Chemical activity as an integrating concept in environmental assessment and management of contaminants

Mackay, Don; Arnot, Jon A.; Wania, Frank; Bailey, Robert E.

doi:10.1002/ieam.139

Cited by 40 publications

(44 citation statements)

References 43 publications

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“…Chemical activity (a, unitless) is closely related to the lipidbased critical body residue as activity in the lipid phase is a product of the chemical's mole fraction in the lipid and the activity coefficient in that phase [1]. The activity coefficients of nonpolar narcotics in octanol (often an assumed surrogate for organic phase toxicity target sites) are relatively constant [15,16]. Chemical activity is directly related to concentration.…”

Section: Alternative Dose Metricsmentioning

confidence: 99%

“…Further analysis indicated that critical body residues associated with acutely lethal baseline neutral narcosis in small aquatic organisms typically range between approximately 2 mmol/kg and 8 mmol/kg (wet wt, $5% body lipid) and that different critical body residue ranges could be associated with standard fish mode of toxic action categories from narcosis to tetrachlorodibenzo-p-dioxin-like toxicity for both acute (lethal) and chronic responses [12,13]. Percentage of volume fractions in organism lipid phases and chemical activity have also been discussed as possible metrics for baseline narcosis toxicity and risk assessment [10,[14][15][16].…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of critical body residue data for acute narcosis in aquatic organisms

McCarty¹,

Arnot

Mackay

2013

Enviro Toxic and Chemistry

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The Environmental Residue Effects Database was evaluated to identify critical body residues of organic chemicals causing acute baseline neutral narcosis in aquatic organisms. Over 15 000 records for >400 chemicals were evaluated. Mean molar critical body residues in the final data set of 161 records for 29 chemicals were within published ranges but varied within and among chemicals and species (~3 orders of magnitude), and lipid normalization did not consistently decrease variability. All 29 chemicals can act as baseline neutral narcotics, but chemicals and/or their metabolites may also act by nonnarcotic modes of action. Specifically, nonnarcotic toxicity of polycyclic aromatic hydrocarbons and/or their biotransformation derivatives may be a significant source of variability. Complete testing of the narcosis-critical body residue hypothesis was confounded by data gaps for key toxicity modifying factors such as metabolite formation/toxicity, lipid content/composition, other modes of toxic action, and lack of steady-state status. Such problems impede determination of the precise, accurate toxicity estimates necessary for sound toxicological comparisons. Thus, neither the data nor the chemicals in the final data set should be considered definitive. Changes to testing designs and methods are necessary to improve data collection and critical body residue interpretation for hazard and risk assessment. Each of the toxicity metrics discussed-wet weight and lipid weight critical body residues, volume fraction in organism lipid, and chemical activity-has advantages, but all are subject to the same toxicity modifying factors.

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Section: Alternative Dose Metricsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Evaluation of critical body residue data for acute narcosis in aquatic organisms

McCarty¹,

Arnot

Mackay

2013

Enviro Toxic and Chemistry

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“…It has recently been proposed and experimentally conrmed that chemical activity is a key parameter for the baseline toxicity of hydrophobic organic chemicals, and that some highly hydrophobic substances can exert baseline toxicity at low aqueous concentrations but at relatively high chemical activities. [9][10][11][12][13][14][15] These, and other studies, suggest that exposure to hydrophobic organic substances is better described by freely dissolved concentrations and chemical activity than the total chemical concentration, since partitioning and diffusive uptake are spontaneous processes that are driven by differences in chemical activity. Because they can accumulate in sediments, PAHs have oen been examined in this environmental compartment, in relation to their role in exposure and their effects on aquatic life.…”

Section: Introductionmentioning

confidence: 89%

Estimating baseline toxicity of PAHs from marine chronically polluted sediments and bioaccumulation in target organs of fish hypothetically exposed to them: a new tool in risk assessment

Rojo-Nieto

Perales

2015

Environ. Sci.: Processes Impacts

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In soils and sediments contaminated by Hydrophobic Organic Compounds (HOCs), the total concentrations are less indicative of potential exposure and distribution than the associated freely dissolved concentrations (Cfree) or chemical activity. Therefore, these two parameters are increasingly used to assess sediment contamination with regard to their (1) partitioning into the water column, (2) bioaccumulation and (3) baseline toxic potential. In this work, sediments from a chronically polluted coastal area, with similar total PAH concentrations, were studied using PDMS coated glass jars (obtaining Cfree(SW) and chemical activity) to predict baseline toxicity and potential bioaccumulation from these sediments. The results indicate that, on the one hand, the chemical activity of the sediments differed by up to one order of magnitude and was below the level at which lethal baseline toxicity is expected, but is still a cause for concern due to the presence of other pollutants and different mechanisms of action. On the other hand, the combination of Cfree measurements and Biota to Sediment Accumulation Factors (BSAFs) allowed concentrations in different target organs of benthic flatfish, hypothetically exposed to these chronically polluted sediments, to be estimated. This new approach allows us to predict the concentration in biological tissues under the study of Cfree(SW) in sediments, as a useful tool in risk assessment.

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“…The approach of using baseline narcosis and relative toxicity ratios has been suggested when graphically comparing multimedia monitored and model-estimated concentrations as fugacities or activities [35,36]. The use of fugacity or activity (which is simply fugacity divided by liquid state vapor pressure) tends to consolidate multimedia levels into a narrower band.…”

Section: Future Prospects and Conclusionmentioning

confidence: 99%

QSARs for aquatic toxicity: celebrating, extending and displaying the pioneering contributions of Ferguson, Konemann and Veith

Mackay

Arnot

Celsie

et al. 2014

SAR and QSAR in Environmental Research

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Significant advances were made in the development of quantitative structure-activity relationships (QSARs) relating molecular structure to aquatic toxicity by three studies over 30 years ago by Ferguson in 1939, Konemann in 1981, and Veith and colleagues in 1983. We revisit the original concepts and data from these studies and review these contributions from the bases of current perspectives on the hypothesized mechanism of baseline narcotic toxicity and the underlying thermodynamic and kinetic aspects. The relationships between LC50, octanol-water partition coefficient, aqueous solubility, chemical activity and chemical volume fraction in lipid phases are outlined including kinetic influences on measured toxicities. These relationships provide a compelling and plausible explanation of the success of these and other QSARs for aquatic toxicity. Suggestions are made for further advances in these QSARs to improve assessments of toxicity by baseline narcotic toxicity and selective modes of action, especially using emerging quantum chemical computational capabilities.

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Chemical activity as an integrating concept in environmental assessment and management of contaminants

Cited by 40 publications

References 43 publications

Evaluation of critical body residue data for acute narcosis in aquatic organisms

Evaluation of critical body residue data for acute narcosis in aquatic organisms

Estimating baseline toxicity of PAHs from marine chronically polluted sediments and bioaccumulation in target organs of fish hypothetically exposed to them: a new tool in risk assessment

QSARs for aquatic toxicity: celebrating, extending and displaying the pioneering contributions of Ferguson, Konemann and Veith

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