XXX are side effects of an activity which affect other people. They can be either positive or nega-tive. Negative XXX include activities by organisations that cause environmental damage, for exam-ple, emission of harmful gases from vehicles, or dumping of chemical waste into the sea. The cost of remedying, where remedies are undertaken, does not fall on the original polluter, but rest with socie-ty at large. What word replaces XXX?