Exposure of Laboratory Animals to SPMD Extracts

In addition to biomarker tests, exposnre stndies nsing selected laboratory test animals have recently been condncted to obtain data related to the consequences of the presence of mixtures of chemicals in habitats of concern. For example, amphibian deformities have been widely reported in North America (Souder, 2000), and have resnlted in numerons attempts to delineate the canses for the high deformity rates observed (Ouellet et al., 1997). Often, it is very difficult to ascertain the effects of contaminants on natural amphibian popnlations, dne principally to the 

At metamorphosis there was equal mortality in both UV treatments, consequently the UV treatments were pooled within SPMD treatments to increase statistical power when analyzing the deformity data. When analyzed independently of SPMD treatment, no significant deformities were found to occur due to the effects of UV (p 0.05). SPMD extracts from the site exhibiting amphibian 

Based upon these resnlts, it is highly probable that waterborne lipophilic chemicals contiibnte to the observed deformities in amphibian popnlations at the impacted site. It is highly improbable that microorganisms or virnses originating from the lake water conld have cansed the deformities becanse the transport corridors in the SPMD membrane are no more than 10 A in cross-sectional diameter (far too small to allow virnses to penetrate the sampler membrane). 

Research stndies employing exposnres of organisms to SPMD extracts in a physiologically nentral medium are increasingly being applied. We envision that this approach will continue to find application in a wide variety of contaminant assessment research studies. 

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