Risk assessment priority pollutants

The output of an exposure and risk assessment will usually describe the levels of exposure and quantity the population exposed for both humans and other biota, and will estimate the associated probabilities of the incidence of adverse health effects. Population exposure or risk, obtained by multiplying the individual (per capita) exposure or risk by the numbers exposed at each level of exposure, may also be a useful measure of impact. Various analyses can be performed on the results, for example, comparison of exposures in a particular geographic area against national average exposure levels. Likewise, for the same pollutant, environmental risks due to a particular industry might be compared against risks associated with occupational or household activities. In addition, the health risk of different substances could be compared for priority setting. 

Apart from of investigating the concentration of priority pollutants to assess the temporal and geographic trends as it has been done in the Ebro river basin until nowadays, the SCARCE project pretends to evaluate the consequences of the climate change in the water quality as well as predicting new environmental risks derived from water scarcity. This will be done by determining the presence of new priority (i.e. perfluorinated compounds) and emerging toxicants in Mediterranean river ecosystems in the Iberian Peninsula. In a subsequent step, the effects of chemical and environmental stressors on the biota will be assessed by combining field and experimental studies. The effects of multiple stressors will be addressed from a multi-biomarker perspective [27]. 

The official list of priority pollutants threatening the aquatic environment is presently based on that reported on Directive 2008/105/EC [27]. It was the output resulting from a previously done risk assessment study carried out by the Fraunhoffer Institute (COMMPS procedure) [28, 29], using monitoring data gathered throughout many European river basins. 

At present the risk assessment of contaminated objects is mainly based on the chemical analyses of a priority list of toxic substances. This analytical approach does not allow for mixture toxicity, nor does it take into account the bioavailability of the pollutants present. In this respect, bioassays provide an alternative because they constitute a measure for environmentally relevant toxicity, that is, the effects of a bioavailable fraction of an interacting set of pollutants in a complex environmental matrix [9-12]. 

A strategy for dealing with pollution of water from chemicals is set out in Article 16 of the Water Framework Directive 2000/60/1 iC (WFD). As a first step of this strategy, a list of priority substances was adopted (Decision 2455/2001/EC), identifying 33 substances or groups of substances of priority concern at Community level. Recently, the European Commission adopted a proposal for a new Directive to protect surface water from pollution (COM (2006) 397 final). The proposed Directive will set limits on concentrations in surface waters of 41 dangerous chemical substances including 33 priority substances and 8 other pollutants that pose a particular risk to animal and plant life in the aquatic environment and to human health. The proposal is accompanied by a communication (COM (2006) 398 final) which elaborates on this approach and an impact assessment (SEC (2006) 947) which illustrates the choices that the Commission made. 

Article 16 of the WFD, which sets out the European Union (EU) strategy against pollution of water by chemical substances, requires the Commission to identify priority substances of European relevance, for which priority action is needed at Community level. The first list of priority substances was adopted in November 2001 (Decision 2455/2001/EC). In order to assess the risk of failing the objective of good chemical status , Member States are obliged to monitor these substances in all water bodies. 

The Royal Commission on Environmental Pollution reported in 1996 that it was not aware of any study that provided firm evidence of adverse effects of contaminated land on health.10 However, the potential for health effects is real. Exposure to chemicals is a risk factor for several diseases and the International Agency for Research on Cancer has classified over 70 chemicals as human carcinogens, 60 as probable and more than 200 as possible carcinogens.11 There is evidence of an environmental influence in human diseases such as cancer,12 including geographic variation in cancer incidence in migrant populations, occupational studies and animal experiments. A number of studies also appear to suggest an association between other health effects and exposure to environmental chemicals. There are thousands of sites contaminated with hazardous chemicals with the potential to expose human populations. In the USA, the ATSDR has estimated that 46 % of the assessed National Priority List sites represent an actual hazard to health.13... 

---