Conference reports

PROBLEM OF GOVERNMENTAL REGULATIONS AND THE TESTING OF BIOMATERIALS

London, 22 March 1979

This day conference was organized by June Wilson of the ICI Central Toxicology Laboratories who welcomed participants and emphasised that while there is a need for a defined set of regulations, the testing must be appropriate to the particular bio- materials and decisions must be made as to which ‘recommendations’, made by those who are actually involved in research, should be afforded the force of law.

Mr. Allum of the Supplies Division in dealing with ‘Legislation and Standards’ referred in detail to the British Standard BS5736 - ‘Evaluation of Medical Devices for Biological Hazards, Part I’ which specifies various tests which should be carried out for a range of applications. He empha- sized the need for good manufacturing practice to ensure reliability of products and the responsi- bility of manufacturers for quality assurance, This theme was continued by Dr. Alex Ross from the Medicines Division of the DHSS, who spoke in relation to the Medicines Act, 1968, which at present excludes instruments, apparatus, appliances and dental fillings, i.e. many biomaterials. However, substances and articles can be brought within the scope of the Act so that bone cements, adhesives and intra-uterine devices all come within the original definition although it does not appear that there will be any attempt to include surgical im- plant materials. Dr. David M. Conning, Director of B.I.B.R.A. lectured on ‘Toxicity Testing of Bio- materials’ and spoke about immediate local systemic effects and delayed sensitisation pheno- mena. Neoplastic changes are wholly separate from the normal range of tissue reactions and may well result from physical rather than chemical factors. We need to know much more about the interaction between surface (chemical and charge effects) and connective tissue. Immune mechanisms, in res- ponse to implanted materials, nearly always appear to result in a continuing reactive process, which is masked because the materials become ensheathed in fibrous tissue. He spoke further about possible sensitisation reactions. In man, carcinogenesis is usually chemical and there is no evidence at present of solid state carcinogenesis. For long-term implants it is essential that their performance over the intended duration be evaluated.

Dr. David Christopher, Huntingdon Research Centre, discussed the ‘Preparation and Testing of Eluates’, distinction being drawn between the processes of extraction (in depth removal) and

elution (surface removal) of endogenous or extra- neous material from the test specimen. The para- meters governing extraction and elution were outlined. Key factors in the selection of procedures for eluate preparation were detailed, and illustrated with reference to a typical standard test, the USP XIX systematic injection test. Deficiencies in this standard, relating to the wide variation in fluid exposure of biomaterials in human use, were identified. Techniques for rendering the acute systemic toxicity test more meaningful, by increas- ing dose, were discussed.

Dr. Jeremy Styles, ICI Central Toxicology Labor- atory spoke on ‘Mutagenicity and Carcinogenicity Testing of Biomaterials’. He mentioned the rela- tionship of short term screening tests such as the Ames and cell transformation assays to this area and its lack of significance for polymers except if leachable materials were present. The transforma- tion of cells occuring in culture media may well be irrelevant to man, since epithelialisation reactions are more appropriate. Professor David E.M. Taylor, Royal College of Surgeons, London concluded the meeting with a paper on “Haemocompatibility Testing of Biomaterials” including the range and limitations of existing standard tests for thrombo- genicity.

This meeting attracted participants from other European countries and was valuable contribution to this important area where fundamental work still needs to be done. Biomaterial scientists should be informed of developments in order that they may by virtue of their experience be able to in- fluence Standards and Government regulations. They cannot opt out of their responsibility for ensuring that the materials are safe for human use and particular emphasis needs to be drawn to the need for long-term testing of implant materials and devices, for the consumer requirement of an indica- tion of reliability will need to be faced up to in the very near future.

The Biomaterials Group and June Wilson in partic- ular are to be congratulated for an excellent meet- ing in the continuing series of one day Biomaterials Group local meetings.

G. W. Hastings

302 J. Biomed. Engng. 1979, Vol. 1, October