Fate and toxic effects of environmental stressors

Authors: Jie Zhuang HanQing Yu Theodore B Henry Gary S Sayler

Publish Date: 2015/10/24

Volume: 24, Issue: 10, Pages: 2043-2048

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Abstract

The potential for toxicants to harm organisms in the environment is influenced by the physicochemistry of the substances and their environmental behaviors and transformation within ecosystems This special issue is composed of 20 papers that report on studies which have investigated the fate and toxicity of various toxicants including engineered nanoparticles pharmaceuticals and personal care products antibiotics pathogens heavy metals and agricultural nutrients The environmental transformations of these substances and how these processes affect their toxicity are emphasized This paper highlights the important findings and perspectives of the selected papers in this special edition with an aim of providing insights into fullscale evaluation on the toxicity of various contaminants that exist in ecosystems General suggestions are provided for the future directions of toxicological researchAnthropogenic activities such as agricultural production urban development and application of novel chemicals and engineering materials have released a huge volume of harmful materials to the environment that have damaged ecosystem functions and threatened human and wild life health UNEP 2013 In addition reutilization of resources eg wastewater and sludge and energy production eg shale gas biofuels and hydrogen produce toxic materials and create toxicological challenges The possibility of that contaminants with toxic properties occur as a consequence of nearly all human activities is a threat that is well recognized and addressing this issue is a high priority topic for environmental scientists and regulatory agencies throughout the world Thus far numerous studies have been conducted to address the risks of various toxicants in the environment but the relations between the fate and the toxicity of contaminants are not yet clearly defined due to the complexity of the environmental behavior of toxicants upon release into the environment and how this may influence toxicological processes Integrated studies of toxicological processes are urgently needed to fully consider and quantify the contributions of each component of the environmental processes that affect toxicity of contaminantGiven the current interest by those in the environmental control arena to understand the fatetoxicity relation of anthropogenic contaminants in ecosystems or production scenarios the guest editors have assembled this special issue of Ecotoxicology Papers were chosen to illustrate the advances in characterizing and evaluating the environmental behaviors and associated toxicity of various pollutants including engineered nanoparticles heavy metals pharmaceuticals and personal care products PPCPs antibiotics pathogens and nutrients This collection of 20 selected papers in this Special Issue represents a result of scientific exchange and research discussion among the scientists and students of the United States and China at the ChinaUS Joint Symposium of Energy Water and Ecosystem Sustainable Development The symposium was jointly organized by the USChina Ecopartnership for Environmental Sustainability and the ChinaUS Joint Research Center for Ecosystem and Environmental Change and held on October 26–28 2014 in Hefei China with the sponsorship of the Natural Science Foundation of China More than eighty representatives from academia government and industry in China and the United States gathered to present and discuss their latest scientific findings and current challenges of toxicological risks encountered in food production energy production and human healthAll of the submitted papers for this special issue were rigorously peer reviewed in accordance with the policies of this journal The articles accepted for publication cover a wide range of topics relating to the fate and toxic effects of various contaminants generated during wastewater treatment and application energy production drinking water supply animal production and agricultural and fishery production To facilitate understanding of the complexity of environmental control to the fate and toxic effects of various stressors the guest editors have grouped the papers into six common themes nanoparticle toxicity influence of wastewater treatment on fate and toxicity of toxicants effect of disinfection on substance toxicity toxicological challenges of renewable energy production ecological effects of excessive nutrients and heavy metal toxicologyThe stability and bioavailability of engineered nanoparticles could be modified by environmental physicochemical conditions As well environmental factors such as humic acid and solution chemistry are important factors determining the fate and toxicity of nanomaterials in the environment In general environmental conditions have a large potential for mediating the toxicity of engineered nanoparticles Du et al 2015 evaluated the toxicity of cellulose nanocrystals CNCs by assessment of the response of constitutively bioluminescent luxCDABEbased bioreporter Escherichia coli 652T7 Results demonstrated that CNCs were not significantly toxic at concentrations at or below 250 mg/L but the toxicity increased linearly as CNC concentrations increased from 300 to 2000 mg/L Longer exposure time and elevated solubility of the CNCs were shown to increase cytotoxicity effects Fang et al 2015 studied the effects of humic acid and ionic strength on the sublethal toxicity of TiO2 nanoparticles to zebrafish by monitoring the changes of superoxide dismutase catalase malonaldehyde and glutathione in gill liver and intestine The nanoparticle aggregation was found not an essential factor to influence nanoparticle toxicity However humic acid and/or ionic strength decreased the bioavailability of TiO2 nanoparticles in water Xiong et al 2015 studied the effect of morphology of Cu/CuxO nanoparticles on their antimicrobial activity Their results show that the flowerlike Cu/CuxO nanoparticles were the most effective form to inhibit microbial growth This morphology dependent effect was attributed to the difference in the surface free energy among different crystal facets of the copper nanoparticlesPharmaceuticals and personal care products PPCPs are often found in the effluents from wastewater treatment plants due to insufficient removal during wastewater treatment processes Agricultural application of reclaimed water sludge and animal wastes has brought PPCPs into the natural environment Qin et al 2015a Because of the biological activity of PPCPs even at low environmental concentrations the potential risks of these substances to humans and organisms in ecosystems have caused great concern However little was known about their environmental behaviors and toxic effects Chen et al 2015 performed a study to assess the removal of frequently occurring pharmaceuticals naproxen fenoprofen ketoprofen dichlofenac and carbamazepine and the biocide triclosan in activated sludge from four different wastewater treatment plants in Demark The most rapid degradation was observed for NSAID pharmaceuticals naproxen fenoprofen and ketoprofen at degradation rates of 46–94  while dichlofenac and carbamazepine were persistent in the wastewater treatment systems Interestingly no relationships were observed between degradation rates and biomass concentrations in the diverse sludge materials that were evaluatedThe presence of toxicants in sewage sludge impacts the potential for the sludge to be used as an amendment to soils For example the presence of nonylphenol in sewage sludge prevents the use of the sludge Composting is one of the most efficient and economical methods of making sewage sludge stable and harmless Zheng et al 2015a studied the nonylphenol degradation rates during composting under the conditions of adding bulking agents sawdust corn stalks and mushroom residue and applying aeration Addition of 20  mushroom residue and 20  sawdust to the sewage sludge led to the highest 716  and lowest 225  apparent nonylphenol degradation rates respectively The study suggests that adding biomass materials and appropriate aerobic conditions could facilitate the degradation of nonylphenol in sewage sludge To monitor the estrogenic androgenic and toxic potencies in wastewater Wang et al 2015a demonstrated a standardized protocol for bioluminescent strains Saccharomyces cerevisiae BLYES BLYAS and BLYR as highthroughput screening tools The standardized protocol was applied for a yearlong monitoring of the effluent of a wastewater treatment plant featuring parallel operated fullscale membrane bioreactor and traditional activated sludge treatment Monitoring results showed that estrogenic activity was persistent in the effluent samples while residual androgenic activity was not detected throughout the monitored period Irrigation of agricultural lands can cause contamination of soils with pharmaceutical substances and risks to human and ecosystem health Xing et al 2015 summarized the progress of studies on the role of soil colloids in mediating the environmental behaviors of pharmaceuticals Reported results showed that colloids can adsorb pharmaceuticals mainly through ion exchange complexation and nonelectrostatic interactions The adsorbed pharmaceuticals may have higher risks to induce antibiotic resistance besides their transport may also be altered considering they have great chance to move with colloids Solution conditions such as pH ionic strength and cations could influence these interactions between pharmaceuticals and colloids Zeng et al 2015 evaluated the health risk of six heavy metals Zn Cu Cr Ni Pb and Cd via dietary intake of wheat grown in a sewage irrigation area for a long history Results showed that the continuous application of wastewater has led to an accumulation of heavy metals in the soil and in wheat The health risk due to the effects of accumulated heavy metals especially Cd and Cr was more significant for children than for adultsToxic risks are associated with disinfection processes applied to animal and human wellbeing as well as drinking water production and supply For instance antibiotics have been widely used for disease prevention and treatment of the human and animals and for growth promotion in animal husbandry However antibiotics can disturb the intestinal microbial community Misuse or overuse of antibiotics can result in increase and spread of microbial antibiotic resistance threatening human health and ecological safety In this special collection Yin et al 2015 reported intestinal microbial community shift and antibiotic resistance alteration of the mice that drink the water containing tetracycline hydrochloride TET Metagenomic analysis showed that TET treatment affected a number of functions of the intestinal microorganisms and enhanced the abundance of antibiotic resistance genes by ~5 times plasmids by ~8 times and integrons by ~200 times in mice gut The research suggests that TET administration could increase the opportunity of antibiotic resistance genes and mobile genetic elements entering into the environment with feces discharge E coli O157H7 is a significant human pathogen that is continually responsible for sickness and even death on a worldwide scale Xu et al 2015b reported that a critical bacterial infection level ie 5–10 × 105 must be reached prior to the onset of cytotoxic effects of E coli O157H7 They found that cells displaying infectionmediated metabolic activity reductions could recover to wild type metabolic activity levels if the infecting bacteria were removed prior to cell death These results indicate that rapid treatment of E coli O157H7 infection could serve to limit host metabolic impact and reduce overall host cell death As for drinking water production Tian et al 2015 reported an innovative and removable water treatment system for reducing waterborne pathogens which consists of strong electric field discharge and hydrodynamic cavitation based on advanced oxidation technologies AOT The biological efficacy and toxicity effects of this AOT based system were evaluated during water disinfection treatments Results showed that high inactivation efficiency of E coli 5 log could be obtained in synthetic contaminated water at low concentration 05–07 mg/L of total oxidants in 3–10 s Drinking water supply is mostly subject to chlorine stress Free chlorine is a potent oxidizing agent and has been used extensively as a disinfectant in processes including water treatment However the excessive residual of free chlorine in water distribution systems might cause adverse health effects As the first effort to assess the fate of chlorine in premise plumbing Zheng et al 2015b investigated the performance of three types of actual premise plumbing pipe materials ie copper galvanized iron and PVC in maintaining free chlorine residual The most rapid chlorine decay was observed in copper pipes suggesting the lower toxic risk of chlorine and the need for higher chlorine dosage to maintain appropriate chlorine level if copper piping is used PVC pipes exhibited the least reactivity with free chlorine implying the higher toxic risk of chlorine and the advantage of PVC material for maintaining free chlorine residual

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