Barium Distributions in Teeth Reveal Early Life Dietary Transitions

A recent study in the prestigious journal Nature has shown that chemical signatures in teeth can be used to uncover aspects of early life dietary transitions. Manish Arora, Ph.D., NIEHS R00 early investigator grantee and former postdoctoral trainee at the Harvard University Superfund Research Program (SRP), and his research team developed a method to measure early life dietary transitions based on barium variations in teeth.

Molar tooth model with the cut face showing color-coded elemental patterns merging with a microscopic map of growth lines, which have been accentuated to reflect their ring-like nature.

"Early life diet, including breastfeeding, is important in so many ways. It is crucial for infant health but can also serve as a pathway for chemical exposure,” said Arora. “Given that maternal recall of breastfeeding practice and early life diet can be biased when recorded many years later, an objective retrospective biomarker would provide a major advance to studies on children's health".

Prenatal barium transfer is restricted by the placenta, but marked enrichment occurs immediately after birth from mother’s milk or infant formulas, which contain higher barium levels than umbilical cord sera. In response to these variations in dietary barium exposure, levels in enamel and dentine increase at birth and remain elevated for the duration of exclusive breastfeeding. Barium levels in teeth rise further with introduction of infant formula because most cow-milk and soy based formulas contain much higher levels of barium than human milk. Arora’s team mapped these barium variations in teeth using a laser ablation method that he has previously successfully used in studies on lead and manganese exposure.

This method has far reaching applications, according to Arora. It can be applied to epidemiologic investigations of the health consequences of breastfeeding and chemical exposures during early life as well as studies on primate evolution. It can also be used to specifically investigate the health effects of barium, and differences between breastfeeding and infant formulas.

“One of the studies we plan to undertake from this work is to investigate how exposure to barium and other elements in early life will affect children’s health,” said Arora. “Our biomarker provides a unique opportunity to study breastfeeding and infant formula use from the perspective of exposure to these elements.”

Arora’s team first analyzed teeth from macaques with known diet histories to refine the method. They later tested teeth of children enrolled in the University of California Berkeley's Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) study, where breastfeeding and infant formula use were recorded prospectively. Researchers found that they were able to predict early life dietary changes in the children based on this newly developed method.

An interesting application of this method arose when a several thousand year old Neanderthal tooth was made available. Using their method, the researchers also document the first early life dietary transition in a juvenile Neanderthal.

For details, see Arora’s publication in the journal Nature  . Arora was also featured on NPR Morning Edition  for his research.

Shine Reaches Out to Superfund Community, Explains SRP Research

Shine presents to community residents near the Tar Creek Superfund Site.

(Photo courtesy of Jim Shine)

Harvard University Superfund Research Program (SRP) scientist Jim Shine, Ph.D. presented new information about lead, zinc, and cadmium in soils to community residents living around the Tar Creek Superfund Site in Oklahoma on May 9-10. Tar Creek is a 40 square-mile Superfund site contaminated with remains from what was once one of the largest lead and zinc mining operations in the world.

Shine introduced the key issue of bioaccessibility of metals, a measure of the potential for human uptake of toxic metals upon exposure. His study found the bioaccessibility of lead, zinc and cadmium in yard soils in the Tar Creek community varied greatly, from about 5 percent to 100 percent.

For risk assessment and clean-up purposes, the U.S. Environmental Protection Agency (EPA)  often uses a fixed value of total amount of metals in soil to determine if a health risk exists and needs to be remediated. Shine explained that the total concentration of lead in the soil is not always the best way to think about health risks.

“The percent biologically available was not correlated with the total concentration, meaning that knowing the total concentration of metals didn’t always paint the best picture of true health risks,” said Shine. “My goal is to let them understand the assumptions that are happening underneath the risk assessments so that the community  themselves can ask the right questions and understand the answers they get in return as the EPA selects clean-up options for their community.”

“I have consistently brought my SRP trainees to this community to talk about their research so they know how research actually relates to the real-world, answering real questions of concern from real citizens” said Shine. “Science is not limited to some assay in a test-tube in a laboratory with no windows.”

Shine began working in Tar Creek in 2004, studying the environmental pathways that determine how toxic metal mining wastes move through the environment and ultimately end up in people. For more information about his work and Tar Creek, visit the Harvard SRP website  .

Audio Recording of Superfund Research Program Partnership Call Now Online

In case you missed it, an audio recording of the "25 Years of the Superfund Research Program (SRP): Highlights and Hopes" Partnership Call sponsored by the Collaborative on Health and the Environment (CHE) is now online  . Originally airing May 23, the four featured speakers were William Suk, Ph.D., M.P.H., Joseph Graziano, Ph.D., Jennifer Schlezinger, Ph.D., and David Ozonoff, M.D., M.P.H.

Suk, director of the SRP since its inception, described the overall structure of Superfund Research Centers, primary goals of the program, and key changes in the program over time.

"We provide hypothesis-driven basic research and applied, product-oriented research for informing the risk assessment process," said Suk.

Graziano, director of the Columbia University SRP, discussed his research on arsenic in drinking water in Bangladesh, which associates exposures with deficits in child intelligence. Schlezinger, a researcher at the Boston University SRP, discussed her experience as a program trainee before leading her own study focused on receptor-mediated toxicity and chemical mixtures. Ozonoff, director of the Boston University SRP, served as a discussion leader.

CHE, founded in 2002, is an international partnership committed to strengthening the scientific and public dialogue on environmental factors linked to chronic disease and disability.

UW SRP Co-Hosts Workshop on the Duwamish River Superfund Cleanup Proposal

The University of Washington (UW) Superfund Research Program (SRP) and the Center for Ecogenetics and Environmental Health (CEEH)  filled the Allen Library Research Commons at UW with approximately 70 attendees for an educational workshop on EPA's Duwamish River Superfund Cleanup Proposal   .

Participants listen to panel presentations.

(Photo courtesy of Jon Sharpe)

The meeting held April 29 included UW students and staff, a Duwamish tribal member, staff from the Environmental Protection Agency (EPA), Washington State Department of Ecology, the City of Seattle (representing the Lower Duwamish Waterway LDW Group  ), and the Duwamish River Cleanup Coalition/Technical Advisory Group  .

Representatives from each group presented their perspectives on the EPA plans for cleanup of the Duwamish River. All participants were also encouraged to make a public comment  by June 13. The comment period is the only chance for the public to speak up and influence the EPA’s Cleanup Plan.

In 2001, a 5.5 mile long stretch of the lower Duwamish River was declared a federal Superfund Site. According to the EPA Proposed Plan   , more than 40 different toxicants contaminate the river, mostly in the river bottom sediment. The contaminants of highest concern are polychlorinated biphenyls (PCBs), dioxins and furans, carcinogenic polycyclic aromatic hydrocarbons (PAHs), and arsenic.

For more information about the workshop and the Duwamish Cleanup Proposal, visit the Ecogenetix website  .

Dartmouth SRP Participates in Water Festival

At the booth, Laurie Rardin explains how arsenic can get into drinking water.

(Photo courtesy of Laurie Rardin)

Students enjoyed hammering clay “cells,” which represented what happens to the cells in your body when they are exposed to arsenic.

(Photo courtesy of Laurie Rardin)

More than 350 fourth grade students from Concord, N.H. elementary schools learned about potential arsenic contamination in drinking water thanks to the Dartmouth College Superfund Research Program (SRP) Community Engagement Core (CEC) and Research Translation Core (RTC), who built a display and interactive exhibit for the New Hampshire (NH) Department of Environmental Services Water Festival.

At Dartmouth’s booth, RTC Coordinator Laurie Rardin and CEC Coordinator Michael Paul explained to the children that according to the N.H. Department of Environmental Services   , arsenic in New Hampshire occurs naturally in the bedrock and can be released into drinking water from private wells drilled into bedrock fractures. The students participated in interactive activities to show them how water doesn’t smell or look differently when contaminated with arsenic, but can still increase the risk of several types of cancer and create health problems such as neurological disorders when a person is exposed.

The Festival was held May 8 in honor of Drinking Water Awareness Week. At the event, students learned about water conservation, water testing, groundwater pollution and keeping water clean. The fourth graders could also participate in a water science fair.

To learn more about Dartmouth’s efforts to explain the risks associated with exposure to arsenic in private well water, visit the Dartmouth SRP website  .   

Maier Recognized as Leading Edge Researcher

Maier (right) receives her award.

(Photo courtesy of UA SRP)

University of Arizona Superfund Research Program (UA SRP) Center Director Raina Maier, Ph.D., received a UA at the Leading Edge Recognition  award for her work on the discovery and environmental applications of biosurfactants.  She received the award at the 10th Annual Innovation Day on March 8, 2013, at UA, which celebrates technology development by highlighting innovative research achievements of students, faculty, and staff. The awards are designed to showcase emerging and important technologies likely to be commercialized in the future.

Through her foundational work on biosurfactant-metal interactions, funded by NIEHS through the UA SRP, Maier has discovered that rhamnolipid biosurfactants strongly and selectively bind to toxic metals and that rhamnolipids are effective in controlling zoosporic plant pathogens. The latter discovery is the subject of a licensed patent and a marketed product called Zonix BioFungicide. Maier envisions biosurfactants as green replacements for more toxic and less biodegradable synthetic surfactants currently on the market.

Visit Maier’s website  to learn more about her biosurfactant research.