Superfund Research Program
Plant Testing Informs Safe Community Gardening Practices
In a new NIEHS-funded study, Superfund Research Program (SRP) Center researchers revealed elevated levels of heavy metals and arsenic in a local community garden grown on a Brownfields site. By installing raised garden beds on the site, they found that they could grow fruits and vegetables that did not accumulate contaminants.
Brownfields are defined as property whose use is complicated by the presence or potential presence of hazardous substances. These sites are attractive for community gardens because they are often the only land in urban areas not being used for other purposes.
At a Brownfields site in southeastern San Diego, the vacant land has been developed into Ocean View Growing Grounds, an urban community garden and greenspace. However, from 1980 to 2012, the site was used as additional parking and storage for a nearby automotive repair facility, which may have introduced a variety of contaminants into the soil. Today, the University of California, San Diego SRP Center leads a testing program in partnership with the Ocean View Community Garden to identify whether potential contaminants in the soil are accumulating in food grown in the garden.
During the four-year project led by Julian Schroeder, Ph.D., the research team tested fruit trees and seasonal produce for lead, cadmium, and arsenic. They also tested the garden’s soil, finding lead and arsenic above the California Human Health Screening Levels.
The researchers found increased lead levels in Mexican lime and Black Mission fig fruit tree leaves, but not in the fruit that would be eaten. In crops grown directly on the ground, researchers found detectable levels of lead in strawberries and arsenic in leafy greens such as lettuce and Swiss chard.
The community also grew seasonal crops in raised beds. Even though the raised beds lacked a boundary layer with the underlying site, the team did not detect contaminants in the crops. Based on their findings, all seasonal produce at the garden is now planted in raised beds and trees are selected based on soil concentration and contaminants.
Because testing for contaminants can be costly for community-run gardens, the researchers recommend partnering with local universities to reduce the cost of testing for contaminants. Such partnerships give universities a way to apply their work in the community.
New Tool Combines Exposure Data to Identify Vulnerable Communities
A new online tool combines environmental and health data to identify communities vulnerable to negative effects of environmental exposures and other stressors in the Houston region. The tool, developed by the Texas A&M Superfund Research Program Center in close partnership with the Environmental Defense Fund, helps communities understand how environmental factors like flooding and air pollution can affect their health.
While many local, state, and federal agencies collect data to identify and understand the factors influencing community health, the public has limited ability to access these data and may lack the technical expertise to interpret the complex information. Led by Weihsueh Chiu, Ph.D., the project focuses on the Houston-Galveston-Brazoria (HGB) region, where intensive industrial activity and periodic natural disasters pose challenges for public health. The free tool, called HGBEnviroScreen, addresses these challenges and empowers residents and community stakeholders.
HGBEnviroScreen uses data from the 1,090 census tracts in the HGB region to identify areas of heightened vulnerability to environmental health effects. The data have been grouped into five categories: social vulnerability, baseline health, environmental exposures, environmental sources, and flooding. The research team integrated and visualized the data using the Toxicological Prioritization Index (ToxPi), a computer modeling tool that combines multiple information sources and creates visual profiles.
Researchers found that the most vulnerable census tracts have multiple predisposing factors such as flooding, social vulnerability, and proximity to environmental sources. According to the researchers, information from HGBEnviroScreen can provide insights into which factors would benefit most from improved planning, policy, and action in order to reduce future vulnerability.
New Membrane Technologies Clean Up Contaminated Water
In two recent studies, researchers at the University of Kentucky SRP Center demonstrated that they can effectively remove contaminants, including trichloroethylene (TCE) and perfluorooctanoic acid (PFOA), from water using specialized membranes. Led by Dibakar Bhattacharyya, Ph.D., the research team developed functional membranes that can both trap and degrade contaminants.
The researchers created specialized membranes integrated with iron-based nanoparticles. The nanoparticles can be regenerated after use, making the technology reusable. Bhattacharyya's group pioneered the synthesis of these nanoparticles to break down chlorinated contaminants. After studying the functional properties of the nanoparticle-based membranes, the team tested the ability of the membranes to break down contaminants individually and in a mixture. They also conducted a longer-term study in the lab to confirm the stability and regeneration of the membranes. They found that the membrane technology quickly and successfully degraded TCE, carbon tetrachloride, and related compounds. According to the team, its approach shows potential for use in real conditions, such as hazardous waste sites.
Starting with the same membrane base, the researchers swapped out the nanoparticles for polymer materials to create specialized membranes to remove PFOA from water. They tested the membranes for functionality and efficiency in the lab. The team reported that manipulating temperature caused the technology to effectively release bound contaminants after cleanup. By making the membranes reusable, the researchers suggest their approach is more cost-effective than existing methods while removing PFOA from water at similar levels.
Early-Life PFAS Exposure May Affect Childhood Metabolism
Exposure to perfluoroalkyl substances (PFAS) during prenatal and early childhood periods could alter metabolic hormones in children, according to a study from the University of Rhode Island Superfund Research Program (SRP) Center. The researchers found that with increased early-life exposure to PFAS, adipokine hormone levels during childhood decreased. Adipokines are a family of hormones thought to play a key role in energy metabolism.
Previous studies linked low levels of adipokines with weight gain, being overweight, and insulin resistance. As a result, these hormone changes could explain the Center's past research findings that revealed associations between PFAS and higher childhood body mass index.
The study's senior author, Philippe Grandjean, M.D., Ph.D., leads a project team at the Center that is studying the effects of early exposure to PFAS, chemicals resistant to breakdown in the environment. Early exposure may occur through a mother's placenta or breast milk, as well as contaminated food or water.
For the study, Grandjean used data from an NIEHS-funded birth cohort in the Faroe Islands, located in the northern Atlantic Ocean. Researchers analyzed PFAS concentrations in blood samples from 80 Faroese mother-child pairs. Blood was taken from mothers during pregnancy and from children at three different points from ages 5-13. Researchers also analyzed concentrations of three different adipokines in children from ages 5-13.
Out of the three adipokines tested, girls experiencing increased concentrations of PFAS exhibited lower levels of two adipokines, and boys exhibited lower levels of the other adipokine. They also found that exposure during the prenatal and early childhood window had a greater overall effect on adipokine changes, compared to other time windows. According to the authors, this study indicates the importance of analyzing windows of susceptibility and sex differences when considering early-life PFAS exposure.