When a toxicological risk assessment associate to aggregate and/or combined exposure should be carried out?

It is important to carry out a toxicological risk assessment associated to aggregate exposure when several routes of exposure to the same pollutant are involved. The most frequent ones are the inhalation and the ingestion (through water and diet). This depends on the characteristics of the area, the type of emission and plant and the toxicological profile of the contaminant(s) emitted by the plant under evaluation.
It is important to carry out a toxicological risk assessment associated to combined exposure when several contaminants are emitted, which may have additive effects (e.g. acting on the same target organ) or may give rise to interactions (synergistic or antagonistic effects). This depends on the toxicological characteristics of the pollutants associated with the plant under evaluation.