Perfluoroalkyl acids (PFAAs) are persistent, ubiquitous environmental contaminants and their long-chain representatives are bioaccumulative. The phase-out of these compounds (e.g. PFOA and PFOS) shifted the production to alternatives. However, little is known about the bioaccumulative behaviour of the alternatives, which are still highly fluorinated. PFAAs are predominantly detected in blood, where they bind to the transport protein serum albumin. This sorption can be described by the albumin/water partition coefficient. It is unclear whether the partition coefficients of the alternatives are lower than or in the same range as those of classical PFAAs. We determined albumin/water partition coefficients for seven perfluoroalkyl carboxylates, three perfluoroalkane sulfonates and four alternatives by dialysis experiments in a physiologically representative system. Quantification was done by LC-MS/MS and a mass balance approach. Logarithmic albumin/water partition coefficients for PFAAs range from 2.8 to 4.8 [L_water kg_albumin ⁻¹] and increase with increasing chain length. Perfluorinated sulfonates sorb more strongly than their carboxylate counterparts. The albumin/water partition coefficients for the alternatives (HFPO-DA, DONA, 9Cl-PF3ONS and PFECHS) are in the same range as for classical PFAAs. Structural modifications such as the introduction of ether groups into the chain do not reduce sorption to albumin, whereas the chlorine atom in 9Cl-PF3ONS seems to even increase the sorption to albumin. We further investigated whether the sorption strength could be affected in the presence of medium- or long-chain fatty acids. Binding competition between medium-chain fatty acids and PFAAs appeared to be possible. However, the presence of physiologically more relevant long-chain fatty acids should not alter the albumin/water partition coefficients of PFAAs.

We investigated if maternal body burdens of perfluoroalkyl acids (PFAAs) at the time of delivery are associated with birth outcome and if early life exposure (in utero/nursing) is associated with early childhood growth and weight gain. Maternal PFAA body burdens were estimated by analysis of serum samples from mothers living in Uppsala County, Sweden (POPUP), sampled three weeks after delivery between 1996 and 2011. Data on child length and weight were collected from medical records and converted into standard deviation scores (SDS). Multiple linear regression models with appropriate covariates were used to analyze associations between maternal PFAA levels and birth outcomes (n=381). After birth Generalized Least Squares models were used to analyze associations between maternal PFAA and child growth (n=200). Inverse associations were found between maternal levels of perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), and perfluoroundecanoic acid (PFUnDA), and birth weight SDS with a change of -0.10 to -0.18 weight SDS for an inter-quartile range (IQR) increase in ng/g PFAA. After birth, weight and length SDS were not significantly associated with maternal PFAA. However, BMI SDS was significantly associated with PFOA, PFNA, and PFHxS at 3 and 4years of age, and with PFOS at 4 and 5years of age. If causal, these associations suggest that PFAA affects fetal and childhood body development in different directions.