The predictive model results can help members of the public, water suppliers and regulators understand the potential for PFAS contamination, guide future studies and inform strategic planning for water resources.

USGS scientists are the first to report national estimates of PFAS occurrence in untreated groundwater that supplies water to public and private wells. This research also provides the first estimate of the number of people across the country who are potentially affected by PFAS-contaminated groundwater.

Along with a scientific report, the USGS published an interactive, online map so users can see probability estimates of PFAS occurrence. Note that predictive results are intended to be evaluated at state, regional and national scales rather than at individual household levels. Probability estimates are for the presence of PFAS in groundwater and do not account for any subsequent actions taken by states, municipalities or individuals to treat drinking water. The model does not include estimates of PFAS concentrations; testing is the only way to confirm the presence of contaminants.

Exposure to certain PFAS may lead to adverse health risks in people, according to the U.S. Environmental Protection Agency. PFAS are a group of synthetic chemicals used in a wide variety of common applications, from the linings of fast-food boxes and non-stick cookware to fire-fighting foams and other purposes. PFAS are commonly called “forever chemicals” because many of them do not easily break down and can build up over time, making them a concern for drinking water quality.

“This study’s findings indicate widespread PFAS contamination in groundwater that is used for public and private drinking water supplies in the U.S.,” said Andrea Tokranov, USGS research hydrologist and lead author of this study. “This new predictive model can help prioritize areas for future sampling to help ensure people aren’t unknowingly drinking contaminated water. This is especially important for private well users, who may not have information on water quality in their region and may not have the same access to testing and treatment that public water suppliers do.”

The EPA has established legally enforceable levels, called maximum contaminant levels, for six types of PFAS in drinking water. The EPA regulates public water supplies, and some states have additional regulations for drinking water. Some homes use private water supplies, where residents are responsible for the maintenance, testing and treatment of their drinking water. Those interested in treatment processes and testing options can read EPA’s guidance or contact their state officials or water supplier.

The states with the largest populations relying on public water supplies with potentially contaminated groundwater sources are Florida and California. Regarding private wells, Michigan, Florida, North Carolina, Pennsylvania, New York and Ohio have the largest populations relying on potentially contaminated groundwater.

The study also presents data according to population percentage. In Massachusetts, for example, the source water for 86 to 98% of people who rely on groundwater from public water supplies could be contaminated with PFAS. In Connecticut, the source water for 67 to 87% of the people who rely on groundwater from private wells could be affected. Details by state can be seen in the report’s tables S6 through S8.

“To derive these estimates, the team analyzed 1,238 groundwater samples collected by USGS scientists and determined how factors such as urban development and well depth can impact PFAS occurrence,” continued Tokranov. “With that information, a detailed machine learning model was developed and used to identify which geographic areas have a higher likelihood for contamination. That information was combined with existing USGS research on the number of people in a given area who rely on groundwater for drinking water to establish population estimates.”

Scientists present separate estimates for public and private wells because they typically receive water from different groundwater depths. Public wells using groundwater as the primary water source are usually deeper than private wells.

There are more than 12,000 types of PFAS, not all of which can be detected with current tests; the USGS study tested for the presence of 24 common types. The USGS estimates consider the presence of at least one of those 24 types of PFAS. The most frequently detected compounds were perfluorobutane sulfonate known as PFBS, perfluorooctane sulfonate known as PFOS and perfluorooctanoate known as PFOA.

This research provides a broad outlook for the Lower 48 states and presents state-level estimates. Scientists did not look in detail at specific cities or provide estimates for the types of PFAS present or PFAS concentrations.

Just published in the journal Science, the University of Otago study provides arguably the world’s most clear-cut case of animal evolution in response to change made by humans.

Co-author Professor Jon Waters, of the Department of Zoology, says the stonefly has become a different colour due to recent deforestation.

“In natural forested regions, a native species has evolved ‘warning’ colours that mimic those of a poisonous forest species, to trick predators into thinking they are poisonous too.

“But the removal of forests since humans arrived has removed the poisonous species. As a result, in deforested regions the mimicking species has abandoned this strategy — as there is nothing to mimic — instead evolving into a different colour.”

Scientists have long wondered whether humans are causing evolutionary changes in natural populations.

The most well-known example of evolution caused by humans was the peppered moth population in the United Kingdom, which changed colour in response to industrial pollution in the 1800s.

But Professor Waters says even that case has been considered controversial.

This new study shows how humans have changed the way native species interact.

Co-author Dr Graham McCulloch says humans have disrupted ecological interactions between species that evolved over millions of years, but some of our native species are resilient enough to overcome this.

“This study is important because it shows that, at least for some of our native species, there is the possibility of adapting to the environmental changes caused by humans, even when the change is rapid,” Dr McCulloch says.

“It also shows that independent populations have undergone similar changes in response to deforestation — there have been similar shifts independently in different parts of the species’ range — showing that evolution can be a predictable process.”

The study was a collaboration between scientists at Northwestern Medicine and a Nigerian team of scientists from the University of Lagos and Lagos University Teaching Hospital (LUTH) in Lagos, Nigeria. Of the 2,319 participants, 106 (4.6%) had long COVID with neurologic symptoms, and some were still experiencing symptoms up to two years after their initial episode of COVID-19. Researchers also found patients who were hospitalized for COVID-19 pneumonia reported a higher frequency of long COVID symptoms than those who were not hospitalized and had mild initial COVID-19 (11.5% vs 3.9%, respectively).

The findings were published today, October 24, in the Journal of NeuroVirology.

The findings highlight the need for improved screening, diagnosis and treatment of neuro-long COVID in Nigeria.

“Based on this data, there is hopefully going to be some intervention to alleviate their suffering,” said Dr. Igor Koralnik, chief of neuro-infectious disease and global neurology at Northwestern University Feinberg School of Medicine. “We’ve determined that even in a resource-limited setting where people have many other problems to worry about, we can still perform these studies, find those patients, and diagnose them.”

Scientists from the Nigerian team include neurologist Dr. Njideka U. Okubadejo and infectious disease physician Dr. Iorhen E. Akase, both of the University of Lagos and LUTH.

Koralnik and his team launched the Northwestern Medicine Neuro-COVID-19 Clinic in May 2020 and were soon evaluating a large number of patients who were exhibiting post-COVID neurologic symptoms. They then began researching the disease. In Nigeria, the opposite has happened. People in Nigeria are not aware that long COVID is a disease for which symptomatic treatments are available, and there was a scarcity of post-COVID clinics even during the height of the pandemic.

“This is why we have to start by doing the research to demonstrate the need for diagnosis and clinical care of these patients and advocate for specialized outpatient clinics,” Koralnik said. “If you don’t know that something exists, you can’t treat it.”

Breakdown of neurologic symptoms

The predominant neurologic symptoms among study participants at any time during the disease course included:

• Difficulty remembering/brain fog (59.4%)
• Fatigue (55.7%)
• Sleep problems (32%)
• Headache (31%)
• Paresthesia, or numbness and pins and needles (11.3%)
• Myalgia, or muscle pain (9.4%).

Of the 66 participants with neuro-long COVID who underwent an in-person neurological evaluation and cognitive screening, 16.9% completed the Montreal Cognitive Assessment, a widely used screening assessment for detecting cognitive impairment, and had results consistent with mild cognitive impairment.

Next steps

In a future study, the scientists plan to treat brain fog and cognitive dysfunction in neuro-long COVID patients in Nigeria by applying the same techniques he and his team are currently using in Chicago, Koralnik said.

COVID-19 continues to occur despite vaccination and boosters, and according to an ongoing household pulse study carried out by the National Center for Health Statistics, approximately 14 million adults in the U.S. are currently experiencing long COVID. Long COVID principally affects adults in their prime, affecting their quality of life and ability to work, contributing to profound public health and socio-economic impacts.

Millenia Jimenez who works in the Koralnik laboratory at Northwestern is a co-author on the study.

Good balance, muscle strength and an efficient gait contribute to people’s independence and well-being as they age. How these factors change, and at what rate, can help clinicians develop programs to ensure healthy aging. Individually, people can train their balance without special equipment and work on maintaining it over time.

In this study, 40 healthy, independent people over 50 underwent walking, balance, grip strength and knee strength tests. Half of the participants were under 65; the other half were 65 and older.

In the balance tests, participants stood on force plates in different situations: on both feet with eyes open, on both feet with eyes closed, on the non-dominant leg with eyes open, and on the dominant leg with eyes open. In the one-legged tests, participants could hold the leg they weren’t standing on where they wanted. The tests were 30 seconds each.

Standing on one leg — specifically the nondominant leg — showed the highest rate of decline with age.

“Balance is an important measure because, in addition to muscle strength, it requires input from vision, the vestibular system and the somatosensory systems,” says Kenton Kaufman, Ph.D., senior author of the study and director of the Motion Analysis Laboratory at Mayo Clinic. “Changes in balance are noteworthy. If you have poor balance, you’re at risk of falling, whether or not you’re moving. Falls are a severe health risk with serious consequences.”

Unintentional falls are the leading cause of injuries among adults who are 65 and older. Most falls among older adults result from a loss of balance.

In the other tests:

• Researchers used a custom-made device to measure participants’ grip. For the knee strength test, participants were in a seated position and instructed to extend their knee as forcefully as possible. Both the grip and knee strength tests were on the dominant side. Grip and knee strength showed significant declines by decade but not as much as balance. Grip strength decreased at a faster rate than knee strength, making it better at predicting aging than other strength measures.
• For the gait test, participants walked back and forth on an 8-meter, level walkway at their own pace and speed. Gait parameters didn’t change with age. This was not a surprising result since participants were walking at their normal pace, not their maximum pace, Dr. Kaufman says.
• There were no age-related declines in the strength tests that were specific to sex. This indicates that participants’ grip and knee strength declined at a similar rate. Researchers did not identify sex differences in the gait and balance tests, which suggests that male and female subjects were equally affected by age.

Dr. Kaufman says people can take steps to train their balance. For example, by standing on one leg, you can train yourself to coordinate your muscle and vestibular responses to maintain correct balance. If you can stand on one leg for 30 seconds, you are doing well, he says.

“If you don’t use it, you lose it. If you use it, you maintain it,” Dr. Kaufman says. “It’s easy to do. It doesn’t require special equipment, and you can do it every day.”

Funding for this study includes the Robert and Arlene Kogod Professorship in Geriatric Medicine and W. Hall Wendel Jr. Musculoskeletal Professorship.

The researchers compared various time windows of exposure, finding that the previous decade of water arsenic exposure up to the time of a cardiovascular disease event contributed the greatest risk. The findings are published in the journal Environmental Health Perspectives.

“Our findings shed light on critical time windows of arsenic exposure that contribute to heart disease and inform the ongoing arsenic risk assessment by the EPA. It further reinforces the importance of considering non-cancer outcomes, and specifically cardiovascular disease, which is the number one cause of death in the U.S. and globally,” said Danielle Medgyesi, a doctoral Fellow in the Department of Environmental Health Sciences at Columbia Mailman School. “This study offers resounding proof of the need for regulatory standards in protecting health and provides evidence in support of reducing the current limit to further eliminate significant risk.”

According to the American Heart Association and other leading health agencies, there is substantial evidence that arsenic exposure increases the risk of cardiovascular disease. This includes evidence of risk at high arsenic levels (>100µg/L) in drinking water. The U.S. Environmental Protection Agency reduced the maximum contaminant level (MCL) for arsenic in community water supplies (CWS) from 50µg/L to 10µg/L beginning in 2006. Even so, drinking water remains an important source of arsenic exposure among CWS users. The natural occurrence of arsenic in groundwater is commonly observed in regions of New England, the upper Midwest, and the West, including California.

To evaluate the relationship between long-term arsenic exposure from CWS and cardiovascular disease, the researchers used statewide healthcare administrative and mortality records collected for the California Teachers Study cohort from enrollment through follow-up (1995-2018), identifying fatal and nonfatal cases of ischemic heart disease and cardiovascular disease. Working closely with collaborators at the California Office of Environmental Health Hazard Assessment (OEHHA), the team gathered water arsenic data from CWS for three decades (1990-2020).

The analysis included 98,250 participants, 6,119 ischemic heart disease cases and 9,936 CVD cases. Excluded were those 85 years of age or older and those with a history of cardiovascular disease at enrollment. Similar to the proportion of California’s population that relies on CWS (over 90 percent), most participants resided in areas served by a CWS (92 percent). Leveraging the extensive years of arsenic data available, the team compared time windows of relatively short-term (3-years) to long-term (10-years to cumulative) average arsenic exposure. The study found decade-long arsenic exposure up to the time of a cardiovascular disease event was associated with the greatest risk, consistent with a study in Chile finding peak mortality of acute myocardial infarction around a decade after a period of very high arsenic exposure. This provides new insights into relevant exposure windows that are critical to the development of ischemic heart disease.

Nearly half (48 percent) of participants were exposed to an average arsenic concentration below California’s non-cancer public health goal <1 µg/L. In comparison to this low-exposure group, those exposed to 1 to <5 µg/L had modestly higher risk of ischemic heart disease, with increases of 5 to 6 percent. Risk jumped to 20 percent among those in the exposure ranges of 5 to <10 µg/L (or one-half to below the current regulatory limit), and more than doubled to 42 percent for those exposed to levels at and above the current EPA limit ≥10µg/L. The relationship was consistently stronger for ischemic heart disease compared to cardiovascular disease, and no evidence of risk for stroke was found, largely consistent with previous research and the conclusions of the current EPA risk assessment.

These results highlight the serious health consequences not only when community water systems do not meet the current EPA standard but also at levels below the current standard. The study found a substantial 20 percent risk at arsenic exposures ranging from 5 to <10 µg/L which affected about 3.2 percent of participants, suggesting that stronger regulations would provide significant benefits to the population. In line with prior research, the study also found higher arsenic concentrations, including concentrations above the current standard, disproportionally affect Hispanic and Latina populations and residents of lower socioeconomic status neighborhoods.

“Our results are novel and encourage a renewed discussion of current policy and regulatory standards,” said Columbia Mailman’s Tiffany Sanchez, senior author. “However, this also implies that much more research is needed to understand the risks associated with arsenic levels that CWS users currently experience. We believe that the data and methods developed in this study can be used to bolster and inform future studies and can be extended to evaluate other drinking water exposures and health outcomes.”

Co-authors are Komal Bangia, Office of Environmental Health Hazard Assessment, Oakland, California; James V. Lacey Jr and Emma S. Spielfogel,California Teacher Study, Beckman Research Institute, City of Hope, Duarte, California; and Jared A Fisher^, Jessica M. Madrigal, Rena R. Jones, and Mary H. Ward^, Division of Cancer Epidemiology and Genetics, National Cancer Institute.

The study was supported by the National Cancer Institute, grants U01-CA199277, P30-CA033572, P30-CA023100, UM1-CA164917, and R01-CA077398; and also funded by the Superfund Hazardous Substance Research and Training Program P42ES033719; NIH National Institute of Environmental Health Sciences P30 Center for Environmental Health and Justice P30ES9089, NIH Kirschstein National Research Service Award Institutional Research Training grant T32ES007322, NIH Predoctoral Individual Fellowship F31ES035306, and the Intramural Research Program of the NCI Z-CP010125-28.