Annex D - Statement for use of the EFSA 2020 Opinion on the risks to human health related to the presence of perfluoroalkyl substances in food in UK risk assessments

Indoor air exposures

1.                 A literature search was carried out for concentrations of PFASs in air. There were only 2 studies for which indoor air samples had been measured for one or more of PFOS, PFOA, PFHxS and/or PFNA in homes. Tables 1 to 4 show the study information and dust concentrations for PFOS and PFOA, PFHxS and PFNA, respectively. Data for the branched and linear isomers of chemicals were summed to provide a single value.

Table 1. Concentrations of PFOS in indoor air (pg/m³) in UK and EU studies where samples were taken in homes, after 2008.

Values are given to 2 significant figures. SEM – standard error of the mean; LB - lower bound assigns the value of zero to non-quantified data; UB - upper bound assigns the value of the LOD/LOQ to non-quantified data; SD – standard deviation; 95% CI – 95th percent confidence interval; LOD – limit of detection; LOQ – limit of quantification.

Table 2. Concentrations of PFOA in indoor air (pg/m³) in UK and EU studies where samples were taken in homes, after 2008.

Values are given to 2 significant figures. SEM – standard error of the mean; LB - lower bound assigns the value of zero to non-quantified data; UB - upper bound assigns the value of the LOD/LOQ to non-quantified data; SD – standard deviation; 95% CI – 95th percent confidence interval; NC not calculated; LOD – limit of detection; LOQ – limit of quantification.

Table 3. Concentrations of PFHxS in indoor air (pg/m³) in UK and EU studies where samples were taken in homes, after 2008.

Values are given to 2 significant figures. SEM – standard error of the mean; LB - lower bound assigns the value of zero to non-quantified data; UB - upper bound assigns the value of the LOD/LOQ to non-quantified data; SD – standard deviation; 95% CI – 95th percent confidence interval; NC not calculated; LOD – limit of detection; LOQ – limit of quantification.

Table 4. Concentrations of PFNA in indoor air (pg/m³) in UK and EU studies where samples were taken in homes, after 2008.

Values are given to 2 significant figures. SEM – standard error of the mean; LB - lower bound assigns the value of zero to non-quantified data; UB - upper bound assigns the value of the LOD/LOQ to non-quantified data; SD – standard deviation; 95% CI – 95th percent confidence interval; LOD – limit of detection; LOQ – limit of quantification.

2.                 The maximum values from the datasets for PFOS (400 pg/m³) and PFOA (440 pg/m³) are both from the study by Goosey and Harrad (2012) and are approximately 3 - 4-fold the next highest values for each of the chemicals. Using these values in the exposure calculation is a conservative approach.

3.                 The exposure estimates are based on concentrations derived as an average of the median (Table 5) or maximum (Table 6) values reported in the literature.

Table 5. Concentrations derived (ng/g) as an average of the median values reported in the literature.

Concentrations are given to 2 sig. figs.

Table 6. Concentrations derived as an average of the maximum values reported in the literature.

Concentrations are given to 2 sig. figs.

4.                 Inhalation rates were taken from the EPA Exposure Factors Handbook (2011) Exposure Factors Handbook 2011 Edition (Final Report) | Science Inventory | US EPA. The number of age groups for which inhalation rates were provided was greater than the 6 population groups. The inhalation rates selected were those that covered much of the UK population group. Average bodyweights for the UK populations were calculated from NDNS (18 months – 95 years) and DNSIYC (4 – 18 months) data for different age groups. These are all shown in Table 7.

5.                 Exposures from inhalation were calculated for median and high concentrations of PFOS, PFOA, PFHxS and PFNA and mean inhalation rates, for each UK population group (Table 8).

Table 7. Dust ingestion rates and average UK bodyweights for UK population groups.

6.             For the average median PFASs concentrations in indoor air in homes, the following ranges of exposures were calculated for all UK population groups for each of the compounds (Table 8):

• PFOS (6.4 pg/m³): 0.0085 – 0.027 ng/kg bw per week
• PFOA (20 pg/m³): 0.027 – 0.083 ng/kg bw per week
• PFHxS (12 pg/m³): 0.016 – 0.050 ng/kg bw per week
• PFNA (2.4 pg/m³): 0.0032 – 0.010 ng/kg bw per week

7.                 For the average maximum PFASs concentrations in indoor air in homes, the following ranges of exposures were calculated for all UK population groups for each of the compounds (Table 8):

• PFOS (200 pg/m³): 0.27 – 0.83 ng/kg bw per week
• PFOA (270 pg/m³): 0.36 – 1.1 ng/kg bw per week
• PFHxS (220 pg/m³): 0.29 – 0.91 ng/kg bw per week
• PFNA (17 pg/m³): 0.023 – 0.070 ng/kg bw per week

8.                 For all PFASs considered, toddlers had the highest exposures via inhalation and seniors had the lowest exposures.

Table 8. Estimated exposures for PFOS, PFOA, PFHxS and PFNA (ng/kg bw per week) from indoor air for UK population groups (mean inhalation rates (m³/day).

Mean inhalation rates: infants 3.4 m³/day; toddlers 9.3 m³/day; children 12 m³/day; teenagers 17 m³/day; adults 16 m³/day and seniors 15 m³/day.

COT
October 2022
Statement Number 04/22

References

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Goosey E and Harrad S. (2012). Perfluoroalkyl substances in UK indoor and outdoor air: Spatial and seasonal variation, and implications for human exposure. Environment International. 45: 86-90.

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U.S. EPA. (2011). Exposure Factors Handbook 2011 Edition (Final Report). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-09/052F, 2011.
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