Human toxicity characterization provides relative comparisons of a large number of chemicals that may have the potential to contribute to cancer or other negative human health effects. The human toxicity potential (HTP) for each emission of a toxic substance to air, water and soil is often measured relative to 1,4 dichlorobenzene (DB) and is expressed as kg 1,4 DB eq. In the results, HTP is scoped only from emissions of NOx, SO2 and particulates. As the substances causing HTP are mostly the same as the acidifying substances, the stages contributing mainly to the two impact categories are also similar. Like AP, HTP is also contributed mainly by the NePeK fertilizer production at the oil palm plantation as seen in Table 3 and Fig. 2.