Pakistani women jostle to receive their ballot papers prior to casting their ballot at a polling station on May 11, 2013 in Lahore. A study in The Lancet provides evidence that free and fair elections are associated with a lower burden of chronic diseases. Daniel Berehulak/Getty Images hide caption

Researchers studied the gut microbes of runners from the Boston Marathon, isolating one strain of bacteria that may boost athletic performance. Nicolaus Czarnecki/Boston Herald via Getty Images hide caption

In Nigeria's oil-rich Niger Delta, oil bunkering — the practice of siphoning oil from pipelines — has transformed parts of the once-thriving delta ecosystem into an ecological dead zone, according to the U.N. Environment Programme. Edward Burtynsky, courtesy Robert Koch Gallery, San Francisco / Nicholas Metivier Gallery, Toronto hide caption

Fecal transplantation is an experimental procedure to treat intestinal conditions, including recurrent, antibiotic-resistant Clostridium difficile infection. But if the donor stool is not properly screened, it can spread other illnesses. SCIENCE PHOTO LIBRARY/Science Source hide caption

An FDA inspection of this Ranbaxy facility in Toansa, Punjab, India, in 2014, revealed drug quality testing violations, resulting in the FDA prohibiting Ranbaxy from marketing drugs in the U.S. that were manufactured at this plant. Dhiraj Singh/Getty Images hide caption

Measles vaccination rates need to be at 93% to 95% to keep herd immunity. Otherwise, very young infants or other vulnerable people can be exposed to the virus. George Frey/Getty Images hide caption

Measles used to be a common childhood disease, but after an effective vaccine was developed, the disease was declared eliminated in the U.S. in 2000. This year's outbreaks, however, put that status in jeopardy. solidcolours/Getty Images hide caption

While it may seem that heaps of plastic from meal kit delivery services like Blue Apron make them less environmentally friendly than traditional grocery shopping, a new study says the kits actually produce less food waste. Derek Davis/Portland Press Herald via Getty Images hide caption

Rain wands would have been planted in the earth to bring seasonal rains. Olivia Sun for NPR hide caption

Fisher-Price has recalled its popular Rock 'n Play sleeper, after the Consumer Product Safety Commission confirmed that least 30 babies' deaths were linked to it. Courtesy of US Consumer Product Safety Commission hide caption

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An aerial view of a combine harvesting corn in a field near Jarrettsville, Md. A new study ties an estimated 4,300 premature deaths a year to the air pollution caused by corn production in the U.S. Edwin Remsberg/Getty Images hide caption

Researchers tested sewage across Europe, including in Germany, where this treatment plant is located, for bacteria with resistance to antibiotics. B&M Noskowski/Getty Images hide caption

An elevated view of smog and air pollution in Hollywood, Los Angeles, California, USA. Dave G. Kelly/Getty Images hide caption

This colorized scanning electron micrograph shows human cells in a lab infected with "pink" influenza viruses. As many as 650,000 people each year die from flu, according to the World Health Organization. Steve Gschmeissner/Science Source hide caption

A female Anopheles gambiae mosquito feeds on human blood through a mosquito net. Emily Lund hide caption

A child takes in the sights under blooming Japanese cherry trees at the Bispebjerg Cemetery in Copenhagen, Denmark. Mads Claus Rasmussen/AFP/Getty Images hide caption

Korean kimchi, made of salted and fermented vegetables, contains microbes that contribute to its distinctive taste. 4kodiak/Getty Images hide caption