“The massive use of antibiotics and antimicrobials in people and animals has led to these substances appearing in unexpected environmental samples,” said Irantzu Vergara, researcher in the UPV/EHU’s IBeA group. Drugs that do not end up fully metabolised in the body reach the environment through various routes (such as manure, sewage sludge used as fertilisers, etc.), are leached into the soil and may end up transferring to crops or earthworms, which are at the base of the food chain. “Although no short-term toxicity has been demonstrated in humans, the unintended consumption of antibiotics in the diet can cause problems for allergic individuals; and the effects of long-term exposure remain unknown. However, the biggest problem associated with this contamination is the spread of multi-resistant bacteria; it is difficult to find an effective treatment in the event of infection, which is responsible for 33,000 deaths per year across Europe,” explained Vergara.

To address this problem, the IBeA research group has developed two analytical methods enabling very low concentrations of antimicrobials in vegetables and earthworms to be detected: “Although high drug concentrations can be expected in manure, much lower concentrations are expected after these substances have transferred to plants or earthworms, so sensitive methods are needed to detect them,” said Vergara.

The methods developed by Vergara in the UPV/EHU labs enable a wide range of antimicrobial drugs to be simultaneously determined, as well as various products deriving from their transformation. As the researcher explained, “the drugs can be excreted in their original form or transformed after being metabolised (after undergoing certain changes in the body). What is more, these are very sensitive compounds which, under conditions of temperature, humidity, light, etc., can be very easily degraded and transformed in the environment.”

The methods constitute a significant breakthrough, as “until now there have been no analytical methods to simultaneously study a wide range of antimicrobials in plants and earthworms, and they did not focus on the analysis of transformation products, either. Each family of antibiotics has different physicochemical properties, and it is very important that the same analytical method can be used to analyse all of them. We have also achieved pretty low detection limits, which allow us to detect very low concentrations of these substances in the environment.”

Samples of vegetables taken in different locations across the Basque Autonomous Community

In the case of vegetables, the research group took samples from different locations of the Basque Country, from both organic and non-organic agriculture. “We set out to measure the scale of the antibiotics problem in the Basque Autonomous Community. The analytical studies conducted revealed data on the existence of antimicrobial drugs and their derivatives in vegetables: we found that there is a transfer of both antimicrobials and degradation products between soil and vegetables. In other words, there is a problem of antimicrobial contamination in the Basque Country,” she added.

In the case of earthworms, however, they conducted an experiment under controlled conditions of exposure, in other words “this is a study designed and conducted in the laboratory using earthworms. We wanted to check whether, in the case of contaminated soil, the earthworms that feed on this soil are able to accumulate antimicrobials in their bodies. The study did in fact reveal an accumulation of these antimicrobials in the body, which generate a large variety of previously unreported transformation products.”

Vergara stressed the need to “continue multidisciplinary research along these lines, as this is a problem that is going to affect everyone over the coming decades.” Water treatment plants currently do not have fully effective treatments to remove residual drugs, and this water is often used for irrigation. “As there is such a large, constant input of antimicrobials into the environment, the bacteria are getting used to coexisting with them and generating resistance,” she explained. The researcher warned that “in fact, there are already cases in which there are no effective treatments for people who become infected with multi-resistant bacteria. It is important to drive forward research in order to minimise the problem or to start to look for solutions in the short to medium term.”

These next-generation biofuels are emerging as a more sustainable substitute for fossil fuel-derived gasoline and diesel that, if carefully managed, could remove more greenhouse gases from the atmosphere than they emit over the course of their lifecycle. And unlike conventional or first-generation biofuels, which are produced from crops like corn and sugarcane that could otherwise be used for food, second-generation biofuels are derived from agricultural waste or non-food crops grown on low productivity or recently abandoned land.

Yet as a still-nascent technology, these next-generation fuels must contend with considerable uncertainty about their role in a low-carbon energy future.

Previous studies on biofuels tend toward two extremes, either focusing on the ‘bio’ — incorporating crop growth, productivity, and land use data without considering downstream supply chain concerns in detail — or the ‘fuels’ — mapping out a supply chain and biorefinery design using overly simplistic land and crop data.

The Princeton study unites the two perspectives to provide a more comprehensive forecast of a supply chain for biofuels across an eight-state region in the Midwest, grounded in highly detailed data. Their findings were published May 22 in Nature Energy.

“What we’re doing with this study is bringing together two different approaches to studying biofuels,” said Christos Maravelias, the Anderson Family Professor of Energy and the Environment and professor of chemical and biological engineering. “A lot of high-quality data at fine spatial scales went into our analyses, giving us a much more holistic view of these systems.”

Optimization from crop growth to sequestration site

Supply chains for biofuels are complex. Feedstocks for biofuels must be grown and harvested from a fragmented network of land. Those feedstocks must then be transported to a centrally located refinery. At the refinery, several different technologies could convert the plant matter into liquid biofuel, and any carbon emissions produced through the conversion process can be captured and subsequently sequestered offsite.

Consequently, decisions made at every point along the supply chain could result in systems with widely diverging costs and emissions impacts, from the crop chosen as a feedstock to the distance between field and refinery and the technology used to convert the plant into biofuels.

“Even seemingly isolated or unrelated decisions, like how much incentive you plan to provide for carbon capture or which conversion technology you favor, can have dramatic impacts on the landscape design of a bioeconomy,” said co-author Caleb Geissler, a graduate student in chemical and biological engineering.

Thus, Geissler said, the optimal landscape design depends on the starting goals: what quantity of biofuels should be produced, at what cost, and at what carbon intensity?

While the researchers cautioned that their model was not designed specifically as a decision-making tool, Maravelias said it provides valuable insights into the economics and environmental impacts of a future bioeconomy. And since second-generation biofuels have yet to achieve widespread commercialization, proactive research now can inform efforts to ensure the fuels are meaningfully implemented into the future energy system.

“The model accounts for all the components of the system, so we can use it to answer many different types of questions,” said Maravelias. “We can use it to identify the optimal way to produce a certain quantity of biofuels while minimizing economic costs. We can use it to identify the system that produces the same amount of fuel while minimizing environmental impacts. Or we could have it design a system that strikes some balance between the two.”

Highlighting the impact of policy

Using their model, the research team could also probe the role of policy incentives in shaping the preferred technologies and emissions impact of a biofuels supply chain.

For instance, the team found that the 45Q tax credit for carbon capture, which provides $85 per ton of sequestered carbon, sufficiently incentivized carbon capture across the system. However, tax credit values below $60 per ton of carbon — the 45Q tax credit was only worth $50 prior to the Inflation Reduction Act of 2022 — were insufficient to drive investment in carbon capture and sequestration. In this case, the system generated rather than removed carbon emissions, though it still produced far fewer emissions compared to today’s fossil fuels.

“Even if the value of an incentive changes, we still wanted our results to be informative,” said Geissler. “It’s also a way to inform policymakers about how varying incentives support different technologies and configurations for the system.”

And while current incentive schemes only assign a monetary value for the carbon captured at the refinery itself, the researchers also modeled alternative scenarios that sought to minimize emissions from the entire supply chain, including both direct emissions from transportation and indirect emissions embodied in the electricity used to power the system.

These alternative scenarios highlighted even more tradeoffs. The tax credit would have to be worth at least $79 a ton to begin incentivizing carbon capture at the refinery and worth around $100 per ton for carbon capture to be installed at every refinery. Below those values, it would often be more cost effective to reduce transportation and offset emissions from purchased electricity before investing in carbon capture.

The researchers even charted pathways that mitigated carbon emissions beyond financial incentives, using site-specific soil carbon sequestration potentials and management decisions, such as whether to fertilize, to yield a landscape design with the greatest overall environmental benefits.

“Because these next-generation biofuels are still emerging as a technology, the model we developed allows us to make sure we’re designing these systems properly,” Maravelias said. “It’s important to have as much information as possible now, before we lock ourselves into less-than-ideal technologies and system configurations.”

New research from Yilan Xu (“E-Lan SHE”), a professor of agricultural and consumer economics at Illinois, found that short but severe episodes of flooding from hurricanes in Texas and Florida triggered an increase in flood insurance sign-ups nationwide depending on how socially connected a county was to the flooded counties.

Xu and co-author Sébastien Box-Couillard, a U. of I. graduate student, published the findings in the journal Economic Inquiry.

The researchers also found regional climate disasters such as flooding can have a ripple effect on climate change behaviors and beliefs throughout an entire social network for up to three years afterwards.

“During natural disasters such as hurricanes, tornadoes and flooding, disaster information spreads fast through social media feeds, lighting up with first-hand evidence such as pictures and video about the event,” Xu said. “Ultimately, that information informs people outside of the immediate disaster area and prompts them to change their views about the risks of climate change.”

For example, when there’s bad storms that result in flooding, “people see images of flooding through their social connections on their Facebook feed and think ‘Hey, this could happen to me, too,'” Xu said. “The exposure to that risk signal then prompts them to update their previous perceptions about whether climate change can affect them, which subsequently transforms their views on local flood risks and decisions regarding signing up for flood insurance.”

To measure climate adaptation behavior informed by changes in climate risk perception, the researchers investigated the uptake in flood insurance policies from the National Flood Insurance Program in the aftermath of two major hurricanes: Hurricane Harvey, which made landfall in Houston in August 2017; and Hurricane Irma, which made landfall in Florida in September 2017. Between the two storms, nearly 80,000 homes in the two regions found themselves with at least 18 inches of floodwater.

Using the Facebook Social Connectedness Index as a measure of social network adjacency that mediates social learning behaviors, the researchers were able to attribute an additional 250,000 policy sign-ups in flooded counties and an additional 81,000 policy sign-ups in unflooded counties over three years, according to the paper.

“Those numbers are fairly robust because flood insurance is not cheap,” Xu said. “At the same time, we find no evidence of an overreaction by homeowners to peer flooding, resulting in over-insurance.”

The increase in the number of flood insurance policies nationwide corresponded to the extent of each county’s social network proximity to the flooded areas, Xu said.

“The social network may facilitate social learning about climate risks in that when you see family or friends experiencing a disaster, you start to think outside of your own bubble,” she said. “Our study sheds light on how social networks can be leveraged to promote timely updates on climate risk perceptions and help correct the underestimation of climate risks.”

The implications of the research point to leveraging social networks to design educational programs and communication vehicles to promote disaster preparedness, adaptation and loss mitigation, Xu said.

“Communication strategies can be designed to enhance information dissemination to the less socially connected communities so that they can be better informed about climate risk and be engaged in climate risk management,” she said.

Climate change is similar to COVID-19 in that “we’re all in this together and what happens in one place can affect others far away,” Xu said.

“In economics, we call that externality,” she said. “A lot of times, a disaster can negatively impact nearby places, which we call a negative externality. But when we learn from a disaster, that’s actually a positive externality. Basically, some people unfortunately experience a disaster, but their friends and family who aren’t in that area can learn from it and prepare better before a similar disaster hits their own area.

“I see that as particularly important in the context of climate change because it’s a very politically fraught issue for some people. Even though it can be really difficult for you to convince someone else that climate change is real, if they see their friends and family experiencing its negative consequences, that’s a prime opportunity for the skeptics to update their thinking about climate change.”

The study will be published in The Proceedings of the National Academy of Sciences on May 20, 2024.

While the health and climate benefits of switching from diesel vehicles to electric ones are well established, this is the first study to specifically quantify how electric school buses can improve human and planetary health.

“Research on air pollution and climate change should strive to quantify health benefits,” said senior author Kari Nadeau, John Rock Professor of Climate and Population Studies and chair of the Department of Environmental Health. “Our findings can inform policymakers that greenhouse gas emissions and air pollution are reduced by implementing solutions like electric vehicle use. Our data offer strong evidence that accelerating the ongoing transition to electric school buses will benefit individual, public, and planetary health.”

There are about half a million school buses in use in the U.S. and a substantial portion are older, highly polluting diesel buses. Switching to electric buses is a difficult decision for local, state, and federal officials as they are expensive and the health benefits are not well known.

To quantify how diesel and electric school buses impact the climate, the researchers compared the amounts of carbon dioxide emitted from diesel school bus tailpipes and from electric school buses’ electricity generation and battery production. To assess the buses’ health impacts, the researchers compared how their respective emissions contribute to fine particulate air pollution (PM2.5), which is linked to adult mortality and the onset of childhood asthma.

The study found that replacing an average diesel school bus in the U.S. fleet in 2017 with an electric one resulted in $84,200 in total benefits per individual bus. Each electric school bus emitted 181 fewer metric tons of carbon dioxide than its diesel counterpart, amounting to $40,400 worth of climate benefits. Meanwhile, each electric school bus was associated with $43,800 in health savings, from less air pollution and reduced rates of mortality and childhood asthma.

The study also found that electric school buses’ health benefits vary depending on location and the age of the diesel bus being replaced. Large metropolitan areas — defined as those with a population of more than one million — derive the most significant health benefits from electrifying fleets of school buses, given the larger number of people whose air quality is improved. The researchers calculated that, in a large city, replacing a 2005 diesel school bus with an electric bus would achieve $207,200 in health benefits per bus.

“In a dense urban setting where old diesel buses still comprise most school bus fleets, the savings incurred from electrifying these buses outweigh the costs of replacement,” Nadeau said. “Not to mention how the tangible benefits of electric school buses can improve lives — especially for racial minorities and those living in low-income communities who are disproportionately impacted by the everyday health risks of air pollution.”

Nadeau and her co-authors noted that the study did not tackle one important question: how electric school buses impact children’s exposure to in-cabin air pollution while riding the bus. Additional research into this topic could further inform policy decisions.

Ernani Choma, research associate in the Department of Environmental Health, and Lisa Robinson, senior research scientist and deputy director of the Center for Health Decision Science, were co-authors.

Now, researchers from Kyushu University, Japan, in collaboration with Queensland University of Technology (QUT), Australia, have conducted a worldwide analysis of voluntary carbon offset programs and identified trends into which types of carbon reduction technologies are selected and prioritized. Their findings, published in the journal, Cleaner Environmental Systems, provide important insights for policymakers to improve the effectiveness and credibility of the carbon offset market.

“The carbon offset market is one of the most economically effective means of reducing carbon emissions,” says first author Professor Hidemichi Fujii of Kyushu University’s Faculty of Economics. “For many companies, becoming more environmentally friendly is an important priority, but reducing their own emissions may not be economically feasible. Instead, by purchasing carbon offsets, organizations can reduce their carbon footprint for a much cheaper price.”

Over the last decade, as demand for carbon offset programs has skyrocketed. But until now, there has been no global analysis into which types of programs are established and why.

In this research, Fujii and Professor Shunsuke Managi from Kyushu University and QUT researchers, Dr. Jeremy Webb, Professor Sagadevan Mundree, Professor David Rowlings, Professor Peter Grace, and Professor Clevo Wilson, analyzed more than 7000 carbon offset programs worldwide from 2006-2020, sourcing data from the Voluntary Registry Offsets Database provided by the University of California, Berkeley.

The researchers split the data by region (the Americas; Africa and the Middle East; the Asia-Pacific, and Other regions) and classified each carbon credit project into three categories: renewable energy like wind and solar; forestry and land management including reforestation and deforestation prevention; and other technologies, such as household technologies and waste management.

The researchers then focused on four indicators to track shifts in the voluntary carbon credit market: PRIORITY, which tracks what percentage of the total carbon credits come from each particular project; SCALE, which measures the total credits issued for each project, IMPORTANCE, which is indicated by the number of projects in each category, and ACTIVITY, which is based on the total number of carbon offset programs.

In forestry and land management, issued carbon credits initially increased due to United Nations-led REDD and REDD+ programs, aimed at reducing deforestation in developing countries. However, after 2016, the priority shifted towards projects such as improving the carbon dioxide absorption in forests, mainly in developed countries, like the United States.

“On the one hand, these nature-positive solutions are very important, as they simultaneously address the problem of climate change and biodiversity loss,” says Webb and Wilson. “On the other hand, these projects are much harder to monitor and estimate the resulting carbon capture, leaving the system open for abuse. Additionally, leakage can occur, which is when stronger forestry protections in one country can drive deforestation somewhere else.”

Webb and Wilson therefore emphasized the importance of establishing a robust regulatory regime and monitoring framework to ensure the effectiveness and credibility of forestry and REDD+ carbon offset programs in the future.

For renewable energy, the researchers found that in recent years, an increase in carbon credits issued was predominantly driven by wind and solar projects, particularly within the Asian-Pacific region.

“Most voluntary carbon credit projects are in India and China, where electricity shortages and coal-related air pollution have incentivized an increase in renewable energy projects like solar and wind,” says Fujii. “Furthermore, the falling costs of these technologies has also boosted their priority.”

For the category of other technologies, the researchers found a significant increase in priority for household and community carbon offset projects, mainly due to improved cookstove programs in South Asia and Sub-Saharan Africa. These projects reduce CO2 emissions and improve health and convenience, explaining their growing priority.

In future research, the team plans to introduce new factors into the analysis, such as legal factors and energy market factors.

“Changes in energy market prices and the new laws will likely impact the price and amount of carbon credits issued in the future, so it is very important to apply econometric models to determine causality in order to verify the effects of policy implementation” concludes Fujii.

In one of the studies, about 10% of children and 35% of adults who got an antibiotic prescription during an office visit had no specific reason for the antibiotic in their record.

The rate of this type of prescribing is especially high in adults treated seen in emergency departments and in adults seen in clinics who have Medicaid coverage or no insurance, the studies show. But the issue also occurs in children.

Without information about what drove these inappropriate prescriptions, it will be even harder for clinics, hospitals and health insurers to take steps to ensure that antibiotics are prescribed only when they’re really needed, the researchers say.

Overuse and misuse of antibiotics raise the risk that bacteria will evolve to resist the drugs and make them less useful for everyone. Inappropriately prescribed antibiotics may also end up doing more harm than good to patients.

“When clinicians don’t record why they are prescribing antibiotics, it makes it difficult to estimate how many of those prescriptions are truly inappropriate, and to focus on reducing inappropriate prescribing,” said Joseph Ladines-Lim, M.D., Ph.D., first author of both of the new studies and a combined internal medicine/pediatrics resident at Michigan Medicine, U-M’s academic medical center.

“Our studies help contextualize the estimates of inappropriate prescribing that have been published previously,” he added. “Those estimates don’t distinguish between antibiotic prescriptions that are considered inappropriate due to inadequate coding and antibiotic prescriptions truly prescribed for a condition that they can’t treat.”

Ladines-Lim worked with U-M pediatrician and health care researcher Kao-Ping Chua, M.D., Ph.D., on the new studies. The one on outpatient prescribing by insurance status is in the Journal of General Internal Medicine and the one on trends in emergency department prescribing is in Antimicrobial Stewardship and Healthcare Epidemiology.

Building on previous research

Chua and colleagues recently published findings about trends in inappropriate antibiotic prescribing in outpatients under age 65, suggesting about 25% were inappropriate. But that number includes antibiotic prescriptions written for infectious conditions that antibiotics don’t help, such as colds, and antibiotic prescriptions that aren’t associated with any diagnoses that could be a plausible antibiotic indication.

The new studies add more nuance to that finding, by looking more closely at these two different types of inappropriate prescriptions.

Most antibiotic stewardship efforts to date have focused on reducing the use of the first type of inappropriate prescription — those written for infectious but antibiotic-inappropriate conditions like colds. The new studies show such patients still account for 9% to 22% of all antibiotic prescriptions, depending on the setting and age group.

But since doctors and other prescribers aren’t required to run a test for a bacterial infection or list a specific diagnosis in order to prescribe antibiotics, symptoms provide potential clues to why they might have written a prescription anyway.

So some of those 9% to 22% of all people receiving antibiotics may have also had a secondary bacterial infection that the clinician suspected based on symptoms.

However, it’s impossible to know.

As for those with no infection-related diagnoses or symptoms in their records who got antibiotics, the researchers suggest that clinicians may not have bothered to add these diagnoses or symptoms to the patient record inadvertently — or even deliberately, to try to avoid the scrutiny of antibiotic watchdogs.

But the researchers also speculate that the lower rate of diagnosis documentation in patients in the healthcare safety net may also have to do with the way healthcare organizations are reimbursed.

Often, clinics and hospitals receive a fixed amount from Medicaid to care for all their patients with that type of coverage. So they aren’t incentivized to create records that are as detailed as for privately insured patients, whose care traditionally is reimbursed under a fee-for-service model.

“This could actually be a matter of health equity if people with low incomes or no insurance are being treated differently when it comes to antibiotics,” says Ladines-Lim, who has also studied antibiotic use related to immigrant and asylum-seeker health and will soon begin a fellowship in infectious diseases.

He said that private and public insurers, and health systems, may need to incentivize accurate diagnosis coding for antibiotic prescriptions — or at least make it easier for providers to document why they’re giving them.

That might even include steps such as requiring providers to record the reason for antibiotic prescribing before prescriptions can be sent to pharmacies through electronic health record systems.

After all, Ladines-Lim said, physicians often have to list a diagnosis that justifies tests they order, such as CT scans or x-rays. With antibiotic resistance posing an international threat to patients who have antibiotic-susceptible conditions, similar steps to justify prescriptions of antibiotics might be advisable.

In addition to Ladines-Lim and Chua, the other authors of the two articles are Michael A. Fischer, M.D., M.S. of Boston Medical Center and Boston University, and Jeffrey A. Linder, M.D., M.P.H. of Northwestern University Feinberg School of Medicine.

The research was funded by a Resident Research Grant from the American Academy of Pediatrics, a Physician Investigator Award from Blue Cross Blue Shield Foundation of Michigan, and a Research Grant from the National Med-Peds Residents’ Association.

The team hopes that by identifying emission hot spots in the supply chain that go into building a house, policy makers can implement strategies to reduce its climate impact. Their analysis was published in the Journal of Environmental Management.

As humanity maneuvers itself through the climate crisis, researchers and industry professionals alike have been working to identify sectors with high CO₂ emissions so they can implement policies that potentially reduce greenhouse gas production. But in today’s highly interconnected economy, figuring out a sector or object’s greenhouse gas output is astoundingly complex.

“For example, it’s easy to calculate how much CO₂ a single automobile will potentially produce. It’s another thing entirely to try and find the totality of emissions a car produces from assembly line to scrap yard. You need to consider the emission that come from the supply chain and manufacturing the raw materials,” explains Professor Shigemi Kagawa from Kyushu University’s Faculty of Economics, whose team has been studying supply chain emissions.

To this end, Kagawa and his team began looking into the combined carbon emissions that come from building a standard wooden house in Japan — which account for approximately 90% of the country’s total housing stock — and which industrial sectors contribute to it the most.

“If you combine the emissions generated by construction activity and the supply chain manufacturing of its essential products it can account for approximately 23% of all global emissions,” explains doctoral candidate Seiya Imada and first author of the study. “94% of that comes from the supply chain alone. Therefore, emission reduction efforts targeting the supply chain is the best way to mitigate any emissions from the construction sector.”

According to the team’s findings, the estimated carbon footprint of building a single wooden house in Japan is 38 tons of CO₂. Making up the largest share of that — accounting for 32% of total emissions — was the electric power sector. Other sectors included pig iron production at 12%, with cement, road freight transport, and private power generation each covering 7% of total emissions.

“We also looked into some of the hotspots in the supply chain network. Our analysis found that the steel manufacturing process accounted for the largest share of the carbon footprint, at approximately 15% of total emissions,” continues Imada. “The second highest contributing group was the division involved in material transport and the building materials for a house’s exterior, like bricks. That group accounted for approximately 7.4% of the total carbon footprint.”

The team hopes these new findings can help both industry groups and consumers re-evaluate the carbon footprint of this sector of the construction industry. Some countries have begun to emphasize the importance of constructing ‘low-carbon’ buildings. And while Japan does encourage methods to reduce a home’s total energy use, it still does not have a policy that specifically targets the reduction of CO₂ during its building phase.

“Policy makers should promote efforts of renovating and remodeling already existing houses. There should also be a focus on reusing the foundation, which are made with materials from high emission sectors,” Concludes Imada. “The supply chain is very complicated, but if we want to avoid the worst results of the climate crisis, we must be able to understand it and implement policies that reduce emissions effectively.”