Advancing noise management in aviation: Strategic approaches for preventing noise-induced hearing loss.

As urbanization and population growth escalate, the challenge of noise pollution intensifies, particularly within the aviation industry. This review examines current insights into noise-induced hearing loss (NIHL) in aviation, highlighting the risks to pilots, cabin crew, aircraft maintenance engineers, and ground staff from continuous exposure to high-level noise. It evaluates existing noise management and hearing conservation strategies, identifying key obstacles and exploring new technological solutions. While progress in developing protective devices and noise control technologies is evident, gaps in their widespread implementation persist. The study underscores the need for an integrated strategy combining regulatory compliance, technological advances, and targeted educational efforts. It advocates for global collaboration and policy development to safeguard the auditory health of aviation workers and proposes a strategic framework to enhance hearing conservation practices within the unique challenges of the aviation sector.

PFAS in Nigeria: Identifying data gaps that hinder assessments of ecotoxicological and human health impacts.

This review examines the extensive use and environmental consequences of Per- and Polyfluoroalkyl Substances (PFAS) on a global scale, specifically emphasizing their potential impact in Nigeria. Recognized for their resistance to water and oil, PFAS are under increased scrutiny for their persistent nature and possible ecotoxicological risks. Here, we consolidate existing knowledge on the ecological and human health effects of PFAS in Nigeria, focusing on their neurological effects and the risks they pose to immune system health. We seek to balance the advantages of PFAS with their potential ecological and health hazards, thereby enhancing understanding of PFAS management in Nigeria and advocating for more effective policy interventions and the creation of safer alternatives. The review concludes with several recommendations: strengthening regulatory frameworks, intensifying research into the ecological and health impacts of PFAS, developing new methodologies and longitudinal studies, fostering collaborative efforts for PFAS management, and promoting public awareness and education to support sustainable environmental practices and healthier communities in Nigeria.

A high-throughput analytical method for complex contaminant mixtures in biosolids.

Biosolids are rich in organic matter and other nutrients that contribute to environmental and agricultural sustainability by improving soil textural and biological properties and enhancing plant growth when applied to agricultural crops. Land application of biosolids encourages resource recovery and circumvents drawbacks associated with landfilling or incineration. However, biosolids contain numerous chemicals at trace levels, and quantitative analysis of such mixtures in this complex matrix is crucial for understanding and managing application risks. There are currently few analytical methods available that are capable of extracting and quantifying a large range of the emerging contaminants found in biosolids. In this study, a simplified, rapid, and robust method of analysis was developed and validated for a high-priority organic contaminant mixture of 44 endocrine disrupting compounds known to occur in biosolids. Analytes consisted of chemicals from many classes with a wide range of physiochemical properties (e.g., log Kow values from -1.4 to 8.9). The biosolids extraction and cleanup protocol was validated for 42 of the targeted compounds. The UPLC-MS2 parameters were validated for all 44 organic contaminants targeted for study. From the two batches of biosolids tested using this analytical method, most of the targeted contaminants (86%) were detected with 100% frequency at concentrations ranging from 0.036 to 10,226 µg/kg dw. Performance results highlighted that internal standards alone could not negate biosolids matrix effects; thus, internal standards and the standard addition method were used for residue quantification. This was the first study to detect and quantify 6PPD-q in biosolids, and the first to quantify lidocaine and 11 other chemicals in biosolids using a single analytical method. This method may be expanded for analysis of additional chemicals in biosolids and comparable matrices.

Evaluation of the Chronic Reproductive Toxicity of a Fluorine-Free Firefighting Foam and a Short-Chain Fluorinated Foam to Northern Bobwhite Quail (Colinus virginianus).

The development of fluorine-free firefighting foams has been proposed as a way to reduce the adverse environmental consequences of foams containing per- and poly-fluoroalkyl substances. While there are likely fewer environmental and ecological concerns with these new fluorine-free foams in terms of persistence and bioaccumulation, it is prudent to evaluate the ecotoxicity of these fluorine-free foam products given the absence of data. Oral chronic drinking water exposure studies on adult pairs of northern bobwhite quail (Colinus virginianus) were conducted with a short-chain fluorinated and a fluorine-free foam: Buckeye Platinum Plus C6 and National Foam Avio Green KHC, respectively, at three exposure concentrations (0.01%, 0.1%, and 0.25%). Adults were monitored for survival, growth, and reproductive output; and chicks were monitored for survival and growth. Growth parameters in adult quail were not affected by exposure to the Buckeye or Avio foam. However, liver lipid content was higher in adult males exposed to the Buckeye foam or the Avio foam at the highest exposure concentrations. Chicks were heavier and had higher growth rates after adult exposure to Avio at the highest exposure level (0.25%) and to Buckeye at the two lowest exposure levels but not at the highest exposure level. The two adverse reproductive effects observed from avian exposure to Buckeye were an increased percentage of cracked eggs and earlier arrested embryonic development. Similarly, chronic exposure to Avio also induced earlier arrested embryonic development. These results show that the fluorine-free foams tested did cause toxicity to bobwhite quail, but whether they pose a risk at contaminated sites requires further laboratory and field study and additional exposure data. Environ Toxicol Chem 2024;43:211-221. © 2023 SETAC.

Influence of methylation and demethylation on plant uptake of emerging contaminants.

Contaminants of emerging concern (CECs) as well as their transformation products (TPs) are often found in treated wastewater and biosolids, raising concerns about their environmental risks. Small changes in chemical structure, such as the addition or loss of a methyl group, as the result of methylation or demethylation reaction, may significantly alter a chemical's physicochemical properties. In this study, we evaluated the difference in accumulation and translocation between four CECs and their respective methylated or demethylated derivatives in plant models. Suspended Arabidopsis thaliana cell culture and wheat seedlings were cultivated in nutrient solutions containing individual compounds at 1 mg/L. The methylated counterparts were generally more hydrophobic and showed comparative or greater accumulation in both plant models. For example, after 1 h incubation, methylparaben was found in A. thaliana cells at levels two orders of magnitude greater than demethylated methylparaben. In contrast, the demethylated counterparts, especially those with the addition of a hydroxyl group after demethylation, showed decreased plant uptake and limited translocation. For example, acetaminophen and demethylated naproxen were not detected in the shoots of wheat seedlings after hydroponic exposure. Results from this study suggest that common transformations such as methylation and demethylation may affect the environmental fate of CECs, and should be considered to obtain a more comprehensive understanding of risks of CECs in the environment.

Acute Oral Toxicity of Nonfluorinated Fire-Fighting Foams to Northern Bobwhite Quail (Colinus virginianus).

Long-chain per- and poly-fluoroalkyl substances (PFAS) have been the active ingredients in firefighting foams for more than 50 years. Due to their extreme persistence, regulatory agencies are concerned about their potential adverse environmental and health impacts. Recently, nonfluorinated chemical constituents have been proposed for use in fire-fighting foams in an effort to reduce the potential negative impacts of PFAS on terrestrial and aquatic flora and fauna. However, it is important to also determine the potential ecotoxicity of these nonfluorinated foam products, because we have little toxicological information for many of them. In preparation for a chronic study, we conducted an acute (24-h) oral toxicity test in northern bobwhite quail (Colinus virginianus) using six different fluorine-free foams; five were commercial foams (BioEx ECOPOL A, Fomtec Enviro USP, National Foam Avio Green KHC, National Foam NFD 20-391, and Solberg Re-Healing Foam), and one was an experimental foam (NRL 502W). A short-chain PFAS-based foam (Buckeye Platinum Plus C6) was also evaluated for comparative purposes. Groups of five birds were initially pseudogavaged with a volume of each product corresponding to a "limit" (the highest exposure concentration expected to occur environmentally). Only one bird (1 of 35) died during the limit test, indicating that all seven products have an acute median lethal dose in adult quail at or above the limit (~1500 mg/kg body wt). Environ Toxicol Chem 2022;41:2003-2007. © 2022 SETAC.

Species- and Tissue-Specific Chronic Toxicity Values for Northern Bobwhite Quail (Colinus virginianus) Exposed to Perfluorohexane Sulfonic Acid and a Binary Mixture of Perfluorooctane Sulfonic Acid and Perfluorohexane Sulfonic Acid.

Per- and polyfluoroalkyl substances (PFAS) are globally distributed and present in nearly every environmental compartment. Characterizing the chronic toxicity of individual PFAS compounds and mixtures is necessary because many have been reported to cause adverse health effects. To derive toxicity reference values (TRVs) and conduct ecotoxicological risk assessments (ERAs) of PFAS-contaminated ecosystems for wildlife, species-specific PFAS chronic toxicity values (CTVs) are needed. The present study quantified PFAS residues from liver and eggs of birds chronically exposed to perfluorohexanoic acid (PFHxA) or a mixture of perfluorooctane sulfonate (PFOS) and PFHxA that produced a no-observable-adverse-effect level (NOAEL) and/or a lowest-observable-adverse-effectlevel (LOAEL). The CTVs we present are lower than those previously reported for birds and should be considered in future regulatory evaluations. From the estimated species- and tissue-specific PFAS CTVs, we found that PFOS and perfluorohexane sulfonate (PFHxS) were more bioaccumulative than PFHxA in avian tissues, but PFHxA was more toxic to reproducing birds than either PFOS or a PFOS:PFHxS mixture. We further determined that avian toxicity was not necessarily additive with respect to PFAS mixtures, which could have implications for PFAS ERAs. The PFAS LOAEL CTVs can be used to predict reproductive and possible population-level adverse health effects in wild avian receptors. Environ Toxicol Chem 2022;41:219-229. © 2021 SETAC.

Chronic Reproductive Toxicity Thresholds for Northern Bobwhite Quail (Colinus virginianus) Exposed to Perfluorohexanoic Acid (PFHxA) and a Mixture of Perfluorooctane Sulfonic Acid (PFOS) and PFHxA.

Terrestrial toxicology data are limited for comprehensive ecotoxicological risk assessment of ecosystems contaminated by per- and polyfluoroalkyl substances (PFAS) partly because of their existence as mixtures in the environment. This complicates logistical dose-response modeling and establishment of a threshold value characterizing the chronic toxicity of PFAS to ecological receptors. We examined reproduction, growth, and survival endpoints using a combination of hypothesis testing and logistical dose-response modeling of northern bobwhite quail (Colinus virginianus) exposed to perfluorohexanoic acid (PFHxA) alone and to PFHxA in a binary mixture with perfluorooctane sulfonic acid (PFOS) via the drinking water. The exposure concentration chronic toxicity value (CTV) representative of the lowest-observable-adverse effect level (LOAEL) threshold for chronic oral PFAS toxicity (based on reduced offspring weight and growth rate) was 0.10 ng/mL for PFHxA and 0.06 ng/mL for a PFOS:PFHxA (2.7:1) mixture. These estimates corresponded to an adult LOAEL average daily intake CTV of 0.0149 and 0.0082 µg × kg body weight-1 × d-1 , respectively. Neither no-observable-adverse effect level threshold and representative CTVs nor dose-response and predicted effective concentration values could be established for these 2 response variables. The findings indicate that a reaction(s) occurs among the individual PFAS components present in the mixture to alter the potential toxicity, demonstrating that mixture affects avian PFAS toxicity. Thus, chronic oral PFAS toxicity to avian receptors represented as the sum of the individual compound toxicities may not necessarily be the best method for assessing chronic mixture exposure risk at PFAS-contaminated sites. Environ Toxicol Chem 2021;40:2601-2614. © 2021 SETAC.

Species- and Tissue-Specific Avian Chronic Toxicity Values for Perfluorooctane Sulfonate (PFOS) and a Binary Mixture of PFOS and Perfluorohexane Sulfonate.

To further characterize avian toxicity to environmental levels of select per- and poly-fluoroalkyl substances (PFAS), we established species- and tissue-specific PFAS chronic toxicity values (CTVs) associated with a lowest-observable-adverse effect level (LOAEL) threshold previously established for northern bobwhite quail (Colinus virginianus) chronically orally exposed via drinking water to either perfluorooctane sulfonate (PFOS) or a simple PFAS mixture. Aided by advances in analytical techniques, the novel avian oral PFAS CTVs reported in the present study are lower than the previously reported toxicity reference values (TRVs) estimated for birds chronically exposed via feed. Thus, current avian PFOS TRVs may not be fully protective of wild avian populations at PFAS-impacted sites. Also, likely due to differences in bioavailability, bioaccessibility, and toxicokinetics among individual PFAS between oral exposure types, we found higher bioaccumulation factors in all assessed tissues from birds exposed via water versus feed. Thus, we propose that future characterization of chemical toxicity due to ingestion exposure initially include a full examination of all probable sources of oral exposure for the most accurate derivation of TRVs and a more complete picture of ecological risk. The avian PFAS LOAEL CTVs established in the present study can be modified with the use of uncertainty factors to derive site-specific avian TRVs for ecological risk assessment at PFAS-impacted sites. From differences observed in the behavior of PFOS when administered as either a single chemical or part of a binary mixture with perfluorohexane sulfonate (PFHxS), we verified that PFOS was absorbed and distributed differently when coadministered with PFHxS and that PFOS likely interacted with PFHxS differently among tissues, helping to explain the differences observed in avian toxicity between exposures. Environ Toxicol Chem 2021;40:899-909. © 2020 SETAC.

Chronic Reproductive Toxicity of Perfluorooctane Sulfonic Acid and a Simple Mixture of Perfluorooctane Sulfonic Acid and Perfluorohexane Sulfonic Acid to Northern Bobwhite Quail (Colinus virginianus).

Per- and poly-fluoroalkyl substances (PFAS) are a broad class of environmentally persistent chemicals that include thousands of potentially toxic synthetic organic molecules. Some PFAS have been shown to cause adverse health effects including decreased total cholesterol, birth weight, and reproductive success in laboratory animals; however, a lack of chronic toxicity data exists for PFAS in avian ecological receptors. The present study reports on the chronic toxicity of perfluorooctane sulfonic acid (PFOS) and a mixture of PFOS and perfluorohexane sulfonic acid (PFHxS) to northern bobwhite quail (Colinus virginianus) via oral exposure from drinking water. Female weight gain was adversely affected at an average daily intake (ADI) of 3.10 × 10-3 ± 0.15 × 10-3 mg PFOS:PFHxS (1.2:1) mixture × kg-1 body weight × d-1 . Successful liberation from the shell once pipped was adversely affected at an ADI of 2.45 × 10-3 ± 0.01 × 10-3 mg PFOS x kg-1 body weight × d-1 . These values are comparatively much lower than the current dietary avian toxicity reference value (TRV) derived from birds that were exposed via feed, suggesting the need for updated avian TRVs. Relationships between test chemical (PFOS) and test substance (PFOS:PFHxS) showed that PFOS and PFHxS have possible interacting effects in avian receptors and likely differing mechanisms of toxicity depending on chemical co-occurrence and dose. Both the single-chemical and mixture exposures produced similar and possibly additive toxicity values. Environ Toxicol Chem 2020;39:1101-1111. © 2020 SETAC.