Abstract
BackgroundPerfluoroalkyl acids (PFAAs) are a family of commonly used synthetic chemicals that have become widespread environmental contaminants. In human serum, perfluorohexane sulfonate (PFHxS), perflurooctane sulfonate (PFOS), and perfluorooctanoate (PFOA) are most frequently detected, in part owing to their long elimination half-lives of between 3.8 yrs (PFOA) and 8.5 yrs (PFHxS). These PFAAs also cross the placenta and have been associated with developmental toxicity, and some are considered likely human carcinogens. Interventions to eliminate PFAAs in highly contaminated individuals would reduce future health risks, but minimal research has been conducted on methods to facilitate accelerated human clearance of these persistent substances.MethodsSix patients with elevated serum concentrations from a single family were treated by intermittent phlebotomy over a 4–5 year period at intervals similar to, or less frequent than what is done for routine blood donation at Canadian Blood Services. The apparent elimination half-life (HLapp) for PFHxS, PFOS, and PFOA in this treated population was calculated in each patient and compared to the intrinsic elimination half-lives (HLin) from a literature reference population of untreated fluorochemical manufacturing plant retirees (n = 26, age >55 yrs).ResultsFor all three PFAAs monitored during phlebotomy, HLapp in each of the family members (except the mother, who had a low rate of venesection) was significantly shorter than the geometric mean HL measured in the reference population, and in some cases were even shorter compared to the fastest eliminator in the reference population.ConclusionThis study suggests significantly accelerated PFAA clearance with regular phlebotomy treatment, but the small sample size and the lack of controls in this clinical intervention precludes drawing firm conclusions. Given the minimal risks of intermittent phlebotomy, this may be an effective and safe clinical intervention to diminish the body burden of PFAAs in highly exposed people.
Highlights
Perfluoroalkyl acids (PFAAs) have had many historic commercial and industrial applications, including surface-treatment of furniture, carpets and clothing for stain resistance, packaging for food, mist suppression in metal plating, and in fluoropolymer manufacturing [1, 2]
For all three PFAAs monitored during phlebotomy, HLapp in each of the family members was significantly shorter than the geometric mean HL measured in the reference population, and in some cases were even shorter compared to the fastest eliminator in the reference population
For perfluorooctanoic acid (PFOA), all children were comparable to the 95th percentile (5 ng/ mL) at the beginning of the intervention, whereas the parents were comparable to the median (2.7 ng/mL) among Canadians
Summary
Perfluoroalkyl acids (PFAAs) have had many historic commercial and industrial applications, including surface-treatment of furniture, carpets and clothing for stain resistance, packaging for food, mist suppression in metal plating, and in fluoropolymer manufacturing [1, 2]. Human elimination half-life (HL), the time required for the amount of a chemical to be reduced by 50% in human serum, is commonly used to describe how fast, or slow, the human body can eliminate a specific compound [12] This parameter can be difficult to measure for persistent contaminants such as PFAAs [13] because of on-going exposure during the monitored elimination period, as well as fluctuations in body weight The apparent elimination half-life (HLapp) for PFHxS, PFOS, and PFOA in this treated population was calculated in each patient and compared to the intrinsic elimination half-lives (HLin) from a literature reference population of untreated fluorochemical manufacturing plant retirees (n526, age .55 yrs). Conclusion: This study suggests significantly accelerated PFAA clearance with regular phlebotomy treatment, but the small sample size and the lack of controls in PLOS ONE | DOI:10.1371/journal.pone.0114295 December 12, 2014
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