The health risk of a chemical is not only related to the toxicological hazards but also to exposure. If this is very low, then the hazards are entirely academic. As exposures increase, the toxic potential can be realised and adverse health effects can occur. With increasing doses, toxic effects will be seen at a higher frequency and a greater severity.
In our health risk assessments, we convert the toxicological hazard profile to a health-based guidance value, and compare this reference point to an estimate of human exposure. Most health effects are only seen above a certain dose (a toxicological “threshold”), and so we are able to conclude with confidence about the quantitative health risk that a particular exposure might pose.