EFSA first published guidance on dermal absorption back in 2012. This guidance has been reviewed on the basis of new available data provided to EFSA by the European Crop Protection Association (ECPA) and the Bundesinstitut für Risikobewertung (BfR), with updated guidance published following a public consultation.  Details on experimental design have not been addressed but recommendations specific to performing and interpreting dermal absorption studies with plant protection products (PPP) are given. The main changes are as follows:

• Variability within results and outliers:  the preferred approach to addressing variability between replicates/animals is to add a multiple of the standard deviation to the mean value. The multiplication factor required depends on the number of replicates used. The greater the replicates used, the lower the multiplication factor.
• Default dermal absorption values are recommended dependent on the type of formulation. The categorised groups are organic solvent-based, water-based/dispersed, solids and other formulation types.
• A tiered approach is presented to allow reading across dermal absorption data between formulation types.
• The use of QSAR or other mathematical models for the prediction of dermal absorption is not recommended.
• The use of nanoparticles in PPP is not addressed.
• The dermal absorption value to be used for dried leaf deposits (worker exposure risk assessment) is the subject of ongoing research.

The dermal absorption guidance can be found on the EFSA website: http://www.efsa.europa.eu/en/efsajournal/pub/4873

Outcome of the public consultation on the draft EFSA guidance on dermal absorption can also be found on the EFSA website: http://www.efsa.europa.eu/en/supporting/pub/1250e

For advice on risk assessment and further information on the registration of plant protection products, biocides or general chemicals, or any other regulatory issues, please contact JSC on +44 (0)1423 520245,enquiries@jsci.co.uk