TUCSON, Ariz. — A pregnant woman’s exposure to trichloroethylene (TCE) may affect fetal heart development, say University of Arizona researchers.

“In areas where there is a high amount of TCE exposure there are increased cases of heart defects,” said Om Makwana, a doctoral student in cell biology and anatomy pursuing the project.

TCE, a carcinogen and toxin found in ground and drinking water, has been around for a long time, but only since the 1970s have people been aware of the adverse affects it can have on the human body.

Funded by the Superfund Basic Research Program, a multi-university program supported by the National Institute of Environmental Health, this research on fetal heart development is ongoing along with many other environmental cleanup projects around the country. Members of the program are devising ways to safely remove toxins from soil and groundwater.

History of TCE in Tucson The connection between TCE and Tucson goes back decades. TCE was originally used as a degreasing agent by the military and military contractors located near Tucson International Airport. During the disposal process, the chemical was dumped directly into the ground in the 1960s and 1970s, according to Environmental Protection Agency spokesman Matthew Jefferson. While sources vary regarding the time period when TCE was first leaked into the Tucson groundwater system, the toxic substance had been there for at least two decades before an Arizona Daily Star investigative reporter, Jane Kay, brought the issue to light in 1985. Kay found higher than normal instances of cancer and lupus erythematos in Tucsonans living near the airport area, and her investigation led to lawsuits and government clean-up efforts. Related Articles Tucson Citizen Los Angeles Times

Initiated 12 years ago, the study looks at the effects of halogenated solvents in embryonic heart development. The project is a joint effort headed up by Ornella Selmin, a molecular toxicologist, and Raymond Runyan, a developmental biologist.

The most significant defects researchers at the University of Arizona are finding are holes in the heart. Whether between the top or bottom two chambers of the heart, a hole forces the heart to work harder to separate oxygenated and non-oxygenated blood.

Congenital cardiovascular defects are the most common of birth defects. About 36,000 children are born with a heart defect each year, according to the American Heart Association.

The heart of a chick embryo has four chambers that function much like the four chambers in a human heart, Makwana said, which is why researchers chose to work with chick embryos.

“The most exciting part is there is a direct link to the environment and the central questions we are trying to answer about the effects of TCE, and hopefully, we will be able to help these patients,” Makwana said.

Drinking Water and TCE

Congress passed the Safe Drinking Water Act in 1974. It was amended twice, most recently in 1996. The law requires the Environmental Protection Agency to set safe standards for levels of chemicals in drinking water.

The maximum allowable amount of TCE in drinking water is 5 parts per billion. Scientists compare that amount to an Olympic-sized swimming pool with 2.5 teaspoons of TCE in it. (Click here to read a TCE brochure)

EPA Clean-up Sites The EPA has identified eight Superfund sites with groundwater contamination in Arizona, including the Tucson International Airport Area Superfund site. For more information on the TCE clean-up sites in the Southwest and around the country, go to the EPA Web site. Source: Superfund Basic Research Project at the University of Arizona

TCE can enter the body in several ways. It can be ingested through vapors in the air or from drinking water. It can also be absorbed through the skin or by contact with contaminated soil.

Tucson Water has nine production wells involved in its drinking water monitoring and cleaning process. (An annual report of water quality and a table of detected water contaminants in Pima County is available on the Tucson Water Web site.)

"We monitor (drinking water) from the source of the water all the way to the distribution office," said Dan Quintanar, project manageer in the water quality division at Tucson Water.

Quintanar says water quality experts monitor drinking water at the source, when it comes into the plant, as well as just before the water goes into the distribution pipeline.

"We do these samples weekly, at a minimum," said Quintanar.

Who Is At Risk?

While hard-to-measure factors like lifestyle, ethnic background and water source can also increase an unborn child’s risk for heart defects, Runyan and his team are confident there are links between TCE and heart defects.

Selmin said that “effects of TCE in someone who consumes more alcohol may be worse than someone who doesn’t drink."

A 2006 National Academy of Sciences report on the human health risks of TCE cited the University of Arizona study implicating TCE in heart defects of chick embryos.

“There are genes that are altered; there is a correlation between TCE and gene expression in the heart,” said André Tavares, a researcher in Runyan’s lab.

Research Methods

Runyan’s team is injecting the egg yolks with 8 parts per billion of TCE.



“My students are injecting TCE into chick embryos to see its effects on heart function," Runyan said. "We are analyzing 20,000 genes in these chicks and about 400 of them show significant developmental changes.”

While no exact numbers have been figured yet, Runyan said chick hearts injected with the toxin have to work approximately 50 percent harder than a normal heart.

For about two years now, researchers have been taking video to show the chick hearts are not functioning at an optimal level. Lab attendants are working with the University of Pittsburgh to try to quantify the visual data. They are expecting the first set of quantative data by the end of the month.

“We can crack the egg and observe the heart developing for 13 days,” Runyan said.

A Possible Resistance Agent

Runyan and Selmin agree that folic acid is one agent that may be able to work against TCE and its negative effects on the fetus.

“Folic acid does seem to protect against heart defects; whether it does against TCE, we don’t know yet. We haven’t found a signature saying exactly what TCE causes, and I don’t know if we will, but we can do a public health service by saying folic acid does seem to combat these effects,” Runyan said.

Selmin’s team is observing 15,000 genes inside pregnant mice. TCE has been added to their drinking water, in order to analyze gene expression and see if folic acid makes a difference in fetal heart development.

“What is remarkable is the heart development in the species is very similar to that of humans,” Selmin said.

Standards for drinking water

Runyan and Selmin say people can help protect themselves by drinking carbon-filtered water.

“Just like you would put a seatbelt on when you get in your car, you should know what’s in your drinking water,” Makwana said.

In September Hillary Clinton, then senator of New York, pushed legislation requiring the Environmental Protection Agency to set tougher regulations regarding TCE. Since then, no such bill has been passed and the national standard set by the EPA for the amount of TCE allowed in drinking water remains 5 parts per billion.

“The government has been dragging their feet for 30 years on this issue. It’s very expensive to clean contaminated sites up,” Runyan said.

Selmin said the many variables involved pose a hurdle for scientists.

“It’s very hard to make a direct link between TCE and the effects it has on the body because water has so many elements,” Selmin said.

Runyan and Selmin are gearing up to pursue their own funding, as the funding for their project only goes through April 2010. They hope to do much more work over the coming years.

“We have made a lot of progress over the last three years,” Runyan said.