Problematic Plastic Tubing

Anthony J. Papa’s experience in his doctor’s office concerning plastic tubing being altered by 4-methylcyclohexanemethanol (MCHM) ought to be expected (C&EN, May 26, page 4). Plasticizers are a major part of flexible plastic tubing, perhaps close to 50% of the total material.

In 1976, D. G. Crosby and I detailed problems with several plasticizers getting freed up and contaminating samples (Bull. Environ. Contam. Toxicol., DOI: 10.1007/bf01685891). The best known was and still is di(2-ethylhexyl) phthalate, listed as DEHP in the Merck Index. It and other such plasticizers should be easily extracted from plastic tubing by MCHM, so the results reported by Papa ought to be expected. Many other problems with escaping plasticizers continue unrecognized.

Our paper reported on finding that polychlorinated biphenyls were used to plasticize various window caulking materials. Wipes of window glass and marble facings on several buildings in San Francisco showed several PCBs present and smeared over large areas of building exteriors. Thousands of buildings could still be bleeding several types of plasticizers into the environment as the Environmental Protection Agency has never recognized the seriousness of this problem.

James Singmaster III
Davis, Calif.