U. MICHIGAN (US) — Pregnant women who are exposed to lead may have teen daughters with a greater risk of developing high blood pressure, according to a new study. The same is not true for sons.
“This study suggests that a common chemical pollutant—lead—can build up in mom’s bones and then increase their daughter’s risk of developing hypertension, the most important risk factor for stroke and heart disease,” says Howard Hu, professor of public health at the University of Michigan.
“It further increases the importance of reducing such exposures. It also significantly increases the pressure to study how such risks get transferred so we can develop better methods of treatment, including better drugs.”
Using data from the Early Life Exposures in Mexico to Environmental Toxicants project, researchers examined the relationship between prenatal lead exposure and blood pressure in 457 children ages 7-15. Researchers measured the lead accumulations in both bone and in the umbilical cords of mothers in the study.
Among female offspring, a 13 ug/g increase in maternal tibia lead was associated with an increase of 2.11 mm Hg in systolic blood pressure, and an increase of 1.60 mm Hg in diastolic blood pressure.
To put those numbers in perspective, Hu says, consider that previous studies have shown that a 2 mm Hg increase in systolic blood pressure results in a 7 percent increase in the risk of death due to ischemic heart disease and a 10 percent increase in the risk of death due to stroke.
Published online in Environmental Health Perspectives, the study is the first to examine the association of a mother’s bone lead levels with blood pressure in her children. The significant gender disparity was a surprise, Hu says.
“We had not previously seen a gender disparity in lead’s impact on blood pressure, and had published studies showing that adult lead exposure was a risk factor for hypertension in both adult men and women.
“But there’s been an increasing amount of evidence for gender differences in susceptibility to environmental toxicants, and our study suggests this is true for offspring when the exposure is prenatal, meaning from mom’s bones.”
It’s been long known that the prevalence of hypertension and heart disease differs between men and women, but scientists don’t know why.
“This promises to shed light on causes of hypertension, for which there currently remains relatively little insight based on many genetic studies and other studies of risk factors in adults,” Hu says.
The findings could mean that higher bone lead in mothers may result in increased risk of hypertension in the women, themselves, but also affect the cardiovascular health of their daughters, and it also highlights the need for secondary preventative measures, such as dietary calcium supplementation.
The study doesn’t mean that boys are totally exempt from lead exposure in utero, Hu says.
“Given that this is the first study to investigate these relationships using the methods we used, it really needs to be reproduced and in other populations before one can conclude that boys are less susceptible.”
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