Chemicals in Household Dust May Promote Fat-Cell Development Interview with:

Christopher D. Kassotis, Ph.D.NRSA Postdoctoral Research ScholarStapleton LabDuke UniversityNicholas School of the EnvironmentDurham, NC 27708 

Dr. Kassotis

Christopher D. Kassotis, Ph.D.
NRSA Postdoctoral Research Scholar
Stapleton Lab
Duke University
Nicholas School of the Environment
Durham, NC 27708 What is the background for this study? What are the main findings?

  • So this was something that Heather Stapleton had been curious about for years, as she’s been one of several researchers characterizing the hundreds of chemicals that have been measured in indoor house dust. Before I came to Duke, one of her PhD students had measured the ability of many common indoor contaminants to activate the peroxisome proliferator activated receptor gamma (PPARg). The majority of these chemicals did, often quite well, which led to them testing indoor house dust extracts, also finding that the majority of dust extracts were also able to do so at very low levels. As PPARg is often considered the master regulator of fat cell development, the next obvious question was whether these common contaminants (and house dust) could promote fat cell development in cell models. My first work at Duke evaluated a suite of common indoor contaminants, finding that many of these chemicals could promote fat cell development, and that low levels of house dust extracts did as well.
  • We next explored this more systematically in a group of adults involved in a thyroid cancer cohort (this was just recently published in Science of the Total Environment:
  • In this study we evaluated the extent to which house dust extracts could promote fat cell development in a common cell model, and associated this with the metabolic health of adults living in these homes. We found that the greater extent of fat cell development was associated with significantly greater thyroid stimulating hormone concentrations (control residents only, with no evidence of thyroid dysfunction) and lower free triiodothyronine (T3) and thyroxine (T4). We further found a significant and positive association between extent of fat cell development and the body mass index (BMI) of all adults in the study. So this suggested that the indoor environment might play a role in the BMI and metabolic health of residents, and we next wondered if this would be more pronounced in children, who may be exposed to these contaminants during a critical window of development.
  • The next step, for our current work, was to substantiate these effects in a larger group of households, each with children.
  • Our major conclusions thus far have been that ~80% of house dust extracts promote significant fat cell development in a cell model – either via development from precursor cells into mature fat cells, measured via accumulation of lipids into the cells, or via the proliferation of those precursor fat cells. We also reported positive correlations of fat cell development with the concentrations of 70 different contaminants in the dust from these homes, suggesting that mixtures of contaminants are likely all acting weakly to produce these effects in combination. We’ve also begun to assess the other chemicals present in dust – chemistry can be either targeted (measuring concentrations of specific known chemicals in a sample), or non-targeted, where you try and determine the identity of the other chemicals in a sample. This has greater utility for identifying many more chemicals, though you will often not get chemical concentrations from this, nor absolute confirmed identification – just varying degrees of certainty based on evidence.

    Thus far we report approximately 35,000 chemicals in house dust samples across this study, and differential analyses have begun to pick out the few (less than 10 in each case) chemicals most differentially expressed between samples that exhibit high degrees of fat cell development in the lab vs inactive samples, for example, or which are differentially present in the homes of children categorized as obese or overweight. We are now working to confirm identity of these select contaminants that are more likely to be causative factors in the results we have observed.

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South Pacific Island Nation First Country to Ban Environmentally Harmful Sunscreens Interview with:
"Protect Coral Reefs" by NOAA's National Ocean Service is licensed under CC BY 2.0Ariel Kushmaro and Esti Kramarsky-Winter
Department of Biotechnology Engineering, Ben Gurion University
Beer Sheva, Israel

The Republic of Palau, a South Pacific island nation, became the world’s first country to ban sunscreen products containing environmentally harmful ingredients What is the background for this announcement? What are the main findings? 

Response: Coral reefs are important ecosystems that are under threat due to global human driven climate change. In addition to global changes, local hazards such as point pollution by eutrophication, dredging and chemical pollution are exacerbating and promoting reef destruction at local levels. This destruction affects not only island nations that depend on these reefs for protection and livelihood, they affect humanity as a whole as they are an important source for food and novel drugs and new materials.

Our recent studies have shown that chemicals found in most commercial sunscreens and creams used to protect humans from deleterious effects of UV A and UVB wash off into the environment are persistent, have endocrine disruptive effects, and thus deleteriously affect marine organisms including corals.  Continue reading

More Acorns = More Mice = More Lyme Disease

The white-footed mouse has been found to be a competent reservoir for the Lyme disease-causing spirochete, Borrelia burgdorferi – Wikipedia image Interview
Richard S. Ostfeld, PhD

Distinguished Senior Scientist
Cary Institute of Ecosystem Studies
Millbrook, NY 12545, USA What is the background for this study? What are the main findings?

Response: Lyme disease and other tick-borne infections occur in large portions of the eastern and Midwestern United States and adjacent Canada, and the geographic range is expanding rapidly, engulfing new communities every year.  Despite the observed increases in incidence rates and geographic range at the national level, considerable variation occurs across space and time, with persistent hot spots, colder spots, bad years, and not-as-bad years.  We undertook this long-term study (19 years) to ask what causes some places and years to be particularly risky and others not as risky, in terms of human exposure to tick-borne disease.  Because diagnosis and treatment of Lyme disease are problematic and highly controversial, and because no vaccines or effective tick-control methods are currently available, we hoped that understanding the causes of high risk would facilitate prevention of human exposure.

We found that, in the oak-dominated forests that pervade the Lyme-disease-endemic zone, acorn production in the autumn is a strong leading indicator of Lyme disease risk two summers later.  Acorn production is associated with marked population increases of white-footed mice and eastern chipmunks, which use abundant acorns as a key over-winter food source, leading to population growth the following year.  Dense summer populations of mice and chipmunks provide the local population of blacklegged ticks with abundant sources of blood-meal hosts.  These small rodents are more permissive of successful tick feeding (other hosts kill many ticks by grooming them as they attempt to feed), and they are also the primary natural reservoirs of infection with the microbial agents causing Lyme disease, anaplasmosis, and babesiosis.  Larval ticks emerging when rodents are highly abundant are highly likely to survive and acquire infection, molting the next year into infected nymph-stage ticks.  Bites from nymph-stage ticks are responsible for the great majority of tick-borne disease cases.  The one-year lag from acorns to rodent populations plus the one year lag from larval ticks biting rodents to nymphal ticks biting people together are responsible for the total two-year lag.

By using motion-sensitive cameras set in over 100 sites over two years, we were also able to ask whether the local community of mammal predators can affect human risk of exposure.  We found that sites with a diverse assemblage of predators, especially foxes, bobcats, and opossums, were associated with reduced tick infection prevalence with the agents of Lyme disease, anaplasmosis, and babesiosis.  When these predators were absent, which sometimes occurred when coyotes displaced them, infection prevalence was significantly higher.  Infection prevalence was also lower in sites within extensive, unbroken forest, and higher in sites with small forest remnants.  Taken together, we determined that an understanding of the food webs within which ticks and pathogens dwell can strongly facilitate the ability to predict when and where risk will be high.  Acorns exert what ecologists call a “bottom-up” effect, whereas the predators enforce “top-down” control.  We found that the ticks were remarkably resilient to most weather-related factors.  However, when winter-spring weather was particularly warm and dry, tick abundance the following summer was reduced.  Cold winters did not kill off the ticks. What should readers take away from your report?

Response: The ecology of tick-borne disease is incredibly complex, but still we can find big signals amongst the noise and predict risk with a good degree of confidence.  Predicting times and places of enhanced risk is particularly important given the frustrations within the public health community and the public at large over the slow pace of progress in improving diagnostic capabilities and treatments.  We are still relying fundamentally on individual efforts to prevent exposure using various self-protections, such as repellents, tick-checks, protective clothing and the like.  Targeting these efforts to times and places where risk is particularly high should help protect public health. What recommendations do you have for future research as a result of this work?

Response: Long-term monitoring of tick populations is crucial for evaluating the importance of ecological variables, like wildlife abundance and weather, in determining risk of human exposure.  In addition, the longer we monitor these variables the more likely we are to see extreme events, which might play outsized roles.  Intensive monitoring like this is also crucial for detecting invasions by other species of tick that are important to public health. For instance, we expect lone star ticks to invade our area from the south, with unpredictable consequences for blacklegged ticks and human health.  We are also concerned about potential invasions by non-native ticks, like the long-horned tick that was recently detected in several eastern and Midwestern states to our south. 

No disclosures 


Richard S. Ostfeld, Taal Levi, Felicia Keesing, Kelly Oggenfuss, Charles D. Canham. Tick-borne disease risk in a forest food web. Ecology, 2018; 99 (7): 1562 DOI: 1002/ecy.2386


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Brightly Colored or Black Older Plastic Toys Can Contain Cadmium, Lead or Bromine Interview with:
“Toys” by Holger Zscheyge is licensed under CC BY 2.0Dr Andrew Turner

Reader in Environmental Science (Biogeochemistry and Toxicology)
School of Geography, Earth and Environmental Sciences
University of Plymouth, UK What is the background for this study? What are the main findings? 

Response: The study arose through a larger investigation into hazardous substances in consumer plastics, both old and new.

The main finding of the present research was the widespread occurrence of restricted elements in old plastic toys, and in particular cadmium, lead and bromine (the latter an indicator of the presence of flame retardants); in many cases, these elements could migrate from the plastic under conditions simulating the human digestive system.

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Genetic Expression of Intelligence Influenced By Environment, Especially in Childhood

“Reading is fun!” by Isaac Wedin is licensed under CC BY Interview with:
Bruno Sauce, PhD and
Louis D. Matzel, PhD
Department of Psychology, Program in Behavioral and Systems Neuroscience
Rutgers University
New Jersey, USA What is the background for this study?

Response: Scientists have known for decades that intelligence has a high heritability, which means that much of the individual differences in IQ we see in people are due to genetic differences. Heritability is a value that ranges from 0.0 (meaning no genetic component) to 1.0 (meaning that the trait is completely heritable). For example, the heritability of breast cancer is estimated at 0.27; the heritability of body mass index is 0.59; and the heritability of major depression is 0.40. In comparison, the heritability of IQ is estimated to be as high as 0.8 – quite a high value!

More recently, however, there have been studies showing that intelligence has a high malleability: the studies cover cognitive gains consequent to adoption/immigration, changes in IQ’s heritability across life span and socioeconomic status, gains in IQ over time from societal and scientific progress, the slowdown of age-related cognitive decline, the gains in intelligence from early education, differences in average IQ between countries due to wealth and development, and gains in intelligence that seem to happen from working memory training.

Intelligence being both highly heritable and highly malleable is seemingly paradoxical, and this paradox has been the source of continuous controversy among scientists.

Why does it matter? Because IQ predicts many important outcomes in life, such as academic grades, income, social mobility, happiness, marital stability and satisfaction, general health, longevity, reduced risk of accidents, and reduced risk of drug addiction (among many other outcomes). A clear understanding of the genetic and environmental causes of variation in intelligence is critical for future research, and its potential implications (and applications) for society are immense.

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Patronizing Hair and Nail Salons Linked To Increased Risk of Skin and Fungal Infections Interview with:
Lindsey Milich Rutgers School of Public Health studiesLindsey Milich

Rutgers School of Public Health studies What is the background for this study? What are the main findings?

Response: Much of the spotlight has been focused on hair and nail technicians, with the focus now shifting towards the health and safety of hair and nail salon clients. We wanted to assess perceived safety and health risks and prevalence of respiratory and dermal symptoms among hair and nail salon clients in New Jersey.

Main findings include dermal/fungal symptoms being more prevalent among clients who visited salons three or more times within the past year, compared with those with fewer reported visits. Respiratory symptom prevalence was higher among clients with fewer salon visits, indicating a “healthy client effect”; clients with these symptoms may be less likely to return.

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Anesthesia, Sterility Measures Contribute To Large Carbon Footprint of Health Care Systems Interview with:
 <a href="">“surgery”</a> by <i> <a href="">Army Medicine</a> </i> is licensed under <a href=""> CC BY 2.0</a>Andrea MacNeill MD MSc FRCSC

Surgical Oncologist & General Surgeon
University of British Columbia
Vancouver General Hospital
BC Cancer Agency What is the background for this study?

Response: Climate change is one of the most pressing public health issues of the present era, responsible for 140,000 deaths annually.  Somewhat paradoxically, the health sector itself has a considerable carbon footprint, as well as other detrimental environmental impacts.  Within the health sector, operating rooms are known to be one of the most resource-intensive areas and have thus been identified as a strategic target for emissions reductions.

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Most Homes Harbor Multiple Allergens Interview with:

Dr. Salo

Dr. Salo

Dr. Pӓivi Salo, PhD Epidemiologist
National Institute of Environmental Health Sciences
NIH What is the background for this study?

Response: Indoor allergens are important risk factors for asthma and respiratory allergies. Only a few studies have investigated residential allergen exposures on a national scale; the National Health and Nutrition Examination Survey (NHANES) 2005-2006 is the largest and most comprehensive study to date. What are the main findings?

Response: Our findings show that exposure to multiple allergens is common in U.S. homes; over 90% of homes had three or more detectable allergens, and 73% of homes had at least one allergen at elevated levels. The presence of pets and pests contributed strongly to elevated allergen levels. Housing characteristics also mattered – elevated exposure to multiple allergens was more likely in mobile homes, older homes, rental homes, and homes in rural areas. For individual allergens, exposure levels varied greatly with age, sex, race, ethnicity, and socioeconomic status. Differences were also found between geographic locations and climatic conditions. What should clinicians and patients take away from your report?

Response: Understanding factors that affect allergen levels in homes is important because elevated allergen levels can trigger and exacerbate symptoms in people who suffer from asthma and allergies. We hope that our findings provide beneficial information to a wide audience from patients to clinicians, identifying factors that influence levels of exposure to individual and multiple allergens What recommendations do you have for future research as a result of this study?

Response: The relationships between allergen exposures, allergic sensitization, and disease are complex. Further research is needed to determine how allergen exposures interact with other environmental and genetic factors that contribute to asthma and allergies. Is there anything else you would like to add?

Response: We also compared allergen exposures and previously reported allergic sensitization patterns from this national survey to provide a more complete picture. The allergy focused component in NHANES 2005-2006, which we developed in collaboration with the National Institute of Allergy and Infectious Diseases (NIAID) and the Centers for Disease Control and Prevention (CDC), allowed national comparisons for the first time. The observed differences and overlaps reflect the complex nature of the relationships between allergen exposures, allergic sensitization, and disease. Thank you for your contribution to the community.


Salo P, Wilkerson J, Rose KM, Cohn RD, Calatroni A, Mitchell HE, Sever ML, Gergen PJ, Thorne PS, Zeldin DC. 2017. Bedroom allergen exposures in US households. J Allergy Clin Immunol; doi: 10.1016/j.jaci.2017.08.033(link is external) [Online 30 November 2017].

Note: Content is Not intended as medical advice. Please consult your health care provider regarding your specific medical condition and questions.







Your Dusty House May Be Making You Fat Interview with:

Heather M. Stapleton PhD Dan and Bunny Gabel Associate Professor of Environmental Ethics and Sustainable Environmental Management EEH Program Chair Nicholas School of the Environment Duke University Durham, North Carolina 27708

Dr. Stapleton

Heather M. Stapleton PhD
Dan and Bunny Gabel Associate Professor of Environmental Ethics and Sustainable Environmental Management
EEH Program Chair
Nicholas School of the Environment
Duke University
Durham, North Carolina 27708 What is the background for this study? What are the main findings?

Response: Building materials and products common to most homes (e.g. furniture, TVs, carpets, etc) are often treated with synthetic chemicals, which migrate out of the products over time and accumulate in house dust, where residents can be exposed to these chemicals on a daily basis.

This study assessed approximately forty chemicals commonly detected and measured in house dust samples for their ability to stimulate the development of fat cells, using a mouse precursor fat cell model. Approximately two thirds of these chemicals were able to promote lipid accumulation by these cells and/or stimulate the proliferation of the precursor fat cells. We then assessed eleven extracts of indoor house dust samples (containing mixtures of these chemicals) and exposed our cells to these extracts, finding that even low levels of these extracts were sufficient to promote the accumulation of lipids and/or the proliferation of the fat precursor cells.

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Land-Based Salmon Farms Degrade Natural Waters With Dissolved Organic Materials Interview with:

Dr. Norbert Kamjunke Helmholtz-Centre for Environmental Research UFZ Department of River Ecology Magdeburg, Germany

Dr. Kamjunke

Dr. Norbert Kamjunke
Helmholtz-Centre for Environmental Research UFZ
Department of River Ecology
Magdeburg, Germany What is the background for this study?

Response: Aquacultures are of great importance worldwide but pollute pristine headwater streams, lakes, and estuaries.

Chilean salmon production is economically important, contributing ~25% of the worldwide salmon yield
(Chile ranks second of the world’s salmon-producing countries). Salmon
farming has continuously increased in recent decades; the annual
salmonid production in Chile was 820,000 tons in 2012, representing a
value of 4.9 billion USD (32% of the total worldwide value of salmonid
production). Small salmon are reared in land-based aquacultures supplied
with stream water, whereas mid-sized fish are grown in cages in lakes
and adult fish in cages along the coast. The effluents from land-based
aquaculture pollute pristine streams with nutrients, antibiotics and
organic carbon, resulting in oxygen depletion and negative consequences
for the abundance and biodiversity of stream organisms. While
aquacultures have recently started to remove suspended matter from waste
water using sedimentation basins and rotating drum filters, dissolved
components are still discharged untreated. Nutrients and dissolved
organic matter (DOM) originating from the leaching of remaining food
pellets, fish faeces and fish excretions are major components released
by aquacultures. One aquaculture in northern Patagonia was estimated to
release DOM amounting to 21% of the carbon applied as feed and 76% of
the annual fish production.
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The 1952 London Smog Event Still Impacts Health Of Those Exposed Today Interview with:

Jamie T Mullins PhD Environmental Economics and Applied Microeconomic Department of Resource Economics University of Massachusetts Amherst Amherst, MA 01003

Dr. Jamie Mullins

Jamie T Mullins PhD
Environmental Economics and Applied Microeconomic
Department of Resource Economics
University of Massachusetts Amherst
Amherst, MA 01003 What is the background for this study? What are the main findings?

Response: Episodic triggers of asthma are widely known, but the root causes of the condition still aren’t well understood. There is also very limited evidence on the long-term impacts of exposure to air pollution. Speaking to both issues, we find evidence linking the development of asthma to exposure to a significant air pollution event early in life.

The 1952 London Smog provides a natural experiment for studying the underlying cause of asthma and the long-term effects of air pollution exposure, while limiting threats from statistical confounding. The London Smog (also called the “Great Smog”) dramatically increased concentrations of air pollution across the city in December of 1952. We compare the incidence of asthma among those exposed to the Great Smog in utero or the first year of life to those in relevant comparison groups, including those conceived after the incident and those residing outside the affected area at the time of the Smog.

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