A risk analysis of the potential harm on the soil environment caused by antibiotics in biosolids

Abstract: The main purpose of this study was to make an initial risk analysis on the probability of antibiotics in biosolids causing adverse effects on agricultural soil environments. The issue on resistance development among bacteria towards antibiotics has also been discussed. Initially, the risk was found to be very high for all of the antibiotics; penicillin, tetracycline, macrolide, quinolone, trimethoprim and sulfonamide. The penicillins were, however, believed to be fairly easily degraded and therefore the risk they constitute might be considerably lower than was first estimated. The tetracyclines and quinolones were on the contrary found to be rather persistent, which strengthened the assumption of them constituting a very high risk. Sulfonamides were found to have a rather low potential to bind to sludge and the risk was therefore assumed to be somewhat overestimated for those drugs. Resistant bacteria have been found in sludge and the conditions in STPs have also shown to be suitable for the spreading of resistance among bacteria. It has further been found that plant uptake is a possible pathway for the resistant bacteria to reach humans. Hence, usage of biosolids on agricultural fields might have negative consequences.