3 research outputs found
Environmental Risks of Medium-Chain Chlorinated Paraffins (MCCPs): A Review
Chlorinated paraffins are industrial
chemicals that can be subdivided
into short-chain (SCCP), medium-chain (MCCP), and long-chain (LCCP)
chlorinated paraffins. The global production volumes of MCCPs are
nowadays suspected to be much higher than those of S- and LCCPs, and
the few available studies on the environmental occurrence of chlorinated
paraffins report often higher MCCP concentrations than S- or LCCP
concentrations in the environment. The present review focuses, therefore,
on MCCPs specifically and provides a literature overview and a data
analysis of the production volumes, PBT properties (persistence, bioaccumulation
potential, and toxicity), and the worldwide measured concentrations
of MCCP in environmental samples, biota, and humans. Furthermore,
we include our own measurements of technical CP formulations from
China, the major global producing country, to estimate the global
production amounts of MCCPs. The key findings from this review are
that (1) MCCPs are toxic to the aquatic environment, and the available
data suggest that they are also persistent; (2) available time trends
for MCCPs in soil, biota, and most of the sediment cores show increasing
time trends over the last years to decades; and (3) MCCP concentrations
in sediment close to local sources exceed toxicity thresholds (i.e.,
the PNEC). Our study shows that overall, MCCPs are of growing concern,
and regulatory actions should be considered seriously
Deconvolution of Mass Spectral Interferences of Chlorinated Alkanes and Their Thermal Degradation Products: Chlorinated Alkenes
Chlorinated
paraffins (CPs) are high production volume chemicals
and ubiquitous environmental contaminants. CPs are produced and used
as complex mixtures of polychlorinated <i>n</i>-alkanes
containing thousands of isomers, leading to demanding analytical challenges.
Due to their high degree of chlorination, CPs have highly complex
isotopic mass patterns that often overlap, even when applying high
resolution mass spectrometry. This is further complicated in the presence
of degradation products such as chlorinated alkenes (CP-enes). CP-enes
are formed by dehydrochlorination of CPs and are expected thermal
degradation products in some applications of CPs, for example, as
metal working fluids. A mathematical method is presented that allows
deconvolution of the strongly interfered measured isotope clusters
into linear combinations of isotope clusters of CPs and CP-enes. The
analytical method applied was direct liquid injection into an atmospheric
pressure chemical ionization source, followed by quadrupole time-of-flight
mass spectrometry (APCI-qTOF-MS), operated in full scan negative ion
mode. The mathematical deconvolution method was successfully applied
to a thermally aged polychlorinated tridecane formulation (Cl<sub>5</sub>–Cl<sub>9</sub>). Deconvolution of mass patterns allowed quantifying fractions of
interfering CPs and CP-enes. After exposure to 220 °C for 2,
4, 8, and 24 h, fractions of CP-enes within the respective interfering
clusters increased from 0–3% at 0 h up to 37–44% after
24 h. It was shown that thermolysis of CPs follows first-order kinetics.
The presented deconvolution method allows CP degradation studies with
mass resolution lower than 20000 and is therefore a good alternative
when higher resolution is not available
Screening of Pesticide and Biocide Patterns As Risk Drivers in Sediments of Major European River Mouths: Ubiquitous or River Basin-Specific Contamination?
Pesticides and biocides (PaB) are
ubiquitously present in aquatic
ecosystems due to their widespread application and have been detected
in rivers at concentrations that may cause distress to aquatic life.
Many of these compounds accumulate in sediments acting as long-term
source for aquatic ecosystems. However, data on sediment contamination
with current-use PaB in Europe are scarce. Thus, in this study, we
elucidated PaB patterns and associated risks in sediments of seven
major European rivers focusing on their last stretch as an integrative
sink of particles transported by these rivers. Sediments were extracted
with pressurized liquid extraction (PLE) using a broad-spectrum method
recovering many compound classes with a wide range of physicochemical
properties. Altogether 126 compounds were analyzed and 81 of them
were detected with LC-HRMS and GC-NCI-MS/MS at least in one of the
sediments. The highest number of compounds was detected (59) in River
Elbe sediments close to Cuxhaven with outstanding concentrations ranging
from 0.8 to 1691 mg/g organic carbon. Multivariate analysis identified
a cluster with 3 ubiquitous compounds (cyhalothrin, carbendazim, fenpropimorph)
and three clusters of chemicals with higher variability within and
between rivers. Risk assessment indicates an acute toxic risk to benthic
crustaceans at all investigated sites with the pyrethroids tefluthrin
and cyfluthrin together with the fungicide carbendazim as the main
drivers. Risks to algae were driven at most sites almost exclusively
by photosynthesis inhibitors with estuary-specific herbicide mixtures,
while in the rivers Po and Gironde cell division inhibitors played
an important role at some sites. Mixtures of specific concern have
been defined and suggested for integration in future monitoring programs