Risk assessment of consumer spray products using in vitro lung surfactant function inhibition, exposure modelling and chemical analysis

Impact of tightening environmental regulations against long-chain perfluoroalkyl acids on composition of durable water repellents containing side-chain fluorinated polymers

Tightening of environmental regulations against long-chain perfluoroalkyl acids (PFAAs) since the 2000s may have led to significant increases in the occurrence of short-chain PFAAs in the environment. Understanding the impact of the regulations on composition of durable water repellents (DWRs) is imperative to guide implementation of pragmatic actions during their use and end-of-life treatment. Substantial decreases in the frequencies of detection and concentrations of long-chain PFAAs and long-chain PFAA-precursors, and substantial increases in those of short-chain PFAAs and short-chain PFAA-precursors, have been observed in the impurities and hydrolysis products of side-chain fluorinated polymers (SCFPs). Comparison of profiles among the DWRs containing fluorinated ingredients in 2011 indicated that DWRs containing C8F17- and C10F21-SCFPs were the dominant products and accounted for 90 % of the samples, whereas DWRs containing C4F9- and C6F13-SCFPs were the dominant products and accounted for 70 % of the samples collected in 2021. Tightening of the regulations have caused decreasing applications of long-chain SCFPs and increasing use of short-chain SCFPs in DWRs containing fluorinated ingredients. The ingredients of one DWR were changed from PFAS-free alternatives to short-chain SCFPs, whereas those of another DWR were changed from short-chain SCFPs to PFAS-free alternatives. The presence of unexplained extractable organic fluorine has been observed in DWRs containing fluorinated ingredients, which may be difficult to be hydrolyzed and form known compounds. A historical series of DWRs available from before and after the tightening of regulations and a multifaceted analytical technique consisting of combustion ion chromatographic and mass spectrometric approaches combined with two extraction techniques involving ultrasonic treatment and alkaline hydrolysis revealed the impact of tightening regulations on composition of DWRs.

The Underlying Mechanism of Poisoning after the Accidental Inhalation of Aerosolised Waterproofing Spray

Waterproofing sprays can cause acute respiratory symptoms after inhalation, including coughing and dyspnoea shortly after use. Here, we describe two cases where persons used the same brand of waterproofing spray product. In both cases the persons followed the instructions on the product and maximized the ventilation by opening windows and doors; however, they still became affected during the application of the product. Products with the same batch number as that used in one case were tested for their effect on respiration patterns of mice in whole-body plethysmographs and lung surfactant function inhibition in vitro. The product was used in spraying experiments to determine the particle size distribution of the aerosol, both using a can from one case and a can with an identical batch number. In addition, the aerosols in the mouse exposure chamber were measured. Aerosol data from a small-scale exposure chamber and data on the physical and temporal dimensions of the spraying during one case were used to estimate the deposited dose during the spraying events. All collected data point to the spraying of the waterproofing product being the reason that two people became ill, and that the inhibition of lung surfactant function was a key component of this illness.

Fluorine Mass Balance, including Total Fluorine, Extractable Organic Fluorine, Oxidizable Precursors, and Target Per- and Polyfluoroalkyl Substances, in Pooled Human Serum from the Tromsø Population in 1986, 2007, and 2015

Of the thousands of per- and polyfluoroalkyl substances (PFAS) known to exist, only a small fraction (≤1%) are commonly monitored in humans. This discrepancy has led to concerns that human exposure may be underestimated. Here, we address this problem by applying a comprehensive fluorine mass balance (FMB) approach, including total fluorine (TF), extractable organic fluorine (EOF), total oxidizable precursors (TOP), and selected target PFAS, to human serum samples collected over a period of 28 years (1986, 2007, and 2015) in Tromsø, Norway. While concentrations of TF did not change between sampling years, EOF was significantly higher in 1986 compared to 2007 and 2015. The ∑12PFAS concentrations were highest in 2007 compared to 1986 and 2015, and unidentified EOF (UEOF) decreased from 1986 (46%) to 2007 (10%) and then increased in 2015 (37%). While TF and EOF were not influenced by sex, women had higher UEOF compared to men, opposite to target PFAS. This is the first FMB in human serum to include TOP, and it suggests that precursors with >4 perfluorinated carbon atoms make a minor contribution to EOF (0-4%). Additional tools are therefore needed to identify substances contributing to the UEOF in human serum.

Risk assessment of the asthma-induction potential of substances in spray products for car cabin detailing - based on EU's Chemical Agents Directive, using harmonised classifications and quantitative structure-activity relationship (QSAR)

Exposure to spray-formulated products for car cabin detailing is a potential risk for asthma induction. With a focus on the asthma-related endpoints sensitisation and irritation of the lungs, we performed an occupational risk assessment based on requirements in the EU Chemical Agents Directive. We identified 71 such spray products available in Denmark. We identified ingredient substances in safety data sheets and screened for harmonised classifications of respiratory sensitisation and airway irritation. For respiratory sensitisation, we also applied quantitative structure-activity relationship (QSAR). We modelled the exposure during 15 min of work inside a car cabin, and determined the risk ratio of the products by further applying occupational exposure limits - mainly derived no-effect levels (DNELs) from the European Chemicals Agency (ECHA) set on respiratory irritation. Four substances had a harmonised classification for respiratory irritation (bronopol, 2-phenoxyethanol, 2-methoxypropanol, and butan-1-ol). Seven substances were positive in the QSAR model for respiratory sensitisation (monoethanolamine, bronopol, glycerol, methyl salicylate, benzoic acid, ammonium benzoate, and sodium benzoate). Two vinyl treatment products had a risk ratio > 1 based on the level of sodium benzoate and its DNEL set on respiratory irritation. Two products had risk ratios of 0.69 and 0.73, respectively, based on 2-methyl-2 H-isothiazol-3-one and its acute DNEL set on respiratory irritation. In conclusion, 10 substances that may pose a risk for asthma induction were identified in the products. Two of the 71 products had a risk ratio > 1, meaning they may pose an asthma-induction risk in the modelled exposure scenario and using respiratory irritation DNELs from ECHA.

Safety data sheets as an information pathway on hazards of occupationally used cleaning agents

To investigate consistency and accessibility of asthma and skin allergy hazard information in safety data sheets (SDSs) for cleaning agents on the Swedish market, we compiled a database of 504 SDSs and 351 therein declared ingredients. Labelling of products was compared to that of ingredients according to harmonised classification. For each ingredient, also notified classification and three additional sources on sensitising properties were compared. Product labelling most frequently indicated corrosion and irritation hazards. Only 3% of products were labelled as skin sensitisers and none as asthmagens. According to harmonised classification, 9% of products contained skin sensitisers, using other information sources increased the number to 46%. While 2% of products contained respiratory sensitisers according to harmonised classification, the number increased to 17% when using other information sources. Furthermore, sensitisers were declared across several sections of the SDSs, hampering easy access of such information. In conclusion, there are inconsistencies in hazard identification of cleaning agents and their ingredients. Hence, SDSs may not altogether fulfil its hazard information role. Improved criteria for identifying sensitisers and respiratory irritants are warranted. Additionally, we argue that all ingredients should be listed in section 3 regardless of concentration, to facilitate access of information about sensitising properties.

Lung surfactant as a biophysical assay for inhalation toxicology

Lung surfactant (LS) is a mixture of lipids and proteins that forms a thin film at the gas-exchange surfaces of the alveoli. The components and ultrastructure of LS contribute to its biophysical and biochemical functions in the respiratory system, most notably the lowering of surface tension to facilitate breathing mechanics. LS inhibition can be caused by metabolic deficiencies or the intrusion of endogenous or exogenous substances. While LS has been sourced from animals or synthesized for clinical therapeutics, the biofluid mixture has also gained recent interest as a biophysical model for inhalation toxicity. Various methods can be used to evaluate LS function quantitatively or qualitatively after exposure to potential toxicants. A narrative review of the recent literature was conducted. Studies focused whether LS was inhibited by various environmental contaminants, nanoparticles, or manufactured products. A review is also conducted on synthetic lung surfactants (SLS), which have emerged as a promising alternative to conventional animal-sourced LS. The intrinsic advantages and recent advances of SLS make a strong case for more widespread usage in LS-based toxicological assays.

Total oxidizable precursors assay for PFAS in human serum

Per- and polyfluoroalkyl substances (PFAS) are a class of chemicals including over 4700 substances. As a limited number of PFAS is routinely analyzed in human serum, complementary analytical methods are required to characterize the overlooked fraction. A promising tool is the total oxidizable precursors (TOP) assay to look for precursors by oxidation to perfluoroalkyl acids (PFAA). The TOP assay was originally developed for large volumes of water and had to be adapted for 250 μL of human serum. Optimization of the method was performed on serum samples spiked with model precursors. Oxidative conditions similar to previous TOP assay methods were not sufficient for complete oxidation of model precursors. Prolonged heating time (24 h) and higher oxidant amount (95 mg of Na₂S₂O₈ per 225 μL of serum) were needed for complete conversion of the model precursors and accomplishing PFAA yields of 35-100 %. As some precursors are not fully converted to PFAA, the TOP assay can only provide semi-quantitative estimates of oxidizable precursors in human serum. However, the TOP assay can be used to give indications about the identity of unknown precursors by evaluating the oxidation products, including perfluoroalkyl sulfonic acids (PFSA) and perfluoroalkyl ether carboxylic acids (PFECA). The optimized TOP assay for human serum opens the possibility for high-throughput screening of human serum for undetected PFAA precursors.