Harbor Porpoise Infection Risk from PCB Exposure
Author Information
Author(s): Ailsa J. Hall, Kelly Hugunin, Robert Deaville, Robin J. Law, Colin R. Allchin, Paul D. Jepson
Primary Institution: Sea Mammal Research Unit, Gatty Marine Laboratory, University of St. Andrews
Hypothesis
Does high exposure to polychlorinated biphenyls (PCBs) increase the risk of mortality from infectious disease in harbor porpoises?
Conclusion
The study found that increased levels of PCBs in harbor porpoises are associated with a higher risk of death from infectious diseases.
Supporting Evidence
- The odds of dying from infectious disease increased by 4.8% for each 1 mg/kg increase in blubber PCBs.
- A doubling of risk occurred at approximately 45 mg/kg lipid.
- The study used a long-term dataset from harbor porpoises in U.K. waters.
- The exposure odds ratio was adjusted for confounding factors such as energetic status, sex, age, region, and season.
Takeaway
This study shows that harbor porpoises with more PCBs in their fat are more likely to get sick and die from infections.
Methodology
A case-control study design was used, comparing infectious disease deaths to physical trauma deaths in harbor porpoises, with logistic regression to control for confounding factors.
Potential Biases
Selection bias could occur if the controls are not representative of the exposure prevalence in the population.
Limitations
Potential selection bias in control selection and misclassification errors may affect risk estimates.
Participant Demographics
The study included 236 harbor porpoises, with cases defined as those that died from infectious diseases and controls as those that died from physical trauma.
Statistical Information
P-Value
p<0.0001
Confidence Interval
95% CI, 1.02–1.07
Statistical Significance
p<0.0001
Digital Object Identifier (DOI)
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