Microplastics (MPs) as an atmospheric pollutant are currently receiving widespread attention. Although atmospheric MPs have been extensively studied, due to different research methods, systematic comparisons of atmospheric MPs are still needed. This review critically reviewed the analytical methods, research status and potential human exposure. In this review, the detection principles, advantages and limitations of different visual and chemical analysis methods are reported, and the potential risks of MPs to the human are also introduced. Based on future research about the human risks, emphasized the importance of establishing standardized research methods.

Rare earth elements (REEs) are a group consisting of the following 17 metals: Ce, Dy, Er, Eu, Gd, Ho, La, Lu, Nd, Pr, Pm, Sc, Sm, Tb, Tm, Y and Yb. In the current century, the number of applications of REEs has significantly increased. They are being used as components in high technology devices of great importance industrial/economic. However, information on the risk of human exposure to REEs, as well as the potential toxic effects of these elements is still limited. In general terms, dietary intake is the main route of exposure to metals for non-occupationally exposed individuals, which should be also expected for REEs. The current paper aimed at reviewing the studies -conducted over the world- that focused on determining the levels of REEs in foods, as well as the dietary intake of these elements. Most studies do not suggest potential health risk for consumers of freshwater and marine species of higher consumption, or derived from the intake of a number of vegetables, fruits, mushrooms, as well as other various foodstuffs (honey, tea, rice, etc.). The current estimated daily intake (EDI) of REEs does not seem to be of concern. However, considering the expected wide use of these elements in the next years, it seems to be clearly recommendable to assess periodically the potential health risk of the dietary exposure to REEs. This is already being done with well-known toxic elements such as As, Cd, Pb and Hg, among other potentially toxic metals.

Substituted p-phenylenediamines (PPDs), a class of antioxidants, have been widely used to extend the lifespan of rubber products, such as tires and pipes. During use, PPDs will generate their quinone derivatives (PPD-Qs). In recent years, PPDs and PPD-Qs have been detected in the global environment. Among them, N-(1,3-dimethylbutyl)-N\'-phenyl-p-phenylenediamine quinone (6PPD-Q), the oxidation product of N-(1,3-dimethylbutyl)-N\'-phenyl-p-phenylenediamine (6PPD), has been identified as highly toxic to coho salmon, with the lethal concentration of 50 % (LC50) being 95 ng/L, highlighting it as an emerging pollutant of great concern. This review summarizes the physicochemical properties, global environmental distribution, bioaccessibility, potential toxicity, human exposure risk, and green measures of PPDs and PPD-Qs. These chemicals exhibit lipophilicity, bioaccumulation potential, and poor aqueous stability. They have been found in water, air, dust, soil, and sediment worldwide, indicating their significance as emerging pollutants. Notably, current studies have identified electronic waste (e-waste), such as discarded wires and cables, as a non-negligible source of PPDs and PPD-Qs, in addition to tire wear. PPDs and PPD-Qs exhibit strong bioaccumulation in aquatic organisms and mammals, with a tendency for biomagnification within the food web, posing health threats to humans. Available toxicity data indicate that PPDs and PPD-Qs have negative effects on aquatic organisms, mammals, and invertebrates. Acute exposure leads to death and acute damage, and long-term exposure can cause a series of adverse effects, including growth and development toxicity, reproductive toxicity, neurotoxicity, intestinal toxicity, and multi-organ damage. This paper discusses current research gaps and offers recommendations to understand better the occurrence, behavior, toxicity, and environmental exposure risks of PPDs and PPD-Qs.

Liquid crystal monomers (LCMs) are a class of emerging contaminants of concern predicted to be persistent, bioaccumulative and toxic (PBT). Being one of the key components in liquid crystal displays (LCDs), the disposal of LCD containing devices is closely related to the emission of LCMs into the environment. LCMs have been detected in a wide range of environmental matrices including dust, sediment, soil, sewage leachate, and air, with concentration ranges between 17 and 2121 ng/g found in indoor residential dust. Furthermore, they have been detected on human skin at concentrations up to 2,071,000 ng/m2 and in the serum of e-waste dismantling workers, at concentrations ranging from 3.9 to 276 ng/mL. Despite the far-reaching contamination of these compounds, there is limited knowledge of their environmental behaviour, fate, and toxicity. Model predictions show that 297 of 330 LCMs are persistent and bioaccumulative compounds, with many more indicated as being toxic. However, current knowledge of their physicochemical and PBT properties is largely restricted to theoretical predictions and limited to a small number of experimental toxicity studies. As an emerging class of contaminants of concern, a lack of standardisation between studies was identified as a key challenge to advancing the state of knowledge of these compounds. Not only are harmonised analytical methods for their determination and quantification in environmental media yet to be established, but there is also a need for a universal abbreviation system. To further harmonise the reporting of data on LCMs we propose reporting the sum concentration of ten priority LCMs, selected on the basis detection frequency, toxicity and potential for human exposure. Of the ten priority LCMs five are fluorinated biphenyls and analogues, four are biphenyls/bicyclohexyls and analogues and one is a cyanobiphenyl.

Micro(nano)plastics (MNPs) have been detected in various ecological environments and are widely used due to their stable properties, raising widespread concern about their potential human reproductive toxicity. Currently, infertility affects approximately 10-30% of couples of reproductive age globally. MNPs, as environmental pollutants, have been shown to exhibit reproductive toxicity through intrinsic mechanisms or as carriers of other hazardous substances. Numerous studies have established that MNPs of varying sizes and types can penetrate biological barriers, and enter tissues and even organelles of organisms through four main routes: dietary ingestion, inhalation, dermal contact, and medical interventions. However, historical research on the toxic effects of MNPs on reproduction mainly focused on lower and aquatic species. We conducted an inclusive review of studies involving terrestrial mammals, revealing that MNPs can induce reproductive toxicity via various mechanisms such as oxidative stress, inflammation, fibrosis, apoptosis, autophagy, disruption of intestinal flora, endocrine disruption, endoplasmic reticulum stress, and DNA damage. In terrestrial mammals, reproductive toxicity predominantly manifests as disruption in the blood-testis barrier (BTB), impaired spermatogenesis, sperm malformation, sperm DNA damage, reduced sperm fertilizing capacity, compromised oocyte maturation, impaired follicular growth, granulosa cell apoptosis, diminished ovarian reserve function, uterine and ovarian fibrosis, and endocrine disruption, among other effects. Furthermore, MNPs can traverse the maternal-fetal interface, potentially impacting offspring reproductive health. To gain a comprehensive understanding of the potential reproductive toxicity and underlying mechanisms of MNPs with different sizes, polymer types, shapes, and carried toxins, as well as to explore effective protective interventions for mitigating reproductive damage, further in-depth animal studies, clinical trials, and large-scale epidemiological studies are urgently required.

As a replacement for polybrominated diphenyl ethers (PBDEs), organophosphorus flame retardants (OPFRs) have been widely used and detected in different indoor environments all over the world. This paper comprehensively describes the concentration levels and distribution information of 11 kinds of OPFRs from 33 indoor dust and 10 air environments, from which TBOEP, TCIPP, and TDCIPP were observed to have higher concentrations in indoor environments. The ΣOPFRs displayed higher concentrations in indoor dust than in indoor air due to the higher molecular weight and vapor pressure of ΣOPFRs in building decoration materials, specifically for TCIPP and TDCIPP compounds. Considering that it is inevitable that people will be exposed to these chemicals in the indoor environments in which they work and live, we estimated their potential health risks through three human exposure pathways and found that the ingestion exposure to TBOEP for toddlers in Japan may reach up to 1270.80 ng/kg/day, which comprises a significant pathway compared to dermal contact and indoor air inhalation. Specifically, the combined total exposure to OPFRs by air inhalation, dust ingestion, and dermal contact was generally below the RfD values for both adults and toddlers, with a few notable higher exposures of some typical OPFRs.

Pollution of micro/nano-plastics (MPs/NPs) is ubiquitously prevalent in the environment, leading to an unavoidable exposure of the human body. Despite the protection of the blood-brain barrier, MPs/NPs can be transferred and accumulated in the brain, which subsequently exert negative effects on the brain. Nevertheless, the potential neurodevelopmental and/or neurodegenerative risks of MPs/NPs remain largely unexplored. In this review, we provide a systematic overview of recent studies related to the neurotoxicity of MPs/NPs. It covers the environmental hazards and human exposure pathways, translocation and distribution into the brain, the neurotoxic effects, and the possible mechanisms of environmental MPs/NPs. MPs/NPs are widely found in different environment matrices, including air, water, soil, and human food. Ambient MPs/NPs can enter the human body by ingestion, inhalation and dermal contact, then be transferred into the brain via the blood circulation and nerve pathways. When MPs/NPs are present in the brain, they can initiate a series of molecular or cellular reactions that may harm the blood-brain barrier, cause oxidative stress, trigger inflammatory responses, affect acetylcholinesterase activity, lead to mitochondrial dysfunction, and impair autophagy. This can result in abnormal protein folding, loss of neurons, disruptions in neurotransmitters, and unusual behaviours, ultimately contributing to the initiation and progression of neurodegenerative changes and neurodevelopmental abnormalities. Key challenges and further research directions are also proposed in this review as more studies are needed to focus on the potential neurotoxicity of MPs/NPs under realistic conditions.

Obesity represents an important public health concern, being one of the leading causes of death worldwide. It is a multifactorial disease with many underlying intertwined causes, including genetic, environmental and behavioral factors. Notably, metabolism-disrupting chemicals (MDCs) can alter the set point control of metabolism, affecting the development and function of the adipose tissue. Epidemiological studies have reported associations between human exposure to MDCs and several altered metabolic endpoints. It is also noteworthy that sex and gender represent important risk factors in the development of obesity. Different sex-related biological and physiological characteristics influence individual susceptibility, whereas gender represents a critical component in determining the different exposure scenarios. Although some advancements in the treatment of obesity have been achieved in preclinical and clinical studies, the obesity pandemic continues to increase worldwide. The present study performed a systematic review of recent studies considering the effects of MDCs on obesity, with a specific focus on sex- and gender-related responses. This review highlighted that MDCs could differently affect men and women at different stages of life even though the number of studies evaluating the association between obesity and MDC exposure in relation to sex and gender is still limited. This evidence should urge researchers to carry out studies considering sex and gender differences. This is essential for developing sex-/gender-tailored prevention strategies to improve public health policies and reduce exposure.

Pollution from plastic debris and microplastics (MPs) is a worldwide issue. Classified as emerging contaminants, MPs have become widespread and have been found not only in terrestrial and aquatic ecosystems but also within the food chain, which affects both the environment and human health. Since the outbreak of COVID-19, the consumption of single-use plastics has drastically increased, intensifying mismanaged plastic waste in countries such as Ecuador. Therefore, the aim of this review is to 1) summarize the state of MP-related knowledge, focusing on studies conducted with environmental matrices, biota, and food, and 2) analyze the efforts by different national authorities and entities in Ecuador to control MP contamination. Results showed a limited number of studies have been done in Ecuador, which have mainly focused on the surface water of coastal areas, followed by studies on sediment and food. MPs were identified in all samples, indicating the lack of wastewater management policies, deficient management of solid wastes, and the contribution of anthropogenic activities such as artisanal fishing and aquaculture to water ecosystem pollution, which affects food webs. Moreover, studies have shown that food contamination can occur through atmospheric deposition of MPs; however, ingredients and inputs from food production, processing, and packaging, as well as food containers, contribute to MP occurrence in food. Further research is needed to develop more sensitive, precise, and reliable detection methods and assess MPs\' impact on terrestrial and aquatic ecosystems, biota, and human health. In Ecuador specifically, implementing wastewater treatment plants in major cities, continuously monitoring MP coastal contamination, and establishing environmental and food safety regulations are crucial. Additionally, national authorities need to develop programs to raise public awareness of plastic use and its environmental effects, as well as MP exposure\'s effects on human health.

Benzophenone ultraviolet light filters (BPs) are high-production-volume chemicals extensively used in personal care products, leading to widespread human exposure. Given their estrogenic properties, the potential health risks associated with exposure to BPs have become a public health concern. This review aims to summarize sources and pathways of exposure to BPs and associated health risks. Dermal exposure, primarily through the use of sunscreens, constitutes a major pathway for BP exposure. At a recommended application rate, dermal exposure of BP-3 via the application of sunscreens may reach or exceed the suggested reference dose. Other exposure pathways to BPs, such as drinking water, seafood, and packaged foods, contribute minimal to the overall dose. Inhalation is a minor pathway of exposure; however, its contribution cannot be ignored. Human exposure to BPs is an order of magnitude higher in North America than in Asia and Europe. Studies conducted on laboratory animals and cells have consistently demonstrated the toxic effects of BP exposure. BPs are estrogenic and elicit reproductive and developmental toxicities. Furthermore, neurotoxicity, hepatotoxicity, nephrotoxicity, and carcinogenicity have been reported from chronic BP exposure. In addition to animal and cell studies, epidemiological investigations have identified associations between BPs and couples\' fecundity and other reproductive disorders, as well as adverse birth outcomes. Further studies are urgently needed to understand the risks posed by BPs on human health.