Cancer Risk Among Tetrafluoroethylene Synthesis and Polymerization Workers

Abstract

Tetrafluoroethylene (TFE), a compound used for the production of fluorinated polymers including polytetrafluoroethylene, increases the incidence of liver and kidney cancers and leukemia in rats and mice. This is the first time the cancer risk in humans has been explored comprehensively in a cohort mortality study (1950-2008) that included all polytetrafluoroethylene production sites in Europe and North America at the time it was initiated. A job-exposure matrix (1950-2002) was developed for TFE and ammonium perfluoro-octanoate, a chemical used in the polymerization process. National reference rates were used to calculate standardized mortality ratios (SMRs) and 95% confidence intervals. Among 4,773 workers ever exposed to TFE, we found a lower rate of death from most causes, as well as increased risks for cancer of the liver (SMR = 1.27; 95% confidence interval: 0.55, 2.51; 8 deaths) and kidney (SMR = 1.44; 95% confidence interval: 0.69, 2.65; 10 deaths) and for leukemia (SMR = 1.48; 95% confidence interval: 0.77, 2.59; 12 deaths). A nonsignificant upward trend (P = 0.24) by cumulative exposure to TFE was observed for liver cancer. TFE and ammonium perfluoro-octanoate exposures were highly correlated, and therefore their separate effects could not be disentangled. This pattern of findings narrows the range of uncertainty on potential TFE carcinogenicity but cannot conclusively confirm or refute the hypothesis that TFE is carcinogenic to humans.

Mortality and cancer incidence in ammonium perfluorooctanoate production workers

“…A job-exposure matrix with annual semiquantitative estimates for TFE and PFOA were considered sufficient to identify relative differences in exposure to both compounds. Consonni et al 14 reported an SMR of 1.4 (95% CI 0.7 to 2.7) for kidney cancer in the cohort, but could not separate the effects of TFE and PFOA with kidney cancer in their exposure trend analyses. It is possible the results of Steenland and Woskie12 are similarly confounded by TFE.…”

“…Although PFOA and TFE exposures were highly correlated, Steenland and Woskie12 considered only PFOA in their analysis indicating that they assumed that TFE's volatile and explosive properties meant it would be well controlled under normal operations, and thus render appreciable exposure to it unlikely. By contrast, another evaluation of TFE synthesis and polymerisation workers (including 40% from the DuPont plant),14 23 reported potential TFE exposure occurring through leaks, opening autoclaves in the polymerisation area, or from decomposition of the polymer. A job-exposure matrix with annual semiquantitative estimates for TFE and PFOA were considered sufficient to identify relative differences in exposure to both compounds.…”

“…Tetrafluoroethylene (TFE) exposure was highly correlated with PFOA exposure, and TFE is a kidney carcinogen in rats 13. Consonni et al 14 examined the effect of this joint exposure of PFOA and TFE in a multiplant cohort study of TFE synthesis and polymerisation workers that included a sizable subset of workers from the DuPont Washington Works plant. Estimated units of exposure to TFE and PFOA were developed but were highly correlated, thus, the independent causal association of PFOA and TFE with kidney cancer could not be identified.…”

Perfluorinated Chemicals as Emerging Environmental Threats to Kidney Health

“…All but two studies were conducted in the United States (17,21), and all but one were cross-sectional, retrospective cohort, or ecological studies (25). In six studies, PFAS exposure was associated with increased mortality from kidney-related cancers (18)(19)(20)(21)(22)24); however, the strength of the association varied, with standardized mortality ratios ranging from 1.07 to 12.8 ( Figure 3).…”

Mortality study of employees at a chemical manufacturing plant using administrative databases

“…We believe that such results are of interest since they are based on a substantial number of cases (a total of 16 cases of stomach cancer and 8 cases of kidney cancer), and regard organs included by IARC as targets for various substances to which the cohort had been exposed: cadmium, arsenic, lead arsenates, trichloroethylene. A study on the long‐term effects of exposure in a cohort of 4,773 workers assigned to the production and/or use of tetrafluoroethylene (TFE) has recently been published; this also includes workers at the Fraschetta plant [Consonni et al, ]. The results of the mortality study highlighted increased risks—not statistically significant—for liver and kidney cancers, as well as leukemia; all such outcomes have been suggested by experimental studies [National Toxicology Program, ].…”