Saturday, December 4, 2010

Humanity's Future: Information Overload

Robert Tercek
At H+ at Caltech (#hplus) this morning, Robert Tercek gave us an introduction to humanity as we know it and how a sudden increase of information will transform it forever.

"The process of improving human life has always been governed by information," Tercek said. Now we're in this new information transformation age, or what he calls living in the era of B.S., or "before singularity."

Just as electricity, vaccines and plumbing once radically changed health of humans in history, we will eventually gain the knowledge to completely change the way we think about health, as well as radically increase the human lifespan in the future.

It will happen by using anti-aging therapies like those posed by Aubrey de Grey, as well as other scientists, increasing knowledge about the human genome, or in other ways never before thought.

Plus, these huge increases of info are changing life as we know it in other ways; for example, the way we use energy today. "We're going to look back at this period and see it as tremendously inefficient," Tercek said.

Tercek goes on about how information drives the advance of civilization. The first major one was speech, followed by writing, for example.

And he points out pretty amazing facts about how the Internet is wiring the world:

- we have people tweeting and blogging, communicating to the world right now
- 35 hours is being uploaded to YouTube per minute
- Facebook sees 2.5 billion uploads of photos per month
- we'll eventually upload all of humanity's knowledge from universities to the Internet.

"Every 2 days we create as much information as we did up to 2003," Tercek said, which is the most info created in all of human history, a history that has been bound by the limitations of the book for the last 500 years. 

"If you look at the advances of the last 15 years and look at the next 15," Tercek said, this gives us quite a lot of reason to be amazed about what the future will bring. 

Then, Tercek gave several more examples of how past advances in increasing information changed the world like the printing press, and how new technologies using "metadata" like mobile devices are changing the world again. 

Plus, he gives us a picture of the future with automated cars (that you can program to pick you up using your iPad), and mentions also Sixth Sense mobile interfaces (which is what I happen to want for Xmas this year). 

In short, information overload is going to make life pretty cool in the future. 

Thursday, December 2, 2010

How lean should one be?

Loss of muscle mass is associated with aging. It is also associated with the metabolic syndrome, together with excessive body fat gain. It is safe to assume that having low muscle and high fat mass, at the same time, is undesirable.

The extreme opposite of that, achievable though natural means, would be to have as much muscle as possible and as low body fat as possible. People who achieve that extreme often look a bit like “buff skeletons”.

This post assumes that increasing muscle mass through strength training and proper nutrition is healthy. It looks into body fat levels, specifically how low body fat would have to be for health to be maximized.

I am happy to acknowledge that quite often I am working on other things and then become interested in a topic that is brought up by Richard Nikoley, and discussed by his readers (I am one of them). This post is a good example of that.

Obesity and the diseases of civilization

Obesity is strongly associated with the diseases of civilization, of which the prototypical example is perhaps type 2 diabetes. So much so that sometimes the impression one gets is that without first becoming obese, one cannot develop any of the diseases of civilization.

But this is not really true. For example, diabetes type 1 is also one of the diseases of civilization, and it often strikes thin people. Diabetes type 1 results from the destruction of the beta cells in the pancreas by a person’s own immune system. The beta cells in the pancreas produce insulin, which regulates blood glucose levels.

Still, obesity is undeniably a major risk factor for the diseases of civilization. It seems reasonable to want to move away from it. But how much? How lean should one be to be as healthy as possible? Given the ubiquity of U-curve relationships among health variables, there should be a limit below which health starts deteriorating.

Is the level of body fat of the gentleman on the photo below (from: ufcbettingtoday.com) low enough? His name is Fedor; more on him below. I tend to admire people who excel in narrow fields, be they intellectual or sport-related, even if I do not do anything remotely similar in my spare time. I admire Fedor.


Let us look at some research and anecdotal evidence to see if we can answer the question above.

The buff skeleton look is often perceived as somewhat unattractive

Being in the minority is not being wrong, but should make one think. Like Richard Nikoley’s, my own perception of the physique of men and women is that, the leaner they are, the better; as long as they also have a reasonable amount of muscle. That is, in my mind, the look of a stage-ready competitive natural bodybuilder is close to the healthiest look possible.

The majority’s opinion, however, seems different, at least anecdotally. The majority of women that I hear or read voicing their opinions on this matter seem to find the “buff skeleton” look somewhat unattractive, compared with a more average fit or athletic look. The same seems to be true for perceptions of males about females.

A little side note. From an evolutionary perspective, perceptions of ancestral women about men must have been much more important than perceptions of ancestral men about women. The reason is that the ancestral women were the ones applying sexual selection pressures in our ancestral past.

For the sake of discussion, let us define the buff skeleton look as one of a reasonably muscular person with a very low body fat percentage; pretty much only essential fat. That would be 10-13 percent for women, and 5-8 percent for men.

The average fit look would be 21-24 percent for women, and 14-17 percent for men. Somewhere in between, would be what we could call the athletic look, namely 14-20 percent for women, and 6-13 percent for men. These levels are exactly the ones posted on this Wikipedia article on body fat percentages, at the time of writing.

From an evolutionary perspective, attractiveness to members of the opposite sex should be correlated with health. Unless we are talking about a costly trait used in sexual selection by our ancestors; something analogous to the male peacock’s train.

But costly traits are usually ornamental, and are often perceived as attractive even in exaggerated forms. What prevents male peacock trains from becoming the size of a mountain is that they also impair survival. Otherwise they would keep growing. The peahens find them sexy.

Being ripped is not always associated with better athletic performance

Then there is the argument that if you carried some extra fat around the waist, then you would not be able to fight, hunt etc. as effectively as you could if you were living 500,000 years ago. Evolution does not “like” that, so it is an unnatural and maladaptive state achieved by modern humans.

Well, certainly the sport of mixed martial arts (MMA) is not the best point of comparison for Paleolithic life, but it is not such a bad model either. Look at this photo of Fedor Emelianenko (on the left, clearly not so lean) next to Andrei Arlovski (fairly lean). Fedor is also the one on the photo at the beginning of this post.

Fedor weighed about 220 lbs at 6’; Arlovski 250 lbs at 6’4’’. In fact, Arlovski is one of the leanest and most muscular MMA heavyweights, and also one of the most highly ranked. Now look at Fedor in action (see this YouTube video), including what happened when Fedor fought Arlovski, at around the 4:28 mark. Fedor won by knockout.

Both Fedor and Arlovski are heavyweights; which means that they do not have to “make weight”. That is, they do not have to lose weight to abide by the regulations of their weight category. Since both are professional MMA fighters, among the very best in the world, the weight at which they compete is generally the weight that is associated with their best performance.

Fedor was practically unbeaten until recently, even though he faced a very high level of competition. Before Fedor there was another professional fighter that many thought was from Russia, and who ruled the MMA heavyweight scene for a while. His name is Igor Vovchanchyn, and he is from the Ukraine. At 5’8’’ and 230 lbs in his prime, he was a bit chubby. This YouTube video shows him in action; and it is brutal.

A BMI of about 25 seems to be the healthiest for long-term survival

Then we have this post by Stargazey, a blogger who likes science. Toward the end the post she discusses a study suggesting that a body mass index (BMI) of about 25 seems to be the healthiest for long-term survival. That BMI is between normal weight and overweight. The study suggests that both being underweight or obese is unhealthy, in terms of long-term survival.

The BMI is calculated as an individual’s body weight divided by the square of the individual’s height. A limitation of its use here is that the BMI is a more reliable proxy for body fat percentage for women than for men, and can be particularly misleading when applied to muscular men.

The traditional Okinawans are not super lean

The traditional Okinawans (here is a good YouTube video) are the longest living people in the world. Yet, they are not super lean, not even close. They are not obese either. The traditional Okinawans are those who kept to their traditional diet and lifestyle, which seems to be less and less common these days.

There are better videos on the web that could be used to illustrate this point. Some even showing shirtless traditional karate instructors and students from Okinawa, which I had seen before but could not find again. Nearly all of those karate instructors and students were a bit chubby, but not obese. By the way, karate was invented in Okinawa.

The fact that the traditional Okinawans are not ripped does not mean that the level of fat that is healthy for them is also healthy for someone with a different genetic makeup. It is important to remember that the traditional Okinawans share a common ancestry.

What does this all mean?

Some speculation below, but before that let me tell this: as counterintuitive as it may sound, excessive abdominal fat may be associated with higher insulin sensitivity in some cases. This post discusses a study in which the members of a treatment group were more insulin sensitive than the members of a control group, even though the former were much fatter; particularly in terms of abdominal fat.

It is possible that the buff skeleton look is often perceived as somewhat unattractive because of cultural reasons, and that it is associated with the healthiest state for humans. However, it seems a bit unlikely that this applies as a general rule to everybody.

Another possibility, which appears to be more reasonable, is that the buff skeleton look is healthy for some, and not for others. After all, body fat percentage, like fat distribution, seems to be strongly influenced by our genes. We can adapt in ways that go against genetic pressures, but that may be costly in some cases.

There is a great deal of genetic variation in the human species, and much of it may be due to relatively recent evolutionary pressures.

Life is not that simple!

References

Buss, D.M. (1995). The evolution of desire: Strategies of human mating. New York, NY: Basic Books.

Cartwright, J. (2000). Evolution and human behavior: Darwinian perspectives on human nature. Cambridge, MA: The MIT Press.

Miller, G.F. (2000). The mating mind: How sexual choice shaped the evolution of human nature. New York, NY: Doubleday.

Zahavi, A. & Zahavi, A. (1997). The Handicap Principle: A missing piece of Darwin’s puzzle. Oxford, England: Oxford University Press.

Tuesday, November 30, 2010

New vitamin D guidelines, a disappointment

Over the past decade, there has been tremendous excitement in the world of nutrition centered around the "sunshine vitamin" for its association with reducing risk of influenza, osteoporosis, autoimmune diseases, heart disease, and even some cancers such as prostate and breast cancer. 

However, this morning, the Institute of Medicine, of the National Academy of Sciences released new guidelines for vitamin D (and calcium) that will come as a disappointment to several researchers who consider the report too conservative to deal with a widespread epidemic.

"Vitamin D is the most common medical condition in the world, believe it or not" said Michael Holick, of Boston University Medical Center, to me in a recent interview. Holick, who routinely prescribes 2000-3000 IU per day to his patients, has studied Vitamin D for more than 40 years. In the 1970s he was the first to isolate the major circulating form of Vitamin D in plasma, 25-hydroxyvitamin D, as well as the active form produced in the kidneys. 

In his recently published book, The Vitamin D Solution, Holick cites evidence that: 
  • Half of all children in the US and Europe are Vitamin D deficient at some time, but almost every single one has vitamin D insufficiency.
  • Over the last 10 years there's been 22 percent reduced levels of vitamin D in the US
  • Last year, a study published in Archives of Internal Medicine, showed 70 percent of whites, 90 percent of Hispanics and 97 percent of blacks in the US have insufficient levels.
  • Even near the equator (where you'd think people were getting plenty of sun –think Saudi Arabia, India, Australia, Brazil, Mexico – between 30 to 80 percent of children and adults are deficient or insufficient.
  • Three out of four people in the US are deficient, most are insufficient. Twenty years ago it was only 1 out of 2.
  • New research has linked several common problems of poor health and accelerated aging to one single thing – vitamin D deficiency or insufficiency
Despite these data, the IOM reported that most people in the U.S. and Canada should be able to obtain sufficient amounts from their diet to meet Dietary Recommended Intakes (DRIs), assuming no other vitamin D was synthesized from the sun in the skin.

The IOM raised the DRIs of vitamin D to 600 International Units (IU) for ages 1-70 and to 800 IU for ages 70 and older. Previously the DRIs were 200 IU for ages 1-50, 400 IU for ages 51-70, and 600 IU for ages 70 and older.

The Tolerable Upper Limit was also raised from 2,000 IU to 4,000 IU for adults, which will allow major manufacturers such as the dairy industry and Coca Cola who make Minute Maid orange juice to consider doubling vitamin D in their products.

The IOM committee chair Catharine Ross, of Penn State, said that after reviewing more than 1,000 published studies and listening to testimonies of scientists there still wasn't enough solid evidence for raising vitamin D DRIs or ULs any higher.

In a press conference this morning, she said, "What we were not able to do is take the currently available clinical data including randomized clinical trials and use that information for Dietary Recommended Intakes. The data are not sufficient at present to conclude that intakes should be higher."

When asked about why the Upper Limit was not raised higher, Ross said, "We needed to take a cautious approach because we're looking to reduce risk to the public. There's evidence of harm at the level of 10,000 IU. So we used 4000 IU per day." She said that there was a gap in evidence in between the two numbers.

Other scientists on the committee chimed in:

"There's considerably more evidence, a tremendous amount for vitamin D," said Patsy Brannon, of Cornell, yet not enough to guide decision making on greater intake. She added, "There is research that points to risk. There's also research that shows no risk. We also lack RCTs. We're still needing more research."

Oncologist Steven Clinton, of Ohio State University, said, "As you look across the literature there are inconsistencies." For example, regarding calcium, it's associated with less colon polyps, but increased risk in prostate cancer. He says that in the future as more data become available, there will be more individualized approaches.

"We are still interested in this molecule that affects thousands of genes in the body. But we cannot make this leap at this point," added biochemist Glenville Jones, of Queens University.

The committee had been asked to set new guidelines for DRIs of calcium and vitamin D as well as Upper Limit intakes.

What about supplements?

Despite headlines from the New York Times and several other news outlets, the IOM committee voiced that they did not intend for this kind of position and clarified that they did not specify where the vitamin D amounts should come from--whether it be from the sun, supplements or diet.

Clinton added that, "especially in Canada, we don't want to close the door on those supplements. There's possibility of using supplements." Although, he said he wondered about whether or not the Canadian Cancer Society would change its recommendation from 1,000 IU to 600-800 IU in light of the IOM's new recommendations.

When asked what to make of the new recommendations when it's clear that skin synthesis upon sun exposure yielded amounts of 20000 IU or higher, Brannon responded: "We set our recommendations based on data for total consumption of vitamin D."

She added that the difference between dietary intakes and the skin synthesis is that the body has a natural ability to rid itself of excess made by the sun, "The sun giveth, the sun taketh away."

Apart from Holick, other scientists have voiced their opinions like those representing the Vitamin D Council: Bruce Hollis of Medical University of South Carolina and Robert Heaney of Creighton University.

They have long recommended taking a supplement by as much as 5,000 IU per day to maintain blood levels between 50-80ng/mL year-round.

As Science News reports, Hollis called the IOM report "a big waste of money," although agreed with the panel's decision to double recommendations for children. In addition, Heaney said, “I don’t think this does anything to create confidence in IOM recommendations."

The entire IOM report is summed up by registered dietitian Debra Riedesel, who posted on Twitter, as @NutritionistaRD, in response to the debate, "Do you trust the scientists who've researched Vit D for years or 14 IOM scientists who only read the research?"

Sunday, November 28, 2010

HealthCorrelator for Excel 1.0 (HCE): Call for beta testers

This call is closed. Beta testing has been successfully completed. HealthCorrelator for Excel (HCE) is now publicly available for download and use on a free trial basis. For those users who decide to buy it after trying, licenses are available for individuals and organizations.

To download a free trial version – as well as get the User Manual, view demo YouTube videos, and download and try sample datasets – visit the HealthCorrelator.com web site.

Wednesday, November 24, 2010

Food sharing: Hunter-gatherer "health insurance"

Kim Hill
By pure chance (involving a failed attempt to go hiking and a speeding ticket), I found myself at a talk given by anthropologist Kim Hill, speaking on the "Emergence of Human Uniqueness: Characteristics Underlying Behavioral Modernity."

I previously wrote an article for Scientific American on an Arizona State University workshop that Hill headed up along with Curtis Marean and Lawrence Krauss last February.

Most of Hill's talk was basically the same stuff I wrote about before like that humans are outliers, not unique in any specific way, but contain a combination of non-unique traits that arose through non-unique processes produced a unique outcome -- a "spectacular anomaly."

"If aliens from outerspace came to the Earth," Hill said, then they would be questioning humans instantly because we're so dominant in several ways: technologically, agriculturally, population-wise, etc.

Some would point to the industrial revolution, but Hill argues that hunter-gatherers would have still attracted aliens' attention because they were still the most prosperous species even before agriculture.Humans engage in more ecological niches than all other species combined.

Besides humans, the most successful terrestrial vertebrate is "Canis lupus" (wolves, and that's not counting dog domestication). Both humans and wolves share something in common: cooperative breeding.

So, how do you get this spectacular anomaly?

Hunter-gatherers colonized all the land mass, produced massive megaliths, created complex institutions, and developed languages and cultures.

Hill discusses how he and other scientists came together to discuss what makes humans unique looking at fields of primatology, evolution, hunter-gatherer work, etc.

What makes us uniquely human is a combination of traits that were critical for producing outlier outcomes:

-Cumulative culture
-Cooperation
-Language
-Cognition

OK, so we know all of this. But now here's the interesting part!

Hill showed data from his work that has to do with the economics of cooperation in humans as compared to chimps. Humans are hypercooperators.

What led to hypercooperation in humans?

Hill discusses that it may be due to:

a) a shift on the feeding niche going from collected foods to extracted foods and predation. This is shown in the paleoanthropolical record from 1) emergence of waist, 2) evidence of cooking, 3) stone tool cut marks.

b) extracted and hunted foods caused by juvenile dependence and long learning period.

Basically, adults need to take care of children for several more years in comparison to chimps. Human kids produce virtually nothing, even as they grow older they produce little versus the adults.

c) high variance in large-package foods promotes food sharing

In other words, Kim says, some adults are hunting and bringing home lots of food, way more than they can eat, or that their nuclear family can eat. This promotes food sharing.

He gives an example of the Ache tribe (hunter-gatherers from Paraguay who he's studied for over 30 years) and how at the end of the day everyone brings their extra food to distribute among the group. Children too are taught to share food from the time they're two years old.

Hill gives data on the percent of food types that are kept versus produced by a nuclear family. Some families give away the majority of food (70 to 90 percent!) they produce (and he joked about comparing that to a tax bracket and socialism).

Food sharing among hunter-gatherers is interesting and complicated, Hill says. The sharing is a type of "health insurance" so that if a man, for example, gets sick or injured taking him out of the production three months, he is covered by the sharing of others. He gives data on "health insurance premiums" given by hunter-gatherers like Ache, Efe, Yora, Tsimane.

Food sharing networks helped us survive and have long lives, Hill said. Because in comparison to chimps, humans have less risk of premature death because if a "chimp falls out of a tree and breaks its arm, it's dead" even though the chimp will heal simply because it will starve to death.

Hill then gave more data on hunter-gatherer habits of women overproducing and then led into cooperative breeding, which is reproducing with the help of others in birth and child rearing.

And, again, wolves are also cooperative breeders, so it's definitely an effective strategy.

"What we now know," says Hill, "is that individuals go through periods of time when they are producing a surplus and other times when families cannot feed all the mouths they have."

To illustrate the point, Hill shows us a picture of a typical hunter-gatherer family that has breeders, helpers, and dependents. He gives data on how these families subsidize food.

"It takes a 'band' to raise a child," is typed up on the slide.

He compares hunter-gatherer systems to an institutionalized social security system. "This is a universal pattern among hunter-gatherer societies," he says. A family without this would not be able to be successful. Kinship like cousins, aunts, and uncles are usually the foundation of human cooperative breeding.

But Hill has been studying how kinship moves to larger social organizations of hunter-gatherer societies.

He showed how chimp communities often are not in contact with each other and often kill each other. But, based on work by Bernard Chapais, pair bonding -- transferring females among groups, for example -- which leads to cooperation between groups.

When a sister is married to a man in another group, a brother will create an alliance with the husband. It leads to sharing food communally.

Hill said people like Paul Davies who are looking for alien species should not be looking for "intelligent life on other planets," but actually be looking for cooperative species -- species that work together to accomplish big tasks.

"Chimps are intelligent and dolphins are intelligent," he said, "but ants are closer to building a spaceship than chimps."

Learn more link: Here's some other crazy neat info from Hill on Amazonian hunter-gatherers widespread belief that they have multiple fathers.

Monday, November 22, 2010

Human traits are distributed along bell curves: You need to know yourself, and HCE can help

Most human traits (e.g., body fat percentage, blood pressure, propensity toward depression) are influenced by our genes; some more than others. The vast majority of traits are also influenced by environmental factors, the “nurture” part of the “nature-nurture” equation. Very few traits are “innate”, such as blood type.

This means that manipulating environmental factors, such as diet and lifestyle, can strongly influence how the traits are finally expressed in humans. But each individual tends to respond differently to diet and lifestyle changes, because each individual is unique in terms of his or her combination of “nature” and “nurture”. Even identical twins are different in that respect.

When plotted, traits that are influenced by our genes are distributed along a bell-shaped curve. For example, a trait like body fat percentage, when measured in a population of 1000 individuals, will yield a distribution of values that will look like a bell-shaped distribution. This type of distribution is also known in statistics as a “normal” distribution.

Why is that?

The additive effect of genes and the bell curve

The reason is purely mathematical. A measurable trait, like body fat percentage, is usually influenced by several genes. (Sometimes individual genes have a very marked effect, as in genes that “switch on or off” other genes.) Those genes appear at random in a population, and their various combinations spread in response to selection pressures. Selection pressures usually cause a narrowing of the bell-shaped curve distributions of traits in populations.

The genes interact with environmental influences, which also have a certain degree of randomness. The result is a massive combined randomness. It is this massive randomness that leads to the bell-curve distribution. The bell curve itself is not random at all, which is a fascinating aspect of this phenomenon. From “chaos” comes “order”. A bell curve is a well-defined curve that is associated with a function, the probability density function.

The underlying mathematical reason for the bell shape is the central limit theorem. The genes are combined in different individuals as combinations of alleles, where each allele is a variation (or mutation) of a gene. An allele set, for genes in different locations of the human DNA, forms a particular allele combination, called a genotype. The alleles combine their effects, usually in an additive fashion, to influence a trait.

Here is a simple illustration. Let us say one generates 1000 random variables, each storing 10 random values going from 0 to 1. Then the values stored in each of the 1000 random variables are added. This mimics the additive effect of 10 genes with random allele combinations. The result are numbers ranging from 1 to 10, in a population of 1000 individuals; each number is analogous to an allele combination. The resulting histogram, which plots the frequency of each allele combination (or genotype) in the population, is shown on the figure bellow. Each allele configuration will “push for” a particular trait range, making the trait distribution also have the same bell-shaped form.


The bell curve, research studies, and what they mean for you

Studies of the effects of diet and exercise on health variables usually report their results in terms of average responses in a group of participants. Frequently two groups are used, one control and one treatment. For example, in a diet-related study the control group may follow the Standard American Diet, and the treatment group may follow a low carbohydrate diet.

However, you are not the average person; the average person is an abstraction. Research on bell curve distributions tells us that there is about a 68 percentage chance that you will fall within a 1 standard deviation from the average, to the left or the right of the “middle” of the bell curve. Still, even a 0.5 standard deviation above the average is not the average. And, there is approximately a 32 percent chance that you will not be within the larger -1 to 1 standard deviation range. If this is the case, the average results reported may be close to irrelevant for you.

Average results reported in studies are a good starting point for people who are similar to the studies’ participants. But you need to generate your own data, with the goal of “knowing yourself through numbers” by progressively analyzing it. This is akin to building a “numeric diary”. It is not exactly an “N=1” experiment, as some like to say, because you can generate multiple data points (e.g., N=200) on how your body alone responds to diet and lifestyle changes over time.

HealthCorrelator for Excel (HCE)

I think I have finally been able to develop a software tool that can help people do that. I have been using it myself for years, initially as a prototype. You can see the results of my transformation on this post. The challenge for me was to generate a tool that was simple enough to use, and yet powerful enough to give people good insights on what is going on with their body.

The software tool is called HealthCorrelator for Excel (HCE). It runs on Excel, and generates coefficients of association (correlations, which range from -1 to 1) among variables and graphs at the click of a button.

This 5-minute YouTube video shows how the software works in general, and this 10-minute video goes into more detail on how the software can be used to manage a specific health variable. These two videos build on a very small sample dataset, and their focus is on HDL cholesterol management. Nevertheless, the software can be used in the management of just about any health-related variable – e.g., blood glucose, triglycerides, muscle strength, muscle mass, depression episodes etc.

You have to enter data about yourself, and then the software will generate coefficients of association and graphs at the click of a button. As you can see from the videos above, it is very simple. The interpretation of the results is straightforward in most cases, and a bit more complicated in a smaller number of cases. Some results will probably surprise users, and their doctors.

For example, a user who is a patient may be able to show to a doctor that, in the user’s specific case, a diet change influences a particular variable (e.g., triglycerides) much more strongly than a prescription drug or a supplement. More posts will be coming in the future on this blog about these and other related issues.

Saturday, November 20, 2010

Chemicals in Store Register Receipts and Fast Food Wrappers

Before the next time you ask a cashier for a receipt, think twice! It might be tainted with bisphenol A, aka BPA.

A recent study in Environmental Health Perspectives showed that cashiers had highest BPA exposure because of its use in thermal paper for register receipts in a monomer form that is readily absorbed through skin.

BPA is also used as a polymer complex in hard, clear polycarbonate plastic water bottles and as epoxy resins lining aluminum cans.

The study raises concerns about widespread exposure to BPA from a variety of sources, especially for women who are pregnant.

Although the actual BPA amounts in receipts is so little it may not pose enough risk to worry about, it does raise concerns for people—those behind a register, for example—who are in contact with the thermal paper regularly.

The news comes no later than a month after Health Canada officially declared BPA a toxic substance that mimics estrogen, potentially increasing risks of breast cancer and prostate cancer.

Additionally, do you need another reason to avoid junk food? Here’s one: New research shows chemicals used to line fast food wrappers and microwave popcorn bags are contaminating the food and can be observed in the blood stream.

According to research from University of Toronto in the same journal, the greaseproof paper that is frequently used in the packaging of these products contain polyfluoroalkyl phosphate esters (PAPs) that break down into perfluorinated carboxylic acids (PFCAs).

PCFAs are known carcinogens and the scientists suggest that food packaging as well as non-stick and other water- and stain-repellant products like kitchen pans and clothing may be increasing exposure.

Controlling human exposure to these, and other, chemicals has become an active area of research recently as the public gains more understanding about the potential health implications caused by these toxic compounds.

Sources:

Braun JM, Kalkbrenner AE, Calafat AM, Bernert JT, Ye X, et al. 2010 Variability and Predictors of Urinary Bisphenol A Concentrations during Pregnancy. Environ Health Perspect doi:10.1289/ehp.1002366

D’eon JC, Mabury SA, 2010 Exploring Indirect Sources of Human Exposure to Perfluoroalkyl Carboxylates (PFCAs): Evaluating Uptake, Elimination and Biotransformation of Polyfluoroalkyl Phosphate Esters (PAPs) in the Rat. Environ Health Perspect doi:10.1289/ehp