Personal Health Care Products Research Articles

Lethal puncturing of planktonic Gram-positive and Gram-negative bacteria by magnetically-rotated silica hexapods

Planktonic bacterial presence in many industrial and environmental applications and personal health-care products is generally countered using antimicrobials. However, antimicrobial chemicals present an environmental threat, while emerging resistance reduces their efficacy. Suspended bacteria have no defense against mechanical attack. Therefore, we synthesized silica hexapods on an α-Fe2O3 core that can be magnetically-rotated to inflict lethal cell-wall-damage to planktonic Gram-negative and Gram-positive bacteria. Hexapods possessed 600 nm long nano-spikes, composed of SiO2, as shown by FTIR and XPS. Fluorescence staining revealed cell wall damage caused by rotating hexapods. This damage was accompanied by DNA/protein release and bacterial death that increased with increasing rotational frequency up to 500 rpm. Lethal puncturing was more extensive on Gram-negative bacteria than on Gram-positive bacteria, which have a thicker peptidoglycan layer with a higher Young's modulus. Simulations confirmed that cell-wall-puncturing occurs at lower nano-spike penetration levels in the cell walls of Gram-negative bacteria. This approach offers a new way to kill bacteria in suspension, not based on antimicrobial chemicals.

Comparative Evaluation of Triclosan in Selected Anti-bacterial Soaps

Background of the topic: Triclosan is a widely used antimicrobial agent in personal care products. Triclosan is readily absorbed into the skin and present in the human tissues and fluids. But the triclosan showed many side effects including carcinoma. Therefore the determination of triclosan in various personal health care products by simplest analytical methods is very much significant. Purpose of the study: The present study was aimed to do the comparative evaluation of triclosan in selected soaps and the evaluation was carried out by using ultraviolet spectroscopy. Methods: Comparative evaluation of the selected four anti-bacterial soaps were carried out and the percentage of triclosan was determined by calibration curve method. The analytical technique used was ultra-violet spectroscopy by using the solvent ethanol. The Linearity was tested using the standard triclosan in the range of 300 µg/ml - 1500 µg/ml. The validation methods such as ruggedness, repeatability, intermediate precision, linearity were done for all the four selected samples. Accurately weighed soap samples and dissolved in 3 ml of water. Transferred this solution into a separating funnel and extracted with chloroform. Organic layer was separated out and pipette out 1 ml of this organic layer and diluted to 10 ml with ethanol. The absorbance of the sample solution was measured at 307 nm. Results: Comparative evaluation of the selected anti bacterial soaps and triclosan content was estimated by UV-spectroscopy. The λmax was found to be 307nm. The method was found to be linear within 300 µg/ml - 1500 µg/ml. The percentage of triclosan present in selected four samples A, B, C and D were 0.28±0.8772, 0.24±0.9878, 0.32±1.123 and 0.73±0.9932 respectively. Conclusions: The percentage of triclosan in sample A sample B were within the limit and sample C and sample D slightly higher than that of the safe limit. The method used for the estimation of triclosan was UV spectroscopy method which was validated using ICH guidelines.

Metagenomic insights into the functional microbial diversity of the lower stretch of the River Ganga: mapping antibiotic and metal resistance genes

The banks of the lower stretch of River Ganga are home to several towns and megapolis representing high density of human population. A stretch of 50 km represented by prefixed stations of the lower part of Ganga (Ganga Environmental Time Series- GETS) was monitored spatiotemporally using eDNA metagenome-based Nanopore sequencing to elucidate structure of microbial communities along with mapping of antibiotic-resistant genes (ARGs), metal resistance genes (MRGs) and mobile genetic elements (MGEs). Besides, in situ environmental parameters, concentration of dissolved nutrients, metals and metalloids were measured. The concentration of dissolved oxygen ranged from 3.4–6.2 mg l−1, indicating deteriorating water quality corresponding to high population density. Dissolved nitrate concentrations were higher in some stations reflecting direct release of untreated municipal sewage into the river. In particular, concentration of metals such as Cd (2.34–38.52 ppb) and metalloids such as As (0–218.7 ppb) were found to be alarmingly high in surface water. Gammaproteobacteria was encountered ubiquitously while rare bacterioplankton represented by eleven classes showed site specificity. Several genes belonging to ARGs were identified and multidrug resistance genes (MDR) were found in all the studied stations exhibiting high abundance. The ‘hotspots’ of ARGs were widespread, possibly owing to rampant usage of personal health care products that may have contributed to observed ARG abundances. High abundance of MRGs comprising arsenic (∼12%) and copper (∼12%) were also identified showing strong correlations with the abundance of ARGs. Correlation and network analysis revealed the potential role of MGEs in the dissemination of ARGs. ANOSIM and cluster analyses supported patchy distribution patterns of microbial communities. The RDA plot showed possible influences of environmental parameters in shaping the microbial community structure and towards dissemination of functional genes such as ARGs and MRGs in the lower stretch of the River Ganga.

Ecofriendly poly(3-hydroxybutyrate-co-4-hydroxybutyrate) microbeads for sanitary products

In the past, plastic microbeads (MBs) were added to personal healthcare products to improve the cleaning and exfoliating effects, but these have been withdrawn owing to their non-degradable nature and contribution to the pollution of marine environment, especially that caused by the adsorption of persistent organic pollutants (POPs) on MBs. Therefore, natural biodegradable alternatives are being developed, but these often do not exhibit sufficient performance to replace non-degradable MBs. In this study, poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB-4HB), a biodegradable aliphatic polyester, was used to prepare MBs via melt-electrospraying. We carried out the rheological characterization of P3HB-4HB with respect to melting temperature, and the melt-electrospray process was optimized to prepare MBs having sizes similar to those of commercially available MBs. Furthermore, the adsorption properties of the P3HB-4HB MBs for POPs were investigated. Unlike commercial MBs, the P3HB-4HB MBs adsorbed significantly fewer contaminants owing to their smooth and regular surfaces. Finally, a cleansing product containing P3HB-4HB MBs was prepared to evaluate their cleaning ability, and we found that the MB-based product could remove dirt and contaminants that were not easily removed by water alone. Thus, the biodegradable P3HB-4HB MBs have great potential for use as sustainable additives for cosmetic products for skin exfoliation.

Hydrogel: A Promising Material in Pharmaceutics.

Hydrogels are natural or synthetic polymeric networks, insoluble in water, or sometimes found as colloidal gel where the dispersion medium is water. Hydrogels can absorb approximately 90% water and are regarded as superabsorbent materials; hence these resemble the natural living tissues more than any other biological- based materials. Because of their ability to absorb water, they are used to investigate the properties of swollen polymer networks and have wide applications in different fields such as contact lenses, drug delivery systems for proteins, and many others. To make them biodegradable, labile chemical bonds are introduced in the main backbone through crosslinking. These unstable bonds can then be broken down by various agents chemically, physically, or enzymatically, generally by hydrolysis or through some controlled parameters. Hydrogels are frequently used in the medical field. For instance, pH and temperature-sensitive hydrogels may be used in the targeted drug delivery which have been explained in detail in the current review. The other applications of hydrogels are also explained with regard to personal health care products, biomedical, bio-separation, wound healing, tissue engineering, and drug delivery, etc., which make them promising materials in pharmaceutics. They are also used in agriculture and environmental remediation. The purpose of this review is to expose their salient features and biomedical applications.

Involvement of perinatal health professionals to reduce the exposure of pregnant women to chemicals

Abstract Background During pregnancy, reducing exposure to chemicals is obvious to many pregnant women (PW), and also perinatal health professionals (PHP), but few of them are aware that these substances are present in everyday products (cleaning products, DIY products, gardening products, personal health care products, cosmetics, food plastic wrappers etc.). AIM This study aimed to estimate the perception of risks related to chemicals by PW, and also to describe the advice provided by PHP to PW. Methods A cross-sectional survey was performed among French PW. Interviewers, using a standardized questionnaire, collected data anonymously. Data focused on socio-demographic and occupational characteristics, perception of environmental risks, identification of chemicals by PW, and preventive advices performed by PHP. Statistical analysis (univariate analysis - logistic regression) were done with Modalisa® 8.0 software (Kynos, Paris). Results 300 PW (29.5 +/- 5 years old) were included. They report a relatively high level of sensitivity to environmental issues (SE Score = 6.3 ± 1.7, on a Likert 0-10 scale). When asked about the level of risk associated with 15 environmental risks, pregnant women placed exposure to chemicals in only twelfth position. Two thirds of PW were interested by the composition of everyday products, and looked at the ingredients mentioned on the labels, but most of them declared that the information present on the labels were not comprehensible. An interest for organic products was noted. These behaviors were related to the age, socio-occupational status, perception of environmental risks. For most of PW, the main sources of information on chemicals were the Internet and medias. Only 5% PW identified PHP as potential interlocutors on this topic. Conclusions For most PW, everyday products were not identified as health risk products. To date, it is important to strengthen the information provided to PW by PHP on the risks linked o chemicals during pregnancy. Key messages Exposures to chemicals present in everyday products (DIY, cleaning products, cosmetics, food plastic wrappers etc.) are not well identified by pregnant women and by perinatal health professionals. Exposure to chemicals must be reduced during pregnancy and health promotion messages must integrate this advice to promote healthy behaviors.

An Eco-friendly Alternative to Polyethylene Microbeads in Personal Healthcare Products

Recently a huge chunk of the population has shifted towards shower gels. The biggest reason might be the fact that shower gels can provide a better care for the skin. They were made with the motive of providing gentle cleansing and moisturizing qualities contrary to that of a regular soap, so that the people can enjoy a better skin care experience. Shower gels generally use chemicals especially sodium lauryl sulfate and betaines. These are believed to cause skin irritation and may not be washed off properly especially in hard water. The recent shower gels have a combined scrubbing effect included along with the scented or flavored body wash. For the scrubbing activity microbeads are employed. These microbeads used as a scrubber are polymers, e.g. being polyethylene or nylon etc. We know how plastics are harmful to us and the environment. And this is a cause of major concern. And since it is small in size it makes it relatively dangerous. Microbeads, because of their small size, have a large surface area by volume which allows them to accumulate highly toxic materials which are toxic to the person and the environment. To overcome the menace of microbeads we propose an alternative

Influence of pH on the toxicity of ionisable pharmaceuticals and personal care products to freshwater invertebrates.

The majority of pharmaceuticals and personal health-care products are ionisable molecules at environmentally relevant pHs. The ionization state of these molecules in freshwater ecosystems may influence their toxicity potential to aquatic organisms. In this study we evaluated to what extent varying pH conditions may influence the toxicity of the antibiotic enrofloxacin (ENR) and the personal care product ingredient triclosan (TCS) to three freshwater invertebrates: the ephemeropteran Cloeon dipterum, the amphipod Gammarus pulex and the snail Physella acuta. Acute toxicity tests were performed by adjusting the water pH to four nominal levels: 6.5, 7.0, 7.5 and 8.0. Furthermore, we tested the efficiency of three toxicity models with different assumptions regarding the uptake and toxicity potential of ionisable chemicals with the experimental data produced in this study. The results of the toxicity tests indicate that pH fluctuations of only 1.5 units can influence EC50-48h and EC50-96h values by a factor of 1.4-2.7. Overall, the model that only focuses on the fraction of neutral chemical and the model that takes into account ion-trapping of the test molecules showed the best performance, although present limitations to perform risk assessments across a wide pH range (i.e., well above or below the substance pKa). Under such conditions, the model that takes into account the toxicity of the neutral and the ionized chemical form is preferred. The results of this study show that pH fluctuations can have a considerable influence on toxicity thresholds, and should therefore be taken into account for the risk assessment of ionisable pharmaceuticals and personal health-care products. Based on our results, an assessment factor of at least three should be used to account for toxicity differences between standard laboratory and field pH conditions. The models evaluated here can be used to perform refined risk assessments by taking into account the influence of temporal and spatial pH fluctuations on aquatic toxicity.

Self-Powered, Rapid-Response, and Highly Flexible Humidity Sensors Based on Moisture-Dependent Voltage Generation.

Most advanced humidity sensors are powered by batteries that need regular charging and replacement, causing environmental problems and complicated management issues. This paradigm has been overcome through the development of new technology based on the concept of simple, self-powered, rapid-response, flexible humidity sensors enabled by the properties of densely packed titanium dioxide (TiO2) nanowire networks. These sensors eliminate the need for an external power source and produce an output voltage that can be readily related to ambient humidity level over a wide range of ambient conditions. They are characterized by rapid response and relaxation times (typically 4.5 and 2.8 s, respectively). These units are mechanically flexible and maintain a constant voltage output after 10 000 bending cycles. This new type of humidity sensor is easily attached to a human finger for use in the monitoring of ambient humidity level in the environment around human skin, near wet objects, or in the presence of moist materials. The unique properties of this new self-powered wearable humidity sensor technology open up a variety of new applications, including the development of electronic skin, personal healthcare products, and smart tracking in the future Internet-of-things.

Antibacterial and antibiofilm activities of eugenol from essential oil of Syzygium aromaticum (L.) Merr. & L. M. Perry (clove) leaf against periodontal pathogen Porphyromonas gingivalis

The antibacterial effect and mechanism of eugenol from Syzygium aromaticum (L.) Merr. & L. M. Perry (clove) leaf essential oil (CLEO) against oral anaerobe Porphyromonas gingivalis were investigated. The results showed that eugenol, with content of 90.84% in CLEO, exhibited antibacterial activity against P. gingivalis at a concentration of 31.25 μM. Cell shrink and lysis caused by eugenol were observed with Scanning Electron Microscopy (SEM). The release of macromolecules and uptake of fluorescent dye indicated that the antibacterial activity was due to the ability of eugenol to permeabilize the cell membrane and destroy the integrity of plasmatic membrane irreversibly. In addition, eugenol inhibited biofilm formation and reduced preformed biofilm of P. gingivalis at different concentrations. The down-regulation of virulence factor genes related to biofilm (fimA, hagA, hagB, rgpA, rgpB, kgp) explained that eugenol suppressed biofilm formation at the initial stage. These findings suggest that eugenol and CLEO may be potential additives in food and personal healthcare products as a prophylactic approach to periodontitis.

The moringa industry in the Philippines: status, challenges and opportunities

Moringa is one of the world's most useful trees and in the Philippines almost all parts of the plant are used for food and traditional medicine. Various research and development efforts are currently focused on food fortification to utilize the nutritional value of moringa and its medicinal potentials. For the past 10 years the moringa industry in the Philippines has grown significantly as research and development efforts have focused on this crop. Moringa leaves and seed oil are the major raw materials used in the food and nutrition industry, in cosmetics and herbal medicine. The leaf powder is mainly used for food fortification as ingredient of bread, noodles, juices, milk and tea, while the leaf powder capsule is mostly used as food supplement and herbal medicine. Moringa oil is predominantly used in cosmetics and personal health care products such as shampoo, soap, perfumes and skin care. More new moringa-based products are being developed by more than 20 food and cosmetic industries in the Philippines. In spite of the growing moringa industry there is a shortage of good quality fresh and dry moringa raw materials. The supply of moringa powder is inadequate and unstable and can be attributed to a scarcity of seed and planting materials. There is no stable and commercial moringa oil industry due to limited seed supply. The moringa industry in the Philippines is slowly being developed with the assistance of the government and private sectors. The next step is to develop a national program for the industry. There are gaps that need to be addressed. Establishing good agricultural practices and stringent regulations to guarantee the quality and stability of moringa products is top priority. Addressing the great demand for planting materials is another major challenge. The opportunities of moringa-based products seem bright and key players are aiming to penetrate the international market.

An LC-MS/MS based survey of contaminants of emerging concern in drinking water in South Africa

Advances in many analytical techniques allow the detection of compounds in water at very low concentrations (ng/L), which has facilitated the identification of many compounds in drinking water that went previously undetected. Some of these compounds are contaminants of emerging concern (CECs), which is broadly defined as any chemical or microorganism that is not currently being routinely monitored but has recently been identified as being present in the environment, and that may pose health or ecological risks. CECs can include pharmaceuticals, personal health care products and pesticides. Some CECs can act as endocrine disruptors, interfering with the normal functioning of the human endocrine system, potentially influencing foetal and child development. Although the level of many of these compounds are orders of magnitude below known acute toxicity levels, the health impact of long term exposure at low levels is mostly unknown. In this study, we present the results of a national survey over four seasons of potential CECs in the drinking water of major South African cities. The contaminants most often detected were the related herbicides atrazine and terbuthylazine, and the anticonvulsant and mood-stabilising drug, carbamazepine. The levels of these CECs were well below maximum levels proposed by the World Health Organization and the US Environmental Protection Agency. However, the range of CECs detected in drinking water, and seasonal and geographic variability in CECs levels, warrant a more frequent screening programme.

Application of microencapsulated essential oils in cosmetic and personal healthcare products - a review.

Nowadays, the consumers around the world are increasingly focused on health and beauty. The renewed consumer interest in natural cosmetic products creates the demand for new products and reformulated others with botanical and functional ingredients. In cosmetic products, essential oils (EOs) play a major role as fragrance ingredients. They can optimize its proprieties and preservation, as well as the marketing image of the final product. Microencapsulation of EOs can protect and prevent the loss of volatile aromatic ingredients and improve the controlled release and stability of this core materials. The importance of EOs for cosmetic industry and its microencapsulation was reviewed in this study. Also a briefly introduction about the preparation of microparticles was presented. Some of the most important and usual microencapsulation techniques of EOs, as well as the conventional encapsulating agents, were discussed. Despite the fact that microencapsulation of EOs is a very promising and extremely attractive application area for cosmetic industry, further basic research needs to be carried out, for a better understanding of the biofunctional activities of microencapsulated EOs and its release modulation, as well as the effects of others cosmetic ingredients and the storage time in the microparticles properties.

Biomedical applications and toxicity of nanosilver : a review

Nanotechnology is a promising arena for generating new applications in medicine. It is advancing rapidly due to the great progress achieved in various fileds including electronics, mechanics, cosmetics, food, etc. In order to successfully bifunctionalise nanoparticles for a given biomedical application, a wide range of chemical, physical and biological factors have to be taken into account. Silver nanoparticles (AgNPs) exhibit strong antibacterial activity owing to their large surface to volume ratios and crystallographic surface structure. Nanosilver particles have been widely used in a range of biomedical applications including diagnosis, treatment, medical device coatings, drug delivery and personal health care products. With the growing application of nanosilver particles in medical contexts, it is becoming necessary for a better understanding the mechanisms of action, biological interactions and their potential toxicity on exposure. This review aims to provide critical assessment of the current understanding of antibacterial activity, biomedical applications and toxicity of silver nanoparticles.

Phosphorus and Emerging Micro-pollutants in Surface Waters: Challenges and Prospects for Water Quality Improvements

An oversupply of Phosphorus in water bodies accelerates growth of algae and higher forms of plant life to produce undesirable impacts on overall water quality. Phosphorus inputs to surface waters arise from a variety of point and nonpoint sources. However much of the P is contributed by agricultural runoff and outfall of treated (or untreated) wastewater in receiving water-bodies. Point sourced-P inputs to waters have considerably decreased in recent years, at least partly driven by regulatory requirements, e.g. the EU Water Framework Directive. This has largely been achieved by removing P from treated wastewaters at sewage treatment works (STWs). Studies have shown that introducing an additional treatment step (“P-stripping”) can significantly reduce P in STW outfalls. Given P deposits are depleting, there is much interest in phosphorus recovery from wastewaters. A few STWs have already started to recover P as struvite (NH4MgPO4.6H2O) mineral – a substitute for commercially produced P-fertilizers. This requires major investment and is not economically viable at small STWs. Nonetheless it is a major breakthrough in terms of P recovery and its use. Effluents from sewage treatment works (STW) can often contain a complex mixture of residual microcontaminants, not removed during wastewater treatment. Organic micro-pollutants have been found in rivers receiving STW effluents. Such residual contaminants have become the focus of an emerging field of water quality study and are collectively referred to as pharmaceuticals and other personal healthcare products, PPHCPs. Many of these chemicals have the ability to effect the hormonal signaling of organisms and are called endocrine disrupting compounds (EDC). Such chemicals have shown some of the most damaging biological effects in aquatic organisms. Biological effects in the aquatic environment are typically related to the development of intersex in fish. Recent research shows the use of STW practices such as upgrading from using a combined trickling filter contact process to activated sludge treatment, ozonation, membrane filtration and use of suspended biofilm reactors reduces the amount of EDCs in waste effluent. It is thus possible to remove contaminants from STW effluents, but it will not be possible without major infrastructure improvements. This paper presents the challenges and prospects of P and micro-organic pollutants in surface waters.

Adverse Effects of Titanium Dioxide Nanoparticles on Human Dermal Fibroblasts and How to Protect Cells

The effects of exposure of human dermal fibroblasts to rutile and anatase TiO(2) nanoparticles are reported. These particles can impair cell function, with the latter being more potent at producing damage. The exposure to nanoparticles decreases cell area, cell proliferation, mobility, and ability to contract collagen. Individual particles are shown to penetrate easily through the cell membrane in the absence of endocytosis, while some endocytosis is observed for larger particle clusters. Once inside, the particles are sequestered in vesicles, which continue to fill up with increasing incubation time till they rupture. Particles coated with a dense grafted polymer brush are also tested, and, using flow cytometry, are shown to prevent adherence to the cell membrane and hence penetration of the cell, which effectively decreases reactive oxygen species (ROS) formation and protects cells, even in the absence of light exposure. Considering the broad applications of these nanoparticles in personal health care products, the functionalized polymer coating can potentially play an important role in protecting cells and tissue from damage.

Computational toxicology: an overview of the sources of data and of modelling methods

Background: Toxicology has the goal of ensuring the safety of humans, animals and the environment. Computational toxicology is an area of active development and great potential. There are tangible reasons for the emerging interest in this discipline from academia, industry, regulatory bodies and governments. Results: Pharmaceuticals, personal health care products, nutritional ingredients and products of the chemical industries are all potential hazards and need to be assessed. Toxicological tests for these products are costly, frequently use laboratory animals and are time-consuming. This delays end-user access to improved products or, conversely, the timely withdrawal of dangerous substances from the market. The aim of computational toxicology is to accelerate the assessment of potentially dangerous substances through in silico models. Conclusions: In this review, we provide an overview of the development of models for computational toxicology. Addressing the significant divide between the experimental and computational worlds–believed to be a prime hindrance to computational toxicology–we briefly consider the fundamental issue of toxicological data and the assays they stem from. Different kinds of models that can be built using such data are presented: computational filters, models for specific toxicological endpoints and tools for the generation of testable hypotheses.

Triclosan and Antimicrobial Resistance in Bacteria: An Overview

Triclosan is a widely used biocide that is considered as an effective antimicrobial agent against different microorganisms. It is included in many contemporary consumer and personal health-care products, like oral and dermal products, but also in household items, including plastics and textiles. At bactericidal concentrations, triclosan appears to act upon multiple nonspecific targets, causing disruption of bacterial cell wall functions, while at sublethal concentrations, triclosan affects specific targets. During the 1990s, bacterial isolates with reduced susceptibility to triclosan were produced in laboratory experiments by repeated exposure to sublethal concentrations of the agent. Since 2000, a number of studies have verified the occurrence of triclosan resistance amongst dermal, intestinal, and environmental microorganisms, including some of clinical relevance. Of major concern is the possibility that triclosan resistance may contribute to reduced susceptibility to clinically important antimicrobials, due to either cross-resistance or co-resistance mechanisms. Although the number of studies elucidating the association between triclosan resistance and resistance to other antimicrobials in clinical isolates has been limited, recent laboratory studies have confirmed the potential for such a link in Escherichia coli and Salmonella enterica. Thus, widespread use of triclosan may represent a potential public health risk in regard to development of concomitant resistance to clinically important antimicrobials.

Determination of triclosan in personal health care products by liquid chromatography (HPLC)

An isocratic reversed-phase liquid chromatographic (HPLC) method is proposed for the practical and reliable determination of triclosan, an antimicrobic agent incorporated into a variety of personal heath care products. Chromatographic separations were performed on a C-18 column using acetonitrile–TEA phosphate (70 mM; pH 3.5) 55:45 (v/v) as mobile phase and UV detection at 230 and 280 nm. The selectivity of the method was assured by the on-line photodiode array detector. The identity of the triclosan peak was also confirmed by HPLC MS. The method was successfully applied to the determination of triclosan in commercially available health care products (deodorant stick, dentifrice gel, mouthrinse, toothpaste and handwash). All the products displayed triclosan concentrations in compliance with the EEC directive (≤0.3%).

The Balmer: Paschen ratio in the chromosphere and the equilibrium populations of hydrogen angular-momentum states

Mexico, the United States, and Canada are home to a diverse array of river systems. As is the case for rivers across the globe, complex mixtures and interactions of stressors have fundamentally altered the structure and function of these ecosystems. Here, we summarize the intensity and extent of major regional stressors to North American rivers and their impacts on important physical, biological, and chemical properties. The large lakes ecoregion is impacted by broad-scale physical alterations of watercourses, which include both point and nonpoint pollution from industry, municipalities, and agriculture. The establishment of invasive aquatic species is another key stressor. The most pressing stressor in polar freshwaters is rapid anthropogenic climate change. Urbanization is a focal stressor in temperate coastal river habitats. Increasing agricultural production, fine-sediment pollution, and nutrient enrichment are major threats to temperate floodplain rivers. Stressors common across temperate upland river systems include increasing populations and urban areas, impoundments and surface-water abstraction, and land-use change. Point-source pollution, nonnative species, and climatic vulnerability are primary stressors affecting tropical and subtropical coastal rivers. Similarly, climate change and human activities that mitigate water scarcity such as impoundments, diversions, crop irrigation, and surface and groundwater withdrawals are principal stressors in xeric and endorheic river systems. Across ecoregions, these and other stressors can interact and cause surprising ecological responses. Further, the development and introduction of new contaminant sources (e.g., genetically modified crops, antibiotics, hormones, pharmaceuticals, and personal health care products) pose new challenges for river conservation.