As income rises, the frequency of fast food visits rise as well, at least until income hits $60,000 a year; sit-down restaurant visits just keep on rising. (The y axis is frequency of visits.)

Obesity rates in the United States are highest among the poor, and high up on most lists of reasons why, you’ll find the truism that fast food is cheap food, and the poor, who can’t afford healthier fare, are its main consumers. A new study suggests, however, that the people eating the most fast food are middle class, with incomes as high as $60,000 a year. Using a national database of about 5,000 people, researchers at UC Davis found that the frequency of people’s visits to fast-food restaurants increased with rising household income until $60,000, when frequency started to go down (though, interestingly, people making more than $100,000 still went to fast food more than those making $20,000). Visits to sit-down restaurants, on the other hand, increased with rising income and just kept on growing.

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Last fall, it came to light that researchers had infected 700 Guatemalan soldiers, prisoners, and mental patients with syphilis in a US Public Health Service study between 1946 and 1948. The American government apologized  for these “abhorrent” practices, and promised to investigate what had happened. A White House bioethics commission released its report on the study this Tuesday—and as horrific as the experiments sounded initially, the full story is even worse.

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Crystals of smashed cement, the perfect size for lodging in lungs,
made up most of the dust rising from the World Trade Center.

When ten million of tons of building, mixed with 91,000 liters of jet fuel, collapse into a smoking heap, an incredible variety of pulverized materials rise into the air. Though no one took samples of the plume that rose up from the World Trade Center on 9/11, samples of the dust that filtered down in the following days and gas emanating from the pile have given a glimpse of what rescue workers and others breathed in: heavy metals from computers, cellulose from paper, shards of metal and stone from the buildings’ walls, calcium carbonate from the tons of smashed cement, fibers from rugs, fragments of glass and burned hair.

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Swine flu is not gone, and it is not stagnant. Though the public health scare about the 2009 swine flu pandemic subsided, the virus—like avian flu—remains in pockets of animals, shuffling its genes while hidden from the watchful eyes of virus experts. Virologists call this genetic switcheroo “reassortment,” and it’s how new and dangerous strains of flu snuck up on humankind in the past—and how they could do it again. This time, though, virologist Jinhua Liu and colleagues are trying to get a jump on the viruses.

For a new study in the Proceedings of the National Academy of Sciences today, this team of Chinese researchers simulated what could be a dire situation for humans: swine flu (H1N1) and avian flu (H9N2) together in one animal. When these flu strains are together they can exchange genetic material. So to test what that mixing might produce, Liu’s team swapped genes between the two and created 127 hybrid viruses, testing each on mice.

Eight of these hybrid strains turned out to be more virulent and dangerous in the mice than their parent strains of swine flu and bird flu. [National Geographic]

According to Dutch virologist Ab Osterhaus, we can’t be sure that these eight nasty strains are the ones that would hit humans hardest—animal studies aren’t perfect.

“Mice mirror, to a certain extent, what happens in humans,” he says, but they are not perfect model animals. Liu agrees. He plans to investigate how contagious his new viral blends are in guinea pigs and ferrets—animals whose respiratory system better reflects our own feverish battle with flu. [ScienceNOW]

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Dialysis can be a life-saver for people with kidney failure, but according to a major investigation, the way we do it and finance it in this country is a total mess.

Writing in The Atlantic, reporter Robin Fields of the nonprofit investigate journalism group ProPublica lays out her long investigation into dialysis. Though the procedure since 1972 has been the only one guaranteed universal coverage to all Americans through Medicare, Fields finds it disturbingly inefficient, with one in four American patient dying within a year of beginning treatment:

Now, almost four decades later, a program once envisioned as a model for a national health-care system has evolved into a hulking monster. Taxpayers spend more than $20 billion a year to care for those on dialysis—about $77,000 per patient, more, by some accounts, than any other nation. Yet the United States continues to have one of the industrialized world’s highest mortality rates for dialysis care. Even taking into account differences in patient characteristics, studies suggest that if our system performed as well as Italy’s, or France’s, or Japan’s, thousands fewer kidney patients would die each year. [The Atlantic]

How did things go so awry? Medicare mandated coverage, the investigation finds, but it did not properly mandate how the clinics spent Medicare’s money.

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Girls around the country are starting puberty ever younger, says a new study out in Pediatrics.

Researchers led by Frank Biro studied more than a thousand girls between six and eight years old from New York, Cincinnati, and San Francisco. Their findings: By the age of 7, about 23 percent of black girls, 15 percent of Hispanic girls, and 11 percent of white girls showed enough breast development to be considered pubescent. Those numbers are even more extreme than the findings of a similar 1997 study that seemed to show the age entering puberty was dropping fast.

Says Biro:

“In 1997, people said, ‘That can’t be right; there must be something wrong with the study’. But the average age is going down even further” [Los Angeles Times].

The starkness of Biro’s statistics has drawn plenty of attention. But just what it means is a difficult question, because there’s no “ideal” age for entering puberty.

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The Environmental Protection Agency has announced its proposal to toughen up the standards for smog-causing pollutants, which would replace the standards set during the Bush administration.

The Obama administration’s proposal sets a primary standard for ground-level ozone of no more than 0.060 to 0.070 parts per million, to be phased in over two decades. Regions with the worst smog pollution, including much of the Northeast, Southern and Central California and the Chicago and Houston areas, would have more time than other areas to come into compliance [The New York Times]. The previous standard was 0.075 parts per million, set in 2008 despite government scientists’ objection that it was not strict enough. Smog is formed when a stew of nitrogen oxides, volatile organic compounds, carbon monoxide, and methane is baked in sunlight.

The new standard won’t be cheap, but proponents say it will save money, and lives, in the long run. The EPA estimates that by 2020 the proposal will cost $19 billion to $90 billion to implement and will yield health benefits worth $13 billion to $100 billion. The proposal would result in 1,500 to 12,000 avoided premature deaths by 2020, though the precise number depends on what limit the agency adopts [Washington Post]. Smog is linked to a wide variety of heart and respiratory diseases. Currently, a majority of the counties that are required to monitor ozone levels would not meet the new standard. If the 0.070 limit is adopted, 515 of the 675 counties that monitor ozone levels would be out of compliance.

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