Background
In evaluating the risks presented by dermal exposure to chemicals, it is essential that
producers, processors and consumers know the extent of permeation through intact
human skin and the bioavailability in the body in comparison with the more general
exposure route via inhalation. In the present EU Technical Guidance Documents for
risk assessment of new and existing chemicals, it has been assumed that the
experience gained from studying the skin permeation of pesticides can be directly
used in assessing the risk of industrial chemicals. This can lead to serious overestimations
of industrial dermal exposure in the risk assessment process.
For industrial chemicals, only limited and variable data are available on experimental
skin permeation rates. The lack of data is further compounded by the fact that the
available data are mostly derived from substances with a high permeation rate e.g.
phenols, aromatic amines, nitro-aromatics, and glycol ethers. The OECD has
agreed methodology guidance in 2002, without recommending a common standard
protocol. A World Congress on Predicting Percutaneous Penetration (PPP) was
held in Antibes (France) in April 2002.
It is thus both timely and appropriate to hold a broad discussion, most suitably in the
form of an international expert workshop. The workshop should build upon a recent
literature survey on dermal deposition in the chemical industry (Wheeler et al, Health
and Safety Laboratory, Sheffield UK) and a related project to determination the
optimal physico-chemical parameters to use in a QSAR approach to predict skin
permeation rate (Cronin et al, John Moore University, Liverpool UK). Both projects
have recently been completed under the LRI HETRA programme (A2.1 and A2.2).
Objectives
- Achieve wide consensus on the most appropriate protocols for measuring dermal permeation of chemicals in vitro and in vivo, in order to achieve a reliable estimate of the permeation rate of human skin in vivo.
- Recommend a common standard protocol for measuring dermal permeation rates in vitro.
- Publish the workshop proceedings, including a review and evaluation of existing methodology for measuring dermal permeation, and the recommended standardprotocol.
CEFIC LRI is further committed to support the Workshop with a substantive RfP that would initiate a test programme for industrially-encountered chemicals, based upon the protocol, together with the development of an improved QSAR for skin permeation rates. The RfP would be the subject of a separate announcement, to coincide with the Workshop
Scope
To organise a limited workshop to:
- Review existing protocols for measurement of dermal permeation of substances through human and experimental animal skin in vitro and in vivo,
- Evaluate the (dis)advantages and reliability of these protocols for use in human risk assessment considering:
- 2.1 The goal to develop a reliable QSAR for estimating permeation through human skin in vivo
- The costs versus performance
- The need for a routine type test
- Required accuracy versus biological variability.
