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Site specific PCB-correlated interspecies differences in organ somatic indices
Diane S Henshel1, Daniel W Sparks
1School of Public and Environmental Affairs, Indiana University, 1315 E. 10th #340, Bloomington, IN 47401, USA. dhenshel@indiana.edu
Ecotoxicology (London, England)
|December 1, 2005
Summary
Polychlorinated biphenyls (PCBs) exposure affects organ somatic indices in nestling birds differently across species. Evaluating PCB congeners, not just total PCBs, is crucial for accurate ecotoxicological assessments.
Area of Science:
- Environmental Toxicology
- Ecotoxicology
- Avian Biology
Background:
- Organ somatic indices (SI) reflect organ health and can be altered by environmental contaminants.
- Polychlorinated biphenyls (PCBs) are persistent organic pollutants known to cause adverse effects in wildlife.
- Passerine birds are valuable bioindicators due to their widespread distribution and ecological roles.
Purpose of the Study:
- To investigate the relationship between site-specific polychlorinated biphenyl (PCB) exposure and organ somatic indices in nestlings of five passerine species.
- To determine if specific organ SI changes can serve as reliable indicators of PCB contamination across different species.
- To assess the importance of congener-specific analysis versus total PCB levels in ecotoxicological evaluations.
Main Methods:
- Correlating organ somatic indices (brain, bursa, heart, kidneys, lungs, pancreas, spleen, stomach, thyroid) with in ovo and post-hatching PCB exposure levels.
- Analyzing data from five passerine species (tree swallow, red-winged blackbird, house wren, Carolina chickadee, eastern bluebird) exposed at PCB-contaminated sites.
- Comparing the direction of mean SI changes in response to increasing contaminant exposure across species.
Main Results:
- Significant or marginally significant variations in organ SI were observed between sites for at least one species for brain, bursa, heart, kidneys, lungs, pancreas, spleen, stomach, and thyroid.
- The direction of mean SI change with increasing PCB exposure varied between species for brain, lung, pancreas, spleen, and thyroid.
- No single passerine species or organ SI reliably represented the overall response to PCB exposure across all species studied.
Conclusions:
- Organ somatic index responses to PCB exposure are species-specific, precluding the use of a single species or organ as a universal ecotoxicological indicator.
- PCB congener analysis is essential, as some dioxin-like congeners may be biologically significant even if total PCB levels are below detection limits.
- Comprehensive ecotoxicological evaluations must consider both species-specific responses and detailed congener analysis for accurate risk assessment.
