Journal of Toxicology and Environmental Health-Part B-Critical Reviews最新文献

Field studies involve combinations of exposure, natural dynamics, and effects in natural and agricultural environments. To be more realistic, field studies focussed on pollinating insects must consider the details of biology, life history, behavior, and pollination ecology of the test species. While expensive and time-consuming, these tests provide the most realistic information, especially for social insects, but are valuable for solitary bee species as well. They are more realistic than laboratory studies because they determine the combined effects of natural stressors including weather, food availability, parasites, and pathogens with anthropogenic stressors, such as the pesticide treatment itself, within agroecosystem landscapes. Twenty-four field studies conducted with bees to support the registration of sulfoxaflor and published work are included, and a standardized rating system for the quality and relevance of the studies was used. The studies included Apis mellifera L., Bombus terrestris L., and Osmia bicornis L. The results show that, when SFX products are applied at the highest labeled application rate with bees actively foraging or fed in syrup at equivalent rates, the effects are minor and temporary. Sublethal effects included lethargy, disorientation, and reduced body mass at emergence. No new modes of action and no treatment-related effects on brood rearing were found.

Effects of sulfoxaflor (SFX) on aquatic invertebrates were assessed by comparing concentrations predicted to occur in or measured in surface waters to thresholds for adverse effects. Due to the specific mode of toxic action, fishes are relatively tolerant of the effects of SFX. Daphnia magna with an LC₅₀ of 378 mg SFX L^-1 (SD = 19.13) was similarly tolerant of the effects of SFX, while the LOEC was > 110 mg SFX L^-1. A threshold for effects on aquatic insects, based on the chironomid midge, C. tentans, had LOAEL and NOAEL values of 0.0455 and 0.0618 mg L^-1, respectively. The acute-to-chronic ratio was 18. Simulation models and parameters selected for a range of applications to crops predicted environmental concentrations (EECs) in surface waters to range from 2.2 to 7.7 µg L^-1. Based on these EECs, the maximum hazard quotient (HQ) was 0.11, which is less than the US EPA level of concern (LOC) of 0.5, which would normally be the threshold to trigger regulatory action or higher-tier assessments. The risks posed by SFX to aquatic organisms are predicted to be de minimis. Hazard quotients based on EEC values predicted in the standard, USEPA farm pond estimated by use of the Pesticides in Water Calculator (PWC version 1.52) for scenarios of maximum application rates for cotton and LOAEL and NOAEL values for aquatic insects for SFX were less than or similar to those for other insecticides including neonicotinoids and organophosphorus compounds.

Neutrophils are the most abundant leukocytes in humans and essential for innate immune responses despite a short lifespan in the bloodstream. A complex and tightly regulated production of neutrophils is required to maintain host defense. This process involves intricate signaling between the bone marrow, blood, and tissue clearance. Deficiency or excessive neutrophil infiltration impairs host defenses. Historically, neutrophils were viewed as initial effectors in innate immune responses. Recent discoveries have expanded our understanding of neutrophil biology, identifying multiple activation states and subsets. These subsets may switch phenotypes based on the composition of the microenvironment and might exhibit reverse migratory behavior, moving from inflamed tissues back into the bloodstream. This versatility poses neutrophils as key players in (1) signaling for host defenses, (2) trained immunity, (3) tissue repair, and (4) cancer biology. Disturbances in neutrophil production, responsiveness, apoptosis, and cell removal significantly affect inflammatory diseases and cancer progression. Environmental factors may directly affect the immune system and trigger the onset of many diseases; however, the precise mechanisms underlying the impact of xenobiotics on neutrophil production and functions remain unclear. This review aimed to summarize the current knowledge on neutrophil ontogeny, plasticity, and roles in inflammation, tissue repair, and cancer, emphasizing their susceptibility to different sources of xenobiotic exposures.

Air pollution exposure is ranked as a leading environmental risk factor for not only cardiopulmonary diseases but also for systemic health ailments including diabetes, reproductive abnormalities, and neuropsychiatric disorders, likely mediated by central neural stress mechanisms. Current experimental evidence links many air pollution health outcomes with activation of neuroendocrine sympathetic-adrenal-medullary and hypothalamic-pituitary-adrenal (HPA) stress axes associated with resultant increases in adrenal-derived hormone levels acting as circulating mediators of multi-organ stress reactions. Epidemiological and experimental investigations also demonstrated sex-specific responses to air pollutant inhalation, which may be attributed to hormonal interactions within the stress and reproductive axes. Sex hormones (androgens and estrogens) interact with neuroendocrine functions to influence hypothalamic responses, subsequently augmenting stress-mediated metabolic and immune changes. These neurohormonal interactions may contribute to innate sex-specific responses to inhaled irritants, inducing differing individual susceptibility. The aim of this review was to: (1) examine neuroendocrine co-regulation of the HPA axis by gonadal hormones, (2) provide experimental evidence demonstrating sex-specific respiratory and systemic effects attributed to air pollutant inhalation exposure, and (3) postulate proposed mechanisms of stress and sex hormone interactions during air pollution-related stress.

Microplastic particles (MPs) have been detected in a variety of environmental samples, including soil, water, food, and air. Cellular studies and animal exposures reported that exposure to MPs composed of different polymers might result in adverse effects at the portal of entry (local) or throughout the body (systemic). The most relevant routes of particle uptake into the body are oral and respiratory exposure. This review describes the various processes that may contribute to the adverse effects of MPs. Only MPs up to 5 µm were found to cross epithelial barriers to a significant extent. However, MPs may also exert a detrimental impact on human health by acting at the epithelial barrier and within the lumen of the orogastrointestinal and respiratory tract. The potential for adverse effects on human health resulting from the leaching, sorption, and desorption of chemicals, as well as the impact of MPs on nutritional status and dysbiosis, are reviewed. In vitro models are suggested as a means of (1) assessing permeation, (2) determining adverse effects on cells of the epithelial barrier, (3) examining influence of digestive fluids on leaching, desorption, and particle properties, and (4) role of microbiota-epithelial cell interactions. The contribution of these mechanisms to human health depends upon exposure levels, which unfortunately have been estimated very differently.

The microbiome-gut-brain axis is altered by environmental stressors such as heat, diet, and pollutants as well as microbes in the air, water, and soil. These stressors might alter the host's microbiome and symbiotic relationship by modifying the microbial composition or location. Compartmentalized mutualistic microbes promote the beneficial interactions in the host leading to circulating metabolites and hormones such as insulin and leptin that affect inter-organ functions. Inflammation and oxidative stress induced by environmental stressors may alter the composition, distribution, and activities of the microbes in the microbiomes such that the resultant metabolite and hormone changes are no longer beneficial. The microbiome-gut-brain axis and immune adverse changes that may accompany environmental stressors are reviewed for effects on innate and adaptive immune cells, which may make host immunity less responsive to pathogens and more reactive to self-antigens. Cardiovascular and fluid exchanges to organs might adversely alter organ functionality. Organs, especially the brain, need a consistent supply of nutrients and clearance of debris; disruption of these exchanges by stressors, and involvement of gut microbiome are discussed regarding neural dysfunctions with Alzheimer's disease, autistic spectrum disorders, viral infections, and autoimmune diseases. The focus of this review includes the manner in which environmental stressors may disrupt gut microbiota leading to adverse immune and hormonal influences on development of neuropathology related to hyperhomocysteinemia, inflammation, and oxidative stress, and how certain therapeutics may be beneficial. Strategies are explored to lessen detrimental effects of environmental stressors on central and peripheral health navigated toward (1) understanding neurological disorders and (2) promoting environmental and public health and well-being.

Rodent inhalation studies indicate styrene is a mouse lung-specific carcinogen. Mode-of-action (MOA) analyses indicate that the lung tumors cannot be excluded as weakly quantitatively relevant to humans due to shared oxidative metabolites detected in rodents and humans. However, styrene also is not genotoxic following in vivo dosing. The objective of this review was to characterize occupational and general population cancer risks by conservatively assuming mouse lung tumors were relevant to humans but operating by a non-genotoxic MOA. Inhalation cancer values reference concentrations for respective occupational and general population exposures (RfC_car-occup and RfC_car-genpop) were derived from initial benchmark dose (BMD) modeling of mouse inhalation tumor dose-response data. An overall lowest BMDL₁₀ of 4.7 ppm was modeled for lung tumors, which was further duration- and dose-adjusted by physiologically based pharmacokinetic (PBPK) modeling to derive RfC_{car-occup/genpop} values of 6.2 ppm and 0.8 ppm, respectively. With the exception of open-mold fiber reinforced composite workers not using personal protective equipment (PPE), the RfC_{car-occup/genpop} values are greater than typical occupational and general population human exposures, thus indicating styrene exposures represent a low potential for human lung cancer risk. Consistent with this conclusion, a review of styrene occupational epidemiology did not support a conclusion of an association between styrene exposure and lung cancer occurrence, and further supports a conclusion that the conservatively derived RfC_car-occup is lung cancer protective.

Globally, national regulatory authorities are both responsible and accountable for health and environmental decisions related to diverse products and risk decision contexts. These authorities provided regulatory oversight and expedited market authorizations of vaccines and other therapeutic products during the COVID-19 pandemic. Regulatory decisions regarding such products and situations depend upon well-established risk assessment and management steps. The underlying processes supporting such decisions were outlined in frameworks describing the complex interactions between factors including risk assessment and management steps as well as principles which help guide risk decision-making. In 2022, experts in risk science proposed a set of 10 guiding principles, further examining the intersection and utility of these principles using 10 diverse risk contexts, and inviting a broader discourse on the application of these principles in risk decision-making. To add to this information, Canadian regulatory practitioners responsible for evaluating health and environmental risks and establishing policies convened at a Health Canada workshop on Principles for Risk Decision-Making. This review reports the results derived from this interactive engagement and provides a first pragmatic analysis of the relevance, importance, and feasibility of such principles for health and environmental risk decision-making within the Canadian regulatory context.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants of significant public health concern, with several that are highly toxic to humans, including some proven or suspected carcinogens. To account for the high variability of PAH mixtures encountered in occupational settings, adjusting urinary 1-hydroxypyrene (1-OHP) levels by the total airborne pyrene (PyrT)/benzo[a]pyrene (BaP) ratio is essential for human biomonitoring (HBM). Given the complexity and cost of systematically monitoring atmospheric levels, alternative approaches to simultaneous airborne and HBM are required. The aim of this review was to catalog airborne PyrT/BaP ratios measured during different industrial activities and recommend 1-OHP-dedicated biological guidance values (BGV). A literature search was conducted. Seventy-one studies were included, with 5619 samples pertaining to 15 industrial sectors, 79 emission processes, and 213 occupational activities. This review summarized more than 40 years of data from almost 20 countries and highlighted the diversity and evolution of PAH emissions. PyrT/BaP ratios were highly variable, ranging from 0.8 in coke production to nearly 40 in tire and rubber production. A single PyrT/BaP value cannot apply to all occupational contexts, raising the question of the relevance of defining a single biological limit value for 1-OHP in industrial sectors where the PyrT/BaP ratio variability is high. Based upon the inventory, a practical approach is proposed for systematic PAH exposure and risk assessment, with a simple frame to follow based upon specific 1-OHP BGVs depending upon the occupational context and setup of a free PAH HBM interactive tool.

The widespread production and use of plastics have resulted in accumulation of plastic debris in the environment, gradually breaking down into smaller particles over time. Nano-plastics (NPs) and microplastics (MPs), defined as particles smaller than 100 nanometers and 5 millimeters, respectively, raise concerns due to their ability to enter the human body through various pathways including ingestion, inhalation, and skin contact. Various investigators demonstrated that these particles may produce physical and chemical damage to human cells, tissues, and organs, disrupting cellular processes, triggering inflammation and oxidative stress, and impacting hormone and neurotransmitter balance. In addition, micro- and nano-plastics (MNPLs) may carry toxic chemicals and pathogens, exacerbating adverse effects on human health. The magnitude and nature of these effects are not yet fully understood, requiring further research for a comprehensive risk assessment. Nevertheless, evidence available suggests that accumulation of these particles in the environment and potential human uptake are causes for concern. Urgent measures to reduce plastic pollution and limit human exposure to MNPLs are necessary to safeguard human health and the environment. In this review, current knowledge regarding the influence of MNPLs on human health is summarized, including toxicity mechanisms, exposure pathways, and health outcomes across multiple organs. The critical need for additional research is also emphasized to comprehensively assess potential risks posed by degradation of MNPLs on human health and inform strategies for addressing this emerging environmental health challenge. Finally, new research directions are proposed including evaluation of gene regulation associated with MNPLs exposure.