An expert in performing electronic microscopy was needed in a lawsuit against a baby powder manufacturing company when patients alleged the product had caused them to develop cancer. Throughout the case, scientific literature was conflicted on whether asbestos-free talc, a popular component in many cosmetic products, could act as a carcinogen. This dissent prompted the use of a tissue analyst to discuss whether talc could be seen in the pelvic cavity of patients.
Question(s) For Expert Witness
- 1. Are you able to identify particles in tissue?
- 2. What methods or tests would you use to identify particles of a substance like talc?
Expert Witness Response E-053090
I have taught, presented, and written on electron microscopy and have worked hands-on with the electron microscope in academic, industrial and forensic matters; identifying foreign particles in tissue is well within my expertise. Depending on the particle morphology, light microscopy may be used to identify particles. Electron microscopy in conjunction with X-ray spectroscopy would be preferred, since it has the advantage of imaging at high magnification with several different imaging modes that can be used to increase the kind of elemental contrast needed to see talc particles in tissue. Additionally, X-ray spectroscopy can provide quantitative elemental analysis of the particles to confirm their chemical makeup.
Expert Witness Response E-061889
Without proper controls and chemical analysis, I don’t think anyone could definitively say that they observed talc in a tissue biopsy from just transmission electron microscopy. Through routine transmission electron microscopy, talc particles will deflect an electron beam and appear as a black substance; however, anything that deflects an electron beam will appear as a black substance. It would be unknown whether the black substance is talc, contamination, or some other metal in high concentration. If chemical analysis of the tissue was used in concert with electron microscopy and resulted in high concentrations of talc at the biopsy site, a microscopist could be more confident identifying the black substance as talc. I would have a control sample with no talc and one with talc to compare to an unknown tissue that may or may not contain talc. I would then send the tissue to a certified lab that can guarantee little to no contamination in the routine tissue preparation for transmission to electron microscopy. Again, this would not positively identify talc beyond a shadow of a doubt because any metal contamination would provide a similar result; however, with good control tissue and a chemical analysis, it would be possible to comment on the scenarios in this case.