Extramural papers of the month
By Nancy Lamontagne
- Green office environments linked with higher cognitive function
- Lead exposure can cause multigenerational epigenetic changes
- Maternal and fetal exposure to parabens
- Prenatal exposure to PBDEs associated with later attention problems
Green office environments linked with higher cognitive function
People who work in well-ventilated offices with below-average levels of indoor pollutants and carbon dioxide showed significantly higher cognitive functioning scores than those working in offices with typical levels, according to a new study funded in part by NIEHS. The findings suggest that improving air quality could greatly increase the cognitive performance of workers.
The double-blind study included architects, designers, programmers, engineers, creative marketing professionals, and managers who worked in a controlled office environment for six days. Participants performed their normal work while exposed to one of four simulated building conditions per day. The indoor environmental quality conditions were conventional, with relatively high concentrations of volatile organic compounds (VOCs), green conditions with low VOC concentrations, green conditions with enhanced ventilation, and conditions with artificially elevated levels of carbon dioxide, independent of ventilation. At the end of each day, participants underwent cognitive testing.
On average, cognitive scores were 61 percent higher on days the participants experienced green conditions with low VOC concentrations and 101 percent higher on the days they experienced green conditions with enhanced ventilation, compared with the conventional building day (p less than 0.0001). VOCs and carbon dioxide were independently associated with cognitive scores. The researchers, who measured nine types of cognitive function, found that the green conditions with low VOCs and green conditions with enhanced ventilation showed the largest improvements in the areas of crisis response, strategy, and information usage.
Citation: Allen JG, MacNaughton P, Satish U, Santanam S, Vallarino J, Spengler JD. 2015. Associations of cognitive function scores with carbon dioxide, ventilation, and volatile organic compound exposures in office workers: a controlled exposure study of green and conventional office environments. Environ Health Perspect; doi:10.1289/ehp.1510037 [Online 26 October 2015].
Lead exposure can cause multigenerational epigenetic changes
An NIEHS-funded study showed that high neonatal blood levels of lead in mothers — indicating that the mothers experienced lead exposure themselves while in the womb — can cause epigenetic changes in their unborn children. This study is one of the first to show that an environmental exposure in pregnant mothers can have an epigenetic effect on DNA methylation in their grandchildren.
Epigenetic changes, such as DNA methylation, are chemical modifications that change how DNA is expressed without altering the genetic code. For this study, researchers measured methylation at more than 450,000 DNA locations, or loci, as well as lead levels in blood and neonatal dried blood spots in 35 mother-infant pairs. The samples came from the Michigan Neonatal Biobank, which contains most of the neonatal dried blood spots from children born in Michigan since 1984.
The researchers found that mothers whose own neonatal blood spots showed high lead levels were correlated with DNA methylation changes at 564 loci in their children’s neonatal blood. These results suggest that lead exposure during pregnancy affects the DNA methylation status of the fetal germ cells, which leads to altered DNA methylation in grandchildren’s neonatal dried blood spots. The study also showed that the altered DNA methylation status detected in the grandchildren’s blood is apparently normalized during postnatal development.
Citation: Sen A, Heredia N, Senut MC, Land S, Hollocher K, Lu X, Dereski MO, Ruden DM. 2015. Multigenerational epigenetic inheritance in humans: DNA methylation changes associated with maternal exposure to lead can be transmitted to the grandchildren. Sci Rep 5:14466.
Maternal and fetal exposure to parabens
An NIEHS grantee and colleagues report that paraben exposure varies greatly among communities and countries, as well as by individual paraben. The new study emphasizes the need to monitor exposure to parabens as individual chemicals and at a community level.
Parabens, which are used as preservatives in personal care products, pharmaceuticals, and some foods, have been shown to act as endocrine disrupters in animal studies. The researchers investigated exposure using 181 maternal urine and 38 umbilical cord blood plasma samples from 185 pregnant women, predominantly of Caribbean- and African-American descent, in Brooklyn, New York. They examined exposure to methyl- (MePB), ethyl- (EtPB), propyl- (PrPB), butyl- (BuPB), and benzylparaben.
Compared to levels reported for the general U.S. population, the study group showed a 4.4 times higher median concentration for MePB and 8.7 times higher concentration for PrPB. The researchers detected MePB in 97.4 percent of the cord blood plasma samples. Upon comparing their findings to data for other communities and countries, the researchers found that the Brooklyn study participants ranked the highest in the world for MePB and PrPB exposure in pregnant women, whereas they ranked among the lowest for EtPB and BuPB.
The authors said that future work should examine the cultural- and country-specific factors that may be responsible for the substantial differences observed between communities and countries, both in the spectrum and degree of paraben exposures.
Citation: Pycke BF, Geer LA, Dalloul M, Abulafia O, Halden RU. 2015. Maternal and fetal exposure to parabens in a multiethnic urban U.S. population. Environ Int 84:193-200.
Prenatal exposure to PBDEs associated with later attention problems
NIEHS grantees reported that prenatal exposure to polybrominated diphenyl ethers (PBDEs), which are used as flame retardants, are associated with attention problems in children 3 to 7 years old. This is one of the first studies to examine prenatal PBDE exposure effects on both preschool and school age development.
Researchers followed 210 mother-child pairs from birth through early childhood. This cohort showed cord plasma PBDE concentrations consistent with exposure levels detected elsewhere in the United States. The researchers used cord blood samples to assess prenatal exposure to PBDEs and then assessed child behavior yearly from age 3 to 7 years using a standardized rating scale.
The researchers detected four types of PBDEs in more than half of the samples, with BDE-47 showing the highest concentrations. After adjusting for factors associated with PBDE exposure levels or neurodevelopment in other studies, the researchers observed an association between childhood attention problems and increasing levels of blood plasma concentrations of BDE-47, -99, -100, and -153, for ages 3, 4, and 7 years. The authors stated the behavior instrument used might not effectively capture behavior patterns at ages 5 and 6 years because the test transitions from a preschool- to school-aged version at those ages.
Citation: Cowell WJ, Lederman SA, Sjodin A, Jones R, Wang S, Perera FP, Wang R, Rauh VA, Herbstman JB. 2015. Prenatal exposure to polybrominated diphenyl ethers and child attention problems at 3–7 years. Neurotoxicol Teratol; doi:10.1016/j.ntt.2015.08.009 [Online 5 Sept. 2015]
(Nancy Lamontagne is a science writer with MDB Inc., a contractor for the NIEHS Division of Extramural Research and Training.)