The use of all medicines, both veterinary and human carries the potential for risk of harm to the environment. Some veterinary medicines, such as antibiotics, anthelmintics and ecto-parasiticides, demonstrate biocidal activity. The use of such substances could have a detrimental impact upon the environment, and it is important to demonstrate that products containing these can be used safely.
It has been a requirement to assess the potential environmental impact of Veterinary Medicine in the UK for many years. Currently the requirements are laid out in Directives 92/18/EC, 2001/82/EC as amended by 2004/28/EC as well as Volume 6b of the Notice to Applicants and Committee for Veterinary Medicinal Products (CVMP) Guidelines. There are also international guidelines (Veterinary International Commission on Harmonisation –VICH GL6 and GL38 which apply in this area).
Environmental Impact Assessment is conducted in a stepwise process. In the Phase 1 assessment the potential exposure to the product, active substance, metabolites etc. are calculated taking into account the target species, the pattern of use, the constituents and the administration method of the product. If the product as used fails to be excluded from further evaluation by way of limited use, low predicted worst case environmental concentrations etc. then it passes to a Phase 2 evaluation which requires the generation of specific environmental effect and fate data. For farm animals the rate of application of manures in relation to nitrogen limits is taken into account. In reality most products intended for farm animals require a Phase 2 assessment.
Phase 2 is divided into two tiers, A and B. Tier A provides a basic data set of effects and fate information arriving at a risk quotient (RQ) of the PEC (predicted environmental concentration) divided by the PNEC (predicted no effect concentration). If the RQ is < 1 this usually indicates no further testing is required.
Fate studies carried out for Tier A are metabolism and excretion, adsorption/desorption, photolysis (aquatic medicines) and degradation. Effects studies look at soil organisms, water organisms and dung fauna. If the RQ is > 1 then Tier B is entered. Here the PNEC is refined with studies on specified microorganisms, plants, algae, daphnia and fish. Issues such as bio-concentration and secondary poisoning may need to be considered.
If there is still an issue then one has to move into real field studies (Tier C).
The need to carry out such a rigorous set of studies to OECD Guidelines for most veterinary medicine products designed for use in farm animals has added to the disincentives to develop new products for farm animals. The environmental risk assessment is an essentially open ended procedure with undefined risks only becoming apparent as one moves through the process. This coupled with the costs of meeting requirements for residue depletion studies to arrive at a maximum residue limit has led to many companies focussing their R & D expenditure on companion animals, where it is also easier to achieve better margins and returns on the investments. The recent requirement to supply an environmental risk assessment for generic applications when all other safety data is carried over from the original product is proving to be a big issue and may limit the introduction of new generics for farm animals.
Cambridge Environmental Assessments (CEA), part of ADAS UK Ltd., can help companies with Environmental Impact Assessments through the provision of expert advice and advocacy.
CEA are particularly skilled in providing solutions to environmental risk assessment issues. In many cases refinement of predicted environmental concentrations can provide a cost effective alternative to additional testing. Refinement may be achieved through application of modelling techniques (e.g. FOCUS tools) or through characterisation of more realistic exposure scenarios.
For further information contact Paul Mason on +44 (0) 1954 268286 or e-mail paul.mason@cea-res.co.uk.