It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Wednesday, July 05, 2023
Fossils reveal how ancient birds molted their feathers— which could help explain why ancestors of modern birds survived when all the other dinosaurs died
IMAGE: FEATHERS FROM A BABY BIRD THAT LIVED 99 MILLION YEARS AGO, PRESERVED IN AMBER.view more
CREDIT: PHOTO BY SHUNDONG BI.
Every bird you’ve ever seen— every robin, every pigeon, every penguin at the zoo— is a living dinosaur. Birds are the only group of dinosaurs that survived the asteroid-induced mass extinction 66 million years ago. But not all the birds alive at the time made it. Why the ancestors of modern birds lived while so many of their relatives died has been a mystery that paleontologists have been trying to solve for decades. Two new studies point to one possible factor: the differences between how modern birds and their ancient cousins molt their feathers.
Feathers are one of the key traits that all birds share. They're made of a protein called keratin, the same material as our fingernails and hair, and birds rely on them to fly, swim, camouflage, attract mates, stay warm, and protect against the sun’s rays. But feathers are complex structures that can’t be repaired, so as a means of keeping them in good shape, birds shed their feathers and grow replacements in a process called molting. Baby birds molt in order to lose their baby feathers and grow adult ones; mature birds continue to molt about once a year.
“Molt is something that I don't think a lot of people think about, but it is fundamentally such an important process to birds, because feathers are involved in so many different functions,” says Jingmai O’Connor, associate curator of fossil reptiles at Chicago’s Field Museum. “We want to know, how did this process evolve? How did it differ across groups of birds? And how has that shaped bird evolution, shaped the survivability of all these different clades?” Two of O’Connor’s recent papers examine the molting process in prehistoric birds.
A paper in the journal Cretaceous Research published in May 2023 detailed the discovery of a cluster of feathers preserved in amber from a baby bird that lived 99 million years ago.
Today, baby birds are on a spectrum in terms of how developed they are when they're born and how much help they need from their parents. Altricial birds hatch naked and helpless; their lack of feathers means that their parents can more efficiently transmit body heat directly to the babies’ skin. Precocial species, on the other hand, are born with feathers and are fairly self-sufficient.
All baby birds go through successive molts— periods when they lose the feathers they have and grow in a new set of feathers, before eventually reaching their adult plumage. Molting takes a lot of energy, and losing a lot of feathers at once can make it hard for a bird to keep itself warm. As a result, precocial chicks tend to molt slowly, so that they keep a steady supply of feathers, while altricial chicks that can rely on their parents for food and warmth undergo a “simultaneous molt,” losing all their feathers at roughly the same time.
The amber-preserved feathers in this study are the first definitive fossil evidence of juvenile molting, and they reveal a baby bird whose life history doesn’t match any birds alive today. “This specimen shows a totally bizarre combination of precocial and altricial characteristics,” says O’Connor, who was the first author of the paper alongside senior author Shundong Bi of the Indiana University of Pennsylvania. “All the body feathers are basically at the exact same stage in development, so this means that all the feathers started growing simultaneously, or near simultaneously.” However, this bird was almost certainly part of a now-extinct group called the Enantiornithines, which O’Connor’s previous work has shown were highly precocial.
O’Connor hypothesizes that the pressures of being a precocial baby bird that had to keep itself warm, while undergoing a rapid molt, might have been a factor in the ultimate doom of the Enantiornithines. “Enantiornithines were the most diverse group of birds in the Cretaceous, but they went extinct along with all the other non-avian dinosaurs,” says O’Connor. “When the asteroid hit, global temperatures would have plummeted and resources would have become scarce, so not only would these birds have even higher energy demands to stay warm, but they didn’t have the resources to meet them.”
Meanwhile, an additional study published July 3 in Communications Biology by O’Connor and Field Museum postdoctoral researcher Yosef Kiat examines molting patterns in modern birds to better understand how the process first evolved.
In modern adult birds, molting usually happens once a year in a sequential process, in which they replace just a few of their feathers at a time over the course of a few weeks. That way, they're still able to fly throughout the molting process. Simultaneous molts in adult birds, in which all the flight feathers fall out at the same time and regrow within a couple weeks, are rarer and tend to show up in aquatic birds like ducks that don’t absolutely need to fly in order to find food and avoid predators.
It’s very rare to find evidence of molting in fossil birds and other feathered dinosaurs, and O’Connor and Kiat wanted to know why. “We had this hypothesis that birds with simultaneous molts, which occur in a shorter duration of time, will be less represented in the fossil record,” says O’Connor— less time spent molting means fewer opportunities to die during your molt and become a fossil showing signs of molting. To test their hypothesis, the researchers delved into the Field Museum’s collection of modern birds.
“We tested more than 600 skins of modern birds stored in the ornithology collection of the Field Museum to look for evidence of active molting,” says Kiat, the first author of the study. “Among the sequentially molting birds, we found dozens of specimens in an active molt, but among the simultaneous molters, we found hardly any.”
While these are modern birds, not fossils, they provide a useful proxy. “In paleontology, we have to get creative, since we don’t have complete data sets. Here, we used statistical analysis of a random sample to infer what the absence of something is actually telling us,” says O’Connor. In this case, the absence of molting fossil birds, despite active molting being so prevalent in the sample of modern bird specimens, suggests that fossil birds simply weren’t molting as often as most modern birds. They may have undergone a simultaneous molt, or they may not have molted on a yearly basis the way most birds today do.
Both the amber specimen and the study of molting in modern birds point to a common theme: prehistoric birds and feathered dinosaurs, especially ones from groups that didn’t survive the mass extinction, molted differently from today’s birds.
“All the differences that you can find between crown birds and stem birds, essentially, become hypotheses about why one group survived and the rest didn’t,” said O’Connor. “I don't think there's any one particular reason why the crown birds, the group that includes modern birds, survived. I think it's a combination of characteristics. But I think it's becoming clear that molt may have been a significant factor in which dinosaurs were able to survive.”
Illustration of what a newly hatched Enantiornithine bird may have looked like.
CREDIT
Image by Yu Chen and Shundong Bi.
An illustration of a more mature juvenile Enantiornithine.
Illustration showing a young Enantiornithine bird.
CREDIT
Image by Yu Chen and Shundong Bi.
Mourning Doves in the Field Museum's bird collections, used to examine molting in living birds.
Mallard ducks (IMAGE)
FIELD MUSEUM
Mallard ducks in the Field Museum's bird collections, used to study molting in modern birds.
CREDIT
Field Museum, Kate Golembiewski
JOURNAL
Communications Biology
SUBJECT OF RESEARCH
Animals
ARTICLE TITLE
Rarity of molt evidence in early pennaraptoran dinosaurs suggests annual molt evolved later among Neornithes
IMAGE: RV SIKULIAQ, A RESEARCH VESSEL OWNED BY THE NATIONAL SCIENCE FOUNDATION, BREAKS THROUGH ARCTIC ICE.view more
CREDIT: PHOTO BY CHRISTINA GOETHEL OF THE UNIVERSITY OF MARYLAND CENTER FOR ENVIRONMENTAL SCIENCES.
There has been much buzz about the warming planet’s melting Arctic region opening shipping routes and lengthening travel seasons in ocean passageways that ice once blocked. Expanded fishing, trade and tourism is envisioned.
Operative word: Envisioned.
Scientists at Michigan State University (MSU), University of Waterloo, and University of Alaska Fairbanks report in Climatic Change where vessels are traveling in the ice-covered waters of the Arctic between Alaska and Russia, and what those reports may mean for important wildlife and communities in the region.
“Even with climate change, sea ice is still a substantial barrier to Arctic vessel traffic,” said Kelly Kapsar, a research associate at MSU’s Center for Systems Integration and Sustainability (CSIS). “Sea ice also provides critical habitat for many endemic Arctic species and a hunting platform for Indigenous subsistence hunters. Understanding when and where ships are entering areas of sea ice can help us to better understand potential impacts of vessel traffic in the region.”
Whether its fishing vessels seeking better catches over a longer season, or Russian shipping companies eager for better ways to deliver oil and gas to Chinese customers, increased marine traffic is a given. Whether this traffic occurs only in the open water season, or also in times of ice cover is not.
But the researchers point out the difference between what ships could do as ice changes, and what they will do can be vastly different.
“Up until now projections have been about theoretical ships, such as noting certain vessel types can travel through up to 2 meters of ice,” Kapsar said. “But that’s like saying a car can drive up to 200 mph – just because it can doesn’t mean it will.”
Combining satellite pictures of ice cover with GPS vessel tracking data the team was able to analyze how the ships have been behaving as the shipping passages change. What they’ve found is that many ships are following the ice, fishing close to the edge of ice packs. The researchers also found marked overlap between areas with vessels traveling in sea ice and the overwintering areas for bowhead whales.
Previous research by another group has demonstrated that between 1990 and 2012, some 12% of bowhead whales harvested by Alaska Native subsistence hunters showed signs they had been tangled in fishing gear, and 2% had scars from being struck by vessels. The new analysis points to a growing threat to wildlife which also are using the receding ice as they travel and breed.
Noise from large boats also can disrupt marine mammals. Ships equipped to break ice potentially could strand both animals and people traveling across the frozen expanses. Increased traffic also raises fear of accidents and oil spills. The new pathways are far away from rescue or clean-up crews.
So far, Kapsar said, their work indicates ship travel reflects a certain caution, offering indications that capability is balanced by practical and economic realities. For now.
Kapsar and co-author Jianguo “Jack” Liu are members of MSU’s Ecology, Evolution, and Behavior Program. “Mapping vessel traffic patterns in the ice-covered waters of the Pacific Arctic” also was written by Lawson Brigham and Grant Gunn. The work is funded by the National Science Foundation.
AUSTIN, Texas — As public concerns mount over lack of transparency in political giving, a new study from researchers at The University of Texas at Austin is the first to illuminate how and why corporations choose to legally conceal their lobbying and campaign contributions.
U.S. companies are required to disclose the total amount they spend on political activity, but beyond that, the disclosure is incredibly vague, according to Tim Werner, associate professor of business, government and society at the McCombs School of Business.
“We don’t even know which individual members of Congress they meet with,” Werner said. “If you’re only looking at observable political activities of corporations, it’s like looking at the tip of the iceberg.”
Below the waterline, Werner and colleagues, Nan Jia of the University of Southern California and Stanislav Markus of the University of South Carolina, found that when corporations conceal their political activities, they may use a wide variety of strategies, including:
Lobbying people who are not obvious political players.
Secretly creating a “citizens coalition” to advocate for their position.
Using obfuscation to spin an issue in their favor.
Contributing to groups that are not legally required to report their donors, known as “dark money” groups.
The research is published in Academy of Management.
How do corporations decide when to use these strategies? The researchers developed a mathematical model of a company’s political decision-making to help predict which activities it’s most likely to hide. Their calculus finds:
The lower the costs of concealment or of being caught, the more likely companies are to attempt it.
Companies are more likely to conceal their activities on issues where they reap most of the benefits or bear most of the costs.
The harder it is to win a lawmaker’s support, the more a company will try to hide its spending to influence that lawmaker.
Werner said this line of research opens an important conversation.
“The more we understand about the reasons a business does or does not conceal its political involvement, the more informed our decision-making around policies related to transparency,” he said.
IMAGE: HEALTH WORKFORCE DIVERSITY TRACKER DATA ON HISPANIC PHYSICIAN CURRENT WORKFORCE, 2010-2019 (NATIONAL)view more
CREDIT: FITZHUGH MULLAN INSTITUTE FOR HEALTH WORKFORCE EQUITY. HEALTH WORKFORCE DIVERSITY TRACKER. WASHINGTON, DC: GEORGE WASHINGTON UNIVERSITY, 2021
WASHINGTON (July 5, 2023)--Although the situation is improving, Latinos and especially Mexican Americans, remain very underrepresented in U.S. health professions that require advanced degrees, according to a study published today in the journal Health Affairs. The study by George Washington University researchers is the first to examine the representation of the four largest Latino populations in the U.S. health workforce and the findings raise concerns about the lack of diversity in the U.S. health workforce.
The study revealed that Mexican Americans, despite being the largest Latino subpopulation in the United States, are greatly underrepresented in the health professions that require an advanced degree. One out of ten people in the United States are Mexican American yet in five of the eight professions requiring advanced education included in the study, Mexican Americans represent one-quarter or less of the professions. This study suggests they and other Latinos in the study face many barriers to occupations in the healthcare field that require an advanced degree such as doctor, nurse or pharmacist.
“Our analysis did not address why Latino representation was low in the health professions requiring advanced degrees,” Indira Islas, who conducted the study while a graduate student at the GW Milken Institute School of Public Health, said. “Other evidence suggests that the findings can be attributed to obstacles such as structural racism.”
Islas and her colleagues at the GW Fitzhugh Mullan Institute for Health Workforce Equity used data from the 2020 American Community Survey, which includes information on ethnicity collected by the Census Bureau. The team compared the representation of non-Latinos and four Latino subgroups, including Mexican Americans, Puerto Ricans, Cuban Americans and other Latinos.
The research showed a surprising finding for one subpopulation. Compared to other Latino groups, Cuban Americans are well-represented in the advanced degree health professions. For example their representation among physicians and dentists is greater than their numbers in the overall population.
The study also found that Mexican Americans, Puerto Ricans and other Latinos were overrepresented in most healthcare support occupations, low-wage jobs such as medical or dental assistants or home health aides.
Latino representation in the health workforce did show improvement during the time frame studied from 2016-2020: For example, Latino representation among recent graduates went from 6.7 to 13.5% for health professions requiring a bachelor’s degree. However, the researchers note that Latinos represented more than 21% of the population ages 20-35.
“There has been significant progress in getting more Latinos into the advanced health professions over the last few years,” Edward Salsberg, Co-Director of the Health Workforce Diversity Initiative at the Mullan Institute, said. “Yet as we can see from this study, much more needs to be done to strengthen and diversify the health workforce in the U.S. A lack of diversity among the health professions can exacerbate health disparities for Latinos and other minority populations.”
Islas, whose family came to the U.S. when she was a child, has experienced some of the obstacles to getting an advanced degree first hand.
Her parents, who were doctors in Mexico, had to find work in factory jobs when the family moved to the U.S. “I remember in high school we didn’t have a lot of resources,” Islas said. But Islas had a dream of becoming a doctor like her parents and she ended up getting a scholarship and went to college. In May of last year, she graduated from GW with a Masters of Public Health. She is now doing a fellowship with the Congressional Hispanic Caucus Institute with plans to apply to medical school in the fall.
For additional data on Latino representation in the health professions including by state and by graduates of individual schools, visit: The Health Workforce Diversity Tracker.
-GW-
JOURNAL
Health Affairs
METHOD OF RESEARCH
Data/statistical analysis
SUBJECT OF RESEARCH
People
ARTICLE TITLE
Documenting Latino Representation in the U.S. Health Workforce
ARTICLE PUBLICATION DATE
5-Jul-2023
New study shows Medicaid expansion associated with increase in palliative care for patients with advanced cancers
IMAGE: MORE PEOPLE WITH ADVANCED CANCERS IN THE UNITED STATES RECEIVED CRITICAL PALLIATIVE CARE SERVICES, ACCORDING TO NEW FINDINGS BY RESEARCHERS AT THE AMERICAN CANCER SOCIETY.view more
CREDIT: AMERICAN CANCER SOCIETY
ATLANTA, July 5, 2023 – More people with advanced cancers in the United States received critical palliative care services, according to new findings by researchers at the American Cancer Society (ACS). Palliative care includes supportive care managed by a healthcare team, such as relief from symptoms, pain, and stress. Researchers also found where a patient lives in the U.S. may determine their use of palliative care. Medicaid expansion under the ACA was associated with the largest increases in palliative care use. The study was published today in the July issue of the journal Health Affairs.
“Our findings are encouraging, especially with growing evidence of the important benefits of palliative care for patients with cancer,” said Dr. Xuesong Han, lead author of the study and scientific director of health services research at the American Cancer Society. “It’s imperative to know how to target ways to increase access to these services, as use, overall, still remains low in the U.S.”
For the study, researchers examined data from the National Cancer Database, a national hospital-based cancer registry jointly sponsored by the American College of Surgeons and ACS. Scientists included data from people aged 18-64 years newly diagnosed with stage IV cancers in 2010-2019.
Researchers discovered the number of eligible patients who received palliative care increased from 17.0 percent pre-expansion to 18.9 percent post-expansion in Medicaid expansion states and from 15.7 percent to 16.7 percent in non-expansion states. The study also showed palliative care associated with Medicaid expansion was largest for patients with advanced pancreatic, colorectal, lung, and oral cavity and pharynx cancers, and non-Hodgkin lymphoma.
“These study results suggest that the expansion of Medicaid coverage may increase palliative care use,” added Han. “They also point to a potentially widening geographic disparity in receipt of guideline-recommended palliative care between states with different health policies regarding income-based Medicaid eligibility requirements.”
“Research continues to underscore the impact increasing access to comprehensive, affordable health insurance through Medicaid has on cancer patient survival and the further importance of providing greater access to palliative care services to those positive outcomes. The American Cancer Society Cancer Action Network (ACS CAN) has led legislation in states to support palliative care access and continues to advocate for legislation at the federal level to promoteincreased access to supportive care at any age or stage of diagnosis nationwide,” said Lisa Lacasse, President of ACS CAN. “To fully improve patient quality of life, Congress should prioritize legislation that educates patients and providers about the availability and benefits of palliative care and expand federal palliative care research. It’s also crucial all remaining states expand access to Medicaid as access to comprehensive health care is key to closing the gap on the health inequities we see in these underserved areas and ensure everyone has a fighting chance against cancer.”
For additional information on palliative care services, visit here at cancer.org.
# # #
About the American Cancer Society The American Cancer Society is a leading cancer-fighting organization with a vision to end cancer as we know it, for everyone. For more than 100 years, we have been improving the lives of people with cancer and their families as the only organization combating cancer through advocacy, research, and patient support. We are committed to ensuring everyone has an opportunity to prevent, detect, treat, and survive cancer. To learn more, visit cancer.org or call our 24/7 helpline at 1-800-227-2345. Connect with us on Facebook, Twitter, and Instagram.
JOURNAL
Health Affairs]
Study finds scant coverage for seniors’
mental health care
Narrow psychiatrist networks for Medicare Advantage highlight lack of access for mental health
Amid heightened demand for mental health care, a new study finds that nearly two-thirds of Medicare Advantage psychiatrist networks contain less than 25% of all psychiatrists in a given service area.
“This means that many people who have coverage through Medicare Advantage plans may not actually have access to psychiatrists, given how few are considered in-network,” said lead author Jane Zhu, M.D., assistant professor of medicine (general internal medicine and geriatrics) in the School of Medicine at Oregon Health & Science University.
The research published today in the July issue of the journal Health Affairs.
Medicare is the federal health insurance program for people who are 65 or older. Medicare Advantage, which covers 28 million Americans through private insurance plans backed by Medicare, has an even narrower network of psychiatrists available to patients than those covered by Medicaid managed care or by insurance plans in the Affordable Care Act. Insurance plans often contract with sets of providers — considered “in-network” — to deliver services to their enrollees.
The researchers built a nationwide data set of health plan networks, their service areas and their participating providers in 2019.
The new study is the latest in a series of findings highlighting a lack of coverage and access to mental health care nationwide. Provider networks are one important lever of access, and Zhu noted that the new study likely understates the problem.
“It’s likely a rosier picture than reality,” Zhu said. “We know the actual number of psychiatrists available to see patients is much lower.”
That’s because even if a psychiatrist is technically in-network, Zhu said an overall national shortage of psychiatrists means that many are fully booked already and aren’t accepting new patients. She said this may translate to higher out-of-pocket costs, delays in care, or foregone treatment.
For Zhu, these findings suggest that it’s necessary for insurers to incentivize more psychiatrists and mental health professionals to accept health insurance, or to expand coverage of services delivered by other health care professionals such as psychologists, counselors or primary care physicians who provide mental health care.
In some areas examined in this latest study, the picture was even more dire, with not a single psychiatrist who accepts Medicare Advantage insurance accepting patients.
“More than half of the counties for which we had data did not have a single [Medicare Advantage]-participating psychiatrist,” the authors write. “Our findings offer upper-bound estimates of network breadth, raising concerns about MA enrollees’ access to mental health services amid the growing prevalence of mental health conditions among older adults.”
In addition to Zhu, co-authors included Mark Katz Meiselbach, Ph.D., and Daniel Polsky, Ph.D., of Johns Hopkins University, and Coleman Drake, Ph.D., of the University of Pittsburgh.
The research was supported by the National Institute of Mental Health of the National Institutes of Health award K08MH123624; the Agency for Healthcare Research and Quality award T32HS00029; and the National Institute on Drug Abuse of the NIH award K01DA051761. The content is the responsibility of the authors and does not necessarily represent the official views of the NIH or AHRQ.
MINNEAPOLIS – Taking good care of your teeth may be linked to better brain health, according to a study published in the July 5, 2023, online issue of Neurology®, the medical journal of the American Academy of Neurology. The study found that gum disease and tooth loss were linked to brain shrinkage in the hippocampus, which plays a role in memory and Alzheimer’s disease. The study does not prove that gum disease or tooth loss causes Alzheimer’s disease; it only shows an association.
“Tooth loss and gum disease, which is inflammation of the tissue around the teeth that can cause shrinkage of the gums and loosening of the teeth, are very common, so evaluating a potential link with dementia is incredibly important,” said study author Satoshi Yamaguchi, PhD, DDS, of Tohoku University in Sendai, Japan. “Our study found that these conditions may play a role in the health of the brain area that controls thinking and memory, giving people another reason to take better care of their teeth.”
The study involved 172 people with an average age of 67 who did not have memory problems at the beginning of the study.
Participants had dental exams and took memory tests at the beginning of the study. They also had brain scans to measure volume of the hippocampus at the beginning of the study and again four years later.
For each participant, researchers counted the number of teeth and checked for gum disease by looking at periodontal probing depth, a measurement of the gum tissue. Healthy readings are from one to three millimeters.
Mild gum disease involves probing depths of three or four millimeters in several areas, while severe gum disease involves probing depths of five or six millimeters in several areas as well as more bone loss and can cause teeth to become loose and eventually fall out.
Researchers found that the number of teeth and amount of gum disease was linked to changes in the left hippocampus of the brain.
For people with mild gum disease having fewer teeth was associated with a faster rate of brain shrinkage in the left hippocampus.
However, for people with severe gum disease having more teeth was associated with a faster rate of brain shrinkage in the same area of the brain.
After adjusting for age, researchers found that for people with mild gum disease, the increase in the rate of brain shrinkage due to one less tooth was equivalent to nearly one year of brain aging. Conversely, for people with severe gum disease the increase in brain shrinkage due to one more tooth was equivalent to 1.3 years of brain aging.
“These results highlight the importance of preserving the health of the teeth and not just retaining the teeth,” Yamaguchi said. “The findings suggest that retaining teeth with severe gum disease is associated with brain atrophy. Controlling the progression of gum disease through regular dental visits is crucial, and teeth with severe gum disease may need to be extracted and replaced with appropriate prosthetic devices.”
Yamaguchi said future studies are needed with larger groups of people. Another limitation of the study is that it was conducted in one region of Japan, so the results may not be generalizable to other locations.
The study was supported by the Japanese Ministry of Education, Culture, Sports, Science and Technology; Keio University; Japan Arteriosclerosis Prevention Fund; Japanese Ministry of Health, Labor, and Welfare; Teikyo University; Pfizer Japan; Bayer Yakuhin; Chugai Pharmaceutical; Daiichi Sankyo; Astellas Pharma; Takeda Pharmaceutical; Health Care Science Institute; Health Science Center; and Takeda Science Foundation.
Learn more about Alzheimer’s disease at BrainandLife.org, home of the American Academy of Neurology’s free patient and caregiver magazine focused on the intersection of neurologic disease and brain health. Follow Brain & Life® on Facebook, Twitter and Instagram.
When posting to social media channels about this research, we encourage you to use the hashtags #Neurology and #AANscience.
The American Academy of Neurology is the world’s largest association of neurologists and neuroscience professionals, with over 40,000 members. The AAN is dedicated to promoting the highest quality patient-centered neurologic care. A neurologist is a doctor with specialized training in diagnosing, treating and managing disorders of the brain and nervous system such as Alzheimer’s disease, stroke, migraine, multiple sclerosis, concussion, Parkinson’s disease and epilepsy.
Body mass index (BMI) may not increase mortality independently of other risk factors in adults, according to a new study published this week in the open-access journal PLOS ONE by Aayush Visaria and Soko Setoguchi of Rutgers University, US.
The prevalence of overweight and obesity has risen dramatically over the last 25 years, and it is well-established that elevated BMI can contribute to several cardio-metabolic conditions. However, studies that have analyzed the association between BMI and all-cause mortality have been inconsistent. Most US studies have used data from the 1960s through 1990s and have included predominantly non-Hispanic White adults.
In the new work, the researchers retrospectively studied data on 554,332 US adults from the 1999-2018 National Health Interview Survey and the 2019 US National Death Index. BMI was calculated using self-reported height and weight and participants were divided into 9 BMI categories for the analysis. Information on demographics, socio-behavioral factors, comorbidities and healthcare access was also available. On average, participants were 46 years old, 50% female and 69% non-Hispanic White. 35% of those included in the study had a BMI between 25 and 30, which is typically defined as overweight, and 27.2% had a BMI above or equal to 30, typically defined as obese.
Over a median follow-up of 9 years and a maximum follow-up of 20 years, the researchers observed 75,807 deaths. The risk of all-cause mortality was similar across a wide range of BMI categories. For older adults, there was no significant increase in mortality for any BMI between 22.5 and 34.9, which extends into the BMI categories typically considered obese. For younger adults, there was no significant increase in mortality for any BMI between 22.5 and 27.4. Overall, for adults with a BMI of 30 or over, there was a 21% to 108% increased mortality risk attributed to their weight. The patterns observed in the overall population remained largely the same in men and women and across races and ethnicities.
The authors conclude that further studies incorporating weight history, body composition and morbidity outcomes are needed to fully characterize BMI-mortality associations, but say that BMI in the overweight range is generally not associated with increased risk of all-cause mortality.
The authors add: “Our study highlights the increasing reservations of using BMI alone to drive clinical decisions. There is no clear increase in all-cause mortality across a range of traditionally normal and overweight BMI ranges; however, that is not to say that morbidity is similar across these BMI ranges. Future studies will need to assess incidence of cardio-metabolic morbidities.”
Citation: Visaria A, Setoguchi S (2023) Body mass index and all-cause mortality in a 21st century U.S. population: A National Health Interview Survey analysis. PLoS ONE 18(7): e0287218. https://doi.org/10.1371/journal.pone.0287218
Author Countries: USA
Funding: The authors received no specific funding for this work.
IMAGE: THIS IS A MATURE DAPHNIA MAGNA IMAGED UNDER A MICROSCOPE AT 20X MAGNIFICATION. THE PHOTO WAS TAKEN AT THE END OF THE 21 DAY EXPOSURE TO SUNSCREEN SO THAT WE COULD MEASURE ITS BODY LENGTH. THE BLACK SPHERES ON THE BOTTOM LEFT ARE DEVELOPING EGGS.view more
CREDIT: AARON BOYD
New research reveals that sunscreen contamination may be less harmful to wildlife than previously thought. This study by Aaron Boyd, a PhD candidate at the University of Alberta in Edmonton, Canada, demonstrates how exposure to sunscreen is actually a low risk for small aquatic animals compared to some of the suncream’s individual chemicals.
Sunscreens contain ultraviolet filters (UVFs) which have been found to be toxic to marine life such as corals, leading to the ban of some UVFs in Hawaii and Palau. If sunscreen is applied to the skin before swimming in lakes and rivers, these UVFs and other chemicals will leach into surrounding waters.
Mr Boyd’s research investigates how the chemical cocktail in sunscreen interacts to affect marine life, instead of just focusing on the UVFs and other chemicals on their own. “Researchers overwhelmingly perform studies testing the toxicity of UVFs in isolation by exposing test organisms to one chemical at a time,” says Mr Boyd. “In fact, less than 3% of aquatic toxicology studies published to date have investigated whole sunscreen mixtures, leaving a massive knowledge gap to be addressed.”
This research compared the long-term toxicity of five different sunscreen mixtures, as well as their individual UVFs, on Daphnia water fleas. Daphnia are invertebrates that are commonly found in freshwater lakes throughout the world and are a good indicator of how pollution affects aquatic life.
“We were very surprised to find that sunscreen mixtures are much less toxic to Daphnia than what would be expected based on the quantity of each UV filter present within the mixtures,” says Mr Boyd. “In fact, we found that Daphnia could survive long-term exposure to sunscreens containing octocrylene at concentrations >50x higher than what would be completely lethal to all Daphnia had they been exposed to the UVF alone.”
The rate at which new chemicals are developed and released into the environment is much faster than the rate at which scientists can proper study the consequences of contamination. “As a result,” says Mr Boyd, “it's important that we utilize our limited research resources effectively by identifying which contaminants are likely to cause harm to the environment, and which contaminants are lower risk.”
“We found that the other components of the sunscreen mixtures reduced the toxicity to such a large extent that perhaps these chemicals are not a contamination concern in most environments, allowing for us to reallocate our limited research resources towards identifying other contaminants that could be much more concerning,” says Mr Boyd. “This potentially indicates that the vast majority of studies investigating the toxicity of individual UV filters could be overestimating the toxicity of these chemicals in aquatic environments.”
Mr Boyd still strongly recommends the use of sunscreen when spending time outdoors. “Regardless of any potential environmental toxicity of sunscreens, always wear sunscreen when going outside for an extended period of time. The threat of cancer is much more severe than the potential effects that sunscreen contamination may cause!”
