Notwithstanding potential differences in efficacy, when trying to judge the relative safety advantage or disadvantage of introducing an alternative chemical product into the marketplace, a comparative persistence, bioaccumulation, and (eco)toxicity (PBT) assessment may be undertaken. Such an assessment generally compares the environmental persistence, bioaccumulation potential in aquatic organisms and aquatic toxicity of the individual constituents between two or more products.
Such a comparative analysis can also be specifically adapted if the focus is on human health concerns rather than (or in addition to) environmental/aquatic toxicity. This may be the case when dealing with products which contain chemicals that persist in the human body and therefore present a potential chronic health risk. Although such assessments do not constitute a risk assessment per se in that they do not quantitate potential exposures for specific scenarios, potential human health risks of the products are discussed broadly by relating hazards of product constituents to the amounts of each constituent present in the products.
A methodological approach is presented which adapts the classic PBT criteria to provide additional consideration of human health issues. For example, environmental persistence (P) is typically described by measured or modelled half-lives in air, water, soil and sediment and results of ready biodegradability testing. Persistence in the human body may be described by half-lives in blood or tissues. Similarly, aquatic toxicity (T) information can be supplemented with human toxicity (T) data initially based on the Globally Harmonized System for Classification and Labelling (GHS) hazard classifications of products and their constituents. This process can then be followed by a more detailed consideration of toxicity information for those constituents triggering a specific ‘severity’ rating.
The adapted comparative PBT assessment allows for a holistic comparison of product safety.