Nonafluorobutane-1-sulfonic acid: toxicological studies and the removal method

Introduction

Nonafluorobutane-1-sulfonic acid, also known as Perfluorobutanesulfonic acid (PFBS;Figure 1), a short-chain alternative to perfluorooctanesulfonic acid (PFOS), is widely used in various products and is increasingly present in environmental media and human bodies. Its toxicological study in conceptus exposure and how to remove it from water were introduced.

Multi-omics reveal disturbance of glucose homeostasis in pregnant rats exposed to PFBS

Recent epidemiological findings have raised concerns about its potential adverse health effects, although the specific toxic mechanism remains unclear. This study aimed to investigate the metabolic toxicity of gestational Nonafluorobutane-1-sulfonic acid exposure in maternal rats. Pregnant Sprague Dawley (SD) rats were randomly assigned to three groups and administered either 3% starch gel (control), 5, or 50 mg/kg bw·d Nonafluorobutane-1-sulfonic acid. Oral glucose tolerance tests (OGTT) and lipid profiles were measured, and integrated omics analysis (transcriptomics and non-targeted metabolomics) was employed to identify changes in genes and metabolites and their relationships with metabolic phenotypes. The results revealed that rats exposed to 50 mg/kg bw·d Nonafluorobutane-1-sulfonic acid exhibited a significant decrease in 1-h glucose levels and the area under the curve (AUC) of OGTT compared with the starch group. Transcriptomics analysis indicated significant alterations in gene expression related to cytochrome P450 exogenous metabolism, glutathione metabolism, bile acid secretion, tumor pathways, and retinol metabolism. Differentially expressed metabolites (DEMs) were enriched in pathways such as pyruvate metabolism, the glucagon signaling pathway, central carbon metabolism in cancer, and the citric acid cycle. Co-enrichment analysis and pairwise correlation analysis among genes, metabolites, and outcomes identified several differentially expressed genes (DEGs), including Gstm1, Kit, Adcy1, Gck, Ppp1r3c, Ppp1r3d, and DEMs such as fumaric acid, L-lactic acid, 4-hydroxynonenal, and acetylvalerenolic acid. These DEGs and DEMs may play a role in the modulation of glucolipid metabolic pathways. In conclusion, our results suggest that gestational exposure to Nonafluorobutane-1-sulfonic acid may induce molecular perturbations in glucose homeostasis. These findings provide insights into the potential mechanisms contributing to the heightened risk of abnormal glucose tolerance associated with Nonafluorobutane-1-sulfonic acid exposure.[1]

Toxicological Study on Preconception Exposure to Nonafluorobutane-1-sulfonic acid

In previous studies, preconception exposure to perfluorooctanesulfonic acid (PFOS) and nonafluorobutane-1-sulfonic acid reduced the reproductive capacity and altered the development of the offspring of C. elegans. However, the specific pathways involved in these observations were not determined. Thus, we investigated how preconception exposure to PFOS (40 μM) and nonafluorobutane-1-sulfonic acid (2000 μM) affected embryonic nutrient loading and offspring development. Preconception exposure to 40 μM PFOS significantly reduced nutrient loading to embryos via vit-6 (vitellogenin) and rme-2 (low-density lipoprotein particle receptor). The insulin/insulin-like growth factor signaling pathway (IIS), daf-2 (homolog of human insulin receptor precursor) and daf-16 (homolog of human forkhead box O) played a role in altering the reproductive capacity caused by preconception exposure to PFOS. Preconception exposure to nonafluorobutane-1-sulfonic acid did not affect nutrient loading but reduced reproductive health via IIS as well as nhr-49 (homolog of human hepatocyte nuclear factor 4α). In addition, preconception exposure to PFOS or nonafluorobutane-1-sulfonic acid resulted in no multigenerational effects on the reproductive health of F1 offspring worms. Preconception exposure to PFOS disrupted parental nutrient production and loading, reproduction, and offspring development, while nonafluorobutane-1-sulfonic acid impaired lipid metabolism and offspring development at higher doses than PFOS.[2]

Comparison of the toxicokinetic behavior of PFHxA and PFBS in cynomolgus monkeys and rats

The toxicokinetics of perfluorohexanoic acid (PFHxA) and nonafluorobutane-1-sulfonic acid(PFBS) were evaluated in Sprague-Dawley rats and cynomolgus monkeys. Systemic exposure to PFHxA was lower than for nonafluorobutane-1-sulfonic acid following single equivalent intravenous or oral (rat only) doses. Serum clearance was more rapid for PFHxA than for PFBS. In rats, exposure to PFHxA and Nonafluorobutane-1-sulfonic acid was up to 8-fold (intravenous) and 4-fold (oral) higher for males than females and serum clearance of PFHxA and PFBS was more rapid in females than males; however, there was no appreciable difference in the extent or rate of urinary elimination between compounds or genders. There were no apparent differences between genders in the serum half-life for PFHxA following 26 days of repeated oral dosing in rats; exposure decreased upon repeated dosing.[3]

The removal method of nonafluorobutane-1-sulfonic acid from water bodies

To address the removal of nonafluorobutane-1-sulfonic acid from water bodies, researchers focused on the cultivation of PFBS-degrading microorganisms, the preparation and characterization of high-temperature pyrolysis peanut shell biochar, and its immobilized microbial composite material. It compared and analyzed the adsorption kinetics and adsorption isotherm curve fitting results of biochar samples and explored the removal effects of high-temperature pyrolysis biochar, microbes, and composite materials on nonafluorobutane-1-sulfonic acid in water under different influencing factors. Researchers  also analyzed the mechanism of action and strengthened the nonafluorobutane-1-sulfonic acid treatment effect in artificial wetland test columns,providing new technological ideas for PFAS governance in water environments. 

(1) High-temperature pyrolysis peanut shell biochar was prepared. Results found that with the increase of pyrolysis temperature, the specific surface area of biochar samples increased, the pore structure became richer, the carbonization degree increased, and the hydrophobicity, aromaticity, and stability also correspondingly increased, with great potential for the removal of organic pollutants. 

(2) The adsorption test results showed that the prepared biochar samples could efficiently remove low-concentration nonafluorobutane-1-sulfonic acid from water. Under a solid-liquid ratio of 0.4g/L, the removal rate of biochar samples for nonafluorobutane-1-sulfonic acid at concentrations from 1 μg/L to 500μg/L could reach more than 99.99%. Equilibrium was reached within 24 hours, and the adsorption kinetics process followed the pseudo-second-order kinetic model, mainly controlled by chemical adsorption, with a maximum adsorption capacity of 39.03 mg/g.Increasing the amount of biochar added and decreasing the initial pH value of the solution could improve the removal rate of PFBS. Under the same conditions, high-temperature pyrolysis biochar prepared at a temperature of 900 °C (B900) had the best nonafluorobutane-1-sulfonic acid removal effect, the widest applicable pH range, and could serve as an ideal microbial immobilization carrier and nonafluorobutane-1-sulfonic acid absorbent. 

(3) Domesticated Pseudomonas aeruginosa can degrade a small amount of nonafluorobutane-1-sulfonic acid in solution without any other carbon sources. When glucose is added as a carbon source,the removal rate of PFBS after 24 days is 19.6%. Increasing the dissolved oxygen content of the reaction system enhances the co-removal of nonafluorobutane-1-sulfonic acid by B900 and microorganisms, and after 24 days, the removal rate reaches 97.89%. The high-temperature pyrolysis biochar immobilized Pseudomonas aeruginosa composite material (B9-Pa) is prepared by adsorption method. The surface of B900 has a biofilmand a large number of active bacteria. It mainly uses the hydrophobicity of B900 to quickly adsorb and the synergistic effect of microorganisms to defluorinate and degrade PFBS, which has significant advantages in the treatment of water environment contaminated by nonafluorobutane-1-sulfonic acid.

(4) The experimental column of B900 and B9-Pa was used to treat PFBS-containing sewage in an artificial wetland. The results showed that the addition of the B900 experimental column had little effect on the concentration of PFBS in the effluent,which was affected by the retention time and dissolved organic matter.  Using B900 and B9-Pa as the substrate fillers of the artificial wetland to treat nonafluorobutane-1-sulfonic acid in the water body, the optimal retention time of the solution is recommended to be 2 days, and the removal rate can exceed 99.38%.[4]

References

[1] Yu G ,Luo T ,Liu Y , et al.Multi-omics reveal disturbance of glucose homeostasis in pregnant rats exposed to short-chain perfluorobutanesulfonic acid.[J].Ecotoxicology and environmental safety,2024,278116402-116402.DOI:10.1016/J.ECOENV.2024.116402.

[2] Li S ,Yue Y ,Qian Z , et al.Preconception exposure to perfluorooctanesulfonic acid (PFOS) and perfluorobutanesulfonic acid (PFBS) impaired reproduction via insulin/insulin-like growth factor signaling pathway without effects on the second generation in Caenorhabditis elegans[J].Toxicology Reports,2025,14101966-101966.DOI:10.1016/J.TOXREP.2025.101966.

[3] Chengelis CP, Kirkpatrick JB, Myers NR, Shinohara M, Stetson PL, Sved DW. Comparison of the toxicokinetic behavior of perfluorohexanoic acid (PFHxA) and nonafluorobutane-1-sulfonic acid (PFBS) in cynomolgus monkeys and rats. Reprod Toxicol. 2009;27(3-4):400-406. doi:10.1016/j.reprotox.2009.01.013

[4] Zu YX.Removal of Perfluorobutanesulfonic Acid in Water by High-temperature Pyrolysis Biochar Immobilized Microorganism[D].Chongqing Jiaotong University,2023.DOI:10.27671/d.cnki.gcjtc.2023.000220.

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