2 research outputs found
DataSheet1.pdf
<p>Expanded polystyrene (EPS) products and their associated chemicals (e.g., styrenes) are widespread in the marine environment. As a consequence, bans on their use for single-use packaging materials are being proposed in several municipalities. To better understand how science can inform decision-making, we looked at the available scientific literature about contamination and effects and conducted experiments to measure chemical leachate from polystyrene products and toxicity from the leachate. We conducted leaching experiments with common food matrices (water, soup broth, gravy, black coffee and coffee with cream and sugar) at relevant temperatures (70 and 95°C) that are consumed in or with several polystyrene products (coffee cup lids, polystyrene stir sticks, polystyrene spoons, EPS cups, EPS bowls, and EPS takeout containers). We analyzed each sample for styrene, ethylbenzene, toluene, benzene, meta- and para- xylene, isopropylbenzene, and isopropyltoluene—chemicals associated with polystyrene products. To determine whether the leachates are toxic, we conducted chronic toxicity tests, measuring survival and reproductive output in Ceriodaphnia dubia. Toxicity tests included nine treatments: seven concentrations of ethylbenzene, EPS cup leachate and a negative control. Overall, we found that temperature has a significant effect on leaching. We only detected leachates in trials conducted at higher temperature −95°C. Ethylbenzene was the only target analyte with final concentrations above the method limit of detection, and was present in the greatest concentrations in EPS and with soup broth. Measurable concentrations of ethylbenzene in the leachate ranged from 1.3 to 3.4 μg/L. In toxicity tests, the calculated LC50 for ethylbenzene was 14 mg/L and the calculated LC20 was 210 μg/L. For the treatment exposed to the EPS cup leachate, mortality was 40%—four times greater than the negative control. Finally, there was no significant difference (p = 0.17) between reproductive output for any treatment with ethylbenzene, but there was a significant reduction (p = 0.01) in reproductive output for the treatment exposed to the EPS leachate compared to the negative control. Thus, although the target analyte ethylbenzene was not toxic at concentrations detected in the leachate, significant adverse effects were detected in the whole EPS cup leachate sample.</p
Characterization and Biological Potency of Mono- to Tetra-Halogenated Carbazoles
This
paper deals with the characterization and aryl hydrocarbon
receptor (AhR) agonist activities of a series of chlorinated, brominated,
and mixed bromo/chlorocarbazoles, some of which have been identified
in various environmental samples. Attention is directed here to the
possibility that halogenated carbazoles may currently be emitted into
the environment as a result of the production of carbazole-containing
polymers present in a wide variety of electronic devices. We have
found that any carbazole that is not substituted in the 1,3,6,8 positions
may be lost during cleanup of environmental extracts if a multilayer
column is utilized, as is common practice for polychlorinated dibenzo-<i>p</i>-dioxin (dioxin) and related compounds. In the present
study, <sup>1</sup>H NMR spectral shift data for 11 relevant halogenated
carbazoles are reported, along with their gas chromatographic separation
and analysis by mass spectrometry. These characterization data allow
for confident structural assignments and the derivation of possible
correlations between structure and toxicity based on the halogenation
patterns of the isomers investigated. Some halogenated carbazoles
exhibit characteristics of persistent organic pollutants and their
potential dioxin-like activity was further investigated. The structure-dependent
induction of CYP1A1 and CYP1B1 gene expression in Ah-responsive MDA-MB-468
breast cancer cells by these carbazoles was similar to that observed
for other dioxin-like compounds, and the magnitude of the fold induction
responses for the most active halogenated carbazoles was similar to
that observed for 2,3,7,8-tetrachlorodibenzo<i>-p-</i>dioxin
(TCDD). 2,3,6,7-Tetrachlorocarbazole was one of the most active halogenated
carbazoles and, like TCDD, contains 4 lateral substituents; however,
the estimated relative effect potency for this compound (compared
to TCDD) was 0.0001 and 0.0032, based on induction of CYP1A1 and CYP1B1
mRNA, respectively