Bioaccumulation in aquatic species is a critical end point in the regulatory assessment of chemicals. Few measured fish bioconcentration factors (BCFs) are available for fragrance ingredients. Thus, predictive models are often used to estimate their BCFs. Because biotransformation can reduce chemical accumulation in fish, models using QSAR-estimated biotransformation rates have been developed. ...

Mandated efforts to assess chemicals for their potential to bioaccumulate within the environment are increasingly moving into the realm of data inadequacy. Consequently, there is an increasing reliance on predictive tools to complete regulatory requirements in a timely and cost-effective manner. The kinetic processes of absorption, distribution, metabolism, and elimination (ADME) determine the ...

Selenium is essential for most of living organisms. In normoxic to moderately hypoxic freshwaters, Se exists predominantly in the (+VI) and (+IV) oxidation states as selenate and selenite respectively, whereas in the biota it is incorporated as Se (-II) or Se (0). At low concentrations, it acts against oxidative damages, but it may be toxic at higher levels. In filter feeders, such as the fresh...

the spatial and temporal distribution of heavy metals in water, sediment and fish (dry weight basis) of buriganga river, bangladesh were determined by atomic absorption spectrophotometer. in water concentration of pb, cd, ni, cu and cr varied seasonally and spatially from 58.17 to 72.45î¼g/l, 7.08 to 12.33î¼g/l, 7.15 to 10.32î¼g/l, 107.38 to 201.29î¼g/l and 489.27 to 645.26î¼g/l, respectively. ...

Traditionally, water quality guidelines/criteria are based on lethality tests where results are expressed as a function of waterborne concentrations (e.g. LC50). However, there is growing interest in the use of uptake and binding relationships, such as biotic ligand models (BLM), and in bioaccumulation parameters, such as critical body residue values (e.g. CBR50), to predict metal toxicity in a...

Several studies have shown that sediment associated black carbonaceous particles can reduce aqueous and bioaccumulated concentrations of hydrophobic organic compounds (HOCs) in benthic organisms. Therefore, carbon amendments (e.g. activated carbon, AC) have been studied as stabilization method for contaminated sediments. However, it appears that the amendments may have also direct adverse effec...

Mercury (Hg) bioaccumulation in salamanders has received little attention despite widespread Hg contamination of aquatic ecosystems and worldwide amphibian declines. Here we report concentrations of methyl Hg (MeHg) and total Hg in larval northern two-lined salamanders (Eurycea bislineata bislineata) collected from streams in Acadia National Park (ANP), Maine, and Bear Brook Watershed, Maine (B...

To improve current bioaccumulation assessment methods, a methodology is developed, applied, and investigated for measuring in vivo biotransformation rates of hydrophobic organic substances in the body (soma) and gastrointestinal tract of the fish. The method resembles the Organisation for Economic Co-operation and Development (OECD) 305 dietary bioaccumulation test but includes reference chemic...

A cadmium tolerant strain of Aspergillus niger and a lead tolerant strain of Rhizopus arrhizus were studied for distribution of accumulated toxic heavy metals in the mycelia in comparison to wild type strains. Accumulated cadmium in the cell wall fractions of cadmium tolerant Aspergillus niger was more than the wild type strain. Cytosolic fraction contained the next highest load of metal. Simil...