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Over 300 species of naturally occurring-organoarsenicals have been identified with the development of modern analytical techniques. Why there so many environmental organoarsenicals exist is a real enigma. Are they protective or harmful? Or are they simply by-products of existing pathways for non-arsenical compounds? Fundamental unanswered questions exist about their occurrence, prevalence and fate in the environment, metabolisms, toxicology and biological functions. This review focuses on possible answers. As a beginning, we classified them into two categories: water-soluble and lipid-soluble organoarsenicals (arsenolipids). Continual improvements in analytical techniques will lead to identification of additional organoarsenicals. In this review, we enumerate identified environmental organoarsenicals and speculate about their pathways of synthesis and degradation based on structural data and previous studies. Organoarsenicals are frequently considered to be nontoxic, yet trivalent methylarsenicals, synthetic aromatic arsenicals and some pentavalent arsenic-containing compounds have been shown to be highly toxic. The biological functions of some organoarsenicals have been defined. For example, arsenobetaine acts as an osmolyte, and membrane arsenolipids have a phosphate-sparing role under phosphate-limited conditions. However, the toxicological properties and biological functions of most organoarsenicals are largely unknown. The objective of this review is to summarize the toxicological and physiological properties and to provide novel insights into future studies. [ABSTRACT FROM AUTHOR]

Freshwater systems are vitally important, supporting diversity and providing a range of ecosystem services. In China, rapid urbanization (over 800 million urban population) has led to multiple anthropogenic pressures that threaten urban freshwater environments. Microplastics (<5 mm) result from intensive production and use of plastic materials, but their effects in urban freshwater environments remain poorly understood. Rising concerns over the ecological effects of microplastics have resulted in increased attention being given to this contaminant in Chinese freshwater systems. Some studies provide quantitative data on contamination loads, but in general relevant knowledge in freshwater environment remains narrow in China, and lacking adequate understanding of threshold levels for detrimental effects. Notably, non-standardized sample collection and processing techniques for point and non-point sources have hindered comparisons of contamination loads and associated risk. Meanwhile, legislative frameworks for managing microplastics in China remain in their infancy. This manuscript critically reviews what is known of the nature and magnitude of microplastic pollution in Chinese freshwater environments, and summarizes relevant Chinese legislation. It provides recommendations for improving the legislative framework in China and identifies research gaps that need to be addressed to improve management and regulatory strategies for dealing with microplastic pollution in Chinese urban freshwater environments. [ABSTRACT FROM AUTHOR]

Since the introduction of antibiotics into clinical practices in the 1940s, antibiotics have become an integral part of animal production to meet the increasing human demand for animal-derived foods. As a result, industrial-scale animal production has emerged as a hotspot for the evolution and dissemination of antibiotic resistance genes (ARGs), thereby potentially contributing to a looming public health crisis. The knowledge of ARGs in livestock systems has been greatly expanded with the recent development of rapid molecular tools. However, comprehensive reviews on ARGs in the animal industry and possible mitigation solutions are still lacking from a One Health perspective. Here we provide this review focusing on human health risks associated with the antimicrobial (antibiotic and metal) usages, ARGs in livestock animals and aquaculture systems in a One Health perspective to untangle the complexities of ARGs across animals, environments and humans. Specifically, this review covers (1) antimicrobials usages in the animal industry, (2) ARGs in animals affected by selective agents, (3) animal-to-human direct/indirect ARG transmission pathways, and (4) mitigation approaches. We highlighted the burden of using antimicrobials in animals for public and environmental health, and also the urgent needs for mitigating the spread of antibiotic resistance from the livestock and aquaculture industries. [ABSTRACT FROM AUTHOR]