TR 057 – Polypropylene Production and Colorectal Cancer

TR 057 : Polypropylene Production and Colorectal Cancer | February 1994

Polypropylene has been produced for over 35 years. It has a wide variety of applications including industrial, food packaging and many domestic uses. High molecular weight substances such as polypropylene are considered chemically and biologically inert with little or no physiological or toxicological effects. The monomer, propylene has been examined in a two-year inhalation study in mice and rats and found to be without carcinogenic activity. No long-term cancer bioassay of polypropylene has been conducted. Subcutaneous implantation induces local tumour response, which is considered to be due to tissue displacement. With this exception there is no evidence that propylene or polypropylene has mutagenic or carcinogenic properties. No identifiable carcinogenic agent was found in the additives and process agents used in polypropylene manufacture.

In man colorectal cancer is a relatively common cancer. It increases markedly with age, particularly in North American, European, and other industrialised populations. Genetic and dietary factors are involved in its etiology. Although not considered an occupational cancer, an excess of colorectal cancer has been reported among workers exposed to asbestos as well as among automotive wood model and pattern makers. Screening, which may be an effective method for reducing the risk of colorectal cancer mortality, includes procedures such as digital rectal examination, faecal occult blood tests, sigmoidoscopy, and more recently, colonoscopy. The two endoscopic approaches are viewed as the most effective techniques.

Early epidemiologic studies of polypropylene production workers and carpet manufacturing employees who used polypropylene reported a significant excess of colorectal cancer. These studies were based on clusters of colorectal cancer. In one study, 5 of the 7 cases were diagnosed within a 5-month period and in the other study 5 cases were diagnosed within an 18-month period. Recent updates of these two original study populations have found no continuation of the excess of colorectal cancer, thereby indicating the chance nature of the clusters. Other investigations of polypropylene production workers in the United States, Germany, Australia and the United Kingdom found no link with colorectal cancer. As a whole, the combined weight of epidemiologic and toxicologic evidence does not support an association between polypropylene production and colorectal cancer.

Consequently medical surveillance programmes to detect colorectal cancer among polypropylene workers are not warranted.