API PUBL 4610-1995

$22.75

Critical Review of Draft EPA Guidance on Assessment and Control of Bioconcentratable Contaminants in Surface Waters

Published By	Publication Date	Number of Pages
API	1995	128

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Description

In 1991, EPA proposed guidance, "Assessment of Bio-concentratable Contaminants in Surface Water," for the identification of potential bio-concentratable compounds which are not currently regulated under the NPDES program. This API technical review of EPA guidance is intended to provide the industry with a better understanding of the proposed manner to determine bio-concentratable contaminants as well as a subject matter review of bioaccumulation in aquatic organisms. The EPA draft guidance does not provide a sound basis for identifying and predicting bioaccumulation of nonpolar organic chemicals of the types found in petroleum industry effluents. Nearly all potentially bio-concentratable organic chemicals (log K_OW3.5) in oil industry effluents are saturated and aromatic hydrocarbons. If present in the effluent at a concentration higher than 100ng/L, they will not pass the initial screening test if initial dilution in the receiving waters is less than 100-fold. The difficult analytical methods proposed for identifying bio-concentratable chemicals in effluents, tissues of aquatic animals, and sediments may produce analytical artifacts in samples containing hydrocarbons. Further, the methods are unlikely to positively identify additional chemicals, not already known to be present in the effluent, for which physical/chemical data required to predict bio-concentration and toxicity, are available.

Bio-concentration models relating the bio-concentration factor (BCF) to log K_OWtend to greatly overestimate concentrations of hydrocarbons in tissues of aquatic organisms. Hydrocarbons are absorbed from the food inefficiently and are metabolized and excreted rapidly by most aquatic animals. Therefore, they do not biomagnify in aquatic food chains. Concentrations of bio-concentratable chemicals in tissues of free-swimming aquatic animals or in sediments of depositional areas near an outfall cannot be used to identify bio-concentratable chemicals in a particular effluent because of uncertainties about the sources of the chemicals, particularly hydrocarbons.

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