Science Concentrates
Partial lead pipe replacement fails Partially replacing lead pipes increases lead in household drinking water Getting rid of lead pipes in drinking water systems seems like a good idea, but in some cases doing something may be worse than doing nothing at all. In a new study, researchers found that when a city replaced only portions of the lead pipes connecting homes to water mains, lead levels in the water doubled immediately and remained elevated for six months (Environ. Sci. Technol. 2016, DOI: 10.1021/acs.est.6b01912). Replacing lead pipe with copper pipe is one of several ways municipal water utilities try to reduce lead exposure from drinking water. In many places, the utilities are only allowed to remove the lead pipe between the main water line and a homeowner’s property boundary, leaving lead pipe running through the property to the home. But connecting new copper pipes to lead ones can prompt electrochemical reactions that release lead ions into the water flowing through them, says Graham A. Gagnon of Dalhousie University. He and his team measured lead levels in water from more than 100 households’ taps before and after the Halifax, Nova Scotia, water utility replaced service lines around the city between 2011 and 2015. A Halifax Water employee In homes with partial line replaces a stretch of lead pipe replacement, lead levels with copper. more than doubled in the first two water samples collected immediately after pipe replacement. Six months later, water samples from 27% of these homes had lead levels that exceeded 15 µg/L, the concentration above which pregnant women and children should not drink, according to Centers for Disease Control & Prevention guidelines. Before replacement, only 13% of those homes topped that threshold. In homes with full service line replacement, lead levels significantly decreased within a month after replacement. However, lead levels in these homes did not drop to zero, and a few samples still exceeded the EPA threshold, possibly because lead tends to deposit in old galvanized iron plumbing and accumulate in faucet aerators, Gagnon says. “This is probably the most extensive field data set yet collected that shows half-replacements are not beneficial and are in fact harmful,” says Marc A. Edwards of Virginia Tech, who investigated high lead levels in drinking water in Flint, Mich., in 2015.—MELISSAE FELLET, special to C&EN
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C&EN | CEN.ACS.ORG | JULY 18, 2016
NEUROSCIENCE
Social behavior may have immune connection Immune cells release protein that regulates social behavior in mice Our brains—and those of other social creatures—have circuitry that helps us navigate our interactions with other people. A new study suggests that these circuits might receive input from the immune system. Researchers led by Jonathan Kipnis of the University of Virginia report that a protein released by certain immune cells can influence social behavior in mice (Nature 2016, DOI: 10.1038/nature18626). The findings, the scientists say, could someday help identify disrupted immune pathways involved in neurological disorders that affect social behavior, such as autism and schizophrenia. T cells, which are about In the study, Kipnis and 10 µm in diameter, could his colleagues impaired the regulate social behavior. immune systems of mice so that the animals lacked mature T cells. These mice weren’t social, performing similarly to mice with autismlike conditions in tests of social behavior. T cells aren’t present in healthy brains. So the scientists wondered how the cells could exert influence on neurons without directly interacting with them. They looked for a molecule released by the T cells that could signal to neurons. Through bioinformatics analyses and further experiments, the team determined that the molecule was interferon-γ, a protein that helps fight off invading pathogens. The researchers could rescue social behavior in the T-cell-deficient mice by injecting them with T cells. But if those T cells lacked the gene for interferon-γ, the mice remained antisocial. Cornelius T. Gross, a neurobiologist at the European Molecular Biology Laboratory, Monterotondo, Italy, says the study presents exciting results for the field. But he points out that the mice receiving cells missing the interferon-γ gene showed some signs of social behavior, albeit not at a statistically significant level. This could mean another molecule besides interferon-γ may be involved, he says. Understanding which molecules are involved and where they are coming from is important, he says, “because showing that under noninjury conditions immune cells in the periphery can signal to and modulate the brain is indeed an important finding.”—MICHAEL TORRICE
CREDIT: HALIFAX WATER (PIPE REPLACEMENT); NIAID/NIH (T CELL)
WATER
