How To Unite the Two Viewpoints On Toxicity?
Manufacturing companies usually look at a product’s toxicity from two points of view: “How sustainable is the product regarding human health and the environment?” and “Does the product pose a risk to specific groups of people, e.g. the workers involved in its production?”
These questions are generally assessed by different ‘silos’ of experts, which do not interact very much. However, as there is an overlap in the required input data, it seems useful to establish a better connection between the two silos.
Risk Assessment Tends To Be Conservative
To assess whether a product presents a risk to specific groups of people, risk assessors use a conservative approach. Safety is evaluated by comparing the predicted level of chemical exposure to a limit value, i.e. an expected safe level. These limits are set in a way that aims, for instance, at a protection of ninety-five percent of species, or an adverse health effect in no more than one in a million persons.
For humans, the daily intake (DI) of a certain chemical is compared to the acceptable daily intake (ADI). If the DI exceeds the ADI, there is a risk to human health with accompanying health consequences. Although it is likely that the consequences for human health are larger than what you would accept, it is unknown how large, as the DI/ADI ratio is not a quantitative estimate of the health consequences of that risk. This type of risk assessment is used, for instance, in determining regulations or standards.
LCA Offers A Best Estimate
Life cycle assessment (LCA) is an approach that evaluates a product’s environmental impact, including the toxic impact of chemicals on ecosystems and human health. In contrast with risk assessment, which is conservative, LCA aims at a best estimate of the toxic impact of a product’s chemical emissions.
LCA gives a quantitative estimate of the actual impact. There are no limit values; the general assumption is that ‘less is better’. The toxic impact of chemical emissions is modelled on the basis of two variables: the quantity emitted and the potential for toxic impact per unit of emission. The latter can, for example, be expressed by the toxic impact per 1 kg emission of a chemical, quantified with a characterisation factor (CF – e.g. the number of disease cases per kg of emitted chemical). CFs for toxicity are used in LCA, but also in ranking substances on the basis of their chemical hazard.
A Powerful Combination
Although it seems that risk assessment and LCA are very different when it comes to estimating product safety, the approaches can be combined in powerful ways. Ideally, manufacturing companies would use risk assessment to qualify which chemicals can be considered safe and therefore suitable for use in their products, and LCA to differentiate between suitable alternatives (see illustration).
This figure shows how manufacturing companies can select the most sustainable and safe chemical ingredients for their products by combining the two points of view: using risk assessment to qualify the chemicals and LCA to differentiate between them.
Step 1: First, the risk assessment focuses on the toxic content of the product, and the toxic substances that may be formed during use or at the end of the product’s life. This step determines whether a product meets the minimum safety standards.
Step 2: Second, the chemical ingredients that were found safe can be compared on the basis of their life cycle implications. The comparison should show which chemicals is preferable based on its environmental impact.
Suppose chemicals A and B are both considered safe for use in the manufacturing of a certain product. Suppose also that end users may experience a similar DI/ADI ratio for the two different chemicals, but that chemical A has a much higher impact on ecosystem quality and also has the largest overall environmental impact. Since chemical B is a more sustainable and equally safe alternative, it is the preferred choice for use in the manufacturing of this product.
Bridging The Gap
I believe that a better connection between the two silos is useful. After all, there is an overlap in the input data required, such as information on the chemicals’ intrinsic toxicity, environmental degradation, distribution through different environmental media, bioaccumulation, et cetera. And, as shown, the combination of the two approaches can help manufacturing companies develop more sustainable products.
How do you make your toxicity assessments? What hotspots or bottlenecks do you encounter? Which improvement opportunities do you value? I’m very interested in hearing from you. If you have any ideas on how to simplify your work when dealing with toxicity, please don’t hesitate to share your views with us. And if you have problems we could help you solve, please let me know. We are happy to help you in your journey towards sustainable products.