Mercury threat spreads through the Amazon food chain<\/p>\n
Trujillo directs the Omacha Foundation, a conservation group focused on aquatic wildlife and river ecosystems, and leads health evaluations of river dolphins. It\u2019s a painstaking operation involving experienced fishermen, veterinarians and locals that takes months of planning and happens a couple of times a year.<\/p>\n
\u201cWe take blood and tissue samples to assess mercury,\u00a8 Trujillo told The Associated Press from the Colombian riverside town of Puerto Narino. \u201cBasically, we\u2019re using dolphins as sentinels for the river\u2019s health.\u201d<\/p>\n
Mercury contamination<\/a> comes mainly from illegal gold mining \u2014 a growing industry across the Amazon Basin<\/a> \u2014 and forest clearing that washes mercury that naturally occurs in soil into waterways.<\/p>\n The miners use mercury to separate gold from sediment, then dump the sludge back into rivers, where it enters fish eaten by people and dolphins. Rising global gold prices have fueled a mining boom, and mercury pollution in remote waterways has increased.<\/p>\n Mercury can damage the brain, kidneys, lungs and immune system and cause mood swings, memory loss and muscle weakness in people, according to the World Health Organization and the U.S. Environmental Protection Agency. Pregnant women and young children are most at risk, with prenatal exposure linked to developmental delays and reduced cognitive function.<\/p>\n \u201cThe maximum any living being should have is 1 milligram per kilogram,\u201d Trujillo said. \u201cHere, we\u2019re seeing 20 to 30 times that amount.\u201d<\/p>\n In previous years, his team found 16 to 18 milligrams per kilogram of mercury in dolphins, which can suffer the same neurological damage, organ damage and other problems as humans. In Colombia\u2019s Orinoco River, levels in some dolphins have reached as high as 42, levels scientists say are among the most extreme ever recorded in the species.<\/p>\n Trujillo said it\u2019s difficult to prove the toxin is directly killing dolphins. Further studies are underway, he added, noting that \u201cany mammal with a huge amount of mercury will die.\u201d<\/p>\n When Trujillo and his team tested their own blood three years ago, his results showed more than 36 times the safe limit \u2014 36.4 milligrams per kilogram \u2014 a level he attributes to decades working in mercury-affected areas and a diet heavy in fish. With medical assistance, his levels have dropped to about 7 milligrams.<\/p>\n \u201cMercury is an invisible enemy until it builds up to a sufficient amount, then it starts to affect the central nervous system,\u201d Trujillo told AP after his team managed to capture and test four pink dolphins. \u201cWe\u2019re already seeing evidence of it in Indigenous communities.\u201d<\/p>\n A series of scientific studies and reports \u2014 including work by the International Pollutants Elimination Network and academic researchers \u2014 have found high mercury exposure among Indigenous peoples across the Amazon, including in Brazil, Peru, Colombia, Suriname and Bolivia. Hair samples showed averages well above WHO\u2019s safe threshold of 1 part per million, with one Colombian community registering more than 22 milligrams per kilogram.<\/p>\n Dolphin populations in this part of the Amazon have plunged, with Trujillo\u2019s monitoring showing a 52% decline in pink dolphins and a 34% drop in gray river dolphins, a different species, in recent decades. The International Union for Conservation of Nature listed the pink dolphin as endangered in 2018. Trujillo said exact numbers for the Amazon are unknown, but his organization estimates 30,000 to 45,000 across the basin.<\/p>\n![\"A](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2025\/09\/250916-pink-dolphin-vl-953a-61b5a5.jpg\")
Scientists and veterinarians examine a pink river dolphin in Puerto Narino, Colombia, on Sept. 7.Fernando Vergara \/ AP<\/p>\n