Everyday chemicals threaten pregnant women
Scientists explain how burning coal produces methyl mercury and raises blood pressure in pregnant women. They also report that parabens, common chemicals in cosmetics, and the antimicrobial agent triclocarban, found in hand and body soaps, both affect newborns.
In a series of multi-institutional studies, Rolf Halden PhD, Center for Environmental Security, Arizona State University, Tempe, and the Department of Environmental Health Sciences, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, has tracked the effects of a wide range of environmental chemicals on human health. In two studies appearing in Environmental Research (1) and the Journal of Hazardous Materials (2), Halden and collaborators examine several common chemicals and resulting health outcomes on mothers and babies.
These studies significantly add to the still limited information on threats posed by methyl mercury, parabens and antimicrobials to fetal and maternal well-being.
They also raise questions about whether more aggressive steps are warranted to help society avoid harmful exposures and consequences.
It is well known that women with chronic or pre-existing high blood pressure are at high risk for cardiovascular disease, and increased complications in pregnancy. But, some women only develop high blood pressure during pregnancy, gestational hypertension, also threatening mother and baby. One of the most common and serious consequences is preeclampsia, which can lead to premature birth, low birthweight and placental abruption — where the placenta peels away from the inner wall of the uterus before delivery.
Now Halden and colleagues have re-examined the effects of mercury as an environmental contaminant falling from coal burning for power generation. Their work points out that mercury does not occur in a single form, different types can be present in the environment. While both inorganic and organic mercury compounds are toxic, most sources of inorganic mercury in the United States were banned in1990, limiting common exposure. But, mercury released during coal and oil burning still is a major environmental pollutant. Falling on water and soil, microorganisms can convert this form of mercury into organic mercury compounds, including the highly toxic methyl mercury that on land pollutes through waste water runoff into water tables underground, connecting to streams and rivers and reappearing in oceans. Arial dipersion through burning pollutes air, also falling into oceans.
Conventional measurements of total mercury levels in human blood fail to draw the subtle distinctions between various mercury subtypes. Also, levels of fatty acids commonly found in fish ( n-3 or omega-3 fatty acids) and the chemical element selenium, interfere with measuring mercury toxicity. After examining the umbilical cord blood (considered a good proxy for estimating maternal exposure to mercury) and blood pressure of 263 pregnant women, during labor and delivery and comparing data on maternal age, race/ethnicity, pre-pregnancy body mass index, neighborhood income, parity and smoking — results indicate:
• systolic blood and pulse pressure in women rose with increasing concentrations of methyl mercury (MeHg)
but decreased with increasing concentrations of inorganic mercury (IHg).
(No association was found between elevated mercury of either subtype on diastolic blood pressure.)
Mechanisms for how blood pressure changes are influenced by methyl and inorganic mercury are still not fully understood. Methyl mercury is a known neurological toxin, now cardiovascular toxicity is also shown to result from eating mercury in foods.
Despite a long-recognized susceptibility of pregnant women to cardiovascular risk, little previous research has explored the potential effects of mercury exposure on cardiovascular health in pregnancy. Usually, such studies rely on the misleading measurements of total mercury level, rather than mercury separated by subtypes. This lack of specificity leads to confusion when assessing health risks to mothers and newborns.
While mercury exposure can act to reduce the size of babies at birth, the presence of food nutrients — including selenium and fatty acids in fish — tend to increase fetal growth, blurring the toxicity picture.
Cosmetics and Soaps (2)
In a second study, Halden and colleagues examined birth outcomes in an immigrant population in Brooklyn, New York, after casual chemical exposures to personal care products. Their earlier studies suggested that fetal exposure to antimicrobials and paraben compounds, common ingredients in many cosmetics and soaps, can also adversely affect health. Their new research confirmed elevated levels of these chemicals in mothers and their developing fetuses. The data measures effects on human newborn health from antimicrobials and parabens as assessed in 185 mothers and 34 neonates in New York, from 2007-2009. Chemical concentrations were tested in urine and umbilical cord blood plasma from mothers in their third trimester. Results provided the first findings consistent with animal models of antimicrobial and paraben exposure, which suggests these chemicals can act as potent disrupters of the hormonal or endocrine system.
Parabens, triclosan and triclocarban fall under the general heading of environmental phenols. They have a tendency to cause hormonal disturbances to fetuses, both in the womb and following birth.
Mothers are exposed primarily through the use of cosmetics and personal care products containing them.
Fetuses get exposed in the womb through the placenta. Newborns also ingest residues of such chemicals contained in breast milk.
Parabens not only appear in cosmetics, but also as preservatives in various foods. They can influence estrogen levels, suggesting they may be toxic to the reproductive system. Two antimicrobial agents known as triclosan (TCS) and triclocarban (TCC), are in an array of common products, from personal care to industrial cleaning, and also display a potential for endocrine disruption. TCC is in many soaps with measurable amounts detected in urine after even a single use of antimicrobial soap. Previous animal studies link TCC to liver tumors, effects on human infants was largely speculative until now.
The new study examined archived samples of third trimester maternal urine (6-9th month) and human cord blood plasma, collected at two different time points. Women were 18-45 years old who had earlier been evaluated for fetal exposure to mercury, TCS and TCC. A questionnaire was used to gather demographic data, including maternal age, race/ethnic origin, and education level, medical history, and to assess sources of environmental chemical exposure, for example, to mercury.
Infant birth weight, body length and head size, and gestational age at birth were measured. Research results are the first to show adverse outcomes in babies exposed to triclocarban (TCC) and metabolites in the womb.
butylparaben: increased pre-term births
butylparaben: decreased birth weight
• propylparaben: decreased body length
• butylparaben, TCC: lower gestational age at birth
The study also measured protective effects on pre-term birth due to benzylparaben (BePB) and low birth weight due to triclcarban. No associations were observed for methyl-paraben (MePB), or ethylparaben (EtPB).
Researchers note that observed effects of parabens and antimicrobials on these crucial parameters of growth may be precursors to other negative effects on developmental well-being in childhood and perhaps, later in life. This is of concern, given the ubiquitous presence of these endocrine-disrupting chemicals in cosmetics and personal care products, placing babies at high risk for exposure.
"Results from this study emphasize opportunities for expecting mothers to optimize the health of their offspring by observing health advisories for seafood consumption, and by avoiding contact with personal care products that contain unnecessary and potentially harmful antimicrobial agents."
Rolf Halden PhD, Center for Environmental Security, Arizona State University, Tempe, and the Department of Environmental Health Sciences, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.
Abstract (1) Methyl mercury, but not inorganic mercury, associated with higher blood pressure during pregnancy
We compared total, methyl and inorganic mercury with blood pressure in pregnancy.
Models controlled for n-3 fatty acids, selenium, and other variables.
Methyl mercury was associated with higher systolic blood pressure and pulse pressure.
Inorganic mercury was associated reduced pulse pressure.
There were no significant associations of total mercury with blood pressure.
Prior studies addressing associations between mercury and blood pressure have produced inconsistent findings; some of this may result from measuring total instead of speciated mercury. This cross-sectional study of 263 pregnant women assessed total mercury, speciated mercury, selenium, and n-3 polyunsaturated fatty acids in umbilical cord blood and blood pressure during labor and delivery. Models with a) total mercury or b) methyl and inorganic mercury were evaluated. Regression models adjusted for maternal age, race/ethnicity, prepregnancy body mass index, neighborhood income, parity, smoking, n-3 fatty acids and selenium. Geometric mean total, methyl, and inorganic mercury concentrations were 1.40 µg/L (95% confidence interval: 1.29, 1.52); 0.95 µg/L (0.84, 1.07); and 0.13 µg/L (0.10, 0.17), respectively. Elevated systolic BP, diastolic BP, and pulse pressure were found, respectively, in 11.4%, 6.8%, and 19.8% of mothers. In adjusted multivariable models, a one-tertile increase of methyl mercury was associated with 2.83 mmHg (0.17, 5.50) higher systolic blood pressure and 2.99 mmHg (0.91, 5.08) higher pulse pressure. In the same models, an increase of one tertile of inorganic mercury was associated with -1.18 mmHg (-3.72, 1.35) lower systolic blood pressure and -2.51 mmHg (-4.49, -0.53) lower pulse pressure. No associations were observed with diastolic pressure. There was a non-significant trend of higher total mercury with higher systolic blood pressure. We observed a significant association of higher methyl mercury with higher systolic and pulse pressure, yet higher inorganic mercury was significantly associated with lower pulse pressure. These results should be confirmed with larger, longitudinal studies.
Ellen M. Wellsa, , , Julie B. Herbstmanb, Yu Hong Linc, Joseph R. Hibbelnc, Rolf U. Haldend, Frank R. Wittere, Lynn R. Goldmanf
Mercury; Methylmercury compounds; Inorganic mercury compounds; Blood pressure; Pregnancy
Abstract (2) Association of birth outcomes with fetal exposure to parabens, triclosan and triclocarban in an immigrant population in Brooklyn, New York
Prior studies suggest associations between fetal exposure to antimicrobial and paraben compounds with adverse reproductive outcomes, mainly in animal models. We have previously reported elevated levels of these compounds for a cohort of mothers and neonates.
We examined the relationship between human exposure to parabens and antimicrobial compounds and birth outcomes including birth weight, body length and head size, and gestational age at birth.
Maternal third trimester urinary and umbilical cord blood plasma concentrations of methylparaben (MePB), ethylparaben (EtPB), propylparaben (PrPB), butylparaben (BuPB), benzylparaben (BePB), triclosan (2,4,4?-trichloro-2?-hydroxydiphenyl ether or TCS) and triclocarban (1-(4-chlorophenyl)-3-(3,4-dichlorophenyl) urea or TCC), were measured in 185 mothers and 34 paired singleton neonates in New York, 2007–2009.
In regression models adjusting for confounders, adverse exposure-outcome associations observed included increased odds of PTB (BuPB), decreased gestational age at birth (BuPB and TCC) and birth weight (BuPB), decreased body length (PrPB) and protective effects on PTB (BePB) and LBW (3?-Cl-TCC) (p < 0.05). No associations were observed for MePB, EtPB, or TCS.
This study provides the first evidence of associations between antimicrobials and potential adverse birth outcomes in neonates. Findings are consistent with animal data suggesting endocrine-disrupting potential resulting in developmental and reproductive toxicity.
Laura A. Geer, Benny F.G. Pycke, Joshua Waxenbaum, David M. Sherer, Ovadia Abulafia, Rolf U. Halden.
Exposure; Antimicrobials; Parabens; Birth outcomes
Return to top of page
Feb 14, 2017 Fetal Timeline Maternal Timeline News News Archive
Expectant mothers can optimize the health of their babies, by observing health advisories to limit
seafood consumption, and avoid contact with personal care products containing potentially harmful
antimicrobial agents with parabens, such as butylparaben, triclosan (TCS), and triclocarban (TCC).
Image Credit: Pinterest composite