Chemicals in common consumer products may play a role in pre-term births : phthalates

2009 study posted for filing

Contact: Laura Bailey baileylm@umich.edu 734-647-1848 University of Michigan

ANN ARBOR, Mich.—A new study of expectant mothers suggests that a group of common environmental contaminants called phthalates, which are present in many industrial and consumer products including everyday personal care items, may contribute to the country’s alarming rise in premature births.

Researchers at the University of Michigan School of Public Health found that women who deliver prematurely have, on average, up to three times the phthalate level in their urine compared to women who carry to term.

Professors John Meeker, Rita Loch-Caruso and Howard Hu of the SPH Department of Environmental Health Sciences and collaborators from the National Institute of Public Health in Mexico and the U.S. Centers for Disease Control and Prevention analyzed data from a larger study directed by Hu, which follows a cohort of Mexican women recruited during pre-natal visits at one of four clinics of the Mexican Institute of Social Security in Mexico City.

Meeker and colleagues looked at data from 60 women: 30 who carried to term and 30 who delivered prematurely (defined as less than 37 weeks gestation). They analyzed urine samples collected during the third trimester and compared them to the control group who carried to term. They found significantly higher phthalate metabolite levels in the women who delivered prematurely.

Premature birth is a significant risk factor for many health problems in childhood that can persist into adulthood, Meeker says. In the United States, premature births have increased by more than 30 percent since 1981 and by 18 percent since 1990. In 2004, premature births accounted for 12.8 percent of live births nationwide.

Premature births, he says, account for one-third of infant deaths in the United States, making it the leading cause of neonatal mortality. Being born too early can also lead to chronic health problems such as blindness, deafness, cerebral palsy, low IQ and more.

Phthalates are commonly used compounds in plastics, personal care products, home furnishings (vinyl flooring, carpeting, paints, etc.) and many other consumer and industrial products. The toxicity varies by specific phthalates or their breakdown products, but past studies show that several phthalates cause reproductive and developmental toxicity in animals.

A couple of human studies have reported associations between phthalates and gestational age, but this is the first known study to look at the relationship between phthalates and premature births, Meeker says.

“We looked at these commonly used compounds found in consumer products based on the growing amount of animal toxicity data and since national human data show that a large proportion of the population are unknowingly exposed,” Meeker said. “One of the problems for consumers is that you don’t know exactly which products contain phthalates because the products do not have to be labeled accordingly.”

Meeker says the U-M study is a stepping stone to larger and more detailed studies examining the role of phthalates and premature births. The researchers hope to examine a larger population of pregnant women to corroborate these initial study findings, and conduct experimental lab studies to further explore the biological mechanisms of how phthalates work in the body.

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The study, “Urinary Phthalate Metabolites in Relation to Preterm Birth in Mexico City,” is available online at: http://www.ehponline.org/docs/2009/0800522/abstract.html. It will appear in a later printed issue of Environmental Health Perspectives.

For more on Meeker: http://www.sph.umich.edu/iscr/faculty/profile.cfm?uniqname=meekerj

Loch-Caruso: http://www.sph.umich.edu/iscr/faculty/profile.cfm?uniqname=rlc

Hu: http://www.sph.umich.edu/iscr/faculty/profile.cfm?uniqname=howardhu

EHS: http://www.sph.umich.edu/ehs/

The University of Michigan School of Public Health has been working to promote health and prevent disease since 1941, and is consistently ranked among the top five public health schools in the nation

Calcium during pregnancy reduces harmful blood lead levels: 1200mg –>31% Reduction

Contact: Laura Bailey baileylm@umich.edu 734-764-1552 University of Michigan

ANN ARBOR, Mich.—Pregnant women who take high levels of daily calcium supplements show a marked reduction in lead levels in their blood, suggesting calcium could play a critical role in reducing fetal and infant exposure.

A new study at the University of Michigan shows that women who take 1,200 milligrams of calcium daily have up to a 31 percent reduction in lead levels.

Women who used lead-glazed ceramics and those with high bone lead levels showed the largest reductions; the average reduction was about 11 percent, said Howard Hu, chair of the Department of Environmental Health Sciences at the School of Public Health.

Hu is the principal investigator of the study and one of the senior authors on the paper, which is available online in Environmental Health Perspectives, the official journal of the U.S. National Institute for Environmental Health Sciences. Hu, who is also affiliated with the University of Michigan School of Medicine, said this is the first known randomized study examining calcium supplementation on lead levels in pregnant women.

“We and others have previously shown that during pregnancy, mothers can transfer lead from their bones to their unborn — with significant adverse consequences–making maternal bone lead stores a threat even if current environmental lead exposures are low,” Hu said.  “This study demonstrates that dietary calcium supplementation during pregnancy may constitute a low-cost and low-risk approach for reducing this threat.”

Lead exposure is a great concern for pregnant and lactating women, especially in developing countries where lead exposures have been high until recently, and for women with occupational exposure. Developing fetuses and nursing babies are exposed to lead from either current exposures to mothers or from the mobilization of maternal skeletal lead stores accumulated from prior years of exposure. Bone lead can stay in the body for decades, so even with minimal environmental exposure, the fetus or nursing infant can still be at great risk from maternal stores of lead.

Lead exposure during fetal development and infancy can cause low birth weight or slow weight gain after birth, cognitive defects such as lower intelligence scores, lower motor and visual skills, or even miscarriage. Damage from lead exposure and poisoning is usually permanent.

“The bottom line is that obstetricians and pediatricians should consider adding calcium supplementation to the prenatal vitamins normally recommended in pregnant women, particularly if their patients have a significant history of environmental or occupational lead exposure,” Hu said.

The study showed that reductions in blood lead levels were more evident in the second trimester at 14 percent than in the third trimester at 8 percent. The most compliant group of women in the study (those who consumed greater than 75 percent of the assigned 1,200 milligram doses of calcium per day) showed a 24 percent decrease.  Women in the most compliant group who also reported using lead glazed ceramics and had the highest bone lead levels saw the greatest reduction of 31 percent.

Researchers analyzed 557 women recruited from the Mexican Social Security Institute prenatal clinics, which treat the low to moderate income population of Mexico City. All were in their first trimester; roughly half were assigned calcium and half a placebo.

This recent study corresponds with a previous study performed by the same group of investigators showing that 1,200-milligram daily calcium supplementation during lactation reduced maternal blood lead by 15-20 percent, and breast milk lead by 5-10 percent. This is the first randomized trial to evaluate the effect of supplementation during pregnancy, when lead is more easily transferred to the fetus, Hu said.

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Co-authors and affiliations include: Adrienne S. Ettinger,  Harvard School of Public Health and U-M SPH; Héctor Lamadrid-Figueroa, Martha M. Téllez-Rojo, and Adriana Mercado- García, Mexican National Institute of Public Health; Karen E. Peterson, Harvard SPH and U-M SPH; Joel Schwartz, Harvard SPH;  Mauricio Hernández-Avila, Mexican National Institute of Public Health and Mexican Ministry of Health

The study is available at: http://www.ehponline.org/docs/2008/11868/abstract.html

For more on Hu, visit: http://www.ns.umich.edu/htdocs/public/experts/ExpDisplay.php?ExpID=1188http://www.sph.umich.edu/iscr/faculty/profile.cfm?uniqname=howardhu

For more on the Department of Environmental Health Sciences at U-M SPH, see: http://www.sph.umich.edu/ehs/

The University of  Michigan  School of Public Health has been promoting health and preventing  disease since 1941, and is consistently ranked among the nation’s top five public health schools.  Faculty and students in the school’s five academic departments and dozens of collaborative centers and initiatives study and solve problems relating to chronic disease, health care quality and finance, emerging genetic technologies, climate change, socioeconomic inequalities and their impact on health, infectious disease, the globalization of health, and more. Whether making new discoveries in the lab or researching and educating in the field, our faculty, students, and alumni are deployed around the globe to promote and protect our health.  See:http://www.sph.umich.edu/