Risk to human health related to the presence of perfluorooctane sulfonic acid and perfluorooctanoic acid in food

Abstract

The European Commission asked EFSA for a scientific evaluation on the risks to human health related to the presence of perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) in food. Regarding PFOS and PFOA occurrence, the final data set available for dietary exposure assessment contained a total of 20,019 analytical results (PFOS n = 10,191 and PFOA n = 9,828). There were large differences between upper and lower bound exposure due to analytical methods with insufficient sensitivity. The CONTAM Panel considered the lower bound estimates to be closer to true exposure levels. Important contributors to the lower bound mean chronic exposure were 'Fish and other seafood', 'Meat and meat products' and 'Eggs and egg products', for PFOS, and 'Milk and dairy products', 'Drinking water' and 'Fish and other seafood' for PFOA. PFOS and PFOA are readily absorbed in the gastrointestinal tract, excreted in urine and faeces, and do not undergo metabolism. Estimated human half-lives for PFOS and PFOA are about 5 years and 2-4 years, respectively. The derivation of a health-based guidance value was based on human epidemiological studies. For PFOS, the increase in serum total cholesterol in adults, and the decrease in antibody response at vaccination in children were identified as the critical effects. For PFOA, the increase in serum total cholesterol was the critical effect. Also reduced birth weight (for both compounds) and increased prevalence of high serum levels of the liver enzyme alanine aminotransferase (ALT) (for PFOA) were considered. After benchmark modelling of serum levels of PFOS and PFOA, and estimating the corresponding daily intakes, the CONTAM Panel established a tolerable weekly intake (TWI) of 13 ng/kg body weight (bw) per week for PFOS and 6 ng/kg bw per week for PFOA. For both compounds, exposure of a considerable proportion of the population exceeds the proposed TWIs.

Keywords: BMD; PBPK; PFOA; PFOS; exposure; food; risk assessment.

Figure 1

Structure of PFOS/PFOA isomers discussed in this opinion (R = CF₂SO₃ (PFOS) or CO₂ (PFOA); R’ = SO₃)

Figure 2

Simplified figure illustrating biodegradation of certain groups of PFASs

Figure 3

Distribution of analytical results for PFOS and PFOA across different European countries

1. AT: Austria; BE: Belgium; CY: Cyprus; CZ: Czech Republic; DE: Germany; DK: Denmark; ES: Spain; FI: Finland; FR: France; GR: Greece; IE: Ireland; IT: Italy; MT: Malta; NO: Norway; SI: Slovenia; UK: United Kingdom; PFOA: perfluorooctanoic acid; PFOS: perfluorooctane sulfonic acid.

Figure 4

Distribution of analytical results for PFOS and PFOA divided by sampling year

1. PFOA: perfluorooctanoic acid; PFOS: perfluorooctane sulfonic acid.

Figure 5

Distribution of analytical results divided in quantified results and left‐censored data (results below the limit of detection (LOD)/limit of quantification (LOQ)) per substance and food category at FoodEx Level 1

Figure 6

Distribution of the LOQs for PFOS (a) and PFOA (b) across food categories after applying the LOQ cut‐offs (box‐plot showing whiskers at minimum and maximum, box at P25 and P75 with line at P50)

Figure C.1

Simulation of plasma PFOA concentration after chronic daily exposure (constant exposure) of 0.85 ng/kg bw per day of PFOA, which is an exposure that results in a steady‐state concentration of 9.4 ng/mL, corresponding to the BMDL ₅ (target concentration associated with an increase of total cholesterol from Steenland et al., 2009)

1. Estimations are from the PBPK model from Loccisano et al. (2011) (coded and simulated by Berkeley Madonna version 8.3.18).

Figure C.2

Simulation of plasma PFOS concentration after chronic daily exposure (constant exposure) of 1.8 ng/kg bw per day of PFOS, which is an exposure that results in a steady‐state concentration of 22 ng/mL, corresponding to the BMDL ₅ (target concentration associated with an increase of total cholesterol from Eriksen et al., 2013).

1. Estimations are from the PBPK model from Loccisano et al. (2011) (coded and simulated by Berkeley Madonna version 8.3.18).

Figure C.3

Simulation of PFOS plasma concentration resulting from chronic daily exposure to 1.8 ng/kg bw per day of PFOS from food after 6 months exclusive breastfeeding with milk (800 mL/day) containing 0.12 ng/mL of PFOS and a serum PFOS at birth of 2.6 ng/mL (corresponding to a mother's plasma PFOS concentration of 7.7 ng/mL, median of medians for adults from opinion), estimated from the PBPK model in Loccisano et al. (2011) with some modifications (coded and simulated by Berkeley Madonna version 8.3.18)

Figure C.4

Simulation of PFOS plasma concentration resulting from chronic daily exposure to 1.8 ng/kg bw per day of PFOS from food after 6 months exclusive breastfeeding with milk (800 mL/day) containing 0.33 ng/mL of PFOS and a serum PFOS at birth of 7.3 ng/mL (corresponding to a mother's plasma PFOS concentration of 22 ng/mL, BMDL ₅ in), estimated from the PBPK model in Loccisano et al. (2011) with some modifications (coded and simulated by Berkeley Madonna version 8.3.18)

Figure C.5

Growth equation based on a French survey, describing the increase in weight according to age, including 4,078 subjects, aged between 3 and 60 years, and 703 subjects of less than 3 years

Figure C.6

Structure of PBPK model for PFOA and PFOS in monkeys and humans from Loccisano et al. (2011)

1. PBPK: physiologically based pharmacokinetic (model); Kt: affinity constant; PFOA: perfluorooctanoic acid; PFOS: perfluorooctane sulfonic acid; Qs: blood flows into and out of tissues – where Qfil is not a blood flow, but is a clearance (L/h) from the plasma to the filtrate compartment; Tm: Transporter maximum.

Figure C.7

Simple one‐compartment model