Increasing use of engineered nanomaterials with novel properties relative to their bulk counterparts has generated a need to define their behaviors and impacts in the environment. The high surface ...area to volume ratio of nanoparticles results in highly reactive and physiochemically dynamic materials in environmental media. Many transformations, e.g. reactions with biomacromolecules, redox reactions, aggregation, and dissolution, may occur in both environmental and biological systems. These transformations and others will alter the fate, transport, and toxicity of nanomaterials. The nature and extent of these transformations must be understood before significant progress can be made toward understanding the environmental risks posed by these materials.
Human exposures to bisphenol A (BPA) are widespread. The current study addresses uncertainties regarding human pharmacokinetics of BPA.
To reduce uncertainties about the metabolism and excretion of ...BPA in humans following oral administration.
We exposed six men and eight women to 100μg/kg bw of deuterated BPA (d6-BPA) by oral administration and conducted blood and urine analysis over a three day period. The use of d6-BPA allowed administered d6-BPA to be distinguished from background native (unlabeled) BPA. We calculated the rate of oral absorption, serum elimination, half-life, area under the curve (AUC), urinary excretion, and metabolism to glucuronide and sulfate conjugates.
Mean serum total (unconjugated and conjugated) d6-BPA Cmax of 1711nM (390ng/ml) was observed at Tmax of 1.1±0.50h. Unconjugated d6-BPA appeared in serum within 5–20min of dosing with a mean Cmax of 6.5nM (1.5ng/ml) observed at Tmax of 1.3±0.52h. Detectable blood levels of unconjugated or total d6-BPA were observed at 48h in some subjects at concentrations near the LOD (0.001–0.002ng/ml). The half-times for terminal elimination of total d6-BPA and unconjugated d6-BPA were 6.4±2.0h and 6.2±2.6h, respectively. Recovery of total administered d6-BPA in urine was 84–109%. Most subjects (10 of 14) excreted >90% as metabolites within 24h.
Using more sensitive methods, our study expands the findings of other human oral pharmacokinetic studies. Conjugation reactions are rapid and nearly complete with unconjugated BPA comprising less than 1% of the total d6-BPA in blood at all times. Elimination of conjugates into urine largely occurs within 24h.
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•Findings are consistent with data from animal and other human studies.•Maximum total serum levels are 3.9ng/ml for each μg ingested per kg.•Maximum unconjugated serum levels are 0.015ng/ml for each μg ingested per kg.•Unconjugated BPA in blood following oral administration is <1% of the total.•Most subjects excreted >90% as conjugated metabolites within 24h.
Tire wear compounds N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD) and its derivative 6PPD-quinone have been considered as emerging pollutants and attracted much attention recently. As an ...antioxidant and antiozonant widely used, 6PPD would be released during the production or use of rubber-related products. Because of the mass production and wide use of rubber-related products, 6PPD and 6PPD-quinone have been identified to be ubiquitous in the environment. In this study, we firstly reviewed the current available literature on the analytical procedures, concentrations and distribution of 6PPD and 6PPD-quinone, and then investigated the potential toxic effects of these two compounds on aquatic organisms. Current studies have been mainly focused on the occurrence of 6PPD and 6PPD-quinone in dust and water, while available information on atmosphere, soil, sediments and organisms is limited. The fate and distribution of 6PPD and 6PPD-quinone would be influenced by environmental factors such as temperature, illumination, and storm events, etc. Although 6PPD and 6PPD-quinone have potential adverse effects on aquatic organisms, and 6PPD-quinone has species-specific toxicity, toxicological mechanisms of these compounds are still unclear. Based on the review and analysis of current studies, some suggestions for future research of 6PPD and 6PPD-quinone are given.
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•This is a first review for tire wear chemicals 6PPD and 6PPD-quinone in environment.•Analytical methods of 6PPD and 6PPD-quinone in different matrices were summarized.•Environmental occurrence and fate of 6PPD and 6PPD-quinone were discussed.•Potential toxicity of 6PPD and 6PPD-quinone to aquatic organisms was investigated.•Deficiencies and perspectives on research of 6PPD and 6PPD-quinone were identified.
Since 2000 there has been an on-going industrial transition to replace long-chain perfluoroalkyl carboxylic acids (PFCAs), perfluoroalkane sulfonic acids (PFSAs) and their precursors. To date, ...information on these replacements including their chemical identities, however, has not been published or made easily accessible to the public, hampering risk assessment and management of these chemicals. Here we review information on fluorinated alternatives in the public domain. We identify over 20 fluorinated substances that are applied in i fluoropolymer manufacture, ii surface treatment of textile, leather and carpets, iii surface treatment of food contact materials, iv metal plating, v fire-fighting foams, and vi other commercial and consumer products. We summarize current knowledge on their environmental releases, persistence, and exposure of biota and humans. Based on the limited information available, it is unclear whether fluorinated alternatives are safe for humans and the environment. We identify three major data gaps that must be filled to perform meaningful risk assessments and recommend generation of the missing data through cooperation among all stakeholders (industry, regulators, academic scientists and the public).
•Alternatives to long-chain poly- and perfluorinated substances (PFASs) are revealed.•Fluorinated alternatives consist of short-chain PFASs and perfluoropolyethers.•Information for exposure assessment of fluorinated alternatives is still scarce.•Gaps in data needed for risk assessment of fluorinated alternatives are identified.
Environmental pollutants have become an increasingly common health hazard in the last several decades. Recently, a number of studies have demonstrated the profound relationship between gut microbiota ...and our health. Gut microbiota are very sensitive to drugs, diet, and even environmental pollutants. In this review, we discuss the possible effects of environmental pollutants including antibiotics, heavy metals, persistent organic pollutants, pesticides, nanomaterials, and food additives on gut microbiota and their subsequent effects on health. We emphasize that gut microbiota are also essential for the toxicity evaluation of environmental pollution. In the future, more studies should focus on the relationship between environmental pollution, gut microbiota, and human health.
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•Gut microbiota are very important for our health.•Gut microbiota are very sensitive to drugs, diet, and even environmental pollutants.•Some environmental pollutants can induce gut microbiota dysbiosis and have multiple potential adverse effects on health.•Gut microbiota are essential for the evaluation of the toxicity of environmental pollutants.
This manuscript is the first to discuss and review the possible effects of environmental pollutants on gut microbiota and their subsequent effects on health.
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•Fate, risk and removal of triclocarban (TCC) was comprehensively summarized.•TCC have been ubiquitously detected and caused serious environmental concern.•TCC is recalcitrant and may ...threat health of living organisms.•Chemical and biological methods have been developed but the efficiency was limited.•The future prospective for the TCC bioremediation was highlighted.
The halogenated antimicrobial triclocarban (TCC) has large production and consumption over last decades. Its extensive utilization in personal care products and insufficient treatment in conventional wastewater treatment plants (WWTPs) has led to its listing as one of emerging organic contaminants (EOCs). Due to the hydrophobicity and chemical stability of TCC, it has been omnipresent detected in terrestrial and aquatic environments, and its prolonged exposure has thrown potential pernicious threat to ecosystem and human health. Considering its recalcitrance, especially under anoxic conditions, both biological and non-biological methods have been exploited for its removal. The efficiency of advanced oxidation processes was optimistic, but complete removal can rarely be realized through a single method. The biodegradation of TCC either with microbial community or pure culture is feasible but efficient bacterial degraders and the molecular mechanism of degradation need to be further explored. This review provides comprehensive information of the occurrence, potential ecological and health effects, and biological and non-biological removal of TCC, and outlines future prospects for the risk evaluation and enhanced bioremediation of TCC in various environments.
•A comprehensive review of the toxicological data set for D4 was performed for hazard identification.•Treatment-related effects were mainly changes in liver weight and rat endometrial ...adenomas.•Observed liver weight changes related to adaptive enzyme induction.•Available data suggest that the observed benign tumors are not relevant to human health.
Octamethylcyclotetrasiloxane (D4) is a volatile cyclic siloxane used primarily as a monomer or intermediate in the production of some silicon-based polymers widely used in industrial and consumer applications and may be present as a residual impurity in a variety of consumer products. A robust toxicological data set exists for D4. Treatment-related results from a chronic inhalation study conducted in rats are limited to mild effects on the respiratory tract, increases in liver weight, increases in the incidence of uterine endometrial epithelial hyperplasia, and a dose-related trend in the incidence of endometrial adenomas. The observed increases in liver weight appear to be related to the induction of hepatic metabolizing enzymes, similar to those that are induced in the presence of phenobarbital. D4 is not mutagenic or genotoxic in standard in vitro and in vivo tests; therefore, the benign uterine tumors observed likely occur by a non-genotoxic mechanism. Results from mechanistic studies suggest that D4 has very weak estrogenic and antiestrogenic activity, as well as dopamine agonist-like activity. In rats, D4 exposure delays ovulation and hypothesized to prolong exposure of the uterine endometrium to endogenous estrogen. Though this mode of action may play a role in the development of benign uterine tumors in the rat, it is considered unlikely to occur in the human due to the marked differences in cycle regulatory mechanisms. Reproductive effects were observed following D4 exposure in female rats. These effects appear to be related to a delay of the luteinizing hormone (LH) surge, which fails to induce complete ovulation in the rat. However, based on differences in ovulatory control in rats and humans, it appears these effects may be species-specific with no risk or relevance to human health. Results from pharmacokinetic studies indicate that dermal absorption of D4 is limited, due to its high volatility and, if absorbed via dermal, oral or inhalation exposure, the majority of D4 is rapidly cleared from the body, indicating bioaccumulation is unlikely.
The antioxidant 6-PPD has been widely used to prevent cracking and thermal oxidative degradation and to extend the service life of tire rubber. 6-PPD quinone (6-PPDQ) is formed via the reaction of ...6-PPD with O3. Due to its acute lethality in coho salmon, 6-PPDQ has become an emerging pollutant of increasing concern. In this review, we provide a critical overview of the generation, environmental distribution, bioavailability, and potential toxicity of 6-PPDQ. The transformation pathways from 6-PPD to 6-PPDQ include the N-1,3-dimethylbutyl-N-phenyl quinone diamine (QDI), intermediate phenol, and semiquinone radical pathways. 6-PPDQ has been frequently detected in water, dust, air particles, soil, and sediments, indicating its large-scale and potentially global pollution trend. 6-PPDQ is bioavailable to both aquatic animals and mammals and acute exposure to 6-PPDQ can be lethal to some organisms. Exposure to 6-PPDQ at environmentally relevant concentrations could induce several types of toxicity, including neurotoxicity, intestinal toxicity, and reproductive toxicity. This review also identifies and discusses knowledge gaps and research needs for the study of 6-PPDQ. This review facilitates a better understanding of the environmental occurrence and exposure risk of 6-PPDQ.
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•Three transformation pathways from 6-PPD to 6-PPDQ were summarized.•6-PPDQ is widely distributed in water, dust, air particles, soil, and sediment environments.•6-PPDQ can be bioavailable and accumulated in organisms.•Exposure to 6-PPDQ can cause several aspects of toxicity in organisms.•Physiochemical property, ecological risk, and health risk of 6-PPDQ can be predicted.
17α-ethynylestradiol (EE2) is a synthetic hormone, which is a derivative of the natural hormone, estradiol (E2). EE2 is an orally bio-active estrogen, and is one of the most commonly used medications ...for humans as well as livestock and aquaculture activity. EE2 has become a widespread problem in the environment due to its high resistance to the process of degradation and its tendency to (i) absorb organic matter, (ii) accumulate in sediment and (iii) concentrate in biota. Numerous studies have reported the ability of EE2 to alter sex determination, delay sexual maturity, and decrease the secondary sexual characteristics of exposed organisms even at a low concentration (ng/L) by mimicking its natural analogue, 17β-estradiol (E2). Thus, the aim of this review is to provide an overview of the science regarding EE2, the concentration levels in the environment (water, sediment and biota) and summarize the effects of this compound on exposed biota at various concentrations, stage life, sex, and species. The challenges in respect of EE2 include the extension of the limited database on the EE2 pollution profile in the environment, its fate and transport mechanism, as well as the exposure level of EE2 for better prediction and definition revision of EE2 toxicity end points, notably for the purpose of environmental risk assessment.
•EE2 was ubiquitously detected in the environment.•EE2 was found to be accumulated in the water, sediment and biota.•EE2 showed the highest estrogenic potency in the in vitro tests.•Long-term exposure of EE2 leads to reduction in the fertility system.•Different concentrations of EE2 have different toxic effects on different organisms.
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