The chlorination of municipal tap water is considered one of the 20th century's best public health ideas. The American Water Works Association credits the practice with increasing life expectancy by 50 percent over the past century by virtually eliminating water-borne diseases such as typhoid fever and cholera. But chlorine in drinking water can cause health risks of its own. And while some of the of those risks, such as reactions with organic compounds that can yield toxic byproducts, are relatively well understood and managed, at least one has been largely overlooked: the effect of chlorinated drinking water on the beneficial bacteria in our guts.
We simply don't know enough about the microbial ecosystem in the human gut to identify every type of bacteria that's important, much less how well those bacteria survive when we guzzle mildly chlorinated tap water.
The notion that our bodies' 100 trillion bacteria act as a crucial internal ecosystem, a sort of sixth human organ, has only recently gained currency among mainstream scientists. Researchers now believe a lack of beneficial bacteria in the gut can trigger certain autoimmune diseases, among them diabetes, asthma, and even neurological conditions such as autism. Those conditions have spread in step with Western society's war on germs, which has scorched our good bacteria along with the bad, throwing our bodies' microbiomes off balance in the same way that a slashed and burned rainforest becomes susceptible to invasive weeds.
Jeff Leach is a leading microbiome researcher and founder of the American Gut Project, which aims to sequence the microbiomes of tens of thousands of Americans. Leach suspects that several factors may impede bacterial diversity in Americans, among them the profligate use of antibiotics, overconsumption of processed foods, and, at least to some extent, consumption of chlorine in tap water. "It's something I've discussed with a number of other microbiologists," he replied when I asked about the possibility. "In short, nobody has done the research, but we are certain that there is an impact."
Based on studies of chlorine's effects on human cells, the Environmental Protection Agency sets the safe level in drinking water at no more than four parts per million. Even that dilute level can wipe out lots other life forms, however, as anyone knows who has filled a goldfish bowl from the tap.
There's no debate that chlorinating our water kills off a wide array of malignant bacteria—just try drinking the tap water in countries that don't fully disinfect it. Much less is known, however, about chlorine's effect on good bacteria that help preserve healthy digestive systems. We simply don't know enough about the microbial ecosystem in the human gut to identify every type of bacteria that's important, much less how well those bacteria survive when we guzzle mildly chlorinated tap water.
Still, some tangential research suggests cause for concern. A 1987 Toxicology study found that consumption of water with even fairly low levels of monochloramine, a commonly used disinfectant that persists in drinking water longer than chlorine, disrupted the immune systems of rats—a finding that's notable given the strong link between the human immune system and gut microbes.
Chlorine in tap water is also known to kill microbes in soil—watch out, home gardeners!—though it doesn't penetrate deep into the ground, and microbial populations typically bounce back quickly after watering.
Though the risks of chlorine in tap water might justify purchasing a low-cost home water filter that can remove it, it's definitely premature to back off of requirements to chlorinate or otherwise disinfect municipal drinking water, as some Wisconsin state legislators proposed a few years ago.
"Chlorination has done tremendous good, so the default is to continue as is," Martin Blaser, the director of the Human Microbiome Project, told me, "but whether or not there are subtler effects needs to be studied."
The domestic fracking boom has been widely celebrated as a godsend in the fight against climate change. In 2007, cheap natural gas began replacing dirtier coal as the fuel of choice in US power plants. By 2012, the switchover was annually saving an estimated 86 million tons of CO2, the carbon equivalent of taking 21 million cars off the road. That's obviously a huge accomplishment, but it comes with a lesser known catch: All of that coal we're no longer using is still getting dug up, sold off, and spewed into the atmosphere.
The carbon pollution savings from our switch from coal to gas has been more than canceled out by an increase in our coal exports, according to a recent study by Shakeb Afsah of the group CO2 Scorecard. After the domestic market for coal dried up in 2007, US exports of steam coal increased by 83 million tons, resulting in the release of an additional 149 million metric tons of CO2. That's 73 percent more CO2 than Americans have saved so far by ditching the black stuff.
The study is mentioned today in a great story by AP's Dina Cappiello, who looks at whether the coal exports will ultimately increase carbon emissions. Coal companies point to studies suggesting international demand for coal is fairly inelastic, meaning that if US coal exports suddenly disappeared, they would simply be replaced by coal from somewhere else. Yet other studies conclude that the US exports depress prices, driving up demand and delaying a switch to cleaner options.
As I've previously noted, huge new coal export terminals proposed on the West Coast have become the latest flash points in the climate wars. Cappiello points out that a single ship full of Appalachian coal, exported from Virginia to South America, contains enough greenhouse gas to match the annual emissions of a small American power plant.
UPDATE: Cappiello's story has spawned new debate over whether coal exports increase emissions. Andrew Revkin weighs in, and CO2 Scorecard responds.
Twitter today followed in the footsteps of Google, Yahoo, LinkedIn, and Facebook by releasing statistics on the race and gender of its workforce. The company certainly deserves credit for voluntarily making its diversity stats public, unlike, say, Apple. "Like our peers, we have a lot of work to do," Janet Van Huysse, its VP of diversity and inclusion, admits on the company blog. But perhaps that's an understatement; Twitter actually lags far behind its peers on some key measures. For instance, only 1 out of every 10 Twitter tech employees is a woman:
In case you're wondering, other large tech companies have significantly better gender diversity (though it's still abysmal compared to professions such as law or medicine). At Facebook and Yahoo, 15 percent of tech workers are women. At Google and LinkedIn, it's 17 percent. In 2010, Mike Swift of the San Jose Mercury Newsfound that women held 24 percent of computer and mathematics jobs in Silicon Valley and 27 percent of those jobs nationally (though those categories may be broader than how they're defined by leading tech companies, as Tasneem Raja explores in this great piece on America's growing gap in tech literacy).
Unlike its peers, Twitter can't entirely blame its dearth of female coders on the talent pipeline: About 18 percent of computer science graduates are women. Instead, Van Huysse points to a slew of efforts to "move the needle" at Twitter, such as supporting the groups Girls Who Code and sf.girls and hosting "Girl Geek Dinners."
As other reporters have noted, major tech firms started releasing their workforce data shortly after I obtained a batch of Silicon Valley diversity figures from the Labor Department and began asking them for comment. But pressure to release the stats has also come from a campaign by Color of Change and Rev. Jesse Jackson's Rainbow Push Coalition, which have demanded the stats during a string of private meetings with Valley execs, and last week launched a Twitter-based campaign to urge Twitter to make its diversity numbers public. Strikingly, only 1 percent of Twitter's tech workforce and 2 percent of its overall workforce is African-American:
Jackson argues that improving Twitter's diversity isn't just the right thing to do; it's also a good business decision. It turns out that "Black Twitter" isn't just a meme. According to a recent Pew survey, 22 percent of African-American internet users are on Twitter, while only 16 percent of White internet users tweet. Meanwhile, usage of Facebook, LinkedIn, and Google+ is roughly the same between Blacks and Whites.
In short, Twitter might make more money by hiring more people who reflect its audience. "There is no talent deficit, there's an opportunity deficit," Jackson said in a press release responding to Twitter's data. "When everyone is 'in,' everyone wins."
Unlike most male dairy calves, Harry, who was born at the Ahimsa Dairy, won't be turned into veal
If you don't eat beef because you feel sorry for those cows in Chick-fil-A ads, then you probably shouldn't drink milk either. The typical male calf born to a dairy cow becomes veal. The typical female is milked for five years—a quarter of her natural lifetime—then sent to the abattoir to become pet food or low-grade hamburger meat. Elsie the Cow, Borden Dairy Company's famous cartoon logo, is smiling only because she doesn't realize that she's about to get euthanized with a cattle gun.
Yet if you're an ethical vegetarian who still can't bear to give up milk, you now have another option: slaughter-free dairy, which comes from farms where cows never get killed. Since 2011, the UK-based Ahimsa Dairy has offered slaughter free-milk and cheese to customers in London. In February, Pennsylvania's Gita Nagari Creamery, which has supplied no-kill milk to the local Hare Krishna community for many years, began offering it to the public through subscription and mail order—for a whopping $10 a gallon. The price includes a $2.50 cow retirement fee and $1.50 for "boy calf care." Less than half of its 60-head herd gets milked; the rest of the animals pull plows or spend their golden years lackadaisically chomping grass.
"For us, the cows or oxen or bulls are seen as extended family members," says Pari Jata, the co-president of Gita Nagari Creamery. "It's very important for us to protect them in their retirement. We take care of them just as one would take care of elderly parents in their old age."
The slaughter-free milk movement takes its cues from India, where many vegetarian Hindus drink milk but consider cows sacred animals that should never be consumed for meat. Yet increasing numbers of Gita Nagari and Ahimsa customers are Westerners who eschew meat for ethical reasons. Both dairies have considered selling their milk in stores; Ahimsa is in talks with a major retailer.
If all dairies became slaughter-free, they'd add yearly greenhouse gas emissions equivalent to four large coal-fired power plants.
As vegetarianism gains popularity, slaughter-free milk could become a bona fide food trend—but there's a catch: It might take a toll on the environment. Cows are already the nation's single largest source of methane, a greenhouse gas produced by oil extraction, decomposing trash, and the guts of grazing animals that's as much as 105 times more potent than carbon dioxide. A single cow farts and belches enough methane tomatch the carbon equivalent of the average car. According to a 2006 United Nations Food and Agriculture Organization report, the world's 1.4 billion cows produce 18 percent of the world's greenhouse gases—more than the entire transportation sector. Since the turn of the 19th century, global methane emissions have increased by more than 150 percent, and cows are largely to blame.
If all dairies became slaughter-free, we'd need three to four times as many dairy cows to produce the same amount of milk, which would mean adding at least 27 million additional cows to our herds. Those added cows would each year produce greenhouse gas emissions equivalent to four large coal-fired power plants. We'd also need more meat cows to keep up with the demand for products such as veal and dog food. Pasturing all of these cows would displace wildlife or agricultural crops, straining biodiversity and increasing food prices.
Jata knows there's a potential for the slaughter-free milk trend to go bad—just like the craze for tofu and soymilk contributed to the spread of soybean plantations in South America's rainforests, she says (though most soybeans are consumed by livestock). "Where does it end?" she asks. "For us, as a community, we bring it all back to local food sources and local practices that are self-contained but shared, so it doesn't create this mass corporation-style approach to everything."
Small, humane dairies can certainly find other ways to mitigate their environmental impacts. The Gita Nagari and Ahimsa dairies employ cow manure to fertilize their organic vegetables and bull power to plow their fields, avoiding carbon-intensive tractors and chemical fertilizers. And the Gita Nagari dairy uses an anaerobic digester to convert manure into a gas that residents of the dairy use for cooking—but this sort of thing would be hard to implement on a larger scale.
For Nicola Pazdzierska, the co-director of the Ahimsa Dairy Foundation, the price and environmental impact of slaughter-free milk underscores the need to rethink our relationship with dairy products. "We're not saying more cows," she told me. "We're saying possibly even fewer cows, but kept in better circumstances." She went on: "We think milk is a precious foodstuff. If you pay more for it, you value it more. You use it more thoughtfully. It should be treated with respect."
Tent Girl. The Lady of the Dunes. The Head in the Bucket. These are just a few of the nicknames given to America's 40,000 unidentified corpses by amateur web sleuths. For decades, members of this thriving, heroic, and macabre internet subculture have been cracking cold cases that have long stumped law enforcement. But what motivates them to spend countless hours poring over police reports and autopsy photos? Deborah Halber replaces the classic whodunit with what you might call a whosolvesit. She discovers that many web sleuths throw themselves into their dark hobby to escape their own damaged lives. Some find their share of fame and fortune; others, only more demons.