Gabriel Lade, Macalester College

About 23 million U.S. households depend on private wells as their primary drinking water source. These homeowners are entirely responsible for ensuring that the water from their wells is safe for human consumption.

Multiple studies show that, at best, half of private well owners are testing with any frequency, and very few households test once or more yearly, as public health officials recommend. Even in Iowa, which has some of the strongest state-level policies for protecting private well users, state funds for free private water quality testing regularly go unspent.

Is the water these households are drinking safe? There’s not much systematic evidence, but the risks may be large.

The U.S. Environmental Protection Agency still relies on a 15-year-old study showing that among 2,000 households, 1 in 5 households’ well water contained at least one contaminant at levels above the thresholds that public water systems must meet. While other researchers have studied this issue, most rely on limited data or data collected over decades to draw conclusions.

I’m an economist studying energy and agriculture issues. In a recent study, I worked with colleagues at Iowa State University, the University of Massachusetts Amherst and Cornell University to understand drinking water-related behaviors and perceptions of households that use private wells. We focused on rural Iowa, where runoff from agricultural production regularly contaminates public and private drinking water sources.

We found that few households followed public health guidance on testing their well water, but a simple intervention – sending them basic information about drinking water hazards and easy-to-use testing materials – increased testing rates. The burden of dealing with contamination, however, falls largely on individual households.

Nitrate risks

We focused on nitrate, one of the main well water pollutants in rural areas. Major sources include chemical fertilizers, animal waste and human sewage.

Drinking water that contains nitrate can harm human health. Using contaminated water to prepare infant formula can cause “blue baby syndrome,” a condition in which infants’ hands and lips turn bluish because nitrate interferes with oxygen transport in the babies’ blood. Severe cases can cause lethargy, seizures and even death. The EPA limits nitrate levels in public water systems to 10 milligrams per liter to prevent this effect.

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Studies have also found that for people of all ages, drinking water with low nitrate concentrations over long periods of time is strongly associated with chronic health diseases, including colorectal cancer and thyroid disease, as well as neural tube defects in developing fetuses.

Nitrate pollution is pervasive across the continental U.S. Fortunately, it is relatively easy to determine whether water contains unsafe nitrate concentrations. Test strips, similar to those used in swimming pools, are cheap and readily available.

The water’s fine … or not

Mailing lists of households with private wells are hard to come by, so for our study we digitized over 22,000 addresses using maps from 14 Iowa counties. We targeted counties where public water systems had struggled to meet EPA safety standards for nitrate in drinking water, and where private wells that had been tested over the past 20 years showed nitrate concentrations at concerning levels.

We received responses from over half of the households we surveyed. Of those, just over 8,100 (37%) used private wells.

Although the Centers for Disease Control and Prevention recommends testing annually for nitrate, just 9% of these households had tested their water quality in the past year.

More concerning, 40% of this group used their wells for drinking water, had not tested it in the past year, and did not filter the water or use other sources such as bottled water. They were drinking straight from the tap without knowing whether their water was safe.

Our survey also showed that, despite living in high-risk areas, 77% of households classified their well water quality as “good” or “great.” This may be driven by a “not in my backyard” mentality. Households in our survey were more likely to agree with the statement that nitrate is a problem in the state of Iowa than to perceive nitrates as a problem in their local area.

Climate change is likely to worsen nitrate contamination in well water. In regions including the Great Lakes basin, increases in heavy rainfall are projected to carry rising amounts of nutrients from farmlands into waterways and groundwater. https://www.youtube.com/embed/yDaaIo3JBNw?wmode=transparent&start=0 Nitrate contamination is often thought of as a rural problem, but in California it also has shown up in urban areas.

Providing information and tools helps

To see whether education and access to testing materials could change views about well water, we sent a mailer containing a nitrate test strip, information about risks associated with nitrate in drinking water, and contact information for a free water quality testing program run by the state of Iowa to a random 50% of respondents from our first survey. We then resurveyed all households, whether or not they received the mailer.

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Over 40% of households that received test strips reported that they had tested their water, compared with 24% of those that did not receive the mailer. The number of respondents who reported using Iowa’s free testing program also increased, from 10% to 13%, a small but statistically meaningful impact.

Less encouragingly, households that received the mailer were no more likely to report filtering or avoiding their water than those that did not receive the mailer.

Households bear the burden

Our results show that lack of information makes people less likely to test their well water for nitrate or other contaminants. At least for nitrate, helping households overcome this barrier is cheap. We asked respondents about their willingness to pay for the program and found that the average household was willing to pay as much as US$13 for a program that would cost the state roughly $5 to implement.

However, we could not determine whether our outreach decreased households’ exposure to contaminated drinking water. It’s also not clear whether people would be as willing to test their well water in states such as Wisconsin or Oregon, where testing would cost them up to a few hundred dollars.

As of 2024, just 24 states offered well water testing kits for at least one contaminant that were free or cost $100 or less. And while most states offer information about well water safety, some simply post a brochure online.

The upshot is that rural households are bearing the costs associated with unsafe well water, either through health care burdens or spending for treatment and testing. Policymakers have been slow to address the main source of this problem: nitrate pollution from agriculture.

In one exception, state agencies in southeastern Minnesota are providing free well water quality testing and offering a few households filtration systems in cases where their wells are laden with nitrate from local agricultural sources. However, this effort began only after environmental advocates petitioned the EPA.

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If state and federal agencies tracked more systematically the costs to households of dealing with contaminated water, the scale of the burden would be clearer. Government agencies could use this information in cost-benefit assessments of conservation programs.

On a broader scale, I agree with experts who have called for rethinking agricultural policies that encourage expanding crops associated with high nutrient pollution, such as corn. More restoration of wetlands and prairies, which filter nutrients from surface water, could also help. Finally, while the Environmental Protection Agency can’t force well owners to test or treat their water, it could provide better support for households when pollutants turn up in their drinking water.

Gabriel Lade, Associate Professor of Economics, Macalester College

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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A. Peter Klimley, University of California, Davis

Many sharks and rays are known to breach, leaping fully or partly out of the water. In a recent study, colleagues and I reviewed research on breaching and ranked the most commonly hypothesized functions for it.

We found that removal of external parasites was the most frequently proposed explanation, followed by predators chasing their prey; predators concentrating or stunning their prey; males chasing females during courtship; and animals fleeing predators, such as a ray escaping from a hammerhead shark in shallow water.

We found that the highest percentage of breaches, measured by the number of studies that described it, occurred in manta rays and devil rays, followed by basking sharks and then by eagle rays and cownose rays. However, many other species of sharks, as well as sawfishes and stingrays, also perform this behavior. https://www.youtube.com/embed/wXkMqk8mwjs?wmode=transparent&start=0 A breaching white shark surprises researchers off Cape Cod, Massachusetts.

Why it matters

It takes a lot of energy for a shark or ray to leap out of the water – especially a massive creature like a basking shark, which can grow up to 40 feet (12 meters) and weigh up to 5 tons (4.5 tonnes). Since the animal could use that energy for feeding or mating, breaching must serve some useful purpose.

Sharks that have been observed breaching include fast-swimming predatory species such as blacktip sharks and blue sharks. White sharks have been seen breaching while capturing seals in waters off South Africa and around the Farallon Islands off central California.

However, basking sharks – enormous, slow-swimming sharks that feed by filtering tiny plankton from seawater – also breach. So do many ray species, such as manta rays, which also are primarily filter feeders. This suggests that breaching likely serves different functions among different types of sharks and rays.

The most commonly proposed explanation for breaching in planktivores, like basking sharks and most rays, is that it helps dislodge parasites attached to their bodies. Basking sharks are known to host parasites, including common remoras and sea lampreys. The presence of fresh wounds on basking sharks that match the shape and size of a lamprey’s mouth suggests that breaching has torn the lampreys off the sharks’ bodies. https://www.youtube.com/embed/zsC61g36EqM?wmode=transparent&start=0 Basking sharks are filter feeders that live on plankton. They may breach to rid their bodies of parasites.

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Other species may breach to communicate. For example, white sharks propelling themselves out of the water near the Farallon Islands may do so to deter other sharks from feeding upon the carcass of a seal.

Researchers have seen large groups of mantas and devil rays jumping together among dense schools of plankton – presumably to concentrate or stun the plankton so the rays can more easily scoop them up. Scientists have also suggested that planktivorous sharks and rays may breach to clear the prey-filtering structures in their gills.

Understanding more clearly when and how different types of sharks and rays breach can provide insights into these animals’ life habits, and into their interactions with their own species and competitors.

How we did our work

I worked with marine scientists Tobey Curtis, Emmett Johnston, Alison Kock and Guy Stevens. Across our various projects, we have seen breaching in bull sharks in Florida, basking sharks in Ireland, white sharks in South Africa and central California, and manta rays in the Maldives. Each of us has proposed different explanations for why the animals did it.

We reviewed scientific studies and video footage to see what species had been observed to breach, under what conditions, and the functions that other researchers had proposed for them doing so. This included information gathered from data logging tags attached to sharks and rays, digital photography, and imagery from underwater and aerial drones.

Our review proposes further studies that could provide more information about breaching in different species. For example, attaching data loggers to individual animals would help scientists measure how quickly a shark or ray accelerates as it propels itself out of the water.

Experiments in aquarium tanks could provide more insight into why the animals breach. For example, scientists could add remoras to a tank containing bull sharks, which can live in an aquarium environment, and observe how the sharks respond when remoras attach themselves to the sharks’ bodies.

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In the field, researchers could play audio recordings of splashes from breaches to elicit withdrawal or attraction responses from sharks tagged with ultrasonic transmitters. There remains much to learn about why these animals spend precious energy jumping out of the water.

The Research Brief is a short take on interesting academic work.

A. Peter Klimley, Adjunct Associate Professor of Wildlife, Fish, & Conservation Biology, University of California, Davis

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The science section of our news blog STM Daily News provides readers with captivating and up-to-date information on the latest scientific discoveries, breakthroughs, and innovations across various fields. We offer engaging and accessible content, ensuring that readers with different levels of scientific knowledge can stay informed. Whether it’s exploring advancements in medicine, astronomy, technology, or environmental sciences, our science section strives to shed light on the intriguing world of scientific exploration and its profound impact on our daily lives. From thought-provoking articles to informative interviews with experts in the field, STM Daily News Science offers a harmonious blend of factual reporting, analysis, and exploration, making it a go-to source for science enthusiasts and curious minds alike. https://stmdailynews.com/category/science/

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Natasha S. Vitek, Stony Brook University (The State University of New York)

A rare, nearly complete fossil of an extinct North American porcupine helped me and my colleagues solve a decades-long debate about how the modern North American porcupine evolved from its ancestors.

Published in Current Biology, our paper argues that North American porcupine ancestors may well date back 10 million years, but they wouldn’t be recognizable until about 8 million years later.

By comparing the bone structure of porcupines across North America and South America, we determined that for those 8 million years, North American porcupines unexpectedly still looked like their cousins, the Neotropical porcupines, which live across tropical Central America and South America today.

Our findings detail the North American porcupine’s evolutionary path from South America – and also solve the mystery of why it’s been so difficult to find its ancestors.

I’m a paleontologist who researches the fossilized bones and teeth of extinct animals. With museum curator Jon Bloch, I created a class where we analyzed bone structure to reach the conclusions of our study.

Why it matters

The modern North American porcupine is distinctive among its spiky relatives. It has a short tail, a jaw that can scrape bark from trees and weighs between 10 and 25 pounds (4.5 and 11.3 kilograms).

While clearly related, Neotropical porcupines look different. They have long, grasping tails, weaker jaws and weigh between 1.5 and 10 pounds (0.68 and 4.5 kilograms).

DNA analyses of modern animals estimate that these two groups separated about 10 million years ago.

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This is where the mystery comes in. Fossils of the North American porcupine are all younger than 1.8 million years old. In other words, roughly 8.2 million years’ worth of fossils of North American porcupine were missing.

All researchers had were bits of jaws and tails that looked like they belonged to Neotropical porcupines.

Two competing hypotheses could explain the similarity.

Some scientists argued that the jaw and tail fossils of early ancestors of North American porcupines should look more like their modern descendants. Researchers who backed this idea suggested that the fossil record was incomplete for some unexplained reason, but that it was still possible that fossils that supported their hypothesis may eventually turn up.

Other scientists suggested that all early ancestral porcupines might have had jaws and tails similar to today’s Neotropical porcupines. North American porcupine ancestors might be hidden in the existing fossil record because – based on jaws and tails alone – they look identical to Neotropical porcupine ancestors. Only younger fossils would show distinctive traits because that’s when those traits appeared.

This debate went on for decades. It was impossible to solve with the available fossils.

How we did our work

Then researchers from the Florida Museum of Natural History unearthed a 2 million-year-old nearly complete skeleton of a porcupine in north-central Florida in 2005.

The fossil had a long tail and no bark-gnawing jaw, similar to Neotropical porcupines. But it also had dozens more bones that we could use to resolve relationships.

Collecting that evidence required combing through all the bones, looking for hundreds of minute details – like the shapes of ridges or patterns of boundaries on bones – and comparing these details with skeletons of modern North American and Neotropical porcupines. Bloch and I created a course in which students each took on one portion of the project.

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Together, we came up with a list of nearly 150 informative details. Even though the specimen had a few traits similar to Neotropical porcupines, more evidence supported the idea that this fossil was a closer relative of North American porcupines.

Since this porcupine had a jaw and tail like its Neotropical cousins, it’s likely that most older relatives of the North American porcupine were also missing the distinctive traits of their modern descendants.

In other words, the solution to the mystery is that the fossil record for North American porcupines appeared young because the reinforced jaw and shorter tail evolved relatively recently. Porcupines looked different than what we expected for much of their 10 million years of ancestry.

The Research Brief is a short take on interesting academic work.

Natasha S. Vitek, Assistant Professor of Ecology and Evolution, Stony Brook University (The State University of New York)

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The science section of our news blog STM Daily News provides readers with captivating and up-to-date information on the latest scientific discoveries, breakthroughs, and innovations across various fields. We offer engaging and accessible content, ensuring that readers with different levels of scientific knowledge can stay informed. Whether it’s exploring advancements in medicine, astronomy, technology, or environmental sciences, our science section strives to shed light on the intriguing world of scientific exploration and its profound impact on our daily lives. From thought-provoking articles to informative interviews with experts in the field, STM Daily News Science offers a harmonious blend of factual reporting, analysis, and exploration, making it a go-to source for science enthusiasts and curious minds alike. https://stmdailynews.com/category/science/

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