9 Toxicity to humans

Survey and environmental/health assessment of fluorinated substances in impregnated consumer products and impregnating agents

9.1 Biochemical effects
9.2 Cancer
9.3 Developmental toxicity

An old study of chemical plant workers exposed to fluorochemicals in the air (up to 3.9 mg/m³) for years showed that these workers had about 100 times higher levels of organic fluorine in their blood (1-71 mg/L serum) than people from the general population. However, no ill effects were attributable to exposure to these fluorochemicals. The half-life of PFOA in these workers was estimated to be 18-24 months (Ubel et al. 1980).

A recent investigation of 24 retired fluorochemical workers showed that the mean half-lives in human blood were 5.4 years for PFOS, 8.5 years for PFHxS, and 3.8 years for PFOA (Olsen et al. 2007a). The half-lives of the fluorinated chemicals in the general population, who is 10-100 times less contaminated than the retired workers, may be even longer.

The renal clearances of PFOA and PFOS are almost neglible in humans (Harada et al. 2005), which means that when these chemicals leave the blood a redistribution probably to internal organs such as the liver and kidneys will happen. The residence times in these organs are not known but must be very much longer.

9.1 Biochemical effects

Findings in animal studies suggest that PFOA affects hormonal states and metabolism of lipids in humans. However, no significant correlation has been observed between serum levels of PFOA (mean 5-7 mg/L) and any biological parameter in ammonium perfluorooctanoate plant workers (Olsen et al. 1998; 1999; 2000).

9.2 Cancer

A retrospective cohort mortality study of a perfluorooctane sulfonyl fluoride (PFOSF) production workforce reported an excess of bladder cancer based on 3 deaths (SMR 12.77) at high-exposure jobs (Alexander et al. 2003).

Workers at a PFOA production plant in the USA whose serum levels averaged 5 ppm had no excess of cancer mortality related to PFOA (Olsen et al. 2004). Olsen et al. (1998) concluded there was reasonable assurance of no substantial hormonal changes associated with PFOA at serum levels measured among these male production employees.

9.3 Developmental toxicity

In a study by Apelberg et al. (2007b) the relationship between PFOS and PFOA concentrations and gestational age, birth weight, and birth size was investigated, and the conclusions were that reductions of birth weight, ponderal index and of head circumference were associated with PFOS and PFOA concentrations among vaginal deliveries. A similar inverse association concerning maternal PFOA concentration and birth weight was found by Fei et al. (2007).