Time Is Running Out

Gregory Wellenius, ScD, leads research focused on understanding the health impacts of the physical and built environment, especially in the context of a rapidly changing climate. His group’s research is focused on informing policy to reduce the adverse health effects of air pollution, noise pollution, other features of our physical environment, and the health threats posed by our changing climate.

Environmental Health in a Changing Climate

Our climate is rapidly changing, with profound and sustained effects on human health. A key focus in this area is evaluating how climatic factors, such as temperature extremes and severe weather, affect human health today and under scenarios of projected change through the end of the century. For example, the group’s recent work suggests that more than 6000 deaths per year across the US are attributable to hot weather, and that the number of heat-related deaths in the 10 largest US metropolitan areas are projected to increase substantially through the end of the century.  A recent study analyzing the health effects of summer weather across 14 New England communities found that deaths and emergency department visits rise significantly, well before the heat index hits the triple digits. This finding resulted in a policy change at the National Weather Service that lowered the Heat Advisory criteria for the New England region from 100 – 104 degrees Fahrenheit to 95 – 99 degrees Fahrenheit. This group is currently finding ways to improve the effectiveness of heat warnings and local heat action plans at reducing heat-related deaths and illness.

The Effects of Air Pollution on Cardiovascular Health

Air pollution is responsible for a staggering 8 million deaths every year. That’s more than 10% of all deaths, worldwide. Of these, an estimated 4.2 million deaths globally are due to ambient (outdoor) air pollution, while 3.8 million deaths are due to household air pollution caused by burning solid fuels for heating and cooking. Dr. Wellenius is a leading expert on the adverse effects of air pollution on cardiovascular health. His research has found that ambient air pollution is associated with higher blood pressure, higher risk of developing hypertension, and higher risk of hospitalization for heart failure and stroke among older adults, as well as higher risk of hypertensive disorders and diabetes in pregnant women. The group’s research also suggests that household air pollution in rural villages in Kenya and peri-urban villages in India have important adverse impacts on blood pressure and cardiovascular risk. Dr. Wellenius has testified to the health effects of air pollution before the US Senate and the US House of Representatives.

Understanding How Natural and Built Environments Affect our Health

Beyond the adverse health effects of urban air pollution, how does the natural and built environment around our homes impact our health? Dr. Wellenius and his colleagues are working to understand how the neighborhood environment affects health. His group has previously shown that living closer to major roadways is linked to a higher risk of hypertension and lower cognitive function among older adults, and to lower birth weight among newborns. Ongoing research suggests that living in neighborhoods with more vegetation, more access to outdoor recreational spaces, closer to bodies of water, or further from major roadways, may be associated with lower risk of adverse birth outcomes among pregnant women. The team is currently investigating the health impacts of the neighborhood environment in Rhode Island, New York City, and other cities around the country.

Joseph Braun, Ph.D., associate professor of epidemiology, investigates the patterns, determinants, health effects, and biological pathways of environmental chemical exposures. Dr. Braun studies the impact of early life environmental chemical exposures on human health. His group asks whether exposure to environmental chemicals before conception, during pregnancy, or in infancy and childhood affect the risk of disease across the lifespan. Dr. Braun and his team are also trying to identify the biological pathways that environmental chemicals use to illicit their deleterious effects. Finally, his group observes how exposure to toxic chemicals changes over the lifespan, and tries to identify ways for people to reduce their exposure.

Chemical Risks for Childhood Obesity and Cardiometabolic Risk

Numerous studies by Dr. Braun’s group have quantified the role of environmental chemicals in the etiology of birth weight, body composition, early childhood growth, breastfeeding duration, and childhood obesity—all known risk factors for cardiometabolic dysfunction later in life. Using sophisticated statistical methods, Dr. Braun’s team is working to identify periods during development when children are particularly susceptible to harm from chemical exposures. For example, in a landmark study, the team found evidence that the impact of phthalates on the risk of childhood obesity depended on when during childhood participants were exposed. Using molecular epidemiology approaches, Dr. Braun’s team also seeks to characterize the biological pathways by which chemical exposures threaten child health, including chemical-related impacts on adrenal function, changes in DNA methylation, and changes in the metabolome (all the metabolites present in your body).

If, When, and How Environmental Chemicals Impact Child Brain Development

Dr. Braun’s group is also identifying chemical risk factors for several childhood neurodevelopmental disorders, including attention-deficit/hyperactivity disorder, autism spectrum disorder, and learning disabilities. They examine a wide range of potential neurotoxicants that are very common in the environment, including lead, triclosan, phthalates, and bisphenol A. A study of 52 different endocrine-disrupting chemicals suggests that exposure to some of these chemicals during pregnancy may be associated with autistic behaviors. Recently, Dr. Braun and his group have been examining the neurotoxicity of triclosan. This antimicrobial compound, found in some antibacterial soaps and body washes, toothpastes, and some cosmetics, has been scrutinized by regulatory agencies because of concerns about its toxicity to people. Dr. Braun’s group found that maternal exposure to triclosan near the time of delivery may be associated with reductions in the cognitive abilities of children. Finally, Dr. Braun’s team has reported that several chemical exposures are associated with alterations in thyroid hormones, suggesting this might be one biological pathway through which these chemicals exert their toxic effects.

Sources and Determinants of Environmental Chemical Exposures and Variability

Dr. Braun’s research group is enumerating the sources and determinants of chemical exposures among couples trying to conceive, pregnant women, and children. Their goal is to provide the evidence necessary for individuals to be able to modify their behavior to limit their exposures to harmful chemicals, and for policy makers to identify exposure sources that are amenable to regulatory interventions. His team has found that the use of many consumer products is associated with higher exposure to several different environmental chemicals in women trying to conceive and children. Recent work by one of Dr. Braun’s’s graduate students found that pregnant women are exposed to a mixture of environmental chemicals and is now trying to determine if this mixture affects infant and child health.

Research on the theme of molecular epidemiology and epigenetics is led by Karl Kelsey, MD, professor of epidemiology and a pioneer in the development of this field. Dr. Kelsey’s research is centered on the development and application of biomarkers useful for population-based studies that have the aim of understanding the effects of environmental exposure to a variety of carcinogens and other toxicants. His group was among the first to use genomic approaches to ask questions about how the biological effects of environmental exposures are modified by normal genetic variation. His laboratory was also among the first to extend the genetic investigations into studies of epigenetics and modifications of the expression of important genetic changes. His current research interests are focused on deepening our understanding how environmental exposures lead to alterations in our immune systems.  As a result of their recent work in epigenetics, Dr. Kelsey’s lab has collaboratively developed innovative approaches to characterizing the immune profile in blood that can be applied to hundreds or even thousands of people, potentially closing a longstanding gap that has made understanding the drivers of immune changes difficult to detect. This work has set the stage for discovering precisely how and when environmental exposures alter our immune systems, potentially contributing to the cause of a significant number of chronic diseases, including cancers.

Biomarkers in Case-Control and Prospective Studies of Gene-Environment Interaction

Dr. Kelsey’s group applies genetic techniques to directly assess genetic susceptibility to environmental and occupational exposures. Collaborating broadly with both national and international groups, Dr. Kelsey’s team tests specific genes for their ability to modify the effect of numerous known carcinogens and toxicants. This work continues, including studies utilizing one of the largest population-based case-control studies of head and neck cancer conducted over a more than 15-year period.

Epigenetics in Molecular Epidemiology

Epigenetic changes to our DNA can be described as occurring ‘on top of’ the regular coding sequences.  Epigenetic alterations, including DNA methylation, are part of the normal regulation of our genes and the complex cellular activities in both health and disease, including cancer. DNA methylation was initially described by cancer biologists as acting to silence genes that are well known to be drivers of the cancer process. As it became clear that the molecular modifications in cancers included these epigenetic changes, Dr. Kelsey’s lab expanded, initially to include the study of epigenetic silencing of these genes, called “tumor suppressor genes.” These studies resulted in the discovery that exposure to carcinogens was associated with very specific changes in DNA methylation profiles. This work increased the general interest in the potential for environmental exposures to alter the epigenome. The Kelsey lab is at the cutting edge of integrating epigenomics in molecular epidemiology.

DNA Methylation as a Biomarker of Immunity

Dr. Kelsey and his team have shown that each type of cell or tissue in the body has a unique DNA methylation profile or signature. This observation has led Dr. Kelsey’s team to develop innovative approaches to assess the methylation profile of DNA from different types of white blood cells, which provide unique insights into the state of our immune systems. Importantly, the immune system is increasingly recognized as playing a key role in all aspects of health and disease and can significantly affect whether cancer becomes established, spreads, or recedes, whether a patient responds to therapy, or whether a transplant is accepted or rejected. This new technique affords us the opportunity to address a longstanding gap in our knowledge—How does environmental exposure specifically alter the immune profile in otherwise normal people? The current work in the group examines numerous environmental exposures and medical treatments, defining the nature of immune profile changes associated with an altered environment.

National Climate Assessment

This Congressionally mandated report, prepared every four years, summarizes the best available science on the changing climate and its impacts on Americans. It’s like a check-up at the doctor’s office, only for the planet. And instead of one doctor, more than 300 experts—including Professor Gregory Wellenius—produce a detailed account of the impacts of continued climate change on the health and wellbeing of people across the country and in each of 10 US regions. Their most recent assessment? The climate in the US has already changed substantially, these changes are primarily due to human activity, and continued climate change will impact nearly every aspect of the way we live, work, and play. nca2014.globalchange.gov

Health Effects Institute

Chartered in 1980 as an independent research organization, the Health Effects Institute provides high-quality, impartial, relevant science on the health effects of air pollution. With funding from government and industry, the Boston-based Institute has informed air quality decisions for a range of pollutants, including carbon monoxide, air toxics, nitrogen oxides, diesel exhaust, ozone, and particulate matter. Professor David Savitz, Chair of the Institute’s Research Committee, contributes to this important effort through the Committee’s work developing requests for applications, selecting studies for funding, and providing oversight and feedback of ongoing studies. www.healtheffects.org

Environmental Health in China

Tongzhang Zheng, Sc.D, professor of epidemiology, investigates environmental exposures, occupational exposures, gene-environment interactions, metabolic disease risk, and women and children’s health in China. China’s extraordinarily rapid economic development has led to severe environmental deterioration. The range and diversity of environmental exposures in China provides a robust setting for studying environmental health effects. Professor Zheng collaborates with the scientists from the Chinese National Cancer Center, China’s National Institute of Environmental Health Sciences, and several universities in China, building large cohort studies that track population-level health impacts over many years. The Jingchuan Metal Exposure Cohort Study, for example, has found increased risk of type 2 diabetes for smelting/refining workers with high metal exposure. In Wuhan, China, 4,000 mother-infant pairs have been enrolled in a prenatal cohort study investigating the impact of environmental exposures on maternal and child health.

Current Topics in Environmental Health
Professor Karl Kelsey introduces students to the field of environmental health, and demonstrates how environmental health is integrated into various aspects of our lives, both directly and indirectly. Topics include: toxic metals, vector-borne disease, food safety, water quality, radiation, pesticides, air quality, hazardous waste, risk assessment, and the role of the community in environmental health.

Climate Change and Human Health
Professor Gregory Wellenius provides students with a broad overview of the diverse impacts of projected climate change on human health, including effects of changing temperatures, extreme weather events, infectious and non-infectious waterborne threats, vector-borne disease, air pollution, the physical and built environment, and policies to promote mitigation and adaptation.

Topics in Environmental and Occupational Epidemiology
Professor Joseph Braun introduces students to the epidemiological study of historical and contemporary environmental/occupational agents, focusing on study design, biases, and methodological tools used to evaluate and extend the evidence linking exposures to human disease.

Place Matters: Exploring Community-Level Contexts on Health Behaviors, Outcomes and Disparities
Place matters for health behaviors and health outcomes. But what is place, and why does it matter? As with many health-related outcomes, the prevalence of ill health is unequally distributed across populations with certain features playing significant roles on health. This course, taught by Professor Akilah Dulin explores the features of community environments and their associations with health behaviors and health outcomes.