12 research outputs found
Synthetic Phenolic Antioxidants and Transformation Products in Human Sera from United States Donors
Synthetic
phenolic antioxidants (SPAs) make up a group of widely
used anthropogenic additives, whose potential for toxicity has received
more attention in recent years. Although SPAs can reach humans through
many exposure pathways, few data on the concentrations of SPAs in
humans are available. In this study, five SPAs were quantified, at
significant concentrations, in 50 individual serum samples collected
from donors in the United States. The measured total SPA concentrations
[0.46–34.7 ng/mL, geometric mean (GM) of 7.77 ng/mL] were dominated
by 2,6-di-<i>tert</i>-butyl-4-methylphenol (BHT) and 2,4-di-<i>tert</i>-butylphenol (DBP), which contributed 42 and 57% on
average to the total concentrations, respectively. Four putative biotransformation
products (TPs) of BHT [2,6-di-<i>tert</i>-butyl-4-(hydroxymethyl)Âphenol
(BHT-OH), 3,5-di-<i>tert</i>-butyl-4-hydroxybenzaldehyde
(BHT-CHO), 2,6-di-<i>tert</i>-butyl-1,4-benzoquinone (BHT-Q),
and 2,6-di-<i>tert</i>-butyl-4-hydroxy-4-methyl-2,5-cyclohexadienone
(BHT-quinol)] were also detected, with total concentrations ranging
from below the method quantification limits to 3.66 ng/mL (GM of 0.77
ng/mL). Five pooled serum samples, each containing sera from at least
1000 donors, were also included in this study. The concentrations
of the SPAs (GM of 24.5 ng/mL) and TPs (GM of 10.4 ng/mL) were even
higher in pooled sera than in individual samples, indicating the prevalent
human burdens of SPAs in a large population. To the best of our knowledge,
this is the first analysis of a wide range of SPAs and TPs in human
sera
Occurrence of Synthetic Phenolic Antioxidants and Major Metabolites in Municipal Sewage Sludge in China
Synthetic
phenolic antioxidants (SPAs) are one group of widely
used additive chemicals, which have not yet had focused attention
except for a few compounds such as 2,6-di-<i>tert</i>-butyl-4-methylphenol
(BHT). In this study, the occurrence and composition profiles of 12
frequently used SPAs and three BHT metabolites were investigated in
fifty-six sludge samples collected from individual wastewater treatment
plants in China. Eleven SPAs were positively found in the sludge samples,
in which, to our knowledge, eight SPA compounds were identified for
the first time in the environment. BHT, 4-<i>tert</i>-octylphenol
(4-<i>t</i>OP), and 2,4,6-tri-<i>tert</i>-bultylphenol
(AO 246) were the most dominant SPAs in the sludge at mean concentrations
of 4.14 μg/g, 374 ng/g, and 98.1 ng/g d.w. (dry weight). Meanwhile,
three BHT metabolites, including 3,5-di-<i>tert</i>-butyl-4-hydroxybenzaldehyde
(BHT-CHO), 2,6-di-<i>tert</i>-butyl-1,4-benzoquinone (BHT-Q),
and 2,6-di-<i>tert</i>-butyl-4-hydroxy-4-methyl-2,5-cyclohexadienone
(BHT-quinol), were also found in most of the samples (>98.2%) with
mean concentrations of 141, 562, and 225 ng/g d.w., respectively.
The activated sludge system (anaerobic, anoxic, and oxic tanks) of
a wastewater treatment plant was further investigated for the removal
efficiencies of the SPAs. High removal efficiencies (80.1–89.2%)
were found for the six detected SPAs in the aqueous phase, while generation
of large proportions of the three BHT metabolites was also observed
Identification of Novel Polyfluorinated Ether Sulfonates as PFOS Alternatives in Municipal Sewage Sludge in China
A 6:2 chlorinated polyfluorinated
ether sulfonate (6:2 Cl-PFAES)
with the trade name F-53B, is an alternative to perfluorooctanesulfonate
(PFOS) in electroplating industry that is uniquely used in China.
It was developed as a mist suppressant initially in the 1970s, but
the environmental behaviors and potential adverse effects of the 6:2
Cl-PFAES have only recently been investigated. In this work, the occurrence
and distribution of perfluoroalkyl sulfonate (PFSA), fluorotelomer
sulfonate (FTSA), and PFAES analogues were investigated in municipal
sewage sludge samples collected around China. Perfluorobutane, perfluorohexane,
perfluorooctane, and perfluorodecanesulfonates, 6:2 and 8:2 FTSAs,
and the emerging 6:2 Cl-PFAES were detected. Moreover, 8:2 and 10:2
Cl-PFAESs were identified for the first time as new polyfluorinated
contaminants using high resolution mass spectrometry. These fluorinated
analytes were further quantified with the aid of commercial and laboratory-purified
standards. PFOS was the predominant contaminant with a geometric mean
(GM) value of 3.19 ng/g dry weight (d.w.), which was subsequently
followed by 6:2 Cl-PFAES and 8:2 Cl-PFAES (GM: 2.15 and 0.50 ng/g
d.w., respectively). Both 6:2 and 8:2 Cl-PFAES were positively detected
as the major components in the F-53B commercial product, and discrete
6:2 Cl-PFAES/8:2 Cl-PFAES ratios in the product and sludge samples
might suggest 8:2 Cl-PFAES had enhanced sorption behavior in the sludge
due to the increase in hydrophobicity
Distribution and Preliminary Exposure Assessment of Bisphenol AF (BPAF) in Various Environmental Matrices around a Manufacturing Plant in China
Increasing attention has been paid to bisphenol A and
bisphenol
(BP) analogues due to high production volumes, wide usage and potential
adverse effects. Bisphenol AF (BPAF) is considered a new bisphenol
analogue which is used as raw material in plastic industry, but little
is known about its occurrence in the environment and the potential
associated risk. In this work, BPAF levels and environmental distribution
were reported in samples collected around a manufacturing plant and
a preliminary exposure risk assessment to local residents was conducted.
BPAF was detected in most of the samples, with levels in river ranging
between 4 ng/L, sediments (0.520–2.00
× 10<sup>3</sup> ng/g dry weight, dw), soils
Metabolites of 2,4,4′-Tribrominated Diphenyl Ether (BDE-28) in Pumpkin after <i>In Vivo</i> and <i>In Vitro</i> Exposure
There is currently limited knowledge
on PBDE metabolism in plants
although they could play an important role in the environmental transformation
of these persistent organic pollutants. In this study, pumpkin (<i>Cucurbita maxima × C. moschata)</i> was chosen as the model
to understand the fate of BDE-28 in plants. MeO-tri-BDEs, OH-tri-BDEs,
and OH-tri-BDEs were found as metabolites in plant samples of both <i>in vivo</i> hydroponic and <i>in vitro</i> tissue
culture exposure. Three MeO-tri-BDEs were further identified as para-substituted
metabolites. MeO-BDEs and OH-BDEs, respectively, accounted for about
1.6% and 1.5% (recovery corrected) of initial amount of BDE-28 according
to the semiquantitative results. Other PBDEs, especially less brominated
PBDEs as impurities in the standard of BDE-28, were also detected.
The impurities and evaporation of the standard must be considered
when trace metabolites are studied in exposure experiments
Synthetic Antioxidants as Contaminants of Emerging Concern in Indoor Environments: Knowns and Unknowns
Synthetic antioxidants, including synthetic phenolic
antioxidants
(SPAs), amine antioxidants (AAs), and organophosphite antioxidants
(OPAs), are essential additives for preventing oxidative aging in
various industrial and consumer products. Increasing attention has
been paid to the environmental contamination caused by these chemicals,
but our understanding of synthetic antioxidants is generally limited
compared to other emerging contaminants such as plasticizers and flame
retardants. Many people spend a significant portion (normally greater
than 80%) of their time indoors, meaning that they experience widespread
and persistent exposure to indoor contaminants. Thus, this Perspective
focuses on the problem of synthetic antioxidants as indoor environmental
contaminants. The wide application of antioxidants in commercial products
and their demonstrated toxicity make them an important family of indoor
contaminants of emerging concern. However, significant knowledge gaps
still need to be bridged: novel synthetic antioxidants and their related
transformation products need to be identified in indoor environments,
different dust sampling strategies should be employed to evaluate
human exposure to these contaminants, geographic scope and sampling
scope of research on indoor contamination should be broadened, and
the partition coefficients of synthetic antioxidants among different
media need to be investigated
Identification and Composition of Emerging Quaternary Ammonium Compounds in Municipal Sewage Sludge in China
Quaternary ammonium compounds (QACs)
have raised considerable attention
due to their wide commercial applications and recent discovery of
unknown persistent analogues in aqueous environment. In this work,
the occurrence and distribution of alkyltrimethylammonium (ATMAC),
benzylakyldimethylethylammonium (BAC) and dialkyldimethylammonium
(DADMAC) homologues were investigated in fifty-two municipal sewage
sludge samples. ATMAC C10–18, BAC C8–18 and paired DADMAC
C8:8-C18:18 as well as emerging homologues such as ATMAC-20, 22 and
mixed DADMAC-16:18 and 14:16 were present. Furthermore, paired DADMAC-20:20
and mixed DADMAC-14:18, 18:20 were identified for the first time by
nontarget qualitative strategies. A triple quadruple mass spectrometer
quantification method was also initially verified with the aid of
laboratory synthesized standards for the analysis of the mixed DADMACs
with no certificated commercial standards currently available. The
total concentrations of ATMACs, BACs and DADMACs were in the range
of 0.38–293, 0.09–191 and 0.64–344 μg/g
dry weight, respectively, and particularly, mixed DADMACs constituted
39 ± 7% of total DADMAC concentrations. The concentrations and
profiles of individual homologues further suggested different QAC
applications and fate in China. Significant correlations were also
found among the concentrations of various QAC homologues as well as
wastewater treatment plant (WWTP) characteristics (total organic carbon
contents and daily treatment volumes)
Observation of Emerging Photoinitiator Additives in Household Environment and Sewage Sludge in China
Photoinitiators
(PIs) are widely used additives in industrial polymerization
process, the contamination of which through migration into foodstuffs
has been subjected to increasing public scrutiny. Nevertheless, little
attention has been paid to the PI residue levels and potential exposure
pathways from other environmental compartments. In the present study,
the occurrence of PI additives with discrete molecular structures,
that is, nine benzophenones (BZPs), four thioxanthones (TXs), and
eight amine co-initiators (ACIs), was investigated in commercial products,
indoor dust and sewage sludge samples. Nine PI compounds were positively
detected in ultraviolet curable resins with concentrations of ∑PIs
(sum of the detected PIs) up to 2.51 × 10<sup>4</sup> ng/g, and
20 PIs can be found in food contact materials with concentrations
of ∑PIs varying from 65.9 to 6.93 × 10<sup>3</sup> ng/g.
The wide usage of PIs in commercial products led to the occurrence
of 19 PIs in indoor dust, with concentrations of ∑PIs in the
range of 245–5.68 × 10<sup>3</sup> ng/g. Meanwhile, all
21 targeted PIs could be identified in the sewage sludge, with concentrations
from 67.6 to 2.03 × 10<sup>3</sup> ng/g. Distinct PI composition
profiles were observed in different investigated compartments, and
BZPs were the dominant homologues in all samples. Most of the target
PIs were further identified as class III chemicals by toxic hazard
estimation algorithm (Toxtree), which indicates the compounds might
be of significant toxicity or have reactive functional groups
Chlorinated Polyfluoroalkyl Ether Sulfonic Acids in Marine Organisms from Bohai Sea, China: Occurrence, Temporal Variations, and Trophic Transfer Behavior
F-53B,
the commercial product of chlorinated polyfluoroalkyl ether
sulfonic acids (Cl-PFESAs), has been used in Chinese chrome plating
industry for 30 years, and was recently identified in the environment,
which caused great concerns. So far, limited investigations have been
performed on their environmental occurrence, fate and impact. In this
study, we demonstrated the wide occurrence of Cl-PFESAs and their
trophic transfer behavior in marine organisms from Chinese Bohai Sea.
6:2 Cl-PFESA (<0.016–0.575 ng/g wet weight) was the dominant
congener, and 8:2 Cl-PFESA (<0.022–0.040 ng/g) was occasionally
detected. Compared to other perfluoroalkyl and polyfluoroalkyl substances
(PFASs) of concern, the levels of Cl-PFESAs were relatively lower
in marine organisms. Based on the comparative analysis of Cl-PFESA
contamination in mollusk samples collected in 2010–2014, both
the concentrations and detection frequencies of Cl-PFESAs tended to
increase in this region. And this kind of chemicals were more vulnerable
to be accumulated in marine organisms at relatively higher trophic
levels. Similar to perfluorooctanesulfonate (PFOS) and the long chain
perfluorinated carboxylates (PFCAs), 6:2 Cl-PFESA could be magnified
along the food chain. Accordingly, the potential threat might be posed
to the wildlife and human beings due to unintended exposure to Cl-PFESAs
Aerobic Soil Biotransformation of 6:2 Fluorotelomer Iodide
6:2
FTI [FÂ(CF<sub>2</sub>)<sub>6</sub>CH<sub>2</sub>CH<sub>2</sub>I] is
a principal industrial raw material used to manufacture 6:2
FTOH [FÂ(CF<sub>2</sub>)<sub>6</sub>CH<sub>2</sub>CH<sub>2</sub>OH]
and 6:2 FTOH-based products and could enter aerobic environments from
possible industrial emissions where it is manufactured. This is the
first study to assess 6:2 FTI aerobic soil biotransformation, quantify
transformation products, and elucidate its biotransformation pathways.
6:2 FTI biotransformation led to 6:2 FTOH as a key intermediate, which
was subsequently biotransformed to other significant transformation
products, including PFPeA [FÂ(CF<sub>2</sub>)<sub>4</sub>COOH, 20 mol
% at day 91], 5:3 acid [FÂ(CF<sub>2</sub>)<sub>5</sub>CH<sub>2</sub>CH<sub>2</sub>COOH, 16 mol %], PFHxA [FÂ(CF<sub>2</sub>)<sub>5</sub>COOH, 3.8 mol %], and 4:3 acid [FÂ(CF<sub>2</sub>)<sub>4</sub>CH<sub>2</sub>CH<sub>2</sub>COOH, 3.0 mol %]. 6:2 FTI biotransformation
also led to a significant level of PFHpA [FÂ(CF<sub>2</sub>)<sub>6</sub>COOH, 16 mol % at day 91], perhaps via another putative intermediate,
6:2 FTUI [FÂ(CF<sub>2</sub>)<sub>6</sub>CHî—»CHI], whose molecular
identity and further biotransformation were not verified because of
the lack of an authentic standard. Total recovery of the aforementioned
per- and polyfluorocarboxylates accounted for 59 mol % of initially
applied 6:2 FTI by day 91, in comparison to 56 mol % when soil was
dosed with 6:2 FTOH, which did not lead to PFHpA. Thus, were 6:2 FTI
to be released from its manufacture and undergo soil microbial biotransformation,
it could form PFPeA, PFHpA, PFHxA, 5:3 acid, and 4:3 acid in the environment