Acute and Chronic Toxicity of Non-fluorinated Fire Fighting Foams to Northern Bobwhite Quail (Colinus virginianus)

Date
2023-12
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Abstract

Concerns surrounding the environmental and health implications of traditional fluorine-based firefighting foams, particularly those containing per- and polyfluoroalkyl substances (PFAS), have prompted the development of potentially safer alternatives. This study offers an assessment of both short-chain fluorine-based and fluorine-free firefighting foams, with a specific focus on their impact on avian health. We evaluated six commercially available fluorine-free foams (BioEx ECOPOL A, Fomtec Enviro USP, National Foam Avio Green KHC, National Foam NFD 20-391, Solberg Rehealing Foam, and NRL 502W), alongside one short-chain fluorine-based foam (Buckeye Platinum Plus C6) supplied by The Strategic Environmental Research and Development Program (SERDP), ER 20-1531. Our investigation commenced with an acute (24-h) oral toxicity test using northern bobwhite quail (Colinus virginianus) by an up-and-down procedure, resulting all seven products exhibiting acute median lethal doses in adult quail at or above the established limit (~ 1500 mg/kg body weight). Following the acute assessment, we conducted a short water avoidance test using Buckeye Platinum Plus C6 to determine appropriate exposure levels for subsequent chronic toxicity experiments on the same avian species. The individual chronic reproductive toxicity studies involved six foams, including Buckeye Platinum Plus C6 (for reference), National Foam Avio Green KHC, Solberg Rehealing Foam, National Foam NFD 20-391, BioEx ECOPOL A, and NRL 502W, administered at exposure levels of 0.01%, 0.1%, and 0.25% to adult quail. The objectives were to evaluate adult survival, growth, and reproductive output of quail following chronic oral exposure via drinking water to firefighting foams, to observe hatching success, chick survival and growth from parental exposure to firefighting foams, to characterize the test chemicals and correlate their ADI (average daily intake) with reproductive and health effects data, and attempt to measure the constitutive chemicals of the foams in adult and juvenile livers and eggs. The adult quail survival rate reached 100% for Buckeye, Solberg, NFD, and BioEx foams, while NRL and Avio foams showed a similar high (94%) survival rate. Notably, our study did not observe any statistically significant treatment-related effects in terms of alterations in adult body weight, growth rates, egg production by adult quail, hatching success, or juvenile survival rates across the various treatment groups for these seven foams when compared to their respective control groups. However, certain specific effects were observed. In the case of Buckeye foam, the highest and significantly different number of cracked eggs occurred at the 0.25% exposure concentration, with a corresponding LOAEL (lowest observed adverse effect level) ADI of 407 ± 24 mg Buckeye foam/kg body weight/day. This finding corresponded to an ADI for PFHxA (a major component of Buckeye foam) of 1.3 x 10-3 mg/kg body weight/day. Chronic exposure to Buckeye, Avio, and NRL foams resulted in earlier arrested embryonic development, occurring at the lowest exposure level (0.01%) for Buckeye foam (LOAEL ADI = 14.1 ± 0.6 mg foam/kg body weight/day) and Avio foam (LOAEL ADI = 14.5 ± 2.3 mg foam/kg body weight/day), and at the 0.1% level for NRL foam (ADI = 154 ± 2.4 mg foam/kg body weight/day). Moreover, the study observed that adult relative liver weight, lipid content in both adult and juvenile livers, and chick growth parameters were affected by the formulated foams, with these effects varying in intensity across different foam concentrations. To ensure the accuracy of our assessments, it was imperative to employ analytical techniques capable of verifying dosing solutions, exposure concentrations, whole-body burdens, and tissue burdens accurately. It's worth noting that safety data sheets may or may not contain specific information regarding the chemical ingredients and their concentrations, mainly due to the proprietary nature of many foam formulations. The short-chain PFAS-based foam, Buckeye Platinum Plus C6, was analyzed for the presence of specific chemicals, including perfluorobutanoic acid (PFBA) and perfluorohexanoic acid (PFHxA). On the other hand, sodium dodecyl sulfate (SDS), N,N-dimethyldodecylamine N-oxide, diethylene glycol monobutyl ether (DGMBE), and hexylene glycol constituted the primary ingredients of the fluorine-free foams used in this study. Notably, these substances have a history of application as surfactants in a wide range of household, commercial, and industrial cleaning products, as well as in personal care items, cosmetics, and pharmaceuticals. Importantly, they are characterized by high biodegradability, non-carcinogenic properties, low toxicity, and minimal bioaccumulation potential. In our efforts to analyze the marker constituents of these foams in the livers and egg tissues of adult and 21-day-old quail, we focused on measuring the levels of PFBA, PFHxA, SDS, and DGMBE. Results revealed that PFBA was below the detection limit in all adult and juvenile livers and egg samples exposed to Buckeye Platinum Plus C6 at concentrations of 0.01%, 0.1%, and 0.25%. PFHxA, while detectable, remained below the limit of quantification in some juvenile livers and egg samples. Significant variations in the content of sodium dodecyl sulfate (SDS) were observed in different experimental conditions. In particular, a statistically significant increase in SDS levels was noted in adult female livers exposed to 0.1% Buckeye foam (p = 0.03). The most substantial and statistically significant SDS accumulation was observed in the livers of female quail exposed to Avio foam at the 0.25% concentration (p < 0.001). Additionally, juvenile quiver livers and eggs also displayed marked increases in SDS content (p < 0.001) in response to Avio foam exposure. Contrastingly, while the SDS content in the livers of adult males and females exposed to the Solberg foam did not exhibit significant treatment effects, juvenile livers displayed a consistent and statistically significant reduction in SDS content (p = 0.007) across all three foam concentrations, attributable to parental exposure. Furthermore, the SDS content in eggs was significantly influenced by the treatments (p < 0.001), with the highest concentration group displaying the most substantial increase (p < 0.001). A distinct pattern emerged with adult male livers exposed to 0.25% NFD foam, as they showed a statistically significant elevation in SDS content (p = 0.004). These treatment effects extended to the SDS content of NFD foam-exposed eggs (p < 0.001). Regarding the presence of specific foam constituents, although the SDS content in BioEx-treated adult male and female livers and juvenile livers did not exhibit treatment effects across all three concentrations due to parental exposure, it is noteworthy that significant differences in SDS content among the treatment groups were observed in eggs (p < 0.001), particularly in the highest concentration group (p < 0.001). These findings highlight the complexity of SDS accumulation patterns in response to foam exposure, with varying impacts across different foam types and concentrations. Significant findings emerged regarding the accumulation of diethylene glycol monobutyl ether (DGMBE) in various study groups. Specifically, in the Avio 0.1% treatment group, adult male livers (p = 0.016) and juvenile livers from the Avio 0.01% and 0.1% groups (p < 0.001) showed the highest and statistically significant DGMBE accumulation. Notably, DGMBE levels in Avio-treated eggs exhibited a gradual increase with escalating exposure concentrations, with a statistically significant amount observed in the Avio 0.25% group (p < 0.001). In the case of NFD foam exposure, both adult male and female livers exhibited significant treatment effects in DGMBE content (p < 0.001), with parental exposure also contributing to treatment effects in juvenile livers (p < 0.001). Remarkably, DGMBE levels in NFD-treated eggs displayed a gradual increase with increasing exposure concentrations, reaching statistical significance in the NFD 0.25% group (p < 0.001). Conversely, DGMBE content in adult and juvenile livers due to parental exposure to BioEx foam showed insignificant variations. However, a notable finding was the significant DGMBE content observed in eggs obtained from the BioEx 0.25% group (p < 0.001). These findings underscore the intricate nature of SDS and DGMBE accumulation patterns in response to foam exposure, with diverse effects observed across various foam types and concentrations. This study offers vital avian ecotoxicity data, which carries substantial implications for risk assessment. It emphasizes the necessity for further investigations into the potential environmental repercussions linked to the adoption of fluorine-free firefighting foam alternatives, particularly regarding their influence on avian species and ecosystems.

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Keywords
Fluorine-free firefighting foam, short-chain fluorinated foam, northern bobwhite quail, avian toxicity, ecotoxicology, risk assessment
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