9 research outputs found
Meta-Analysis of Mass Balances Examining Chemical Fate during Wastewater Treatment
Mass balances are an instructive means for investigating the fate of chemicals during wastewater treatment. In addition to the aqueous-phase removal efficiency (Φ), they can inform on chemical partitioning, transformation, and persistence, as well as on the chemical loading to streams and soils receiving, respectively, treated effluent and digested sewage sludge (biosolids). Release rates computed on a per-capita basis can serve to extrapolate findings to a larger scale. This review examines over a dozen mass balances conducted for various organic wastewater contaminants, including prescription drugs, estrogens, fragrances, antimicrobials, and surfactants of differing sorption potential (hydrophobicity), here expressed as the 1-octanol−water partition coefficient (<i>K</i><sub>OW</sub>) and the organic carbon normalized sorption coefficient (<i>K</i><sub>OC</sub>). Major challenges to mass balances are the collection of representative samples and accurate quantification of chemicals in sludge. A meta-analysis of peer-reviewed data identified sorption potential as the principal determinant governing chemical persistence in biosolids. Occurrence data for organic wastewater compounds detected in digested sludge followed a simple nonlinear model that required only <i>K</i><sub>OW</sub> or <i>K</i><sub>OC</sub> as the input and yielded a correlation coefficient of 0.9 in both instances. The model predicted persistence in biosolids for the majority (>50%) of the input load of organic wastewater compounds featuring a log<sub>10</sub> <i>K</i><sub>OW</sub> value of greater than 5.2 (log<sub>10</sub> <i>K</i><sub>OC</sub> > 4.4). In contrast, hydrophobicity had no or only limited value for estimating, respectively, Φ and the overall persistence of a chemical during conventional wastewater treatment
Contribution of Polybrominated Dibenzo‑<i>p</i>‑dioxins and Dibenzofurans (PBDD/Fs) to the Toxic Equivalency of Dioxin-like Compounds in Archived Biosolids from the U.S. EPA’s 2001 National Sewage Sludge Survey
The
World Health Organization recently proposed the inclusion of
brominated congeners in addition to chlorinated congeners when computing
the toxic equivalency (TEQ) of dioxin-like compounds (DLCs) in assessments
of human health risks. In the present study, 12 polybrominated dibenzo-<i>p</i>-dioxins and furans (PBDD/Fs) were analyzed by gas chromatography/high
resolution mass spectrometry in the composited, archived biosolids
that were collected in 32 U.S. states and the District of Columbia
from 94 wastewater treatment plants by the United States Environmental
Protection Agency in its 2001 national sewage sludge survey. Two PBDDs
and five PBDFs were detected in the biosolids composites at varying
frequencies (40–100%) with a total mean concentration of 10,000
ng/kg dry weight (range: 630–42,800), of which 1,2,3,4,6,7,8-hepta-BDF
constituted about 95% by mass. Relative to commercial polybrominated
diphenyl ether (PBDE) formulations, the ratio of PBDD/Fs to PBDEs
in biosolids was 55-times higher (∼0.002% vs ∼0.11%),
which indicates potential PBDE transformation or possibly additional
sources of PBDD/Fs in the environment. The TEQ contribution of PBDD/Fs
was estimated at 162 ng/kg 2,3,7,8-tetrachlorodibenzo-<i>p</i>-dioxin (TCDD) (range: 15–672), which is equivalent to 75%
(range: 12–96%) of the total TEQ in biosolids. The TEQ of DLCs
released annually to U.S. soils as a result of the land application
of biosolids was estimated at 720 g (range: 530–1600 g). Among
all known DLCs determined in biosolids, brominated analogs contributed
370% more TEQ than did chlorinated congeners, which indicates the
need to include brominated DLCs in the exposure and risk assessment
of land-applied biosolids
Mass Balance Assessment for Six Neonicotinoid Insecticides During Conventional Wastewater and Wetland Treatment: Nationwide Reconnaissance in United States Wastewater
Occurrence
and removal of six high-production high-volume neonicotinoids
was investigated in 13 conventional wastewater treatment plants (WWTPs)
and one engineered wetland. Flow-weighted daily composites were analyzed
by isotope dilution liquid chromatography tandem mass spectrometry,
revealing the occurrence of imidacloprid, acetamiprid, and clothianidin
at ng/L concentrations in WWTP influent (60.5 ± 40.0; 2.9 ±
1.9; 149.7 ± 289.5, respectively) and effluent (58.5 ± 29.1;
2.3 ± 1.4; 70.2 ± 121.8, respectively). A mass balance showed
insignificant removal of imidacloprid (<i>p</i> = 0.09,
CI = 95%) and limited removal of the sum of acetamiprid and its degradate,
acetamiprid-<i>N</i>-desmethyl (18 ± 4%, <i>p</i> = 0.01, CI = 95%). Clothianidin was found only intermittently, whereas
thiamethoxam, thiacloprid, and dinotefuran were never detected. In
the wetland, no removal of imidacloprid or acetamiprid was observed.
Extrapolation of data from 13 WWTPs to the nation as a whole suggests
annual discharges on the order of 1000–3400 kg/y of imidacloprid
contained in treated effluent to surface waters nationwide. This first
mass balance and first United States nationwide wastewater reconnaissance
identified imidacloprid, acetamiprid, and clothianidin as recalcitrant
sewage constituents that persist through wastewater treatment to enter
water bodies at significant loadings, potentially harmful to sensitive
aquatic invertebrates
Prenatal exposure to tobacco smoke leads to increased mitochondrial DNA content in umbilical cord serum associated to reduced gestational age
<p>We investigated if prenatal exposures to tobacco smoke lead to changes in mitochondrial DNA content (mtDNA) in cord serum and adversely affect newborns’ health. Umbilical cord serum cotinine levels were used to determine in utero exposure to smoking. Cord serum mtDNA was measured by quantitative polymerase chain reaction analysis of the genes coding for cytochrome c oxidase1 (<i>MT</i>-<i>CO1</i>) and cytochrome c oxidase2 (<i>MT</i>-<i>CO2</i>). Log transformed levels of mtDNA coding for <i>MT</i>-<i>CO1</i> and <i>MT</i>-<i>CO2</i> were significantly higher among infants of active smokers with higher serum level of cotinine (<i>p</i> < 0.05) and inversely associated with gestational age (<i>p</i> = 0.08; <i>p</i> = 0.02). Structural equation modeling results confirmed a positive association between cotinine and <i>MT</i>-<i>CO1</i> and2 (<i>p</i> < 0.01) and inverse associations with gestational age (<i>p</i> = 0.02) and <i>IGF</i>-<i>1</i> (<i>p</i> < 0.01). We identified a dose-dependent increase in the level of <i>MT</i>-<i>CO1</i> and <i>MT</i>-<i>CO2</i> associated to increased cord serum cotinine and decreased gestational age.</p
Human Fetal Exposure to Triclosan and Triclocarban in an Urban Population from Brooklyn, New York
Triclosan
(TCS) and triclocarban (TCC) are antimicrobial agents
formulated in a wide variety of consumer products (including soaps,
toothpaste, medical devices, plastics, and fabrics) that are regulated
by the U.S. Food and Drug Administration (FDA) and U.S. Environmental
Protection Agency. In late 2014, the FDA will consider regulating
the use of both chemicals, which are under scrutiny regarding lack
of effectiveness, potential for endocrine disruption, and potential
contribution to bacterial resistance to antibiotics. Here, we report
on body burdens of TCS and TCC resulting from real-world exposures
during pregnancy. Using liquid chromatography tandem mass spectrometry,
we determined the concentrations of TCS, TCC, and its human metabolites
(2′-hydroxy-TCC and 3′-hydroxy-TCC) as well as the manufacturing
byproduct (3′-chloro-TCC) as total concentrations (Σ−)
after conjugate hydrolysis in maternal urine and cord blood plasma
from a cohort of 181 expecting mother/infant pairs in an urban multiethnic
population from Brooklyn, NY recruited in 2007–09. TCS was
detected in 100% of urine and 51% of cord blood samples after conjugate
hydrolysis. The interquartile range (IQR) of detected TCS concentrations
in urine was highly similar to the IQR reported previously for the
age-matched population of the National Health and Nutrition Examination
Survey (NHANES) from 2003 to 2004, but typically higher than the IQR
reported previously for the general population (detection frequency
= 74.6%). Urinary levels of TCC are reported here for the first time
from real-world exposures during pregnancy, showing a median concentration
of 0.21 μg/L. Urinary concentrations of TCC correlated well
with its phase-I metabolite ∑-2′-hydroxy-TCC (<i>r</i> = 0.49) and the manufacturing byproduct ∑-3′-chloro-TCC
C (<i>r</i> = 0.79), and ∑-2′-hydroxy-TCC
correlated strongly with ∑-3′-hydroxy-TCC (<i>r</i> = 0.99). This human biomonitoring study presents the first body
burden data for TCC from exposures occurring during pregnancy and
provides additional data on composite exposure to TCS (i.e., from
both consumer-product use and environmental sources) in the maternal–fetal
unit for an urban population in the United States
Characterization, Recovery Opportunities, and Valuation of Metals in Municipal Sludges from U.S. Wastewater Treatment Plants Nationwide
U.S. sewage sludges were analyzed for 58 regulated and nonregulated
elements by ICP-MS and electron microscopy to explore opportunities
for removal and recovery. Sludge/water distribution coefficients (<i>K</i><sub>D</sub>, L/kg dry weight) spanned 5 orders of magnitude,
indicating significant metal accumulation in biosolids. Rare-earth
elements and minor metals (Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy,
Ho, Er, Tm, Yb, Lu) detected in sludges showed enrichment factors
(EFs) near unity, suggesting dust or soils as likely dominant sources.
In contrast, most platinum group elements (i.e., Ru, Rh, Pd, Pt) showed
high EF and <i>K</i><sub>D</sub> values, indicating anthropogenic
sources. Numerous metallic and metal oxide colloids (<100–500
nm diameter) were detected; the morphology of abundant aggregates
of primary particles measuring <100 nm provided clues to their
origin. For a community of 1 million people, metals in biosolids were
valued at up to USValue) to capture
the <i>relative potential for economic value from biosolids</i> revealed the identity of the 13 most lucrative elements (Ag, Cu,
Au, P, Fe, Pd, Mn, Zn, Ir, Al, Cd, Ti, Ga, and Cr) with a combined
value of US $280/ton of sludge
Extraction and Quantification of Carbon Nanotubes in Biological Matrices with Application to Rat Lung Tissue
Extraction of carbon nanotubes (CNTs) from biological matrices such as rat lung tissue is integral to developing a quantification method for evaluating the environmental and human health exposure and toxicity of CNTs. The ability of various chemical treatment methods, including Solvable (2.5% sodium hydroxide/surfactant mixture), ammonium hydroxide, nitric acid, sulfuric acid, hydrochloric acid, hydrofluoric acid, hydrogen peroxide, and proteinase K, to extract CNTs from rat lung tissue was evaluated. CNTs were quantified using programmed thermal analysis (PTA). Two CNTs were used to represent the lower (500 °C) and upper (800 °C) PTA limit of CNT thermal stability. The recovery efficiency of each of the eight chemical reagents evaluated was found to depend on the ability to (1) minimize oxidation of CNTs, (2) remove interfering background carbon from the rat lung tissue, and (3) separate the solid-phase CNTs from the liquid-phase dissolved tissue <i>via</i> centrifugation. A two-step extraction method using Solvable and proteinase K emerged as the optimal approach, enabling a recovery of 98 ± 15% of a 2.9 ± 0.19 μg CNT loading that was spiked into whole rat lungs. Due to its high yield and applicability to low organ burdens of nanomaterials, this extraction method is particularly well suited for <i>in vivo</i> studies to quantify clearance rates and retained CNTs in lungs and other organs
Transformation Products and Human Metabolites of Triclocarban and Triclosan in Sewage Sludge Across the United States
Removal
of triclocarban (TCC) and triclosan (TCS) from wastewater
is a function of adsorption, abiotic degradation, and microbial mineralization
or transformation, reactions that are not currently controlled or
optimized in the pollution control infrastructure of standard wastewater
treatment. Here, we report on the levels of eight transformation products,
human metabolites, and manufacturing byproducts of TCC and TCS in
raw and treated sewage sludge. Two sample sets were studied: samples
collected once from 14 wastewater treatment plants (WWTPs) representing
nine states, and multiple samples collected from one WWTP monitored
for 12 months. Time-course analysis of significant mass fluxes (α
= 0.01) indicate that transformation of TCC (dechlorination) and TCS
(methylation) occurred during sewage conveyance and treatment. Strong
linear correlations were found between TCC and the human metabolite
2′-hydroxy-TCC (<i>r</i> = 0.84), and between the
TCC-dechlorination products dichlorocarbanilide (DCC) and monochlorocarbanilide
(<i>r</i> = 0.99). Mass ratios of DCC-to-TCC and of methyl-triclosan
(MeTCS)-to-TCS, serving as indicators of transformation activity,
revealed that transformation was widespread under different treatment
regimes across the WWTPs sampled, though the degree of transformation
varied significantly among study sites (α = 0.01). The analysis
of sludge sampled before and after different unit operation steps
(i.e., anaerobic digestion, sludge heat treatment, and sludge drying)
yielded insights into the extent and location of TCC and TCS transformation.
Results showed anaerobic digestion to be important for MeTCS transformation
(37–74%), whereas its contribution to partial TCC dechlorination
was limited (0.4–2.1%). This longitudinal and nationwide survey
is the first to report the occurrence of transformation products,
human metabolites, and manufacturing byproducts of TCC and TCS in
sewage sludge
Organic Contaminants in Chinese Sewage Sludge: A Meta-Analysis of the Literature of the Past 30 Years
The
production of sewage sludge is increasing in China but with
unsafe disposal practices, causing potential risk to human health
and the environment. Using literature from the past 30 years (<i>N</i> = 159), we conducted a meta-analysis of organic contaminants
(OCs) in Chinese sludge. Most data were available from developed and
populated regions, and no data were found for Tibet. Since 1987, 35
classes of chemicals consisting of 749 individual compounds and 1
mixture have been analyzed, in which antibiotics and polycyclic aromatic
hydrocarbons (PAHs) were the most targeted analytes. For 13 classes
of principal OCs (defined as chemicals detected in over five studies)
in sludge, the median (expressed in nanograms per gram dry weight)
was the highest for phthalate esters (27 900), followed by
alkylphenol polyethoxylates (12 000), synthetic musks (5800),
antibiotics (4240), PAHs (3490), ultraviolet stabilizers (670), bisphenol
analogs (160), organochlorine pesticides (110), polybrominated diphenyl
ethers (100), pharmaceuticals (84), hormones (69), perfluorinated
compounds (21), and polychlorinated biphenyls (15). Concentrations
of PAHs in sludges collected between 1998 and 2012 showed a decreasing
trend. Study findings suggest the need for a Chinese national sewage
sludge survey to identify and regulate toxic OCs, ideally employing
both targeted as well as nontargeted screening approaches