Under German national legislation, we are familiar with occupational exposure limits, biological limit values, and maximum workplace concentrations—also known as tolerance concentrations. These values must be reported and can be found in the 900 series of the TRGS (for more on this, see our blog post on AGW and BGW).1
In addition to the limit values mentioned above, safety data sheets often include DNEL or PNEC values. The following section explains how these values are determined, what exactly they indicate, how they can be used in practice, and whether their inclusion is mandatory.
Where do these values come from?
If we look at the terms used—”Derived No Effect Level” and “Predicted No Effect Concentration”—it quickly becomes clear that, for one thing, these are threshold values below which the substance has no observable effect on humans or the environment. Furthermore, it is clear that these are calculated values (derived/predicted) derived from measured values and weighting factors.2 3 Specifically, DNEL and PNEC values are specified in the registration dossiers under REACH.
What do these values indicate?
The DNEL values relate to health risks to humans, further subdivided into the working population and the general population, because different exposure scenarios apply here. They are calculated based on toxicological data, as well as “Occupational Exposure Limits” (essentially the European AGWs) and specific weighting factors, which are higher for workers handling the substance than for the general population.
PNEC values relate to the (primarily aquatic) environment and have no direct equivalent in occupational safety, such as DNEL <-> r AGW.
How can these values be used in practice?
There are always multiple DNEL and PNEC values because different populations and environmental compartments are considered, with different exposure routes and over different time periods.
In most cases, DNEL values provide information on systemic and local effects, acute and chronic effects, and the exposure routes of inhalation, skin contact, and eye contact for both the working population and the general population. Values are not always available for all combinations.
PNEC values often include data on concentrations in water bodies (freshwater and seawater), the corresponding sediments, wastewater treatment plants, and dry soil. It is less common for these values to pertain directly to flora or fauna, but there are sometimes data on secondary poisoning (prey) and on bioaccumulation in predators through the food chain.
Is this information required?
As a rule, the DNEL and PNEC values for a substance are specified in the lead dossier filed with ECHA; as such, these values are official and were determined in accordance with strict guidelines.
However, providing this information is not always mandatory; DNEL/PNEC values must only be reported if a chemical safety assessment is required, i.e., if the quantity threshold of 10 metric tons per year for placing the substance on the market is exceeded. The determination of DNEL/PNEC values is part of the exposure scenarios for the substance safety assessment.
Please note: This requirement applies only to pure substances and their manufacturers. For the use of substances with DNEL/PNEC values in mixtures, the following applies: If a component has such values, they must be listed in the mixture’s SDS; however, an exposure scenario or chemical safety report does not need to be prepared.
Conclusion: DNEL/PNEC values must be specified for the ingredients in mixtures, if they are available.
Starting with version 13.1, GeSi³ can help you determine these values. The ECHA Connector’s additional functionality has been expanded to include the retrieval of values from registration dossiers.
