Extramural papers of the month
By Nancy Lamontagne
- Cost of mercury pollution
- Reducing air pollution continues to increase life expectancy
- Tributyltin linked to transgenerational obesity
- Early pregnancy inflammation could increase autism risk
Cost of mercury pollution
According to study partly supported by NIEHS, each year in Europe, more than 1.8 million children are born with unsafe prenatal methylmercury exposures. Preventing prenatal methylmercury exposure could save the European Union 8-9 billion euro per year in lost earning potential.
Exposure to methylmercury typically occurs from eating fish, which bioconcentrate the contaminant. Methylmercury affects brain development leading to a lower IQ and, thus, lower earning potential. To calculate the costs associated with this exposure, the researchers examined mercury concentrations in hair samples from the DEMOCOPHES study of exposure to environmental chemicals, as well as other studies. They assumed that mercury levels below 0.58 micrograms per gram of hair would have little adverse effect.
The researchers estimated that preventing exposure within the European Union would bring an annual benefit equivalent to 600,000 IQ points per year, corresponding to the estimated annual economic benefit of 8-9 billion euro. Prevention would have the most impact in southern Europe, where hair-mercury concentrations were the highest. The study did not examine less tangible benefits of protecting against methylmercury exposure, and supports the need for interventions to minimize exposure.
Citation: Bellanger M, Pichery C, Aerts D, Berglund M, Castano A, Cejchanova M, Crettaz P, Davidson F, Esteban M, Exley K, Fischer ME, Gurzau AE, Halzlova K, Katsonouri A, Knudsen LE, Kolossa-Gehring M, Koppen G, Ligocka D, Miklavcic A, Reis MF, Rudnai P, Tratnik JS, Weihe P, Budtz-Jorgensen E, Grandjean P. 2013. Economic benefits of methylmercury exposure control in Europe: Monetary value of neurotoxicity prevention. Environ Health; doi:10.1186/1476-069X-12-3 [Online 7 January 2013].
Reducing air pollution continues to increase life expectancy
NIEHS grantees report that air pollution reductions occurring from 2000 to 2007 were associated with improved life expectancy. These results show that the last decade of air pollution control continues to positively affect public health.
From 2000 to 2007, U.S. levels of particulate matter, less than 2.5 micrometers in diameter (PM2.5), declined, but at a slower rate than between 1980 and 2000. To find out if these levels continued to improve life expectancy, the researchers looked at yearly average PM2.5 and life expectancy data for 545 rural and urban U.S. counties from 2000 to 2007. Controlling for socioeconomic status, smoking prevalence, and demographic characteristics, they found that the average life expectancy increased by 0.35 years for every 10 microgram per meter decrease in PM2.5 concentration (SD = 0.16 years, P = 0.033). The association between life expectancy and air pollution levels was stronger in more urban and densely populated counties.
A commentary on the study says that the findings provide support for continuing efforts to further decrease air pollution in the United States and globally, where some people experience much higher concentrations of particulate matter than in the United States.
Citation: Correia AW, Pope CA 3rd, Dockery DW, Wang Y, Ezzati M, Dominici F. 2013. Effect of air pollution control on life expectancy in the United States: an analysis of 545 U.S. counties for the period from 2000 to 2007. Epidemiology 24 (1):23-31. [Commentary]
Tributyltin linked to transgenerational obesity
An NIEHS-supported study showed that mice prenatally exposed to the endocrine disruptor tributyltin (TBT) were more likely to be obese, and the effects persisted in subsequent generations not directly exposed to TBT. The findings hold important implications for understanding obesity in people.
TBT is used as an antifungal agent in some paints, certain plastics, and consumer products. To analyze the effects of TBT, the researchers exposed pregnant mice to doses comparable to the established human tolerable daily intake. The offspring of the pregnant mice exposed to TBT, and the subsequent two generations of mice, had a greater number of fat cells, larger fat cells, and heavier fat depots. The TBT exposure also reprogrammed mesenchymal stem cells so that they were more likely to become adipocytes instead of bone, and produced changes in the liver that resembled nonalcoholic fatty liver disease. If TBT has similar effects on people, then exposure to it and other endocrine disruptors could reprogram the metabolism of exposed individuals and future generations, predisposing them toward weight gain.
Citation: Chamorro-Garcia R, Sahu M, Abbey RJ, Laude J, Pham N, Blumberg B. 2013. Transgenerational inheritance of increased fat depot size, stem cell reprogramming, and hepatic steatosis elicited by prenatal exposure to the obesogen tributyltin in mice. Environ Health Perspect; doi:10.1289/ehp.1205701 [Online 15 January 2013].
Early pregnancy inflammation could increase autism risk
Inflammation during pregnancy could be associated with an increased risk for autism, according to new research that was partially funded by NIEHS.
The researchers looked at an inflammatory biomarker called gestational C-reactive protein (CRP) in the Finnish Maternity Cohort, which contains an archive of serum samples collected from about 810,000 pregnant women in Finland. They also used national psychiatric registries that contain virtually all treated autism cases in the population.
Analysis of CRP in archived maternal serum corresponding to 677 childhood autism cases and an equal number of matched controls, revealed that the risk of autism among children in the study was increased by 43 percent among mothers with CRP levels in the top 20th percentile, and by 80 percent for maternal CRP in the top 10th percentile. These findings could not be explained by maternal age, paternal age, gender, previous births, socioeconomic status, preterm birth, or birth weight. The researchers caution that the results should be viewed in perspective, since the prevalence of inflammation during pregnancy is substantially higher than the prevalence of autism.
Citation: Brown AS, Sourander A, Hinkka-Yli-Salomäki S, McKeague IW, Sundvall J, Surcel HM. 2013. Elevated maternal C-reactive protein and autism in a national birth cohort. Mol Psychiatry; doi:10.1038/mp.2012.197 [Online 22 January 2013]. [Story]
(Nancy Lamontagne is a science writer with MDB, Inc., a contractor for the NIEHS Division of Extramural Research and Training, Superfund Research Program, and Worker Education and Training Program.)