9 research outputs found
Identifying Bioaccumulative Halogenated Organic Compounds Using a Nontargeted Analytical Approach: Seabirds as Sentinels
<div><p>Persistent organic pollutants (POPs) are typically monitored via targeted mass spectrometry, which potentially identifies only a fraction of the contaminants actually present in environmental samples. With new anthropogenic compounds continuously introduced to the environment, novel and proactive approaches that provide a comprehensive alternative to targeted methods are needed in order to more completely characterize the diversity of known and unknown compounds likely to cause adverse effects. Nontargeted mass spectrometry attempts to extensively screen for compounds, providing a feasible approach for identifying contaminants that warrant future monitoring. We employed a nontargeted analytical method using comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC/TOF-MS) to characterize halogenated organic compounds (HOCs) in California Black skimmer (<i>Rynchops niger</i>) eggs. Our study identified 111 HOCs; 84 of these compounds were regularly detected via targeted approaches, while 27 were classified as typically unmonitored or unknown. Typically unmonitored compounds of note in bird eggs included tris(4-chlorophenyl)methane (TCPM), tris(4-chlorophenyl)methanol (TCPMOH), triclosan, permethrin, heptachloro-1'-methyl-1,2'-bipyrrole (MBP), as well as four halogenated unknown compounds that could not be identified through database searching or the literature. The presence of these compounds in Black skimmer eggs suggests they are persistent, bioaccumulative, potentially biomagnifying, and maternally transferring. Our results highlight the utility and importance of employing nontargeted analytical tools to assess true contaminant burdens in organisms, as well as to demonstrate the value in using environmental sentinels to proactively identify novel contaminants.</p></div
Relative Abundance of Individual Compounds, excluding PCBs.
<p>Each point represents one egg sample (n = 4), including non-detects. Non-detects are shown with a value of zero (multiple non-detects overlap). PCBs are included in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0127205#pone.0127205.s003" target="_blank">S1 Fig</a>.</p
Relative Abundance of Compound Classes.
<p>Each point represents detection in a single egg sample (n = 4). The abundance is the sum total of the normalized peak areas for all compounds in the class, in each sample. The line is the median abundance for the compound class. The source of each compound class is indicated in the legend. Non-detects are shown with a value of zero (multiple non-detects overlap).</p
Nontargeted Comprehensive Two-Dimensional Gas Chromatography/Time-of-Flight Mass Spectrometry Method and Software for Inventorying Persistent and Bioaccumulative Contaminants in Marine Environments
Analytical methods for contaminant monitoring are generally
targeted;
i.e., they measure defined lists of compounds. Routine monitoring
projects using targeted methods are not usually designed to screen
for unrecognized or novel contaminants and therefore miss compounds
within the region or population of study that cause, or have the potential
to cause, adverse biological impacts. We describe a nontargeted analytical
method utilizing direct sample introduction coupled to comprehensive
two-dimensional gas chromatography with time-of-flight mass spectrometry.
To test the capabilities of this instrumental method within the context
of marine contaminant surveys, we characterized a broad array of nonpolar,
persistent, and bioaccumulative contaminants in Atlantic common dolphin
(Delphinus delphis) blubber, including
compounds that are not typically monitored. Compound identifications
were made by searching a standard reference database, by contemporaneously
analyzing mass spectra from reference standards, and by de novo interpretation.
We identified a total of 271 compounds belonging to 24 classes; all
compounds but 1 were halogenated. Anthropogenic contaminants and halogenated
natural products were concurrently detected. A total of 86 compounds
were anthropogenic contaminants that are not routinely targeted in
environmental surveys, and 54 compounds were halogenated natural products.
A total of 112 spectra were identified de novo, demonstrating that
exclusive reliance on commercially available reference standards and
mass spectral libraries may miss a significant fraction of identifiable
compounds. We also cataloged 27 halogenated mass spectra that were
not able to be identified. Due to the volume and complexity of the
identification data, we developed custom software to organize and
provide shared access to the identified mass spectra and related information.
The nontargeted analytical method and data reporting system, in combination
with the analysis of a high-trophic-level sentinel species, demonstrates
a framework for creating an inventory of persistent and bioaccumulative
contaminants in marine environments, with the future goal of suggesting
new compounds for further investigation by targeted monitoring and
risk assessment
Comprehensive Screening Links Halogenated Organic Compounds with Testosterone Levels in Male <i>Delphinus delphis</i> from the Southern California Bight
While environmental
pollutants have been associated with changes
in endocrine health in cetaceans, efforts to link contaminant exposure
with hormones have largely been limited to a list of known, targeted
contaminants, overlooking minimally characterized or unknown compounds
of emerging concern. To address this gap, we analyzed a suite of potential
endocrine disrupting halogenated organic compounds (HOCs) in blubber
from 16 male short-beaked common dolphins (<i>Delphinus delphis</i>) with known maturity status collected from fishery bycatch in the
Southern California Bight. We employed a suspect screening mass spectrometry-based
method to investigate a wide range of HOCs that were previously observed
in cetaceans from the same region. Potential endocrine effects were
assessed through the measurement of blubber testosterone. We detected
167 HOCs, including 81 with known anthropogenic sources, 49 of unknown
origin, and 37 with known natural sources. The sum of 11 anthropogenic
and 4 unknown HOC classes were negatively correlated with blubber
testosterone. Evidence suggests that elevated anthropogenic HOC load
contributes to impaired testosterone production in mature male <i>D. delphis</i>. The application of this integrative analytical
approach to cetacean contaminant analysis allows for inference of
the biological consequences of accumulation of HOCs and prioritization
of compounds for future environmental toxicology research
Leached Compounds from Smoked Cigarettes and Their Potential for Bioaccumulation in Rainbow Trout (Oncorhynchus mykiss)
Cigarette butts are one of the most prevalent forms of
litter worldwide
and may leach toxic compounds when deposited in aquatic environments.
Previous studies demonstrated that smoked cigarette leachate is toxic
toward aquatic organisms. However, the specific bioavailable chemicals
from the leachate and the potential for human and wildlife exposure
through the food chain were unknown. Using a nontargeted analytical
approach based on GC×GC/TOF-MS, 43 compounds were confirmed to
leach from smoked cigarettes when exposed to a water source. Additionally,
the bioaccumulation potential of organic contaminants in an edible
fish, rainbow trout (Oncorhynchus mykiss), was assessed through direct exposure to the leachate of smoked
cigarettes at 0.5 CB/L for 28 days. There was a significant reduction
in fish mass among the exposed rainbow trout vs the control group
(χ2 (1) = 5.3, p = 0.021). Both
nontargeted and targeted chemical analysis of representative fish
tissue identified four tobacco alkaloids, nicotine, nicotyrine, myosmine,
and 2,2′-bipyridine. Their average tissue concentrations were
466, 55.4, 94.1, and 70.8 ng/g, respectively. This study identifies
leached compounds from smoked cigarettes and demonstrates the uptake
of specific chemicals in rainbow trout, thus suggesting a potential
for accumulation in food webs, resulting in human and wildlife exposure
Nontargeted Biomonitoring of Halogenated Organic Compounds in Two Ecotypes of Bottlenose Dolphins (<i>Tursiops truncatus</i>) from the Southern California Bight
Targeted
environmental monitoring reveals contamination by known
chemicals, but may exclude potentially pervasive but unknown compounds.
Marine mammals are sentinels of persistent and bioaccumulative contaminants
due to their longevity and high trophic position. Using nontargeted
analysis, we constructed a mass spectral library of 327 persistent
and bioaccumulative compounds identified in blubber from two ecotypes
of common bottlenose dolphins (<i>Tursiops truncatus</i>) sampled in the Southern California Bight. This library of halogenated
organic compounds (HOCs) consisted of 180 anthropogenic contaminants,
41 natural products, 4 with mixed sources, 8 with unknown sources,
and 94 with partial structural characterization and unknown sources.
The abundance of compounds whose structures could not be fully elucidated
highlights the prevalence of undiscovered HOCs accumulating in marine
food webs. Eighty-six percent of the identified compounds are not
currently monitored, including 133 known anthropogenic chemicals.
Compounds related to dichlorodiphenyltrichloroethane (DDT) were the
most abundant. Natural products were, in some cases, detected at abundances
similar to anthropogenic compounds. The profile of naturally occurring
HOCs differed between ecotypes, suggesting more abundant offshore
sources of these compounds. This nontargeted analytical framework
provided a comprehensive list of HOCs that may be characteristic of
the region, and its application within monitoring surveys may suggest
new chemicals for evaluation
Nontargeted Biomonitoring of Halogenated Organic Compounds in Two Ecotypes of Bottlenose Dolphins (<i>Tursiops truncatus</i>) from the Southern California Bight
Targeted
environmental monitoring reveals contamination by known
chemicals, but may exclude potentially pervasive but unknown compounds.
Marine mammals are sentinels of persistent and bioaccumulative contaminants
due to their longevity and high trophic position. Using nontargeted
analysis, we constructed a mass spectral library of 327 persistent
and bioaccumulative compounds identified in blubber from two ecotypes
of common bottlenose dolphins (<i>Tursiops truncatus</i>) sampled in the Southern California Bight. This library of halogenated
organic compounds (HOCs) consisted of 180 anthropogenic contaminants,
41 natural products, 4 with mixed sources, 8 with unknown sources,
and 94 with partial structural characterization and unknown sources.
The abundance of compounds whose structures could not be fully elucidated
highlights the prevalence of undiscovered HOCs accumulating in marine
food webs. Eighty-six percent of the identified compounds are not
currently monitored, including 133 known anthropogenic chemicals.
Compounds related to dichlorodiphenyltrichloroethane (DDT) were the
most abundant. Natural products were, in some cases, detected at abundances
similar to anthropogenic compounds. The profile of naturally occurring
HOCs differed between ecotypes, suggesting more abundant offshore
sources of these compounds. This nontargeted analytical framework
provided a comprehensive list of HOCs that may be characteristic of
the region, and its application within monitoring surveys may suggest
new chemicals for evaluation
Nontargeted Screening of Halogenated Organic Compounds in Bottlenose Dolphins (<i>Tursiops truncatus</i>) from Rio de Janeiro, Brazil
To
catalog the diversity and abundance of halogenated organic compounds
(HOCs) accumulating in high trophic marine species from the southwestern
Atlantic Ocean, tissue from bottlenose dolphins (<i>Tursiops
truncatus</i>) stranded or incidentally captured along the coast
of Rio de Janeiro, Brazil, were analyzed by a nontargeted approach
based on GC×GC/TOF-MS. A total of 158 individual HOCs from 32
different structural classes were detected in the blubber of 4 adult
male <i>T. truncatus</i>. Nearly 90% of the detected compounds
are not routinely monitored in the environment. DDT-related and mirex/dechlorane-related
compounds were the most abundant classes of anthropogenic origin.
Methoxy-brominated diphenyl ethers (MeO-BDEs) and chlorinated methyl-
and dimethyl bipyrroles (MBPs and DMBPs) were the most abundant natural
products. Reported for the first time in southwestern Atlantic cetaceans
and in contrast to North American marine mammals, chlorinated MBPs
and DMBPs were more abundant than their brominated and/or mixed halogenated
counterparts. HOC profiles in coastal <i>T. truncatus</i> from Brazil and California revealed a distinct difference, with
a higher abundance of MeO-BDEs, mirex/dechloranes and chlorinated
bipyrroles in the Brazilian dolphins. Thirty-six percent of the detected
HOCs had an unknown structure. These results suggest broad geographical
differences in the patterns of bioaccumulative chemicals found in
the marine environment and indicate the need to develop more complete
catalogs of HOCs from various marine environments