Testing Fish for Harmful Chemicals: PCBs and Dioxins

Jim Crocker
19th April, 2025

Testing Fish for Harmful Chemicals: PCBs and Dioxins

Fish sampled from three distinct aquatic environments in Antioquia—the Cauca River (CAU), Magdalena River (PUB), and Gulf of Urabá (TUR)—revealed that low background levels of pollutants depended more on the biological characteristics of the fish species than on the geographic source.

Image adapted from: Avila et al. / CC BY (Source)

Key Findings

  • A study in Antioquia, Colombia found PCB levels in local fish were low and within safe background ranges
  • PCB concentrations were higher in fatty river fish but not in marine species, indicating diet and fat influence
  • No significant pollution hotspots were detected, ensuring that consuming these fish poses minimal health risks
Persistent organic pollutants (POPs) such as polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) pose significant environmental and health risks due to their ability to persist in the environment, accumulate in living organisms, and cause adverse effects on humans and wildlife. Addressing the presence and distribution of these pollutants is crucial for environmental health and safety. A recent study conducted by researchers at *Universidad de Antioquia (UdeA)*[1] aimed to assess the occurrence, distribution, and levels of PCBs, PCDDs, and PCDFs in fish samples from the Antioquia region in Colombia. The research involved analyzing 90 samples from various fish species to determine the concentration of these pollutants. The findings revealed that the levels of the six indicator PCBs ranged between 26.6 pg·g⁻¹ wet weight (w.w) to 1.33 ng·g⁻¹ fat, with an average value of 395 pg·g⁻¹ w.w (16.7 ng·g⁻¹ fat) and a median of 186 pg·g⁻¹ w.w (8.24 ng·g⁻¹ fat). For dioxin-like PCBs, concentrations varied from 3.09 pg·g⁻¹ w.w (0.135 ng·g⁻¹ fat) to 567 pg·g⁻¹ w.w (33.9 ng·g⁻¹ fat), with mean and median toxic equivalent values of 46.6 fg·TEQ·g⁻¹ w.w and 12.0 fg·TEQ·g⁻¹ w.w, respectively. Importantly, PCDD/PCDF levels were below the quantification limits of the analytical methods used. Overall, PCB and PCDD/PCDF concentrations in the fish samples were within background levels, and no hotspots of contamination were identified. This study provides a comprehensive overview of the current status of these pollutants in the region, supporting future research and policy-making efforts. This research builds on previous studies that have monitored POPs in different environmental media within Colombia. For instance, a study in Manizales[2] examined PCDD/Fs in ambient air and found that concentrations were comparable to those in larger cities, with sources primarily linked to combustion processes such as diesel engines and public transportation. Similarly, passive air sampling in Medellin[3] evaluated various POPs, including organochlorine pesticides and PCBs, establishing baseline levels and highlighting the need for enhanced analytical capacities in national laboratories. Additionally, research on PCBs in human milk across seven Colombian cities[4] indicated low levels of these pollutants, suggesting minimal risk to breastfed infants and reinforcing the importance of breastfeeding practices. The Antioquia study employed rigorous analytical methods to ensure accurate detection and quantification of POPs in fish tissues. By analyzing both wet weight and fat concentrations, the researchers could assess the bioaccumulation of these pollutants in aquatic organisms. The absence of PCDD/PCDF above quantification limits suggests that current environmental controls and regulations may be effective in preventing significant contamination in the region's water bodies. Furthermore, the findings align with earlier studies that reported low to background levels of POPs in various environmental compartments, thereby corroborating the notion that Colombia has made progress in managing these persistent contaminants. Understanding the distribution of POPs in fish is particularly important as it relates to human exposure through diet. Fish are integral to the local diet in Antioquia, and monitoring pollutant levels ensures that consumption does not pose health risks. The study’s results, showing no elevated hotspots, are reassuring for public health and support the safety of fish as a dietary component. This aligns with the findings from the PCB analysis in human milk[4], where low PCB levels indicated minimal exposure risks for infants. Moreover, the Antioquia study’s comprehensive approach provides a foundation for ongoing environmental monitoring and the development of targeted strategies to further reduce POPs. By establishing current pollutant levels, future studies can track trends and evaluate the effectiveness of regulatory measures. This proactive monitoring is essential, especially in light of the Medellin study[3], which emphasized the need for improved analytical capabilities to broaden the scope of pollutant monitoring. In conclusion, the assessment of PCBs, PCDDs, and PCDFs in fish from the Antioquia region offers valuable insights into the environmental status of these persistent pollutants. The findings indicate that pollutant levels are within safe, background ranges, supporting the safety of fish consumption and reflecting positively on Colombia’s environmental management efforts. This study not only advances our understanding of POP distribution in aquatic ecosystems but also underscores the importance of continuous monitoring to safeguard both environmental and human health.

EnvironmentEcologyAnimal Science

References

Main Study

1) Occurrence, distribution, and levels of Polychlorinated Biphenyls (PCB), Polychlorinated Dibenzo-p–Dioxins (PCDD), and Polychlorinated Dibenzofurans (PCDF) in fish from the Antioquia Region, Colombia

Published 16th April, 2025

https://doi.org/10.1007/s10661-025-13956-0

Related Studies

2) Polychlorinated dibenzo-p-dioxin and dibenzofuran in urban air of an Andean city.

https://doi.org/10.1016/j.chemosphere.2011.06.035

3) Occurrence and distribution of persistent organic pollutants (POPs) in the atmosphere of the Andean city of Medellin, Colombia.

https://doi.org/10.1016/j.chemosphere.2022.135648

4) Human Biomonitoring of Polychlorinated Biphenyls (PCBs) in the Breast Milk of Colombian Mothers.

https://doi.org/10.1007/s00128-022-03577-5


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