Papers of the Month
By Sara Amolegbe
Sex-specific weight differences linked to pesticide exposure
Exposure to pesticides before birth have different effects on body weight and body composition in boys and girls, according to an NIEHS-funded study. Maternal DDT exposure was associated with higher weight in girls, and maternal pyrethroid exposure was linked to lower weight in boys.
The researchers looked at markers of exposure to the pesticides DDT, DDE, and pyrethroids in a group of mothers near the end of their pregnancies in Limpopo, South Africa. Then, they measured the body mass index and weight of the children at 1 and 2 years of age. According to the authors, these findings suggested that pesticides might play a role in the growing obesity epidemic among South African girls and increasingly higher rates of underweight noted in South African boys.
Using sophisticated statistical pollutant models, the researchers looked at both individual and joint effects of the different pesticides. The authors noted differences in effects when looking at the mixture of insecticides compared with individual exposures. For example, the relationship between pyrethroid exposure and lower weight became stronger with increased exposure to DDE. The authors emphasized the importance of using advanced statistical methods to examine the health effects of chemical mixtures, rather than conventional approaches.
Citation: Coker E, Chevrier J, Rauch S, Bradman A, Obida M, Crause M, Bornman R, Eskenazi B. 2018. Association between prenatal exposure to multiple insecticides and child body weight and body composition in the VHEMBE South African birth cohort. Environ Int 113:122–132.
Labor-management cooperation improves facility safety
A new study showed that providing occupational safety and health training to the entire work force and listening to worker concerns at a chemical facility encouraged communication and led to significant safety improvements. The efforts were supported by NIEHS worker training center infrastructure.
Managers at the Afton Chemical Corporation's Sauget facility, in collaboration with the International Chemical Workers Union Council Local 871C, worked together to provide the U.S. Occupational Safety and Health Administration’s 10-hour training to all Sauget employees. They followed the training with a series of group discussion sessions in which participants were encouraged to articulate health and safety concerns.
According to the study, participants discussed 104 health and safety concerns that required attention around the plant. In just two years, nearly every concern was resolved, in many cases more cost efficiently than that usually done with top-down decision-making. The facility also instated a streamlined process to identify and resolve new concerns as they arose.
Authors noted that the health and safety improvements required dedicated funding, as well as union and management leadership who were willing to work together. According to the authors, the successful cooperative effort could serve as a model for many other facilities.
Citation: Mahan B, Maclin R, Ruttenberg R, Mundy K, Frazee T, Schwartzkopf R, Morawetz J. 2018. Labor-management cooperation in Illinois: How a joint union company team is improving facility safety. New Solut doi: 10.1177/1048291118759303. [Online 21 February 2018].
Exosomes — missing link in asbestos-related biological effects
NIEHS grantees discovered that cells exposed to asbestos excrete exosomes with altered protein signatures, and these exosomes can alter cancer-related genes in mesothelial cells. Exosomes, which are small membrane-bound structures secreted by cells, have roles in cellular waste disposal, as well as in normal physiology and disease.
The researchers examined the effects of asbestos exposure in lung epithelial cells and macrophages, two types of cells that initially encounter inhaled asbestos fibers. They compared exposed and unexposed cells by examining the protein levels inside the exosomes that the cells released. They observed significantly different protein signatures in exosomes from the asbestos-exposed cells. They then added the exosomes from asbestos-exposed cells to healthy human mesothelial cells and measured dramatic changes in several cancer-related genes in the cells.
According to the authors, the genetic alterations may explain how asbestos exposure may lead to cancer. Importantly, the study also shows the potential of using protein profiles of exosomes as markers for the development or progression of asbestos-related disease.
Citation: Munson P, Lam YW, Dragon J, MacPherson M, Shukla A. 2018. Exosomes from asbestos-exposed cells modulate gene expression in mesothelial cells. FASEB J; doi: 10.1096/fj.201701291RR [Online 19 March 2018].
Childhood exposure to flame retardant chemicals declines following phaseout
An NIEHS-funded study found that childhood exposure to polybrominated diphenyl ethers (PBDEs), a flame retardant once widely used in consumer products, significantly decreased between 1998 and 2013. Exposure to PBDE was previously linked to attention problems and altered mental and physical development in children.
Researchers followed 334 mother-child pairs in New York City from before birth through adolescence. They collected umbilical cord blood at birth and blood from the children at ages 2, 3, 5, 7, and 9 years, and found PBDEs in every child blood sample. Over time, levels of BDE-47, the component of the PBDE mixture that is most frequently detected in humans, decreased by about 5 percent per year from 1998 to 2013. Looking only at only blood samples collected after birth, researchers observed a 13 percent decrease per year between 2000 and 2013.
Children who were 2 to 3 years old before the phaseout took effect in 2004 to 2005 had significantly higher levels of BDE-47 in their blood than children who turned age 2 to 3 years following the phaseout. Overall, children in that age group had the highest concentrations of BDE-47 in their blood than any other age group, perhaps because they spent more time on the floor and had more contact with dust.
According to the authors, these findings suggest that although PBDE levels have been decreasing since the phaseout, they continue to be detected in the blood of young children nearly 10 years following their removal from U.S. commerce.
Citation: Cowell WJ, Sjodin A, Jones R, Wang Y, Wang S, Herbstman JB. 2018. Temporal trends and developmental patterns of plasma polybrominated diphenyl ether concentrations over a 15-year period between 1998 and 2013. J Expo Sci Environ Epidemiol; doi:10.1038/s41370-018-0031-3 [Online 4 April 2018].
(Sara Amolegbe is a research and communication specialist for MDB Inc., a contractor for the NIEHS Division of Extramural Research and Training.)