Millions of pounds of toxic and hazardous substances are released into Houston’s air each year from petrochemical refineries, chemical plants and other industries along the Houston Ship Channel and the Gulf Coast. When a pregnant woman is exposed to toxic air, the embryo and developing fetus can be harmed as the toxins are carried in the mother’s blood into the womb.

The array of toxins in the Houston air include: acrylonitrile, hexane, trichloroethene, propane, dichlorodifluoromethane, 2-mutanone, propane, chloromethane, p/m-xylene, tolulene, 1,2,4-trimethylbenzene, ethyltoluene, c3-alkylbenzene, p/m xdylene, tetrachloroethene, carbon tetrachloride, methylbutane, 2-butanone, and pentadiene isomer or isoprene. Each has a health effect ranging from mild irritations of eyes, nose and throat, to hearing and color vision loss, to heart attack. Many affect the nervous system. Some are linked to cancer (www.epa.gov/earth1r6/6lab/hgcamp/hgcamp.htm).

According to the most recent Environmental Protection Agency’s Toxic Release Inventory (TRI), more than 20,500,000 pounds of toxic chemicals, plus about 62 grams of dioxin and dioxin-like compounds, were released from plants, refineries, and other facilities in Harris County in 2002 (www.epa.gov/triexplorer). This amount is roughly comparable to pollution from about 7,500 trucks or SUVs, each driven 14,000 miles a year. Not included are certain volatile organic compounds (VOCs) and other unreported emissions from Harris County facilities, such as toxins that leak from facilities’ pipes. Yet even more toxic air pollution wafts into Harris County from Texas City plants in Galveston County and other large chemical complexes in Brazoria County lying just upwind.

Neil Carman, PhD, Texas Sierra Club’s Clean Air program director, says the TRI figures are “just the tip of the iceberg” when it comes to the amount of pollution coming out of Harris County plants and refineries.

Exposure to this amount of air pollution can cause DNA damage in a developing fetus, which increases health risks and developmental problems.

A mother’s womb is meant to be a safe haven for the fetus to grow and develop. Cradled in a fluid-filled sac and attached to the mother’s uterine wall by the umbilical cord, the fetus receives oxygen, food, and protective antibodies through the network of blood vessels in the umbilical cord.

“The fetus can be affected by anything the mother eats, drinks, or breathes,” says Stephen King, Houston toxicologist, epidemiologist, and clinical ethicist. “The fetuses of pregnant women living near point sources (refineries, chemical plants, etc.) of air pollution are at a greater risk because they have daily exposure to these toxins in the ambient air,” he adds.

When the womb becomes a toxic environment the baby may need to get out early, resulting in premature birth and/or low birth weight, according to Winifred Hamilton, PhD, director of Baylor College of Medicine’s Environmental Health Section. “In a toxic situation, the fetus is susceptible in the same way the mother is,” Hamilton says. “The big concern when we talk about low birth weight or premature birth is the heart and brain, and certain neurological disorders,” she adds.

Other organs of a fetus deprived of oxygen may not receive necessary nourishment for healthy development. Hamilton says researchers are beginning to look at how this affects health later in life and whether there is a connection to increasing incidences of kidney disease, diabetes, and other diseases that are becoming more prevalent.

Studies show prenatal exposure to air pollution affects fetus
Recent studies confirm that fetal exposure to toxins through the mother’s blood is a real threat to the health of newborns.

A study reported in the August 2004 issue of Environmental Health Perspectives found that the amount of polychlorinated biphenyls (PCBs) found in blood samples from mothers exposed to background levels of the toxin is related to umbilical cord levels. PCBs are endocrine disrupters, which interfere with the normal function of hormones. PCBs also are known to increase cancer risks and cause nervous system problems. The researchers concluded that “…the only way to reduce the exposure of the fetus to these potentially toxic compounds is to reduce the body burden of PCBs in pregnant women.” They also suggested that more research in humans is needed to evaluate the potential negative effects of endocrine disrupters on fetuses.

Another study found that prenatal exposure to second-hand smoke and pollution from motor vehicles, power plants, and other combustion sources at levels encountered in New York City adversely affects fetal development. The study, conducted by Columbia University, Centers for Disease Control and Prevention, and the National Center for Environmental Health, involved infants of non-smoking African-American and Dominican women living in New York City. Researchers measured DNA damage from environmental tobacco smoke (ETS), benzo[a]pyrene(BaP), and other polycyclic aromatic hydrocarbons (PAHs) – very toxic air pollutants released by the combustion of fossil fuels and tobacco. The newborns with DNA damage from PAHs had lower birth weight and smaller head circumference. Several studies show that reduction in birth weight and head circumference at birth is related to lower IQ as well as poorer cognitive functioning and school performance in childhood.

A study looking at the relationship between low birth weight and air pollution exposure levels in Seoul, Korea found that exposure to carbon monoxide, sulphur dioxide, and nitrogen dioxide between the third and fifth months of pregnancy contributes to risks for low birth weight.

Birth defects associated with exposure to carbon monoxide and ozone
A California-based study found that women living in areas with the highest amounts of carbon monoxide and ozone had nearly three times the risk of having an infant with a cardiac defect than did women living in areas with the least polluted air. As exposure to carbon monoxide and ozone exposure during the second month of pregnancy increased, so did the risk of birth defects. (The human heart begins to develop during the second month of pregnancy.) Researchers commented that these findings have implications for urban areas throughout the United States because they demonstrate that relatively low levels of air pollutants are “potentially quite toxic.”

Fathers’ exposure to PAHs increases risk of brain tumors
Prospective fathers as well as mothers need to be concerned about exposure to toxins in their environment, according to findings of the SEARCH International Childhood Brain Tumor Study. This large study compared data from 1,218 cases of brain tumors with 2,223 controls and found that children of parents who have occupational exposure to PAHs before conception have an increased risk of brain tumors.

Preparing for the birth of a healthy baby
Reducing the risk of birth defects, developmental problems, cancer, and other diseases for the newborn begins with the health of the parents. Even before conception:

Minimize exposure to toxins.
Live a healthy lifestyle that includes good nutrition, exercise, and stress management. A healthy lifestyle can help minimize DNA damage from toxins in the environment, according to Dr. Winifred Hamilton.

• Eat organically grown foods when you have a choice.
• Check the labels of personal care products such as soaps, lotions, and shampoos to make sure you aren’t using toxic chemicals on your body.
• Avoid or reduce the use of pesticides, solvents, and other toxic substances in your home and garden.
• Avoid freeways and even being in cars as much as possible, especially during the first three months of pregnancy, advises Dr. Neil Carman. Studies show benzene levels to be very high on freeways and inside cars.
• Avoid living near freeways, incinerators and/or chemical plants, and refineries.
• Minimize use of fossil fuels by driving less and choosing renewable sources of electricity when available. When buying a car, consider one of the new hybrid models that make good use of technology to significantly reduce gasoline consumption.
• Contact your national, state and local representatives and ask them to become knowledgeable about the health risks of polluting the environment, and to take leadership in protecting all citizens’ health (You can find representatives’ contact information in the “Links” section of the CLEAN website’s menu.