Defra - Department for Environment, Food and Rural Affairs.

Science Search

Science and Research Projects

Return to Science Search homepage   Return to Project List

To Investigate the Potential Impact of Tank Mixing on the Dermal Penetration of Pesticide Active Substances - PS2607

The main objective of the research is to establish the influence of mixing of pesticide formulations (“tank mixing”), and/or the extension of such formulations with adjuvants (such as wetters or stickers), on the dermal absorption of the active substance compared with single “as sold” formulations. Both the concentrate formulation and typical dilution rates used for application in the UK will be evaluated. Suitable combinations of actives, mixtures and adjuvants would be selected following a survey of UK pesticide use, and a review of physicochemical properties of active substances and co-formulants shortlisted. Dermal absorption and penetration will be assessed using an in vitro model using human skin. Mixtures of concentrated and dilutes pesticide formulations and adjuvants would be used with the in vitro laboratory studies. There is an option to carry out a limited occupational exposure study to evaluate the relationship between the laboratory and field data for the dermal absorption of a selected compound used formulated alone and in a tank mixture. In vitro data generated will be used to extend the capability of currently available predictive models for dermal penetration. The results of the proposed research would provide information which could be used by DEFRA to improve risk assessment of exposure to pesticides during tank mixing and extension with adjuvants. This will add to the aims of PSD to provide assurance that accurate risk assessments are being used to ensure the safety of pesticide users and the environment. It would also enable PSD to provide advice about best practise for tank mixes and adjuvants in order to minimise the risk of dermal exposure of workers and the general public to pesticides.
1. To select the most suitable actives, formulations, tank mixes and adjuvants in order to determine the effects of tank mixes, co-formulants and adjuvants on the dermal penetration of actives relevant to UK usage (CSL, in consultation with PSD);
2. To measure the dermal penetration of selected actives using human skin in vitro in the presence of mixtures of formulations (tank mixes), co-formulants and adjuvants, and compare with dermal penetration from single formulations (Toxicology Unit, Environmental Medicine, University of Newcastle and HPA Chemical Hazards and Poisons Division (CHPD) Newcastle);
3. To carry out limited field biomonitoring studies on workers using tank mixes, in order to confirm the relationship between exposure and amount absorbed (CSL) OPTIONAL
4. To report findings, describe the influence of tank mixes and adjuvants on dermal absorption and penetration of the actives, and make recommendations to PSD on the basis of these findings (all partners).
5. Evaluation of the suitability of existing QSAR models to predict dermal penetrability of pesticides, or other organic compounds
Project Documents
• Final Report : To Investigate the Potential Impact of Tank Mixing on the Dermal Penetration of Pesticide Active Substances   (511k)
Time-Scale and Cost
From: 2005

To: 2007

Cost: £78,928
Contractor / Funded Organisations
Central Science Laboratory, University - Newcastle
Health Effects              
Operator Safety              
Pest and Weed Control              
Pesticide use              
Plants and Animals              
Public Health              
Fields of Study
Pesticide Safety