Environmental health

A tiny, vibrant world thrives along the rocky bottom of most streams. As sunlight filters through the water, mayfly nymphs, no larger than your fingernail, cling to algae-coated cobbles. Their brushlike mouthparts scrape the greenish coating, leaving faint trails as they feed. Six spindly legs anchor them against the current, while feathery gills wave gently, drawing oxygen from the flowing water. This scene is common in well-maintained creeks and streams that flow through populated areas. But when wildfires sweep through, the toxic materials left behind can devastate this ecosystem. When you think of urban wildfires, you might picture charred trees and houses. But beneath the surface of nearby streams, fires can also cause a silent upheaval – one that affects populations of creatures that are important indicators of the water’s health. Images of some of the benthic invertebrates that help keep streams healthy, and whose disa...

Flint, Michigan, made headlines in 2015 when tests revealed dangerously high lead levels in its drinking water. The city had switched its water supply to the Flint River a year earlier, and corrosive water had damaged aging lead pipes, exposing thousands of people to lead contamination. The result was a human health crisis that residents are feeling the effects of to this day. And Flint was only the tip of the iceberg. The EPA estimates that 9.2 million service lines that deliver drinking water to U.S. homes and businesses are made of lead. The federal government considers replacing these lead pipes a top priority and has launched a variety of initiatives to help, including the 2021 Infrastructure Law, which committed US$15 billion over five years to lead pipe replacement. The EPA is now proposing to require the removal of lead pipes across the U.S. within 10 years. The agency has been silent, however, regarding what should replace lead....

It’s become common to read that microplastics – little bits of plastic, smaller than a pencil eraser – are turning up everywhere and in everything, including the ocean, farmland, food and human bodies. Now a new term is gaining attention: nanoplastics. These particles are even tinier than microplastics – so small that they’re invisible to the naked eye. Nanoplastics are a type of microplastic, distinguished by their extremely small size. Microplastics are usually less than 5 millimeters across; nanoplastics are between 1 and 1,000 nanometers across. For comparison, an average human hair is roughly 80,000-100,000 nanometers wide. Nanoplastics are attracting growing concern thanks to recent technological advances that have made researchers more able to detect and analyze them. Their smaller size means that they are more easily transported over long distances and into more diverse environments than microplastics. They can more easily penetrate cells a...

Chemists invented PFAS in the 1930s to make life easier: Nonstick pans, waterproof clothing, grease-resistant food packaging and stain-resistant carpet were all made possible by PFAS. But in recent years, the growing number of health risks found to be connected to these chemicals has become increasingly alarming. PFAS – perfluoroalkyl and polyfluoroalkyl substances – are now either suspected or known to contribute to thyroid disease, elevated cholesterol, liver damage and cancer, among other health issues. They can be found in the blood of most Americans and in many drinking water systems, which is why the Environmental Protection Agency in April 2024 finalized the first enforceable federal limits for six types of PFAS in drinking water systems. The limits – between 4 and 10 parts per trillion for PFOS, PFOA, PFHxS, PFNA and GenX – are less than a drop of water in a thousand Olympic-sized swimming pools, which speaks to the chemicals’ toxicity. The...

The more scientists learn about the health risks of PFAS, found in everything from nonstick cookware to carpets to ski wax, the more concerning these “forever chemicals” become. The U.S. Environmental Protection Agency now believes there is no safe level for two common PFAS – PFOA and PFOS – in drinking water, and it acknowledges that very low concentrations of other PFAS present human health risks. The agency issued the first legally enforceable national drinking water standards for five common types of PFAS chemicals, as well as PFAS mixtures, on April 10, 2024. I study PFAS as an environmental health scientist. Here’s a quick look at the risks these chemicals pose and efforts to regulate them. What exactly are PFAS? PFAS stands for per- and polyfluoroalkyl substances. This is a large group of human-made chemicals – currently estimated to be nearly 15,000 individual chemical compounds – that are used widely in consumer products and i...