Papers of the Month
By Megan Avakian
Higher BPA levels linked to worse asthma in children
NIEHS grantees found that children, especially boys, with elevated levels of bisphenol A (BPA) in their urine had more asthma symptoms. The study is the first to examine children’s exposure to BPA and its common replacements bisphenol S (BPS) and bisphenol F (BPF), with respect to asthma severity. BPA, used to make polycarbonate plastics and epoxy resins, may be present in dental sealants, the lining of food and drink cans, toys, plastic dinnerware, and other consumer products. Most people are exposed through their diet.
The study included 148 children with asthma from low-income neighborhoods aged 5 to 17 years. Participants, most of whom were Black, were part of the Mouse Allergen and Asthma Cohort Study, conducted between 2007 and 2009 in Baltimore. The researchers analyzed stored urine samples and data from clinical visits, including asthma symptoms, health care visits, lung function, and inflammation.
A 10-fold increase in urinary BPA levels was associated with a 40% increase in the chance of children experiencing coughing, wheezing, or chest tightness. Similarly, for each 10-fold increase in urinary BPA, the chances of asthma-related acute care or emergency-room visits increased by 84% and 112%, respectively. Both increased asthma symptoms and health care visits were statistically significant only for boys. Higher BPS or BPF levels were not consistently associated with more asthma symptoms or health care visits.
Given widespread exposure to BPA and high prevalence of child asthma in the U.S., the researchers called for additional studies to verify their findings. If confirmed, children with asthma may benefit from reduced contact with BPA, say the researchers.
Citation: Quiros-Alcala L, Hansel NN, McCormack M, Calafat AM, Ye X, Peng RD, Matsui EC. 2020. Exposure to bisphenols and asthma morbidity among low-income urban children with asthma. J Allergy Clin Immunol; doi:10.1016/j.jaci.2020.05.031 [Online 28 July 2020].
Dragonflies provide insight into mercury pollution, citizen science study finds
A new NIEHS-funded study found that immature dragonfly larvae can be used to estimate the amount of mercury present in local fish, amphibians, and birds. The study used data from a national-scale citizen science project that began more than a decade ago.
Researchers compiled data on mercury levels in thousands of larval dragonflies collected from 457 locations across 100 U.S. National Park Service sites between 2009 and 2018. They also examined factors, such as habitat type, that may account for variation in dragonfly mercury concentrations, which were nearly two times higher in habitats with flowing water, like rivers and streams, compared with still water sites like lakes and ponds. The researchers suggested that dragonfly larvae can be used to assess mercury in aquatic food webs, because fish and amphibians from the same locations showed similar levels. These findings were used to develop an index of mercury risk to aquatic ecosystems. The team determined that 56% of the park sites were categorized as moderate hazards and 12% presented high or severe hazards to fish, wildlife, or human health. Resource managers can use this approach to more thoroughly assess the threat mercury may pose to ecosystems.
Collectively, this study demonstrated that dragonfly larvae offer a simple and cost-effective tool for estimating mercury exposure in fish and wildlife. It also provides a successful framework for engaging citizen scientists.
Citation: Eagles-Smith CA, Willacker JJ, Nelson SJ, Flanagan Pritz CM, Krabbenhoft DP, Chen CY, Ackerman JT, Campbell Grant EH, Pilliod DS. 2020. A national-scale assessment of mercury bioaccumulation in United States national parks using dragonfly larvae as biosentinels through a citizen-science framework. Environ Sci Technol 54(14):8779–8790.
Stool microbiome unlocks advances in diagnosing liver disease
NIEHS grantees and collaborators developed a rapid, low-cost tool to accurately diagnose liver fibrosis and cirrhosis. The noninvasive method uses stool samples to characterize the gut microbiome, or the bacteria that live in gut, which has been linked to liver health. The method could lead to improved patient care and treatment outcomes for liver disease.
Fibrosis, or the formation of scar tissue in the liver, can be reversed if diagnosed early. Long-term, repeated scarring can lead to cirrhosis and permanent liver damage. Researchers studied stool samples from 163 patients with liver disease and their healthy family members. Using metabolic and genetic profiling and machine learning, they developed a gut microbiome signature for liver disease based on differences in the types and amounts of bacteria in patients compared to healthy individuals. A microbiome signature based on 19 bacterial species present only in the patient group accurately diagnosed cirrhosis in 94% of patients. To further validate the signature, they applied it to cirrhosis patient populations in China and Italy and correctly identified the disease in more than 90% of cases. Additionally, the signature distinguished early stage fibrosis from cirrhosis.
This universal gut microbiome signature can identify cirrhosis across geographically separated cohorts, independent of the effects of genetics and environment. According to the authors, the method has immense potential to improve liver disease diagnosis, especially in resource-limited settings where other screening options might not be available.
Citation: Oh TG, Kim SM, Caussy C, Fu T, Guo J, Bassirian S, Singh S, Madamba EV, Bettencourt R, Richards L, Raffatellu M, Dorrestein PC, Yu RT, Atkins AR, Huan T, Brenner DA, Sirlin CB, Knight R, Downes M, Evans RM, Loomba R. 2020. A universal gut-microbiome-derived signature predicts cirrhosis. Cell Metab; doi:10.1016/j.cmet.2020.06.005 [Online 30 June 2020].
Radioactive air particles increase inflammation in elderly men
Elderly men exposed to radioactive air pollution particles had increased levels of inflammatory biomarkers linked to heart disease, according to an NIEHS-funded study. The findings point to inflammation as the pathway by which radioactive particulate matter may increase cardiovascular disease risk.
Radon, a naturally-occurring gas, breaks down into radioactive particles that attach to particulate air pollution and can release radiation in the lungs if inhaled. The study included 752 men in the greater Boston area aged 75 years on average. The researchers used daily measurements from five radiation monitors in the study area to calculate short- and medium-term average exposures to particle radioactivity. Using statistical models, they found positive associations between particle radioactivity and biomarkers of both inflammation and vascular dysfunction. They separated effects of radioactivity from other pollutants by using models with and without adjustment for fine particulate matter, black carbon, and other compounds. Men with increased exposure to short-term particle radioactivity had higher levels of the inflammatory biomarker C-reactive protein. Vascular dysfunction biomarkers were similarly increased with higher short-term exposure. The effects of exposure to radioactive particles remained after adjustment for air pollutants, in most cases.
Citation: Blomberg AJ, Nyhan MM, Bind MA, Vokonas P, Coull BA, Schwartz J, Koutrakis P. 2020. The role of ambient particle radioactivity in inflammation and endothelial function in an elderly cohort. Epidemiology 31(4):499–508.
(Megan Avakian is a science writer for MDB Inc., a contractor for the NIEHS Division of Extramural Research and Training.)