The harms and health risks of substances are increasingly predictable

Bioassays are effective tools for investigating whether substances in water could have adverse effects on human health. At KWR and elsewhere, better methods for the deployment of bioassays are constantly being developed. For example, research conducted as part of the Water Technology TKI and in the WiCE-programme has shown that bioassays deliver considerable added value for the assessment of options for reusing water.

Developments in bioassays

The WiCE study and recent DPWE research conducted by KWR with the Water Laboratory in the DPWE programme specifically examined DNA damage due to chemical contaminants (genotoxicity). Damage to DNA of this kind can occur in several ways and a set of different bioassays has therefore now been proposed to assess genotoxicity on the basis of those different pathways.

Less-than-lifetime exposure and uncertainties

When assessing whether substances pose a risk to human health, the first step has traditionally been to look at the available toxicity data after lifetime exposure that can be found in databases and the literature. However, lifetime exposure does not always occur: there are also situations where exposure is short-term. Uncertainty factors are included in the estimate to allow for a broad margin of possible variation between individuals (different people) and for stating the toxicity measured in model organisms in terms of toxicity for humans. These uncertainty factors can result in conservative values for safe exposure. Where the initial assessment indicates a possible health risk, follow-up research is required. KWR has made two methodologies applicable as part of the BTO programme for refining the assessment of substances for human health risks related to water quality issues. One approach focuses on assessing the risk associated with less-than-lifetime exposure; the other focuses on taking uncertainties better into account to make more accurate risk assessments (probabilistic risk assessment).

Bioassays and risk assessment methodologies can be used more effectively

Thanks to this newly developed knowledge, bioassays can be used more effectively and`methodologies are now available for water-relevant substances to make better and more accurate estimates of exposure to a substance and the potential health risk. The latter research has been described in, among other places, an article that recently received an H2O award.