Tag Archives: organic contaminants

Perfluoroalkyl Substances in the Aquatic Environment

Xiao F. Emerging poly- and perfluoroalkyl substances in the aquatic environment: A review of current literature. Water research 2017 Jul 15;124:482-495. doi: 10.1016/j.watres.2017.07.024.

Poly- and perfluoroalkyl substances (PFASs) comprise a group of synthetic organic surfactants with a wide range of industrial and commercial applications. A few PFASs such as perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) are now known to be ubiquitously present in the aquatic environment. They have become a global concern because of the toxicity and bioaccumulative properties. With the increasing availability of high-resolution mass spectrometers, many novel PFASs have been identified. Studies published between 2009 and 2017 have discovered 455 new PFASs (including nine fully and 446 partially fluorinated compounds), 45%, 29%, 17%, and 8% of which are anions, zwitterions, cations, and neutrals, respectively. They have been identified in natural waters, fish, sediments, wastewater, activated sludge, soils, aqueous film-forming foams, and commercial fluoropolymer surfactants. This article integrates and critically evaluates what is known about these newly identified PFASs. It discusses the different aspects of detection methodologies. It also surveys the removal of these compounds during conventional and advanced drinking-water and wastewater treatment, predicts the relevant physicochemical properties by means of four software programs, and identifies major knowledge gaps. Notably, a number of these newly identified PFASs are potential precursor compounds of PFOS and PFOA. Studies are critically needed to understand the removal and transformation of these compounds in natural and engineered environmental systems and their contribution, if any, to the secondary formation of PFOS and PFOA in these systems.

Crude oil contamination of plastic and copper drinking water pipes

Huang X, Andry S, Yaputri J, Kelly D, Ladner DA, Whelton AJ. Crude oil contamination of plastic and copper drinking water pipes. Journal of hazardous materials. 2017 Jun 17;339:385-394. doi: 10.1016/j.jhazmat.2017.06.015.

This study was conducted to determine the susceptibility of plastic (i.e., PEX, HDPE and CPVC) and copper pipes to short-term contamination by crude oil. Pipes were exposed to highly and slightly contaminated drinking water for the typical duration of Do Not Use drinking water orders. PEX pipes sorbed and desorbed the greatest amount of monoaromatic hydrocarbons (MAHs), whereas copper pipes were less susceptible to contamination. For benzene, toluene, ethylbenzene, and xylenes (BTEX) quantified in water, only benzene exceeded its health based maximum contaminant level (MCL). The MCL was exceeded for copper pipe on day 3, for CPVC pipe through day 9, and PEX and HDPE pipes through day 15. The BTEX compound concentration in water after the pipes were returned to service depended on the initial crude oil concentration, material type, and exposure duration. Total organic carbon (TOC) measurement was not helpful in detecting oil contaminated water. Except BTEX, trimethylbenzene isomers and a couple of polycyclic aromatic hydrocarbons (PAHs) with and without MCLs were also detected desorbing from PEX-A pipe. Oil contaminated water must be thoroughly characterized and pipe type will influence the ability of drinking water levels to return to safe limits.

Occurrence and Removal of Phthalates from Wastewater

Gani KM, Tyagi VK, Kazmi AA. Occurrence of phthalates in aquatic environment and their removal during wastewater treatment processes: a review. Environ Sci Pollut Res Int. 2017 May 31. doi: 10.1007/s11356-017-9182-3.

Phthalates are plasticizers and are concerned environmental endocrine-disrupting compounds. Due to their extensive usage in plastic manufacturing and personal care products as well as the potential to leach out from these products, phthalates have been detected in various aquatic environments including drinking water, groundwater, surface water, and wastewater. The primary source of their environmental occurrence is the discharge of phthalate-laden wastewater and sludge. This review focuses on recent knowledge on the occurrence of phthalate in different aquatic environments and their fate in conventional and advanced wastewater treatment processes. This review also summarizes recent advances in biological removal and degradation mechanisms of phthalates, identifies knowledge gaps, and suggests future research directions.

Toxicity evaluation of organic extracts from drinking water, Guangdong Province

Guan Y, Wang X, Wong M, Sun G, An T, Guo J, Zhang G. Evaluation of Genotoxic and Mutagenic Activity of Organic Extracts from Drinking Water Sources. PloS one. 2017 Jan 26;12(1):e0170454. doi: 10.1371/journal.pone.0170454.

An increasing number of industrial, agricultural and commercial chemicals in the aquatic environment lead to various deleterious effects on organisms, which is becoming a serious global health concern. In this study, the Ames test and SOS/umu test were conducted to investigate the potential genotoxicity and mutagenicity caused by organic extracts from drinking water sources. Organic content of source water was extracted with XAD-2 resin column and organic solvents. Four doses of the extract equivalent to 0.25, 0.5, 1 and 2L of source water were tested for toxicity. All the water samples were collected from six different locations in Guangdong province. The results of the Ames test and SOS/umu test showed that all the organic extracts from the water samples could induce different levels of DNA damage and mutagenic potentials at the dose of 2 L in the absence of S9 mix, which demonstrated the existence of genotoxicity and mutagenicity. Additionally, we found that Salmonella typhimurium strain TA98 was more sensitive for the mutagen. Correlation analysis between genotoxicity, Organochlorine Pesticides (OCPs) and Polycyclic Aromatic Hydrocarbons (PAHs) showed that most individual OCPs were frame shift toxicants in drinking water sources, and there was no correlation with total OCPs and PAHs.

Human Health Risk Associated with Perfluorinated Carboxylates (PFCAs)

Rand AA, Mabury SA. Is there a human health risk associated with indirect exposure to perfluorinated carboxylates (PFCAs)? Toxicology. 2016 Nov 19. pii: S0300-483X(16)30281-5. doi: 10.1016/j.tox.2016.11.011.

The production and widespread use of poly- and perfluorinated alkyl substances (PFAS) has led to their presence in environment, wildlife, and humans. Particularly, the perfluorinated carboxylates (PFCAs) are pervasive throughout the world and have been found at ng/mL concentrations in human blood. PFCAs, especially those having longer carbon chain lengths (≥C6), are associated with developmental and hormonal effects, immunotoxicity, and promote tumor growth in rodents through their role as PPARα agonists. Humans are directly exposed to PFCAs primarily through contaminated food, drinking water, and house dust. However, indirect exposure to PFCAs through the biotransformation of fluorotelomer-based substances may also be a significant, yet relatively underappreciated pathway. We are exposed to fluorotelomer-based substances through use of consumer products, ingestion of food, or from inhalation of dust particles, but the risk of this exposure has been largely uncharacterized. Here, we summarize the work that has been done to characterize toxicity of the classes of fluorotelomer-based substances shown to biotransform to PFCAs: the polyfluoroalkyl phosphate esters (PAPs), fluorotelomer alcohols (FTOHs), fluorotelomer iodides (FTIs), and fluorotelomer acrylate monomers (FTAcs). These fluorotelomer-based substances biotranform to yield PFCAs, yet also form bioactive intermediate metabolites, which have been observed to be more toxic than their corresponding PFCAs. We address what is known regarding the toxicity of the fluorotelomer-based substances and their metabolites, with focus on covalent binding to biological nucleophiles, such as glutathione, proteins, and DNA, as a possible mechanism of toxicity that may influence the risk of indirect exposure to PFCAs.

Occurrence of Nonylphenol and Bisphenol A in Household Water Pipes

Cheng YC, Chen HW, Chen WL, Chen CY, Wang GS. Occurrence of nonylphenol and bisphenol A in household water pipes made of different materials. Environmental monitoring and assessment 2015 Oct;188(10):562. doi: 10.1007/s10661-016-5556-0.

We assessed the occurrence of nonylphenol (NP) and bisphenol A (BPA) in tap water supplied through polyvinyl chloride (PVC), stainless steel, and galvanized pipes. Water samples were collected from selected households in Taipei and Kaohsiung (Northern and Southern Taiwan, respectively) in different seasons to elucidate the effects of pipeline materials and ambient temperatures on NP and BPA concentrations in tap water. We detected higher concentrations of NP in tap water from households using PVC pipes (64-195 ng/L) than from those using stainless steel pipes (17-44 ng/L) and galvanized pipes (27-96 ng/L). To verify that water can absorb NP and BPA from PVC pipes, we sealed Milli-Q and tap water in PVC and stainless steel pipes to assess the potential release of NP and BPA from the pipes into the water. Both NP and BPA concentrations initially increased with contact time in the PVC pipes, and the concentration profiles during the retention appeared to be more strongly affected by ambient temperatures. Concentration variations in the stainless steel pipes were smaller than those in the PVC pipes.

Mineralization of 2,6-Dichlorobenzamide in Sand Filters

Vandermaesen J, Horemans B, Degryse J, Boonen J, Walravens E, Springael D. Mineralization of the common groundwater pollutant 2,6-dichlorobenzamide (BAM) and its metabolite 2,6-dichlorobenzoic acid (2,6-DCBA) in sand filter units of drinking water treatment plants. Environmental Science and Technology. 2016 Aug 17.

The intrinsic capacity to mineralize the groundwater pollutant 2,6-dichlorobenzamide (BAM) and its metabolite 2,6-dichlorobenzoic acid (2,6-DCBA) was evaluated in samples from sand filters (SFs) of drinking water treatment plants (DWTPs). Whereas BAM mineralization occurred rarely and only in SFs exposed to BAM, 2,6-DCBA mineralization was common in SFs, including those treating uncontaminated water. Nevertheless, SFs treating BAM contaminated water showed the highest 2,6-DCBA mineralization rates. For comparison, 2,6-DCBA and BAM mineralization were determined in various topsoil samples. As in SF samples, BAM mineralization was rare, whereas 2,6-DCBA mineralization capacity appeared widespread, with high mineralization rates found especially in forest soils. Multivariate analysis showed that in both SF and soil samples, high 2,6-DCBA mineralization correlated with high organic carbon content. Adding a 2,6-DCBA degradation deficient mutant of the BAM mineralizing Aminobacter sp. MSH1 confirmed that 2,6-DCBA produced from BAM is rapidly mineralized by the endogenous microbial community in SFs showing intrinsic 2,6-DCBA mineralization. This study demonstrates that (i) 2,6-DCBA mineralization is widely established in SFs of DWTPs, allowing the mineralization of any 2,6-DCBA produced during BAM degradation and (ii) the first metabolic step in BAM mineralization is rare in microbial communities, rather than its further degradation beyond 2,6-DCBA.