The US Geological Survey (USGS) scientists have detected high concentrations of selenium and mercury in the Grand Canyon food webs. The detection has lead to concerns about the health and safety of fish and wildlife in the area.

Study ecologist, Dr. David Walters, and his colleagues at the USGS collected the data from six distinct locations along the Colorado River, which goes through the Grand Canyon. The study was published in the journal Environmental Toxicology and Chemistry.

The researchers found concentrations of selenium and mercury in a number of creatures in the area like minnows, fish and invertebrates. The concentrations exceeded the thresholds for dietary toxicity for fish and other wildlife that are dependent on these aquatic animals.

According to the findings, the average amount of mercury in a number of the fish specimens would make them unfit for human intake as well. As per the National Wildlife Federation (NWF), mercury is believed to be an unsafe neurotoxin that has a severe impact on the nervous system of humans and animals alike.

The Environmental Protection Agency (EPA) said, "Selenium can cause various health problems in people, such as the loss of teeth and hair as well as issues with alertness". There are some selenium compounds that are linked to the development of tumors in human liver.