By now everybody reading this is probably familiar with the theory, popularized in Freakonomics, that legalized abortion was the key factor in the dramatic fall in U.S. crime rates in the 1990s. But as I wrote back in 2005, I've always found the lead hypothesis more compelling -- high exposures to lead in paint and gasoline helped fuel the dramatic rise in violent crime in the 1960s and '70s, and the fall in crime could be attributed to the switch to unleaded gasoline and lead-free paint.

The Freakonomics guys have tackled this issue on their blog here, without a lot of passion for the hypothesis. (Just for the sake of completeness, they wrote about the possible effect that falling abortion rates might have on future levels of crime here.)

I bring all this up because the lead-crime link is in the news again today:

Two studies showed that people with high levels of lead in childhood grew up with blocks of missing brain cells -- and they also were far more likely to be arrested for crimes, especially violent crimes.

The effect is so strong that it may account for a large percentage of crimes in inner-city areas, where old houses are far more likely to have lead paint, said Kim Dietrich of the University of Cincinnati in Ohio, who led one of the studies in the Public Library of Science journal PLoS Medicine.

"There are some data that suggest that in fact lead does run in parallel with crime trends over the past several decades," Dietrich said in a telephone interview.

The interesting finding here is that lead exposure permanently wipes out an entire section of cells in the brain, and that the damage is usually irreversible.

Then there's this:

In a third, unrelated study, a team of University of Pittsburgh researchers showed adults can be inoculated with a second wave of lead as they get older.

Writing in the Archives of Environmental and Occupational Health, Lisa Morrow and colleagues showed that lead can leach into the blood from bones as people age and lose bone mass.

By pure coincidence, I spent part of the afternoon yesterday hunting down information about how the aging brain is affected by a lack of exercise, and how that ties into falls and loss of functional abilities.

It's easy enough to say that a lack of serious exercise will lead to a cascade of problems, including loss of strength and power, a slower metabolism, a decline in balance, and smaller, more brittle bones.

But I've never considered the possibility that those shrinking bones could spill some nasty toxins back out into an aging person's blood. Could that possibly explain, in some minor way, why exercise helps prevent dementia in old age?

Or, to put it another way, could this help us understand why sedentary behavior is so strongly linked to Alzheimer's?

Wednesday blog meat:

* Also worth noting today: child obesity rates seem to be leveling off.

* A new study suggests that a person with ADHD costs his or her employer more than 20 days a year in absence or lost productivity. The news reports don't specifically say it, but I have to think employers would leap at the chance to get a few more employees on Ritalin. Now I'm waiting for the study that shows employees with ADHD who're being treated with stimulants outperform their neurotypical colleagues.

Interest in health and fitness moves in cycles, a phenomenon I wrote about on my old blog here and here. We're now at, or nearing the end of, an intense, vigorous cycle of interest in fitness and nutrition -- a period that, ironically enough, saw a tremendous surge in obesity rates.

If these things follow society-wide trends, then it would make sense to see them play out at the micro level -- among friends and family members. And, indeed, last summer researchers published a study suggesting that obesity spreads along social networks. (I wrote about that study on the new MPF here and here.)

Last week, those same researchers came out with a study suggesting that the same phenomenom occurs with smokers who want to quit. So, if the researchers are correct in their methodology and conclusions, the patterns show that people quit smoking in clusters based on their social networks -- the more unacceptable smoking became, the more socially isolated the non-smokers became. Similarly, as obesity became more normal and thus acceptable, people gained weight in patterns that also follow social networks.

In today's Washington Post, reporter Rob Stein tries to make sense of the issue:

Taken together, these studies and others are fueling a growing recognition that many behaviors are swayed by social networks in ways that have not been fully understood. And it may be possible, the researchers say, to harness the power of these networks for many purposes, such as encouraging safe sex, getting more people to exercise or even fighting crime.

"What all these studies do is force us to start to kind of rethink our mental model of how we behave," said Duncan Watts, a Columbia University sociologist. "Public policy in general treats people as if they are sort of atomized individuals and puts policies in place to try to get them to stop smoking, eat right, start exercising or make better decisions about retirement, et cetera. What we see in this research is that we are missing a lot of what is happening if we think only that way."

My immediate hunch is that public-policy decision-makers have perhaps cast too wide a net. If we're talking about social networks, then we know that certain individuals hold more important positions than others within each network. Marketing researchers know this already, and Malcolm Gladwell illustrated the phenomenon in The Tipping Point.

The key, then, is to target the most influential individuals within social networks. But how? I'll try to wonk it out a little, and then you can take over in comments.

Let's say that the problem we're addressing is obesity. First, we have to figure out who's gaining the most weight, and who's at the greatest health risk from that weight gain. Since we know that obesity is a bigger problem among the least educated and the least affluent, we probably should start with them.

If I were a marketing researcher, I'd probably want to look at social networks among blue-collar workers, and then figure out who's most influential within those networks. Coworkers? Pastors? Family members? Neighbors? Then I'd ask if the social networks are different for white, black, and Latino populations, for males vs. females, urban vs. rural, old vs. young, and first-generation immigrants vs. those who've been here longer.

Once I knew all that, I'd try to figure out how the most influential members of the various social networks get their information. TV? Radio? Church? Word of mouth within the workplace or neighborhood?

Only then would I be able to tackle the biggest challenge of all: crafting a message that's appropriate for the medium and that would actually influence the people I'm targeting.

But what if I got to the end of the process and realized there's no actionable message to deliver? I started my marketing research with the understanding that obesity is disproportionately a problem among the least educated and least affluent. What do I do if my research suggests that education and income aren't just symptoms, but are in fact the problem?

We've all heard a survival story or two about someone who survived a calamity by drinking his own urine. If nothing else, it prevents dehydration. Some have even suggested that urine has health benefits that go beyond mere survival in desperate circumstances.

Slate's Explainer column puts the kibosh on that idea:

A healthy person's urine is about 95 percent water and sterile, so in the short term it's safe to drink and does replenish lost water. But the other 5 percent of urine comprises a diverse collection of waste products, including nitrogen, potassium, and calcium -- and too much of these can cause problems. When you drink your own pee, all the stuff that your kidneys had attempted to excrete comes right back into your stomach, and much of it ends up back in your kidneys. After several days of this, your urine will become highly concentrated with dangerous waste products, and drinking it can cause symptoms similar to those brought on by total kidney failure. At that point, you're doomed either way -- from dehydration on the one hand or renal meltdown on the other. (Even if one could filter out most of the unwanted products in urine, the cycle would not be sustainable for long. In addition to what he or she pees out, the average human excretes about half a quart of water a day through sweating and exhaling.)

This is my favorite part:

Drinking urine can be especially dangerous for survivors of crushing injuries. When muscle fibers are damaged, the cells can begin leaking potassium and phosphorous into the bloodstream. Even a victim with healthy kidneys might not be able to clear the dangerous build-up; someone who had been drinking his own urine would be at much greater risk. (For the same reason, a person drinking his own urine should stay away from high-potassium foods like bananas.)

So I guess I have to abandon the idea I had for my next book: The Super-Pee Diet: Lose Weight With Potassium!

Thursday blog meat:

* A new study demonstrates that smoking is a social thing -- people used to smoke in clusters, then subsequently quit in clusters. The downside? Socially marginalized people who continue to smoke are further marginalized.

* Don't taze me, bro! Those things can kill you.

I don't associate Indiana Jones with fast food. He strikes me as more of a hunter-gatherer type than a drive-through guy. But that hasn't stopped the filmmakers who created him from tying their franchise to burgers and candy bars, and physician Rahul Parikh, writing for Salon, calls them on it:

I'm a pediatrician, and every day I see overweight kids coming into my office. Getting families and kids to change how they eat is an uphill battle, and it doesn't get easier when big studios like yours wheel and deal with companies that peddle junk food and fast food.

You tied Star Wars to Pepsi and Frito-Lay, plastering Yoda and Obi-Wan over 2-liter bottles and Doritos bags. Recently I was watching CNBC and saw the chief marketing officer of Burger King unveil the Indy Whopper, a mammoth, juicy burger with pepper jack cheese and jalapeño sauce (to give it "adventure," the CMO pointed out), a tie-in to Indiana Jones and the Kingdom of the Crystal Skull. I see you also got Mars to manufacture a Snicker's Adventure Bar with coconut and chai that has Dr. Jones' face on the wrapper.

Besides the fact that none of these foods is healthy, one has to ask if they're what your characters would eat. Would Lord Vader chug down a Pepsi before he wielded his light saber? (If he did, would he drink it with a straw or take off his entire mask?) Wouldn't Indy, now a senior citizen, have more than just a little bump in his cholesterol if he had scarfed down his namesake burger with fries and a soda? How could he be fit enough to chase down ancient relics while dodging boulders and outwitting Nazis?

I agree wholeheartedly with Dr. Parikh, and I recommend reading the entire essay. But it also brings to mind a growing problem with fast food that may end up being a  good thing for the rest of us: the utter incompetence of fast-food restaurants to deliver food fast.

I should preface this by saying that I've worked more minimum-wage jobs than I can recall. A lot of them were in food service -- everything from a greasy smorgasbord in Barnhart, Missouri, to the five-star Hotel Bel-Air in Los Angeles.

In college I worked at McDonald's, where I came to understand how hard and thankless a job it is to flip hundreds of burgers in a single shift. I don't know how it works now, but back then the guy working the burger grill had four or five different timers whose beeps governed his actions. You miss one beep from one timer, and you mess the whole thing up.

On top of that, you had a manager who directed the volume of the burgers you flipped. In the middle of the lunch or dinner rush, you went to what was called "turn/lay," which means you threw down a new set of frozen burger patties as soon as you flipped the last set. That may have been the most profound stress-hormone-generating system I've ever encountered, because now you had those four or five timers overlapping each other. If you stopped to think about any part of the process, you were screwed.

I mention all this because I think I understand as well as anyone my age just how hard it is to do fast food right. And, increasingly, fast-food restaurants demonstrate that they simply can't get it right anymore.

My kids love Wendy's, and I confess that in a pinch I'll settle for one of their burgers. But Wendy's never ever gets our family's order right. I shit you not: It's been years since we've gotten what we ordered from a Wendy's drive-through. And it's not just Wendy's. Our local Boston Market has gone from "erratic" to "consistently bad" when it comes to filling our orders. We never ate a lot of fast food, but now we go weeks at a time without having any.

If my experiences reflect a real trend, then the Phantom Menace of fast food may kill itself off with incompetence before it kills the rest of us off with crappy food.

Wednesday blog meat:

* The major health threat du jour: Fruit smoothies rot your teeth! The fix is pretty simple -- just brush your teeth. 

* I love this headline: "Teen sex study doubts 'technical virginity'." (If I wanted to triple the number of unique visitors to MPF today, I'd explain what the headline means.)

When Viagra first hit the pharmacies, I remember thinking, "There has to be a catch." I had just started working at Men's Health, and my colleagues and I wondered what the potential downsides could be. I'm not sure if I had this particular thought at the time, but at some point I equated Viagra with liposuction: Some of the people who got the operation or used the pill were probably ignoring symptoms of bigger problems.

Someone getting lipo might have problems that could be (and probably should be) addressed with diet and exercise. But what about the guy who needs Viagra to pop wood? Soon enough, doctors began to talk about some of the problems commonly associated with erectile dysfunction, including heart disease and diabetes. If someone can take a pill to change a licorice whip into a meat stick, there's less motivation to deal with the underlying medical issues that kept Chubby from inflating in the first place.

So it's not surprising to see this new report:

Findings from two studies of men with diabetes add to the evidence that erectile dysfunction can be a powerful early warning sign for serious heart disease.

A Hong Kong study of 2,306 men with diabetes but no signs of heart disease found that those with erectile dysfunction at the start were 58 percent more likely to have a heart attack or other major cardiac problem over the next four years than those with adequate sexual function.

And Italian physicians who followed 291 men who had diabetes and early coronary heart disease for four years reported similar numbers -- those with erectile dysfunction were twice as likely as men without the problem to have major adverse events, including strokes.

Here's why this information matters:

"These reports add two things to what we already know," said Dr. R. Parker Ward, an associate professor of medicine at the University of Chicago, who led an earlier study linking erectile dysfunction with heart disease. "One is that they indicate the importance of erectile dysfunction in diabetic patients in terms of predicting future cardiovascular events. These studies suggest that the additional presence of erectile dysfunction places them at incrementally higher risk. Secondly, they show that even when considered in combination with traditional risk factors, erectile dysfunction offers incremental information about the risk of future cardiovascular events."

As it happens, this seemingly unrelated story appeared right below the one I just highlighted on the Google News search engine this morning:

A Catholic priest has filed a restraining order against the parents of a severely autistic 13-year-old boy in an effort to keep him from attending the church in Bertha on Sundays.

The Rev. Daniel Walz alleges that Adam Race's unruly behavior endangers others who attend the Church of St. Joseph.

There's no real connection here, except it made me think back to my own Catholic upbringing. Typically, families in our parishes had more kids than you could count on one hand. In other words, not a lot of erectile dysfunction going on there. I think the credit goes to the tradition of telling young Catholics early and often about the evils of sex. The more you condemn it, the more enticing it becomes, and soon you have entire generations of male Catholics thinking about sex all day and ejaculating as many times as humanly possible at night.

Of course I'm mostly just joking here -- I assume Catholic men have as much ED as anyone else. (And I'd hate to be the one who had to decide whether or not an autistic teen can attend Mass, no matter how disruptive he is.) But on the bright side, those frequent ejaculations do seem to have long-term benefit to the furtive wankers who induce them.

So there's that.

Tuesday blog meat:

* Most people talk about losing one's marbles as if it's a bad thing. Not necessarily.

* Presidential health: It's too important to leave to the president's personal physician.

My two daughters share a room, where they sleep in bunk beds -- older daughter on top, younger daughter on the bottom bunk. Here's how they started the morning when I went in to wake them up:

Younger daughter, to me: "I had trouble sleeping last night because my belly hurt."

Older daughter: "Did not!"

How 'bout those reflexes? All she had to hear was "trouble sleeping" and she automatically went on the attack, assuming she was being blamed for something.

As it happens, I had just clicked on this story when it came time to wake them up:

Women who are stressed about money, relationships and other problems during pregnancy may give birth to babies who are predisposed to allergies and asthma, U.S. researchers said on Sunday.

The findings, presented at a meeting of the American Thoracic Society in Toronto, suggest a mother's stress during pregnancy may have lasting consequences for her child.

"This research adds to a growing body of evidence that links maternal stress such as that precipitated by financial problems or relationship issues to changes in children's developing immune systems, even during pregnancy," Dr. Rosalind Wright of Harvard Medical School in Boston said in a statement.

Wright and colleagues found mothers who were the most distressed during pregnancy were most likely to give birth to infants with higher levels of immunoglobulin E or IgE -- an immune system compound -- even though their mothers had only mild exposure to allergens during pregnancy.

Studies in animals have found that a mother's stress amplifies the effects of allergen exposure on the immune system of the developing offspring. The Harvard team set out to see if they could find the same in humans.

This makes sense to me given my family's history. My older brother was born in 1955 in the hospital at Guantanamo Bay Naval Base, Cuba, while my father was serving with the marines. That was two years after the start of the Cuban Revolution; Fidel Castro was released from prison a couple months before my brother was born.

As you can imagine, that would be somewhat stressful for a young mother who's pregnant with her second child. And my brother ended up having a lot of problems with allergies and asthma as a kid.

Which brings me back to my daughters, and a question left over from the research:

Is it possible for the process to work in reverse? Can kids who create stress for their parents give the adults more severe allergies than they already have? I feel an attack coming on ...

Monday blog meat

* In praise of (natural) trans fats.

* Apple and grape juice may prevent arterial blockages. I guess that means they're slightly better for you than packets of granulated sugar.

Rob Siders  sent along this hilarious look at seven pieces of fitness equipment being sold to consumers. All seven are, bottom line, basic things we all have sitting around our homes.

My favorite is the Bender Ball, which the author, Glenn Thompson, describes here:

A recent trend in fitness has been the emphasis on developing core strength. A popular way of doing this is to perform exercise movements while balancing yourself on a ball, which forces various muscles to help stabilize you. The Bender Ball is a tiny version of the bigger ball that you can already find a typical gym, and it apparently gives you ridiculous abs and a sports bra.

(You have to check out the video  for that line about abs and a sports bra to pay off.)

Read the whole thing for pure entertainment value, and then use the Comments to share your own ideas for useless and obvious fitness equipment based on stuff you have gathering dust in your basement.

My big idea is the Squat Stick. It's just a broomstick for overhead squats , but I think the profit margin would be fantastic.

Okay, so we didn't switch over to the new software platform last night. Apparently there was a power outage in Austin, Texas, and that somehow threw everything off. It's kind of complicated, which means it's so far over my head I can't see it without binoculars.

So, with apologies for the delay, yesterday's warning is now tonight's warning: The site will be dark for a few hours, and by Friday morning you should see the new, improved MPF.

An Australian researcher has an idea:

Hard-hitting messages like ... what? "Feel bad about yourself because you have a genetic predisposition to gain weight and your parents fed you crap"?

When I was growing up, smoking was acceptable everywhere. I woke up every morning to the smell of my parents smoking at the breakfast table. (To this day, I don't drink coffee, since I associate coffee with cigarettes. That's how I became a Diet Coke addict.) I remember sitting on a bench in a shopping mall -- I was probably 14 -- and waving away the smoke of the person who'd sat down next to me. The smoker looked at me with pure contempt and said, "You could move, you know."

The problem was me, not him or his habit. Smokers ruled the known world. It was unfathomable to them that nonsmokers were repelled by the noxious fumes they emitted.

Today, as we all know, smokers are increasingly cut off from the rest of us. Not only is it forbidden in offices and restaurants, but you can't even smoke in many of the parks where our kids play sports. Smoking in public is so rare that my kids point it out with disgust every time they see it.

But how do you point out someone in the process of getting fat? A cigarette is a cigarette, and you know it when you see or smell it. But who's to say what types of food are making any individual person gain unhealthy amounts of weight? Do you outlaw eating fast food in public? Tax it until it's unaffordable? Do you go after high-fat food? High carbs? Do you tell people who're sitting down that they need to be up and moving? And if you're going to do that, how do you distinguish between people who're resting and those who haven't done anything to make them fatigued in the first place?

Really, what we're talking about here is pointing a finger at people who're already overweight. Otherwise, I can't see how you distinguish between food that's being eaten for sustenance and food that's being converted to body fat. I sometimes eat fast food when it's the only practical choice -- you probably do too. So is somebody going to tell me and my skinny kids that we can't eat the only available food when we're hungry? Or will they ignore us and pick on the overweight people at the next table or park bench?

Same with physical activity: We'd have to put the pressure on people who're overweight, and ignore sedentary people who, thanks to a lucky roll of the genetic dice, stay thin without exercise.

More to the point: When we marginalize smokers, we don't really marginalize the fact of their addiction. We don't forbid the wearing of nicotine patches or the chewing of Nicorette gum in public places. We say "no smoking," and that's it.

But if we're going to follow that same path in the fight against obesity, we eventually have to turn on obese people and marginalize them. And, really, I can't think of a worse way to achieve an otherwise admirable public-health imperative.

Wednesday blog meat

• Is it my imagination, or did Gina Kolata just write the perfect advertisement for The New Rules of Lifting for Women? Would've been nice if she'd mentioned the book, but if readers take the article as a call for action, they should be able to find it with a quick Google search.
• Unintentionally funny photo caption: "Executing a push-up like this ratchets up the difficulty level ..." Gee, ya think? (This only makes sense if you click on the link and see the photo.)
• This site will be dark for a few hours tonight, and then relaunch on Thursday with a new software platform that should make it even easier for you to contribute news, opinions, and even photos. If you want to see examples of the new platform, check out some of the SB Nation baseball blogs. (Viva El Birdos, the St. Louis Cardinals blog, is my favorite.) Posting with the new software should make things a lot easier and faster for me, which means I'll be able to write more posts than I do now. With the current software, I have to do all the HTML coding with the cut-and-paste method, which means I write everything in a Word file and then transfer it to MPF, which takes twice as much time and effort as I used to invest on the original MPF. It's been worth it to me because so many more people see what I write on the new site, and it's so much easier for readers to post replies and participate in the conversation. The new software should give me -- and us -- the best of both worlds: I'll be able to post faster and more often, and you'll still be able to jump in and tell me how stupid I am whenever the need arises.
  

If you have a daughter who plays sports, and haven't yet seen Michael Sokolove's feature about girls and knee injuries in the New York Times Magazine, you should drop what you're doing and read it now.

Here's how Sokolove describes the crux of the problem (and I do mean "crux," since we're talking about injuries to the anterior cruciate ligament):

Here's how serious the injury risk is for young female athletes:

One part that will probably catch a lot of readers by surprise is the assertion that parents aren't the ones pushing girls to play more and play harder:

I can vouch for this. My older daughter is the athletic adventurer in our family. She taught herself to ride a two-wheeler at 5, and when she was 7 was the first kid in her league to head the ball in a soccer game. (It went out of bounds. I think it took her two more years before she successfully headed a ball in the right direction.) Out of the blue, she'll try to do one-arm push-ups, or announce that she wants to take up fencing. It's always a surprise. Her team had a really bad game on Saturday morning, but in the last five minutes of the first half she played the best soccer of her life so far. Her coach once compared her to Rudy: She's small for her age, and not nearly as fast or skilled as the best players in her league. But when she's on, she competes as hard as anybody.

By contrast, my younger daughter has almost no competitive instincts at all. She's regressed as a soccer player this year, and has already said she doesn't want to play next year. She wants to take an extra ballet class instead, which is fine with me. There are plenty of injury risks with ballet, but since the whole point is to move with full control over the body, the risk of catastrophic injury to knee ligaments is a lot lower.

No matter what, with kids and sports it's always an adventure, and there's always something to worry about. But it beats the hell out of the alternative, doesn't it?

Monday blog meat

• From the Freakonomics blog: a primer on primates.
• From T-nation: perhaps the best collection of push-up variations ever compiled.