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Lead Exposure During Pregnancy - What You Need To Know

By: 
Renee Despres
Thursday, March 14, 2013 - 22:23

Pregnant? Thinking about getting pregnant – tomorrow, next year, or ten years from now? You need to get the lead out -- and ask your public health officials to do the same. Doctors have long known that women who are exposed to high levels of lead during pregnancy are more likely to experience miscarriage,

stillbirth, low birth weight, and preterm birth; their children are more likely to have learning and behavioral problems. But new research suggests that exposure during pregnancy to even tiny amounts of lead -- far below the level of lead poisoning -- may cause problems. 

In a study of 285 pregnant women, researchers from George Washington University’s School of Public Health and Health Services in D.C. found that women who had almost any level of lead in the blood had higher blood pressure than their lead-free peers. High blood pressure is a potentially dangerous problem for both pregnant women and their offspring. This was true even for women whose blood lead levels were well below thresholds considered safe by the Centers for Disease Control and Prevention (CDC) and the Occupational Safety and Health Administration (OSHA). The research team, led by Lynn Goldman, M.D., M.S., M.P.H., published their results February 3 in the journal Environmental Health Perspective. 

Blood Pressure Rises Even when Blood Lead Levels Below “Safe” Limits

A slight rise in blood pressure is expected during the last 12 weeks of pregnancy, because the heart must pump harder to supply enough blood to many more blood vessels. Blood pressure is recorded using two numbers, which are usually separated by a slash. A blood pressure reading of 120/80 mm Hg (milligrams of mercury) is considered normal for pregnant women. The top number, called the systolic pressure, is the pressure in the blood vessels when the heart contracts. The bottom number, called the diastolic pressure, is the pressure in the blood vessels when the heart is relaxed.

The research team, led by Lynn Goldman, M.D., M.S., M.P.H., monitored 285 pregnant women at Johns Hopkins Hospital in Baltimore, Maryland. They measured blood lead levels in umbilical cord blood and tracked the women’s blood pressure.

The CDC recommends that pregnant women or children reduce blood lead exposure if their blood lead levels are 5 micrograms (ug) per deciliter (dL) or higher. But Goldman’s team found that lead affected pregnant women’s blood pressure at a much lower level – about 1 ug/dL. Among women with blood lead levels of 1 ug/dL or higher, systolic pressure increased by 6.9 mmHg, and diastolic pressure increased by 4.4 mmHg. The team statistically controlled for other factors that might contribute to higher blood pressure, including ethnicity, obesity, anemia, household income and smoking.

“We didn’t expect to see effects at such low levels of lead exposure,” says Goldman, “but in fact we found a strong effect.”

No Link to Eclampsia

While any increase in blood pressure during pregnancy is worrisome, researchers did not find a link between blood lead levels and a condition called pregnancy-induced hypertension, which occurs when blood pressure climbs during pregnancy.

Pregnancy-induced hypertension can lead to a potentially dangerous condition called preeclampsia, which is characterized both by an increase in blood pressure and the presence of protein in the urine. Preeclampsia generally occurs after the 20th week of pregnancy. In turn, preeclampsia can progress to eclampsia, characterized by a sudden and dramatic increase in blood pressure, seizures, and coma.

Eclampsia is a life-threatening event for both pregnant woman and fetus and requires emergency medical care. Eclampsia also increases a woman’s risk of future heart attack.

Lead: A Public Health Priority

Since 1990, lead exposure has steadily declined in most parts of the United States, primarily because lead has been banned in gasoline and strict regulations for drinking water have been imposed. But this study suggests that lead restrictions should remain a public health priority.

“Hopefully our study will contribute to efforts to determine what a safe level of lead is for adults,” said Ellen Wells, PhD, first author of the study and postdoctoral scholar at Case Western Reserve University School of Medicine in the Department of Environmental Health Sciences. “Because lead is stored in bones for many years,” Wells says, “even childhood exposure could impact lead levels in pregnancy.”

The best way to reduce lead in women’s blood is to prevent exposure, not only during but also prior to pregnancy. Limiting levels of lead permitted in adults at the workplace might be a good place to start. “The occupational standard right now is a level of 40 um/dL,” says Goldman, “and we see blood pressure changes at a level of 2.”

Researchers suggest that there need to be more stringent limits on lead exposure in workplaces and in homes. On January 4, President Obama signed a bill into law that would reduce exposure to lead by tightening restrictions on lead in drinking water plumbing. The bill follows a series of investigations finding significant levels of lead in water in schools and in households in New York City and Washington, D.C.

Reducing Your Lead Exposure

You cannot see, smell, or taste lead, which makes it difficult to know whether you're being exposed or not. Adults are often exposed to lead in the workplace. Exposure as high as 40 ug/dL is allowed by OSHA standards. According to the CDC, occupational lead exposure is common among police officers, car mechanics, artists, construction workers, glass manufacturers, and many other workers.

To help reduce your exposure: 

  • If you work in a job that exposes you to lead, talk with your employer about changing positions while pregnant or breastfeeding.
  • Avoid home remodeling projects while you're trying to conceive, pregnant, or breastfeeding. Chips from old paint that contains lead are a common source of lead exposure. Dust from paint can fly during remodeling, and house dust or soil can be contaminated by the leaded paint.
  • Do not use traditional home health remedies such as azarcon and greta, which are used for upset stomach or indigestion in many Hispanic households
  • Do not consume imported candies
  • Avoid imported toys and toy jewelry
  • Do not use imported cosmetics
  • Avoid imported pottery and ceramics
  • Filter your water. Drinking water may be contaminated by lead leaching from lead pipes, solder, brass fixtures, or valves.
  • Check common household items such as tea kettles and vinyl miniblinds, for lead content
  • Avoid hobbies that expose you to lead, such as making stained glass or jewelry-making. If you must perform these activities, wash your hands and body thoroughly and often. Never touch your mouth after handling objects with high lead content.
  • If you work in a job that exposes you to lead, talk with your employer about changing positions while pregnant or breastfeeding.
  • Hand your partner the laundry detergent. Even if a pregnant woman does not work in a job that exposes her to lead, she can be exposed via her husband or other family members who may carry lead home on their clothes.

Take Away Messages

  • Even a tiny amount of lead in the blood of pregnant women was linked to increased blood pressure.
  • Pregnant women may be as  sensitive to the effects of lead as are young children.
  • More research is needed to determine acceptable levels of lead exposure for adults, but for pregnant women it may be much lower than previously thought.
  • Public health policies such as strict restrictions on drinking water plumbing can effectively reduce lead exposure.
  • Adults are often exposed to relatively high levels of lead at home, at work, and through their hobbies.

References

American College of Obstetricians and Gynecologists. (2004). High blood pressure during pregnancy. http://www.acog.org/~/media/For%20Patients/faq034.pdf?dmc=1&ts=20130314T2221388662

Centers for Disease Control and Prevention. (March 2010). Lead: Information for workers. http://www.cdc.gov/niosh/topics/lead/WorkerInfo.html

Centers for Disease Control and Prevention. Lead and Children. http://www.cdc.gov/Features/ChildhoodLead/

Organization of Teratrology Information Specialists. (March 2010). Lead and Pregnancy. http://www.otispregnancy.org/files/lead.pdf

Wells EM, Navas-Acien A, Herbstman JB, Apelberg BJ, Silbergeld EK, Caldwell KL, et al. 2011. Low Level Lead Exposure and Elevations in Blood Pressure During Pregnancy. Environ Health Perspect: http://ehp03.niehs.nih.gov/article/fetchArticle.action?articleURI=info%3Adoi%2F10.1289%2Fehp.1002666

Photo by Evi T'Bolt