Reflections on new directions for risk assessment of environmental chemical mixtures

Currently risk assessment of chemicals tackles them as single substances affecting individual health endpoints. In reality, human exposure occurs to mixtures of chemicals, as they are present in the environment and consumer products. Combining the information from environmental fate analysis, epidemiological data and toxicokinetic/dynamic models helps estimate internal exposure. Coupling these data with gene and protein expression profiles as signatures of exposure to classes of toxicants to derive biologically-based dose-response estimates may open the way towards adopting a biological connectivity approach to risk assessment. This work gives examples of applications of this approach on combined exposure to mixtures of volatile organic chemicals and estimation of body burden from chronic exposure to mixtures of chemicals and of the associated health risk. Conclusions are drawn as to the future scientific developments that will meet the requirements of integrated health risk assessment to protect public health from environmental and consumption-related stressors.