Chlorodifluoroacetic acid fate and toxicity to the macrophytes<i>Lemna gibba, Myriophyllum spicatum</i>, and<i>Myriophyllum sibiricum</i>in aquatic microcosms

Hanson, Mark L.; Sibley, Paul K.; Mabury, Scott A.; Muir, Derek C. G.; Solomon, Keith R.

doi:10.1002/etc.5620201215

Cited by 21 publications

(1 citation statement)

References 35 publications

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“…in ecotoxicological risk assessment, in the context of this study, is promising. These plants can be evaluated for a wide variety of effect measures and develop well under semi-natural field conditions ( , ). The use of single species effect measure distributions for aquatic plants appears to be a useful approach for assessing the risk to these organisms from contaminants.…”

Section: Discussionmentioning

confidence: 99%

New Technique for Estimating Thresholds of Toxicity in Ecological Risk Assessment

Hanson

Solomon

2002

Environ. Sci. Technol.

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The use and utility of the no observed effect concentration (NOEC) in ecological risk assessment is a contentious issue. One concern is that the NOEC is not representative of a concentration at which no biologically significant effect is occurring. A new method has been developed to estimate the threshold of toxicity, or a true NOEC, for aquatic plants. The method involves determining the effective concentration (ECx) of a number of endpoints from one species. These ECx values are plotted on a log-probability scale. The x-intercept, or a low centile, of the distribution can be interpreted as the threshold of toxicity for that plant at that response level. This threshold is the concentration at which no effects should be observed for any endpoint above that response level. It is based on the assumptions that multiple effect measures from a single species will be log-normally distributed and thatthe distribution contains all possible endpoints for that species. The thresholds and the distributions can then be used as a substitute for the NOEC or ECx in risk assessment techniques, such as hazard quotients and probabilistic ecological risk assessment. This new method of estimating toxicitythresholds is more realistic than the use of arbitrary uncertainty factors, is more conservative than current probabilistic risk assessment methods, allows for simple comparison between species and exposure duration to a toxicant, and may be useful for assessing mixture toxicity. This technique was applied to field derived data with Lemna gibba, Myriophyllum spicatum, and M. sibiricumto assess potential risks from monochloroacetic acid (MCA). Using this new risk assessment method, we conclude that MCA does not appear to pose a risk to aquatic macrophytes under field conditions at current environmental concentrations.

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Section: Discussionmentioning

confidence: 99%

New Technique for Estimating Thresholds of Toxicity in Ecological Risk Assessment

Hanson

Solomon

2002

Environ. Sci. Technol.

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Variation, replication, and power analysis ofMyriophyllumspp. microcosm toxicity data

Hanson¹,

Sanderson

Solomon

2003

Enviro Toxic and Chemistry

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Myriophyllum spp. have been proposed as a new standard laboratory aquatic macrophyte test species for the registration of pesticides. The main objectives of this investigation were to determine the power of Myriophyllum sibiricum and Myriophyllum spicatum toxicity data derived from an outdoor microcosm bioassay, to evaluate the variation of 10 different aquatic plant endpoints and to calculate the minimum detectable difference for these endpoints, to determine the replication required to detect ecologically significant changes from control for these endpoints, and to make recommendations for future field studies with Myriophyllum spp. Control data from four different studies that characterized haloacetic acid toxicity with Myriophyllum spp. for durations of three to six weeks during the summer of 1999 with five treatment levels (n = 3), including control, were examined. Endpoint coefficient of variation ranged, on average, from 6 to 28%. Node number and plant length endpoints were consistently the most statistically powerful for both plant species. It was possible to detect approximately 30% change from control in both endpoints with high statistical power (beta = 0.2, alpha = 0.05, n = 3). The range of minimum detectable differences was 40 to 60% for the other endpoints. Replication to detect a > or = 25% change from control would require an n of 2 to 21, depending on the endpoint. Myriophyllum sibiricum had slightly lower coefficients of variation and thus required fewer replicates than M. spicatum to be statistically significantly different from control values. Variation within microcosm studies was not significantly different from that of controlled laboratory studies, implying that most of the variation observed in the field is inherent in the plants. Based on statistical sensitivity, ecological relevance, and toxicological sensitivity, we recommend using plant length and root endpoints as indicators of toxicity under field conditions.

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Using mass defect plots as a discovery tool to identify novel fluoropolymer thermal decomposition products

et al. 2014

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Fire events involving halogenated materials, such as plastics and electronics, produce complex mixtures that include unidentified toxic and environmentally persistent contaminants. Ultrahigh-resolution mass spectrometry and mass defect filtering can facilitate compound identification within these complex mixtures. In this study, thermal decomposition products of polychlorotrifluoroethylene (PCTFE, [-CClF-CF2 -]n), a common commercial polymer, were analyzed by Fourier transform ion cyclotron resonance mass spectrometry. Using the mass defect plot as a guide, novel PCTFE thermal decomposition products were identified, including 29 perhalogenated carboxylic acid (PXCA, X = Cl,F) congener classes and 21 chlorine/fluorine substituted polycyclic aromatic hydrocarbon (X-PAH, X = Cl,F) congener classes. This study showcases the complexity of fluoropolymer thermal decomposition and the potential of mass defect filtering to characterize complex environmental samples.

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Chlorodifluoroacetic acid fate and toxicity to the macrophytesLemna gibba, Myriophyllum spicatum, andMyriophyllum sibiricumin aquatic microcosms

Cited by 21 publications

References 35 publications

New Technique for Estimating Thresholds of Toxicity in Ecological Risk Assessment

New Technique for Estimating Thresholds of Toxicity in Ecological Risk Assessment

Variation, replication, and power analysis ofMyriophyllumspp. microcosm toxicity data

Using mass defect plots as a discovery tool to identify novel fluoropolymer thermal decomposition products

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