In response to the coronavirus (COVID-19) pandemic, there has been an increased need for personal and environmental decontamination to aid in curbing transmission of the SARS-CoV-2 virus. Products used for this purpose include sanitizers for hands and disinfectants for surfaces. The active chemical ingredients used in these products, termed antimicrobials, can enter waste streams after application and may be emerging as more prominent environmental contaminants. Even prior to COVID-19, there was recognized need to examine their implications for aquatic biota, which is now made more pressing due to their exaggerated use in response to the pandemic. Our objectives were to identify current antimicrobial active ingredients, quantify their increased use, and determine which may be candidates for further consideration as possible aquatic contaminants. By consulting multiple sources of publicly available information in Canada, we identified current-use antimicrobials from the lists of sanitizers and surface disinfectants approved for use against SARS-CoV-2 by Health Canada and the drug registration database. To estimate the use of sanitizers and disinfectants, we evaluated import quantities and grocery store retail sales of related compounds and products (Statistics Canada) and both lines of evidence supported increased use trends. The list of identified antimicrobials was refined to include only candidates with potential to reach aquatic ecosystems, and information on their environmental concentrations and toxicity to aquatic biota was reviewed. Candidate antimicrobials ( n = 32) fell into four main categories: quaternary ammonium compounds (QACs), phenols, acids, and salts. Benzalkonium chloride, a QAC, was the most prominent active ingredient used in both nonalcohol-based hand sanitizers and surface disinfectants. Four QACs followed in prevalence and the next most used antimicrobial was triclosan (hand sanitizers only), an established and regulated environmental contaminant. Little information was found on environmental concentrations of other candidates, suggesting that the majority would fall into the category of emerging contaminants if they enter aquatic systems. Several were classified as acutely or chronically toxic to aquatic biota (Globally Harmonized System), and thus we recommend empirical research begin focusing on environmental monitoring of all candidate antimicrobials as a critical next step, with detection method development first where needed.

A literature review of bioaccumulation and biotransformation of organic chemicals in birds was undertaken, aiming to support scoping and prioritization of future research. The objectives were to characterize available bioaccumulation/biotransformation data, identify knowledge gaps, determine how extant data can be used, and explore the strategy and steps forward. An intermediate approach balanced between expediency and rigor was taken given the vastness of the literature. Following a critical review of > 500 peer-reviewed studies, > 25,000 data entries and 2 million information bytes were compiled on > 700 organic compounds for ~ 320 wild species and 60 domestic breeds of birds. These data were organized into themed databases on bioaccumulation and biotransformation, field survey, microsomal enzyme activity, metabolic pathway, and bird taxonomy and diet. Significant data gaps were identified in all databases at multiple levels. Biotransformation characterization was largely fragmented over metabolite/pathway identification and characterization of enzyme activity or biotransformation kinetics. Limited biotransformation kinetic data constrained development of an avian biotransformation model. A substantial shortage of in vivo biotransformation kinetics has been observed as most reported rate constants were derived in vitro. No metric comprehensively captured all key contaminant classes or chemical groups to support broad-scope modeling of bioaccumulation or biotransformation. However, metrics such as biota-feed accumulation factor, maximum transfer factor, and total elimination rate constant were more readily usable for modeling or benchmarking than other reviewed parameters. Analysis demonstrated the lack of bioaccumulation/biotransformation characterization of shorebirds, seabirds, and raptors. In the study of bioaccumulation and biotransformation of organic chemicals in birds, this review revealed the need for greater chemical and avian species diversity, chemical measurements in environmental media, basic biometrics and exposure conditions, multiple tissues/matrices sampling, and further exploration on biotransformation. Limitations of classical bioaccumulation metrics and current research strategies used in bird studies were also discussed. Forward-looking research strategies were proposed: adopting a chemical roadmap for future investigations, integrating existing biomonitoring data, gap-filling with non-testing approaches, improving data reporting practices, expanding field sampling scopes, bridging existing models and theories, exploring biotransformation via avian genomics, and establishing an online data repository.

Polybrominated diphenyl ethers (PBDEs) are additive flame retardants that are environmentally persistent and bioaccumulative. The developmental effects of in ovo exposure to environmentally relevant levels of the PBDE technical mixture, DE-71, on male reproductive physiology in captive American kestrels (Falco sparverius) was determined. Males were exposed in ovo by direct maternal transfer to DE-71 at three mean concentrations of 289 ng/g ww (low exposure), 1131 ng/g ww (high-exposure), or background levels of 3 ng/g ww (control). As adults, males were paired with unexposed females for breeding and, 1 year later, sacrificed for testes evaluation. While breeding, high-exposure males demonstrated a trend of reduced circulating testosterone levels when their female mate commenced egg laying when compared with controls (p = 0.056). No differences in circulating free T₄ or T₃ were detected. Sperm numbers were elevated on the perivitelline layer of the first egg of both high- and low-exposure males when compared with controls (p = 0.021). High-exposure males had a higher gonadosomatic index (p = 0.046) and heavier right testis than controls (p = 0.034) with a similar trend for their left testis (p = 0.055). High-exposure males had more seminiferous tubules containing lumen than controls (p = 0.030), and in proportion to the total number of tubules, low-exposure males had more tubules containing lumen than did controls (p = 0.016). Only high-exposure males had fewer than half of tubules containing final spermatids (43%). The results of the present study demonstrate that embryonic exposure to technical DE-71 affects the reproductive tract of adult male kestrels.