Friday, January 7, 2011

How Safe is TB Testing?

I began to wonder about this as I signed on to a new job that requires annual TB testing.  I came across a very lengthy article (1) that discussed TB testing in detail.  Some important takeaways were:
  • the chemicals used for the TB test are typically made up of TUBERSOL® and Phenol (a preservative - see the toxicological profile for Phenol)
  • TUBERSOL® is a known mutagen 
  • the CDC states that TB testing is safe during pregnancy, even though there has never been any mutagenicity testing performed and Tubersol is a known mutagen
  • according to the 1972 edition of Encyclopedia and Dictionary of Medicine and nursing defines Phenol as "an extremely poisonous antiseptic, germicidal, and disinfectant"
  • Phenol is associated with skin cancer development when injected in animals 
  • the CDC states that the TB testing is safe, even though no carcinogenicity studies have been performed
  • targeted TB testing in health care workers is only recommended (not required) by the CDC; although some facilities make testing mandatory amongst employees (and subject to termination for refusal)
Specifically, in the FDA document on Tuberculin (TUBERSOL®), it states:
  • "Animal reproduction studies have not been conducted with TUBERSOL.  It is also not known whether TUBERSOL can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity.  TUBERSOL should be given to a pregnant woman only if clearly needed."
    The article also discussed conflicts of interest amongst doctors establishing treatment guidelines on disease treatment.  Some interesting facts according to a cited JAMA article(2) on the website I'm referencing:
    • 85% of guideline authors have some sort of relationships with drug companies, and they are often not disclosed
    • 38% of respondents said they had served as employees or consultants for drug companies; 58% received research money
    • 59% had links with drug companies whose medications were considered in the particular guidelines they authored, almost all cases predating the guideline creation process 
    •  These numbers may be even greater, as only 52% of authors responded
    Wow!  Great to know that the information OUR doctors read to learn how to properly treat US, is written by doctors that frequently have conflicts of interest.  Just another reason why it is so important for YOU to be in charge of your own health and be an advocate for proper care.

    Also worth mentioning:
    Another interesting document I came across indicates that the current limit values for Phenol were set over 40 years ago(5).  The document states that the limit values need to be reconsidered because research indicates that Phenol is harmful even at very low levels in animal experiments.  In addition to serving as a preservative in TB testing, phenol is used in plastic and dyes (and is frequently used in childrens toys and our food packaging).

    2) N.K. Choudhry, et. al. Relationships between authors of clinical practice guidelines and the pharmaceutical industry JAMA; 287,612-617, 2002

    1 comment:

    1. Since writing this article, I've learned there is also a blood test you can have done to test for TB. See the test description here: