Response to Letter to the Editor on Bil et al. 2021 “Risk Assessment of Per‐ and Polyfluoroalkyl Substance Mixtures: A Relative Potency Factor Approach”

Bil, Wieneke; Zeilmaker, Marco J.; Fragki, Styliani; Lijzen, Johannes; Verbruggen, Eric; Bokkers, Bas

doi:10.1002/etc.5236

Cited by 7 publications

(17 citation statements)

References 13 publications

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“…Most of the existing guidelines and regulations focus on PFOA and PFOS. , The latest recommendation from the EFSA included four different PFAS to be considered, ignoring risks from other PFAS because of scarce toxicological data. Therefore, indicatively we also performed a preliminary risk assessment based on different RPFs proposed ,, (Table ). In the assessments, including 21-PFAS for Bil et al, 7-PFAS for Bil et al, and 7-PFAS for Rietjens et al, thus not incorporating ultrashort PFAS, all drinking waters produced from groundwater have PEQ lower than the EFSA safe level 3.7 ng/L.…”

Section: Resultsmentioning

confidence: 99%

“…For the human health risk assessment, the sum of the linear and branched isomers was considered for all investigated PFAS. The PFOA equivalent (PEQ) was calculated as described by Bil et al, 32 and based on the reported RPFs in three different studies 32,33,39 (list of RPFs provided in Table S2), summing all PEQ for PFAS and compared to the equivalent safe level of the EFSA of 3. The LOD was determined by using the average of the analyte concentration in the procedural blanks plus three times the standard deviation, and in the case of no detection of targeted PFAS in the procedure blank the LOD defined as the lowest point in the calibration curve.…”

Section: Data Analysis and Methods Validationmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Occurrence, Fate, and Related Health Risks of PFAS in Raw and Produced Drinking Water

Sadia

Nollen

Helmus

et al. 2023

Environ. Sci. Technol.

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This study investigates human exposure to per-and polyfluoroalkyl substances (PFAS) via drinking water and evaluates human health risks. An analytical method for 56 target PFAS, including ultrashort-chain (C2−C3) and branched isomers, was developed. The limit of detection (LOD) ranged from 0.009 to 0.1 ng/L, except for trifluoroacetic-acid and perfluoropropanoic-acid with higher LODs of 35 and 0.24 ng/L, respectively. The method was applied to raw and produced drinking water from 18 Dutch locations, including groundwater or surface water as source, and applied various treatment processes. Ultrashort-chain (300 to 1100 ng/L) followed by the group of perfluoroalkyl-carboxylic-acids (PFCA, ≥C4) (0.4 to 95.1 ng/L) were dominant. PFCA and perfluoroalkyl-sulfonic-acid (≥C4), including precursors, showed significantly higher levels in drinking water produced from surface water. However, no significant difference was found for ultrashort PFAS, indicating the need for groundwater protection. Negative removal of PFAS occasionally observed for advanced treatment indicates desorption and/or degradation of precursors. The proportion of branched isomers was higher in raw and produced drinking water as compared to industrial production. Drinking water produced from surface water, except for a few locations, exceed non-binding provisional guideline values proposed; however, all produced drinking waters met the recent soon-to-be binding drinking-water-directive requirements.

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Section: Resultsmentioning

confidence: 99%

Section: Data Analysis and Methods Validationmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Occurrence, Fate, and Related Health Risks of PFAS in Raw and Produced Drinking Water

Sadia

Nollen

Helmus

et al. 2023

Environ. Sci. Technol.

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“…In this paper, we did not consider the ratios of (AF-adjusted) RPs as RPFs, as sometimes used by the European Food Safety Authority (EFSA) [ 20 ], because this approach does not meet the conditions needed to derive unbiased relative potencies. To derive RPFs, several conditions must be met: (1) the same endpoint should be considered, (2) the dose response curves should be parallel (on log scale), (3) the compounds should not interact, i.e., dose addition applies, and (4) RPFs should be derived from experiments with (very) similar experimental setups to avoid differing setups and conditions that influence the derived potency differences [ 22 , 24 , 25 ]. The second condition is of importance because only when curves are parallel, the RPF is not dose-dependent, i.e., one and the same RPF can be applied to all doses of a compound to derive its equivalent reference compound dose.…”

Section: Introductionmentioning

confidence: 99%

Combined Exposure to Multiple Mycotoxins: An Example of Using a Tiered Approach in a Mixture Risk Assessment

Brand

Bokkers

Biesebeek

et al. 2022

Toxins

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Humans are exposed to mycotoxins on a regular basis. Exposure to a mixture of mycotoxins may, therefore, result in a combination of adverse effects, or trigger the same effects. This should be accounted for when assessing the combined risk of multiple mycotoxins. Here, we show the outcome of using different approaches in assessing the risks related to the combined exposure to mycotoxins. We performed a tiered approach using assessment groups with a common target organ (kidney, liver and haematologic system), or a common adverse effect (phenomenon) (reduced white blood cell count), to combine the exposure to mycotoxins. The combined exposure was calculated for the individuals in this assessment, using the Monte Carlo Risk Assessment (MCRA) tool. The risk related to this combined exposure was assessed using toxicological reference values, e.g., health based guidance values. We show that estimating the combined risk by adding the single compounds’ risk distributions slightly overestimates the combined risk in the 95th percentile, as compared to combining the exposures at an individual level. We also show that relative potency factors can be used to refine the mixture risk assessment, as compared to ratios of toxicological reference values with different effect sizes and assessment factors.

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“…The RPF method assumes that chemicals do not interact biologically with one another and contribute to a common effect—in this case, the relative liver weight increase in male rats. This assumption results in dose–response curves on a logarithmic scale 8 , 9 that are parallel for each chemical examined.…”

mentioning

confidence: 99%

Truth in the Serum? Estimating PFAS Relative Potency for Human Risk Assessment

Schmidt¹

2022

Environ Health Perspect

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Response to Letter to the Editor on Bil et al. 2021 “Risk Assessment of Per‐ and Polyfluoroalkyl Substance Mixtures: A Relative Potency Factor Approach”

Cited by 7 publications

References 13 publications

Occurrence, Fate, and Related Health Risks of PFAS in Raw and Produced Drinking Water

Occurrence, Fate, and Related Health Risks of PFAS in Raw and Produced Drinking Water

Combined Exposure to Multiple Mycotoxins: An Example of Using a Tiered Approach in a Mixture Risk Assessment

Truth in the Serum? Estimating PFAS Relative Potency for Human Risk Assessment

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