAC surfactants hardly subject to anaerobic biodegradation kept on dropping and therefore the soil contamination by these substances, too. Although polycarboxylates neither in the water nor in the soil are biodegradable, their concentrations are below the level to remobilize heavy metals and to damage mikroorganisms, worms or plant seeds. Eventually harmful ingredients of agricultural cleaning agents and disinfectants do not reach cultivated soils to a critical extent. Measured to the loading limit values according to the German Sewage Sludge Ordinance, the risks of the numerous single ingredients of the cleaning and disinfecting agents mostly used in the dairy and cattle farming (22000 t disinfectants for milking equipment, 3500 t udder dips, 1000 t claw hardener are rather low. However, the water solution of copper sulphate on some dairy farms used to disinfect claws leads to a non negligible contamination of the slurry and indirectly of the soil by heavy metals.