Platinum catalyst review

Introduction
At the IRG's open day in October 2000, concern was raised that platinum compounds present in breast implants could give rise to toxic effects. In response, the IRG requested MHRA to review the chemistry and toxicity of platinum compounds used in the manufacturer of breast implants and to assess the extent of exposure to these compounds in women with breast implants.

MHRA obtained relevant data and prepared a report under the direction of IRG members. The report was presented to the IRG and discussed at their meeting in April 2004. The attached paper, which was submitted to the IRG at the same time summarises the finding of the full report but excludes commercial information provided to the IRG in confidence by manufacturers. The IRG agreed that this summary and a record of the IRG discussion during the meeting would form a suitable basis for a publication on this website.

› Summary paper submitted to the IRG

IRG discussion
The IRG agreed that the report gave an excellent overview of the subject from a toxicological perspective, breaking it down into its relevant components: the chemical nature and toxicity of the catalysts used an an assessment of the risk. The report was thus considered an adequate basis for drawing conclusions about the toxicity of platinum compounds in silicone breast implants.

Platinum compounds generally raise two significant potential toxicological concerns: some of them are highly toxic (e.g. halogenated compounds such as cis-platin) and some are respiratory sensitizers. However, the data reviewed by the IRG provided a high degree of reassurance that neither of these concerns is relevant with the platinum catalysts used in breast implants.

The IRG reviewed unpublished data by Lykissa, suggesting that platinum was present in silicone gel breast implants in a range of forms, some of which are toxic. However, the IRG confirmed that platinum is present in breast implants only in a form that is comparatively unreactive and stable and thus not of toxicological concern. The Group paid particular attention to data on the potential for immunotoxicity and sensitisation. Slight effects had been observed with some immunological parameters, but these were not considered to have any significance to human health. The IRG noted that only halogenated platinum compounds act as respiratory sensitisers or genotoxins. Since the compounds used in breast implants are not halogenated, there is no risk to human health in these respects. Members concluded that the data available indicated that the compounds were non-genotoxic, non-immunotoxic and, in general, comparatively benign. They thus do not represent a significant toxicological hazard.

Using worst case assumptions, the IRG estimated that exposure to platinum compounds from breast implants is of the order of 1µg/kg/day. This is extremely low and several orders of magnitude lower that the dose that might be expected to result in harm to health.

Conclusion
The IRG concluded that the presence of platinum compounds in breast implants does not represent a risk to human health.

In particular, with respect to the questions raised at the IRG Open Meeting:

1. If platinum is put into the implant in the zero oxidative state, does it change chemically or physically over time after implantation with systemic consequences?
It cannot be excluded that a small fraction of the platinum catalyst in the implant might change oxidative state over time, but this is without any noticeable systemic consequences. The lack of systemic consequences is most likely a result of the extremely low expected maximum exposures.

2. The Institute of Medicine report states that 75% of the platinum in an average Silastic implant is in the gel, presumably as a colloidal, elemental platinum residual. Is the remaining 25% in a toxic form with serious health and genotoxic effects?
The larger part of the platinum catalyst is indeed in the gel, most likely in the zero oxidative state. The remainder is in the elastomeric shell, also most likely in the zero oxidative state.

and, with respect to the questions raised by MHRA:

The full report assessed by the IRG was an adequate basis for drawing conclusions about the toxicity of platinum compounds in silicone breast implants.

The full report assessed by the IRG should remain a confidential committee document, since it contains commercially restricted information obtained under a confidentiality agreement. The summary report prepared by MHRA, together with a detailed accound of the IRG discussion during the meeting, accurately represents the IRGs views and conclusions. These should be published on the IRG website.

No additional data are needed to reach a judgement on the toxicological risk of platinum catalysits. The toxicological risk from platinum catalysts is acceptable.

April 2004