GC–MS Finds Hormone Disruptors in Brazilian Lagoon

New kinds of pollutants are showing up more frequently in lakes, rivers, and coastal waters, raising worries about how long they stick around and how they affect wildlife. This is especially true for coastal lagoons near busy human activity. This has inspired a team of researchers to study the mud at the bottom of Maricá Lagoon in Rio de Janeiro, Brazil, testing it for medications, chemicals from detergents and plastics (including the chemical bisphenol A [BPA]), and estrogen hormones, and checking whether the mud had estrogen-like effects. Their goal was to determine whether the pollution and its effects changed from one year to another, even though people kept adding pollutants to the lagoon. The team collected mud from the same seven spots during the dry season in 2021 and again in 2023. They measured how coarse or fine the mud was, used gas chromatography–mass spectrometry (GC–MS) to identify and measure the pollutants, and used the yeast estrogen screen (YES) bioassay with specially designed yeast cells to detect estrogen-like activity. A paper based on this research was published in the journal Environmental Monitoring and Assessment.¹

Why Are Tropical Coastal Lagoons So Vulnerable to Pollution?

Tropical coastal lagoons are especially prone to building up pollution. Their water doesn't mix much with the open sea, it moves slowly, and mud settles quickly to the bottom, so pollutants that cling to particles tend to get trapped there.^2,3 In addition, these lagoons often receive runoff and waste from crowded surrounding areas, both from specific sources like sewage pipes and from scattered sources across the land. This makes them especially likely to collect hormone-disrupting chemicals in their mud, where they can linger for a long time.⁴Hormone-disrupting chemicals are being more often recognized as a danger to wildlife in the water. Even so, little is known about how much of them ends up in the mud of tropical coastal lagoons or what effects they have there.^5,6

What Did the Testing Reveal About Pollution in the Coastal Ecosystem?

Laboratory testing found several kinds of pollutants in the samples: chemicals from detergents and plastics (4-octylphenol and 4-nonylphenol), BPA, estrogen hormones, and substances linked to medications. BPA turned up most often, at levels of about 0.10 to 0.47 billionths of a gram per gram of sample. It was followed by 4-octylphenol and 4-nonylphenol, which showed up at similarly tiny amounts.

Other findings include:

One sampling site, M7, stood out: 9 of the 12 chemicals the researchers were looking for were found there, making it a local pollution hotspot.

Some samples showed hormone-like effects that mimic estrogen. One sample, however, was so toxic to the test cells that it may have hidden any estrogen-like effects.

Comparing the two rounds of sampling showed that the types of pollutants and their effects varied from year to year, although several chemicals were present in both years.

“These findings,” write the authors of the paper,¹ “demonstrate persistent and spatially heterogeneous contamination and highlight the value of integrating targeted chemical analyses with bioanalytical tools to assess contaminant occurrence and biological effects in coastal ecosystems.”

Read More on Similar Subjects
GC-MS/MS Maps OCP, PCB Levels in Greek Coastal Sediments

References

• da Silva de Freitas, A.; de Oliveira Santos, A. D.; Sanson, A. L. et al. Temporal Variability of Emerging Contaminants and Estrogenic Activity in Sediments of a Tropical Coastal Lagoon. Environ Monit Assess. 2026, 198 (10), 1073. DOI: 10.1007/s10661-026-15919-5
• Kebedew, M. G.; Tilahun, S. A.; Zimale, F. A. et al. Relating Lake Circulation Patterns to Sediment, Nutrient, and Water Hyacinth Distribution in a Shallow Tropical Highland Lake. Hydrology 2023, 10 (9), 181. DOI: 10.3390/hydrology10090181
• Walton, R. E.; Moorhouse, H. L.; Roberts, L. R. et al. Using Lake Sediments to Assess the Long-term Impacts of Anthropogenic Activity in Tropical River Deltas. Anthr. Rev. 2024, 11 (2), 442–462. DOI: 10.1177/20530196231204334
• Castaño-Ortiz, J. M.; Gil-Solsona, R.; Ospina-Alvarez, N. et al. Bioaccumulation and Fate of Pharmaceuticals in a Mediterranean Coastal Lagoon: Temporal Variation and Impact of a Flash Flood Event. Environ. Res. 2023, 228, 115887. DOI: 10.1016/j.envres.2023.115887
• Becerra-Rueda, O. F.; Rodríguez-Figueroa, G. M.; Marmolejo-Rodríguez, A. et al. Pharmaceutical Residues in Sediments of a Coastal Lagoon in Northwest Mexico—Occurrence and Environmental Risk Assessment. J. Xenobiotics 2024, 14 (4), 1757-1770. DOI: 10.3390/jox14040093
• Teixeira, M.:Cesar, R.; de Souza Abessa, D. M. et al. Ecotoxicological Assessment of Metal Pollution Using Aquatic Organisms in Surface Sediments from a Tropical Urbanized Lagoon System. Estuar. Coast. 2026, 49, 71–91. DOI: 10.1007/s12237-026-01675-9