Significant numbers of dead fish were reported in the river La Pasión in the Petén region in Guatemala during two instances in April and June 2015. Pesticide contamination or the depletion of oxygen by organic matter, alternatively a combination of both these factors, was put forward as a possible cause of the mortalities. The source of the pollution was believed to be overflowing at the oxidation basin of a nearby palm oil production plant. The events led to severe impacts on the livelihoods of approximately 15,000 people living in the riverine communities, dependant on La Pasión’s waters for drinking, sanitation, cooking and fishing.
Sampling and analysis of river water was undertaken in connection with the two events by national laboratories and showed traces of the pesticide malathion. To confirm the results, the Guatemalan Government requested support from the international community to investigate the immediate risks to human health due to residual contamination. Subsequently, two international experts were mobilized through the United Nations Environment Programme (UNEP) / Office for the Coordination of Humanitarian Affairs (OCHA) Joint Environment Unit with support of the European Commission’s Humanitarian Aid and Civil Protection department and the Swedish Civil Contingencies Agency to provide technical sampling and analysis advice to the national and local authorities.
The experts collected six water and two sediment samples which were tested for a range of pesticides. The sampling and analysis, carried out two months after the first reports of an incident, could not determine the content of the previous discharge(s). Access to the palm oil production plant was denied and information on processes and chemicals use could not be verified. As such, the cause of the fish mortality could not be conclusively determined. However, field measurements of the river pH, conductivity and oxygen show the conditions to be average. While no pesticides were detected in the water samples, one of the sediment samples showed traces of the insecticide endosulfan sulphate.
No residual pesticides were found in the river water samples which would pose immediate risks to human health. Laboratory results of samples taken earlier by other teams from the palm oil oxidation pond support the theory of oxygen depletion causing the fish mortality, but do not explain the reported additional impacts on animals, including birds, or the reported impacts on human health such as skin rashes. While no analytical evidence of pesticide contamination was found, on-site observations and interviews make it clear that the aquatic system is under threat of contamination. The river is affected by untreated wastewater from communities, by waste and agriculture and industry runoff. These underlying factors can rapidly change the status and conditions of the water in the river and its tributaries, making it difficult to assess the watercourse as permanently suitable for drinking water.
It is recommended that distribution of water continue until safe water sources have been identified for all affected communities. A sampling plan focusing on the use of river water for consumption and livelihoods in affected communities should be developed and must explore options for alternative sources of drinking water. Existing emergency response plans should be reviewed and updated and need to include early warning and monitoring of, and communication with, the region’s agriculture and industries. In the long-term, national legislation related to environmental monitoring of industrial and agricultural activities should be strengthened, implemented and enforced.
- UN Office for the Coordination of Humanitarian Affairs
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