Papers of the Month
By Nancy Lamontagne
Study identifies top ten consumer product chemicals found in dust
By conducting a meta-analysis of data from dust samples collected throughout the United States, researchers funded by NIEHS identified the top ten consumer product chemicals found in household dust. The findings suggest that people are continually exposed via indoor dust to multiple chemicals that cause adverse health effects.
Using a literature search, the researchers identified 45 chemicals from five chemical classes that had been measured in U.S. indoor dust in three or more data sets. By combining these data in a meta-analysis, they identified 10 harmful chemicals that were present in 90 percent of the dust samples across multiple studies. The top 10 list included five phthalates, with di(2-ethylhexyl)phthalate found at the highest concentrations. Indoor dust also consistently contained phenols, flame retardants, and highly fluorinated chemicals. The analysis estimated that phthalates and replacement flame retardants were taken in by the body in higher amounts than the other compounds. Phthalates and perfluoroalkyl substances were associated with the greatest number of health hazards. The study showed that many of the chemicals in dust were known to affect the reproductive and endocrine systems.
The new findings will be helpful for shaping future exposure and health studies, as well as informing intervention development and public policy. The researchers also offered recommendations to improve the comparability of future dust studies.
Citation: Mitro SD, Dodson RE, Singla V, Adamkiewicz G, Elmi AF, Tilly MK, Zota AR. 2016. Consumer product chemicals in indoor dust: a quantitative meta-analysis of U.S. studies. Environ Sci Technol 50(19):10661−10672.
Prenatal exposure to high butterfat and BPA affected sperm development in rats
NIEHS grantees report that male rats prenatally exposed to a diet of high butterfat and bisphenol A (BPA) showed impaired sperm development that was more severe than those exposed to BPA or high butterfat alone. This is one of the first studies to examine the potential additive effects of BPA and high butterfat.
To evaluate the effects of BPA and fatty acids on male reproductive function, the researchers fed pregnant rats a diet containing low percent butterfat, high percent butterfat, or high percent olive oil, with or without BPA. To mimic an aging hormonal system, some male offspring from these rats received hormonal treatment from the time they were 70 to 210 days old. Another group of male offspring aged naturally from birth to 18 months, the equivalent of 45 human years.
In both the hormone-treated group and the naturally-aging group, the researchers observed impairment in the process of sperm development, known as spermatogenesis. This effect occurred in in adult male rats with gestational exposure to BPA alone, the high butterfat diet alone, or high butterfat and BPA together. Compared with the single-treatment groups, the high butterfat and BPA group experienced more severe effects, including atrophy. In contrast, gestational exposure to the olive oil diet or olive oil with BPA did not affect spermatogenesis. The researchers say that more research is needed to understand how BPA and a high butterfat diet might interact to increase spermatogenesis defects.
Citation: Tarapore P, Hennessy M, Song D, Ying J, Ouyang B, Govindarajah V, Leung YK, Ho SM. 2016. High butter-fat diet and bisphenol A additively impair male rat spermatogenesis. Reprod Toxicol pii: S0890-6238(16)30339-2.
Rising health care costs from infections linked with bacteria in plumbing
With funding from NIEHS, a new analysis of 100 million Medicare records from U.S. adults aged 65 years and older revealed rising health care costs for infections associated with pathogens that can live in household or building plumbing. Based on their findings, the authors called for an urgent dialog across governmental and disciplinary divides and for more studies on preventing exposure to opportunistic pathogens in home and building plumbing through drinking water exposure.
Although modern water treatment facilities rid water of fecal-borne pathogens, the pipes and fixtures in home and buildings — known as premise plumbing systems — can harbor microorganisms such as Legionella pneumophila, Mycobacterium avium, and Pseudomonas aeruginosa. These opportunistic pathogens live in the inner surfaces of pipes where they can collect and grow as microbial biofilms, making them resistant to antibiotics and disinfectants, and able to withstand environmental stresses.
The researchers found that between 1991 and 2006, more than 617,000 hospitalizations related to L. pneumophila, M. avium, and P. aeruginosa resulted in around $9 billion in Medicare payments, an average of $600 million a year. Antibiotic resistance, which was reported for less than two percent of hospitalizations, increased the cost per case by between 10 and 40 percent. The researchers hypothesized that the antibiotic resistance might occur because organisms growing in a biofilm can transfer genetic elements, including antibiotic resistance genes.
Citation: Naumova EN, Liss A, Jagai JS, Behlau I, Griffiths JK. 2016. Hospitalizations due to selected infections caused by opportunistic premise plumbing pathogens (OPPP) and reported drug resistance in the United States older adult population in 1991-2006. J Public Health Policy; doi:10.1057/s41271-016-0038-8 [Online 12 September 2016].
New method for evaluating chemical alternatives
An NIEHS grantee and colleagues developed and demonstrated a new method for quickly evaluating the health impacts of existing complex substances. The new approach could help minimize toxicity testing in animals, especially when assessing chemical alternatives.
The researchers developed a chemical profiling technique that combines experimental and computational information to categorize complex substances, including mixtures. Their method integrates chemical and biological data by using a series of cell models to screen chemicals for similarities in biological activity, which indicates whether a substance will affect living cells or tissues.
Using their new approach, the researchers analyzed 21 petroleum substances from five product groups. They exposed heart and liver cells to extracts of the petroleum substances and then combined the cellular response data with transcriptome data from the liver cells to place the petroleum substances into distinct groups. They found that the bioactivity of the petroleum substances could be grouped in a manner similar to categories based on the manufacturing process. They also observed a high degree of correlation between bioactivity and physico-chemical properties and saw the groupings improve when they combined chemical and biological data.
Citation: Grimm FA, Iwata Y, Sirenko O, Chappell GA, Wright FA, Reif DM, Braisted J, Gerhold DL, Yeakley JM, Shepard P, Seligmann B, Roy T, Boogaard PJ, Ketelslegers HB, Rohde AM, Rusyn I. 2016. A chemical-biological similarity-based grouping of complex substances as a prototype approach for evaluating chemical alternatives. Green Chem 18:4407−4419.