Chemicals and Toxins — What Is Safe?

One of the most common questions I get from SquintMom readers is along the lines of is item/substance/compound XYZ toxic? I’d like to go ahead and answer this once and for all: YES, it is.

Now let me explain what I mean, and how I can answer this very generic question in a catch-all way without specifying the item/substance/compound to which I refer. Because he said it so well that it doesn’t need rephrasing, I’ll quote the Renaissance-era botanist Philippus Aureolus Paracelsus, who said:

All substances are poisons; there is none that is not a poison. The right dose differentiates a poison from a remedy.

Phrased more generally, this is simply that any substance can be either safe or toxic; the dose (quantity) to which one is exposed is what makes the difference. I’ve mentioned in previous posts (like this one about oxybenzone in sunscreen) that the notoriously jumpy Environmental Working Group (EWG) systematically fails to recognize this particular principle; they have a tendency to vilify anything that proves toxic in any dose, under any conditions. This attitude, however well intentioned, leads us to some interesting places. Pause for a moment and check out the cautionary website Note that the highly toxic dihydrogen monoxide (DHMO) is associated with cancer (it’s found in every tumor ever identified), has serious environmental impact (it’s a major greenhouse gas and overexposure is associated with thousands upon thousands of deaths every year), and, per the website:

[DHMO’s] basis is the highly reactive hydroxyl radical, a species shown to mutate DNA, denature proteins, disrupt cell membranes, and chemically alter critical neurotransmitters.

Sounds horrid, doesn’t it? No doubt we should ban it. Except that… is a joke website, and dihydrogen monoxide is the almost never-used, formal chemical name for water.

None of the information on is false, which is what makes it both amusing and apropos to this discussion. Water does, in fact, directly result in many deaths. Not only through “overexposure” via flooding and/or drowning, but also through overconsumption. For instance, in 2007, a radio station held a contest (“Hold your wee for a Wii”), the idea of which was to drink as much water as possible without a bathroom break; the caller who drank the most would win a coveted Wii game console. Contestant Jennifer Strange won (and then lost) by consuming more than 2 gallons of water in the space of less than an hour. She died shortly thereafter of hyponatremia, a condition in which there is an insufficient concentration of sodium in the body fluids to support life (sodium is critical to cellular function, neural conduction, muscular contraction, brain function, and so forth). This is not the only incident of water toxicity on record; similar cases have resulted from fraternity hazings, bizarre diet plans, and overconsumption of water during endurance sporting events like marathons.

On the other hand, there are substances that we typically consider highly toxic that are, in the right dose, of great medicinal utility. Clostridium botulinum is a species of bacteria that produces botulinum toxin, generally considered the deadliest substance on Earth. The average 150 pound man would have a 50:50 chance of survival if exposed to merely 341 ng (that’s less than a millionth of a gram) of pure botulinum toxin. Regardless, marketed under the trade name Botox, botulinum toxin is used for cosmetic purposes (wrinkle treatment and prevention). Of perhaps greater medical importance, it’s also used to ease the painful symptoms of temporomandibular joint syndrome (TMJ) and other spasmodic disorders, and mitigate the symptoms of diabetic neuropathy (damage to peripheral nerves, often in the feet, due to diabetes).

Further complicating matters, our perception that “natural” substances are somehow safer or better for us than “artificial” substances is misinformed. A simple example is the flavoring agents found in many foods. While the common perception is that natural flavors come from the food of which they taste (strawberry flavor, for instance, comes from strawberries), nothing could be further from the truth. In reality, natural and artificial flavors are generally identical chemicals, collected or produced in different ways.* Natural almond flavor, for instance, isn’t a mixture of “natural substances” that come from almonds. Instead, it’s a chemical called benzaldehyde that is extracted from peach pits. Artificial almond flavor is also benzaldehyde, but unlike natural almond flavor, the artificial stuff is made in the lab. Funnily enough, it’s possible to get benzaldehyde made in the lab much more pure than that extracted from peach pits. Further, the stuff that comes from peach pits — the natural almond flavor, remember — contains small amounts of deadly cyanide that occurs naturally in those same peach pits (one of many reasons it’s not wise to eat the pits of stone fruit).

*Eric Schlosser’s excellent book Fast Food Nation contains a very interesting chapter on this topic, for further reading.

Where does this leave us, in trying to avoid toxins? First, as a chemist, let me just say that the word toxin is very often misused in popular sources and conversation, and the word chemical is almost always misused. “Chemicals” are not bad things that cause harm and should be avoided. Instead, they are matter; they are what makes up the physical universe. Nothing that has mass and occupies space — nothing we touch, eat, drink, breathe — is not chemical. There’s no such thing as chemical-free bread, shampoo, or paint. Water is a chemical (and — let’s not forget — a toxic one at that). With regard to toxins, the word is used too often in a vague, handwaving sense on the Interwebs. I see pop-authors (who are generally trying to sell something) write about how Product X contains “toxins,” and should therefore be avoided, or Product Y (which they’re selling) contains no toxins.* I’m not sure what these folks mean when they say “toxins” (and since they rarely name said toxins, I’m not sure they know either); after all, let’s not forget that all substances are toxic in the right dose.

*Or worse yet, Product Y (which they’re selling) is a detoxifying agent. This is ridiculous; almost all humans (with the exception of a few with significant disease) are possessed of one of the most powerful detoxifying mechanisms known to man — a liver. Livers work really well, particularly when they’re left alone to do their job.

This is not to say that we should all go about our business with no concern whatsoever for the things we touch/eat/drink/breathe; it’s simply to say that we simultaneously worry too much and worry too little about “chemicals.” To take one particular example, a few scare-articles about bisphenol A (BPA) have some of us so worried (and confused) that we’re willing to shell out extra cash for BPA-free diaper wipe containers, toys, and even a bath toy organizer. In reality, if BPA has any effect at all in doses to which we’re routinely exposed (which has not yet been established), it would require significant physical contact with the compound to absorb it. Holding, playing with, or storing one’s bath toys in a BPA-containing item would not be a problem, particularly given that while the absorption rate of BPA through human skin hasn’t been thoroughly evaluated or established, it nevertheless appears to be significantly lower than the (already modest) rate of absorption through the skin of other animals (Marquet et al). Based upon the current research, might it be worth avoiding storing food in BPA-containing plastics? Possibly. This is because food might leech BPA out of the plastic in sufficient quantities to possibly have some effect on people (because we eat the food, which gives it an easy route into the system). Is it worth it to avoid all BPA in our houses, however? Simply, no. And on that note, it particularly amuses me to watch women with painted nails shopping for BPA-free toys for their daughters (also with painted nails), given that the exposure to potentially harmful substances (like toluene) is much greater when one physically paints said chemicals on one’s body.*

*For those who are curious, I do paint my nails, because I really don’t think this is that big a deal. But it’s certainly a more significant exposure to chemicals (ew! chemicals!) than touching a rubber ducky in the tub.

So, we worry too much. But we also worry too little. In our desire for the “natural” (whatever that means), we choose the cyanide-laced flavoring agent over the one made under strict conditions and control in the lab. We go to the natural foods store and buy herbs to treat our ailments — which are essentially unregulated for either safety or efficacy, and which may interact unsafely with prescription and over-the-counter drugs or be toxic in their own right — rather than using the “unnatural chemicals” prescribed by medical professionals, despite the fact that the latter have undergone many years of pre-marketing research, followed by decades of post-marketing surveillance. We’re more willing to expose our children to the 1/330 risk of death due to the measles than the 1/3000 risk of a moderate side effect of measles vaccination (e.g. seizure with no permanent effects, mild rash), and immeasurably small risk of serious side effect. We further eschew the vaccination because, in a complete failure to understand the mechanics of human immunity, we have come to believe that “natural” immunity from disease is superior to “artificial” immunity from vaccination. When it comes to the “natural” versus the “toxic” and/or “chemical,” we’re chasing flies out of the chicken coop while the foxes sneak in.

So what do we do about it? This is difficult. We know that all substances are toxic in the right (wrong?) dose, but when it comes to many substances, we still don’t know what that dose is. Some exposures are unavoidable (by virtue of living in a city, for instance, one is going to be exposed to a certain amount of benzene from exhaust, industrial processes, etc). Some exposures are avoidable, but avoiding them reduces quality of life (no one HAS to eat foods containing coloring agents, for instance, many of which are of questionable safety, but the complete avoidance of these would make for a stoic existence, particularly for children). In most cases, when it comes to toxic chemicals (and once more, all substances are chemicals, and all chemicals are toxic when one is exposed to them…all together now…in the right dose), one must do a risk-to-benefit analysis. Some cases are relatively clear. Is codeine toxic? Yes, in the right dose. Is it worth the risk to take codeine for recreational purposes? Probably not. Is it worth the risk to take codeine after a painful surgery? Probably. Is water toxic? Yes, in the right dose. Is it worth the risk to drink water when one is thirsty? Absolutely. Is it worth the risk to drink water to win a contest? Probably not. Some cases are less so, as with the previous example of BPA. With the evidence still equivocal, financial means and convenience likely become a large part of the decision. Those of greater means or with greater willingness to be inconvenienced might buy the BPA-free rubbery ducky, the BPA-free cabinet safety locks. Others might decide to buy the BPA-free food storage, but be content with the plain old, BPA-containing bath caddy. Regardless of these personal decisions when it comes to substances of yet-unknown safety, it’s worth remembering that the media, the product manufacturers, and the fad-authors capitalize upon the lucrative combination of public confusion and fear, and that the words “chemical,” “toxic,” “artificial,” and “natural” are as powerful as they are misused and misunderstood.


Marquet et al. In vivo and ex vivo percutaneous absorption of [14C]-bisphenol A in rats: a possible extrapolation to human absorption? Arch Toxicol. 2011 Sep;85(9):1035-43. Epub 2011 Feb 2.

Exercising While Breastfeeding

A reader recently asked whether exercise — specifically marathon training — affects lactation and breastfeeding. I did a little digging and came up with some information, but decided the article fit better at another site for which I write: Trail and Ultra Running. Here’s a brief summary of my findings, based upon the current research:

  • Moderate exercise (about 45 min/day, 5 days/week, moderate intensity) probably has no negative effect on milk production
  • Short-term vigorous exercise probably has no negative impact on milk production
  • Habitual moderate-volume exercisers may make slightly more milk than sedentary women
  • Exercise that results in short-term (~2 weeks) significant caloric deficit probably has no negative effect on milk production
  • There’s no evidence that habitual moderate exercise negatively impacts nutritional content of milk or immunologic factors (like antibodies)
  • Moderate exercise doesn’t appear to increase the amount of lactic acid (a waste product of exercise) in milk, while intense exercise increases lactic acid in milk for about 90 minutes; this doesn’t affect nutrition, but may impact flavor
  • Infants may or may not respond negatively to temporarily increased levels of lactic acid in milk; women can pump before exercising if this is a concern
  • Lactic acid clears from the milk as it clears from the blood; there’s no need to “pump and dump” after vigorous exercise

Read the entire post here.

Sunscreen Safety and Oxybenzone

Is oxybenzone in sunscreen safe? From Squintmom/Beautiful EntropyI love getting questions about science-related issues from readers. I particularly love it when a question intersects with an issue I myself am curious about, as happened when a reader got in touch with me last week:

I need some advice about sunscreen. I just read some articles on CNN about new FDA guidelines and the Environmental Working Group’s 2012 sunscreen review. Of particular concern is oxybenzone. The FDA claims it’s safe and very effective at protecting against UVA and UVB rays. However, the EWG says that oxybenzone is carcinogenic. Hmm… use sunscreen to prevent skin cancer, but sunscreen causes… skin cancer? That seems like a big time conundrum to me. The other thing I wonder about is who is the EWG? All I really know is they came up with the “Dirty Dozen” foods you should always buy organic. So what’s the deal? Should I toss all of last year’s sunscreen with oxybenzone and buy new? Is the EWG generally a trustworthy, “non-woo” authority?

The oxybenzone molecule

Let’s start with my professional opinions of the Food and Drug Administration (FDA) and of the Environmental Working Group (EWG). The FDA is routinely accused by consumer groups and conspiracy theorists of being “in bed with Big Pharma,” engaging in cover-up operations, putting profit ahead of consumer health, and so forth. I really don’t agree with this take on the organization, as I discuss in this post. The FDA’s history in the US is one of a largely appropriate trajectory. They’re a behemoth organization, and as such, they move slowly. They’re slow to approve new drugs because they insist on rigorous testing; this is one of the things that pisses off consumers who want to see new drugs come to market quickly. They’re relatively quick to warn consumers if there’s evidence that a pharmaceutical or substance is harmful, though they’re not alarmist and rarely respond to the results of an isolated study. The FDA is, to put it simply, stuck performing an impossible balancing act: they’re under public pressure to approve substances quickly, while they’re simultaneously under public pressure to keep anything that could potentially be harmful off the market. These missions are mutually exclusive, and I have to say that for the most part, the FDA handles their task as elegantly as a behemoth government organization can do. Have they made mistakes? Absolutely. But what I appreciate about the FDA is that they correct over time, such that their trajectory is generally appropriate and stable.

The EWG, on the other hand, is far more alarmist than the FDA. They’re not a government organization, but are rather a research and lobbying group made up of citizens and scientists. A survey of toxicologists (unaffiliated with the organizations about which they were questioned) revealed that most felt the EWG overstates risks associated with products. Specifically, toxicologists gave the EWG an accuracy score of 4.2 (1 = significantly understates risks, 3 = accurately states risks, 5 = significantly overstates risks). By comparison, the FDA got a 3 from the toxicologists, indicating that they felt the organization was accurate in assessing and reporting risks. For those who are curious, the U.S. Centers for Disease Control and Prevention (CDC) and the American Medical Association (AMA) also scored near 3, reflecting accurate portrayal of risks, while Greenpeace got a 4.5 — the highest score given — for significant overstating of risks. The Pharmaceutical Research and Manufacturers of America (PhRMA), on the other hand, scored a 2.3 for being the most significant understater of risks. Note that PhRMA is not a government organization, and is not tied to the FDA, the CDC, or other government health regulators.

As far as the EWG goes, I think they have their place. They report on research, but often issue warnings on the basis of single studies or studies with limited applicability. Case in point, they warn consumers against sunscreen containing retinyl palmitate (vitamin A) on the basis of a 2009 study that looked at mice rubbed with the chemical and exposed to light. The vitamin A mice developed more tumors, leading the EWG to report a link between retinyl palmitate in sunscreen and cancer. However, there are significant issues that limit the study’s applicability. Most notably, sunscreen only ever contains a small amount of retinyl palmitate. Dose is very important in toxicology; any substance — even water — is toxic in sufficient quantity. As such, a pure retinyl palmitate rub applied to mice doesn’t provide information about the toxicity of small amounts of the compound in sunscreen. In the end, groups like the EWG help to promote research on issues pertaining to toxicology and public safety, but speaking for myself, I look for corroborating research or concern from more moderate institutions before acting on an EWG warning. In response to the question from the start of this post, I think we can safely say that the EWG is “non-woo,” but they are a little jumpy.

On to sunscreen safety. First and foremost, there’s a major risk-to-benefit analysis that one must conduct when determining whether to use sunscreen and what type to use. This is because the sun emits ultraviolet radiation (UV) that damages cells, leading to development of wrinkles, aging of tissues, and skin cancer. Sunburns are an indication of particularly severe cellular damage — just one or two sunburns before the age of 18 significantly increases risk of skin cancer later in life — but even a so-called “healthy” tan is a sign that damage has occurred. Sunscreen is a part of protecting the skin from sun damage, but it’s not the entire equation. In fact, staying out of the sun during intense radiation hours (midday) and using physical protection such as clothing, sunglasses, and hats provides the best protection from harmful UV radiation. No sunscreen provides complete protection. To this end, one of the new FDA regulations regarding sunscreen labeling is that sunscreens will no longer be allowed to refer to themselves as “sunblock,” on the grounds that this inappropriately overstates protection. While there’s been some muttering by the EWG and other groups about whether sunscreen truly helps to prevent skin cancer, these concerns are largely based upon use of sunscreens that protect from only one type of UV radiation (broad-spectrum sunscreens are best, but not all sunscreens are broad-spectrum) and inappropriate use of or reliance on sunscreen. The general consensus among medical and government organizations, including the CDC and the AMA, is that sunscreen is an important component of safe-sun behavior.

The active ingredients of a barrier sunscreen.

There are two major classes of sunscreens: barrier sunscreens containing minerals (like zinc oxide and titanium dioxide) that reflect light, and chemical sunscreens that absorb the light and prevent it from penetrating cells. There is essentially no risk of absorbing the barrier compounds through the skin, leading even the EWG to note that these sunscreens are likely the safest and most effective. In times past, barrier sunscreens were unpopular because they had a greasy white appearance on the skin (remember Zinka from the 80s?). Newer technology allows for smaller particles (nanoparticles) of barrier compounds, which are less visible on the skin, though some formulations may still be greasy. There’s also some question as to whether these nanoparticle formulations appropriately protect from UVA, one of the types of UV (UVB is the other type). Unfortunately, while the sunlight reaching Earth is made up of mostly UVA, the SPF rating on sunscreen applies to UVB protection only. The new FDA regulations propose a set of standards for reporting UVA protection, as UVA exposure also leads to skin cancer. With regard to barrier sunscreens, then, the most effective UV protection comes from the old-school stuff: greasy, white, and slathered on thick. The next most effective UV protection comes from a nanoparticle formulation combined with a chemical sunscreen containing oxybenzone or similar for enhanced UVA protection. Of course, protection from UV is only part of the equation when it comes to assessing sunscreen safety; the other part is the safety of the sunscreen ingredients themselves.

The active ingredients of a chemical sunscreen.

Oxybenzone is currently raising hackles at the EWG, and is one of the reasons that their Sunscreens 2012 report contains so few “approved” choices. The compound occurs in nature — it’s in flower pigments — and is incredibly common in personal care products. It’s not only a sunscreen, it’s also a fragrance enhancer, preservative, flavor enhancer, and so on. The CDC reports that a recent random sample of Americans revealed oxybenzone in 97% of urine samples (Calafat et al). However, the significance of this information has not yet been determined. The EWG calls oxybenzone a “potential hormone disruptor,” citing the European Commission on Endocrine Disruption (pdf) (ECED), which basically means that the EWG is saying they don’t like oxybenzone on the grounds that the ECED doesn’t like oxybenzone. As to why the ECED takes issue with it, they (like the EWG) are exceedingly cautious. The EWG cites two studies (Ma et al,* Ziolkowska et al) that show the potential for weak endocrine disruption. {Note that the Ma et al reference is incomplete on the EWG website, and I was able to find no evidence of it in the scientific literature}. The extent to which the results of these studies, conducted on cells with pure oxybenzone compound, are relevant to use of the compound in sunscreen are unknown. As the American Cancer Society points out:

Virtually all substances known to cause cancer in humans also cause cancer in lab animals. But the reverse is not always true – not every substance that causes cancer in lab animals causes cancer in people. There are different reasons for this.

First, most lab studies of potential carcinogens (cancer-causing substances) expose animals to doses that are much higher than common human exposures. This is so that cancer risk can be detected in relatively small groups of animals. But doses are very important when talking about toxicity. For example, taking a couple of aspirin may help with your headache, but taking a whole bottle could put you in serious trouble. It’s not always clear that the effects seen with very high doses of a substance would also be seen with much lower doses.

Second, there may be other differences between the way substances are tested in the lab and the way they would be used, such as the route of exposure. For example, applying a substance to the skin is likely to result in much less absorption of the substance into the body than would be seen if the same substance is swallowed, inhaled, or injected into the blood. The duration and dose of the exposure also help determine the degree of risk.

While the above refers to cancer risk, the same is true of other toxic effects of compounds that are revealed through laboratory and animal studies. With specific regard to cancer and oxybenzone, even the cautious EWG notes that there’s no evidence that oxybenzone is carcinogenic — or, more accurately, THERE IS evidence that oxybenzone IS NOT carcinogenic (non-mutagenic in 4 of 4 studies: CTFA, 1980; DHEW, 1978; Hill Top Research Labs, 1979; Litton Bioneics, 1979).

Taking all the information together and conducting a risk-to-benefit analysis, I think it’s fair to say that because of the limited data available and the availability of alternatives to oxybenzone, it may be worth avoiding it in sunscreen, but there’s no reason to get particularly excited about previous use or occasional future use. Given that it’s present in almost all chemical (non-barrier) sunscreens, this essentially leaves the barrier sunscreens containing zinc oxide and titanium dioxide. If one chooses to use the nanoparticle formulations with somewhat reduced UVA protection, one must then decide whether to use a chemical sunscreen for additional protection — but this once again leads to oxybenzone exposure.

One last thing: with regard to old sunscreen, if in doubt, throw it out. The CDC recommends that sunscreen be no more than three years old if there’s no expiration date on the bottle. If the bottle has an expiration date, abide by it. The protective chemicals in sunscreen break down over time, meaning that protection wanes.

Science Bottom Line:* Given that there is no sunscreen that provides complete protection, the evidence suggests that the safest choice (particularly for children) is the use of zinc oxide or titanium dioxide sunscreen (I prefer nanoparticle formulations for convenience and aesthetics), without a chemical sunscreen backup. This should be augmented through the judicious use of shade, clothing, sunglasses, and hats, particularly during the most intense periods of sunlight.


How do you protect your family’s skin outdoors?



Calafat et al. Concentrations of the sunscreen agent benzophenone-3 in residents of the United States: National Health and Nutrition Examination Survey 2003–2004. Environ Health Perspect. 2008 Jul;116(7):893-7.

Ziolkowska et al. Endocrine disruptors and rat adrenocortical function: studies on freshly dispersed and cultured cells. Int J Mol Med. 2006 Dec;18(6):1165-8.

2011 U.S. Measles Rates Highest In 15 Years

I’m willing to bet he would have been happier with the shot.

Misconceptions and fear have been fueling the anti-vaccination movement in recent years, particularly with regard to the measles, mumps, and rubella (MMR) vaccine. This is in part because a study published in The Lancet that linked the MMR vaccine to autism (Wakefield et al). In addition to rampant misinformation spread via the Internet, the Wakefield study continues to fuel public concern, despite thorough and unanimous scientific debunking by more than 20 studies (Poland), retraction by all but one of the authors – Wakefield himself — and retraction by The Lancet.

Unfortunately, despite overwhelming scientific evidence that the risks associated with the MMR vaccine are small and uncommon, particularly relative to the serious and more common risks associated with contracting the measles, some parents continue to refuse to immunize their children.

A report by the U.S. Centers for Disease Control and Prevention (CDC) not only underscores the significant risks associated with being unvaccinated for the measles, it also helps demonstrate the fallacious nature of many of the arguments against vaccination and highlights the importance of vaccination in protecting the community.

According to the CDC report, there were more measles cases reported in the U.S. in 2011 than in any of the prior 15 years. A total of 222 cases were reported, the majority of them in people less than 20 years of age. 65% of cases were in unvaccinated individuals, and another 21% of cases were in individuals whose vaccination status was unknown or not on record. Of those who were unvaccinated, a fraction (27 total cases) were under 12 months of age, and were therefore too young for the vaccine.

In light of this disturbing report, some common myths about measles…and the facts:

Myth: Measles is exceedingly rare in the U.S., as vaccination rates are generally high. Unless my children will be traveling to Europe or other parts of the world with higher measles rates, they don’t require measles protection.

Fact: While measles isn’t as common in the U.S. as it is elsewhere in the world (there were no U.S. cases in 2000, for instance), it’s imported from other countries (either by foreign travelers or by U.S. travelers returning from a measles-prone area) and can spread in the U.S., mainly due to unvaccinated individuals. Measles is contagious for about four days before any rash appears, meaning that travelers from foreign countries can bring the disease to the U.S. without being aware that they are doing so. The CDC notes that most cases of measles in the U.S. were brought in from Europe. Further, measles is so contagious that casual exposure to an infected individual (even one who doesn’t yet show signs of the disease) is very nearly 100% effective in transmitting the infection. Measles is spread through the air, meaning that it’s possible to get the disease without any physical contact with an infected individual.

Myth: Measles is a common, routine childhood illness, and there’s no reason to vaccinate for it.

Fact: Measles was common in the U.S. before the introduction of the vaccine in 1963. The disease is so contagious that essentially 100% of the population contracted it prior to the development of the vaccine. Simply because a disease was once common, however, does not mean it is “routine” or harmless. Measles complications are relatively common, and include severe dehydration and pneumonia. 32% of individuals who contracted measles in the U.S. in 2011 had to be hospitalized for complications. Thankfully, there were no deaths among these individuals. However, swelling of the brain and death are possible complications of the disease, occurring in about 3/1000 cases. Even among the individuals who do not require hospitalization, measles is a truly miserable experience. It comes with a high fever, which is accompanied by muscle aches, headache, and sensitivity to light. Unlike chicken pox, to which measles is sometimes erroneously compared because they both cause skin rashes, measles is respiratory and causes a dry cough and extremely sore throat, which contributes to dehydration. The rash can be very extensive (in many cases, it enters the mouth), and itches.

Myth: The MMR vaccine is more dangerous than the measles.

Fact: The MMR vaccine is associated with some mild side effects, including an innocuous and temporary rash in about 5% of vaccinated individuals. Moderate side effects, such as seizure, are very rare, occurring in about 1/3000 doses. Note that the moderate side effects (which are not life-threatening) are three times rarer than the risk of death from the measles. Serious side effects of the MMR vaccine, including death, are so rare that they can’t be statistically quantified. In other words, people die so rarely after getting an MMR that no one can be sure the death was due to the shot.

Myth: Since almost everyone in the U.S. is vaccinated against measles, my child will be protected.

Fact: The vast majority of U.S. citizens are vaccinated against measles. This means that measles won’t be able to take hold and spread across the country in the form of an epidemic, as it could have done before 1963. However, the disease can still spread from one individual to the next, particularly in areas of lower MMR compliance. The 222 cases of measles in the U.S. were primarily due to small outbreaks (there were 17 such outbreaks), where the average outbreak size was 6 individuals. Put another way, for every one case of measles brought into the country by a foreign traveler or returning U.S. citizen, five people who had never left the country got sick.

Myth: If I choose not to vaccinate my children, I’m not hurting anyone but my own family.

Fact: This is not so. To protect a group of people from a disease as effectively as possible, it’s important to keep the vaccination rate as high as possible. The fewer unvaccinated individuals in a population, the less likely that someone with measles will come into contact with an unvaccinated individual, which reduces the likelihood of an outbreak. Vaccines are highly effective — vastly more so than most other medical treatments — but they’re not 100%. This is especially true in children who have had only one of their MMR shots (the CDC recommends a booster at age 4-6). Maximizing the number of immunized individuals helps to protect those for whom vaccination may not be effective. There are also those, including babies under one year of age, who are not eligible for vaccination. Maximizing the vaccination rate among the eligible minimizes the risk to vulnerable members of the population.


If you vaccinate, do you worry about those who don’t? If you don’t vaccinate, what about it makes you uncomfortable?



Poland. MMR Vaccine and Autism: Vaccine Nihilism and Postmodern Science. Mayo Clin Proc. 2011 Sep;86(9):869-71.

Wakefield et al. Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children [retracted in: Lancet. 2010;375(9713):445]. Lancet. 1998;351(1903):637-641.

Breast Milk For Pain Relief

Image from Melimama, Wikimedia Commons

There are two interesting studies on breast milk as an analgesic (pain reliever) in this month’s issue of Pediatrics. Each compares the effects of breast milk to those of oral sugar (either glucose or sucrose) for relieving pain during the ubiquitous neonatal heel stick procedure.

The first study looked at late preterm infants (gestational age 34-36 weeks), and measured pain as indicated by crying and pain response (evaluated using the Premature Infant Pain Profile [PIPP] scale) [1]. All infants were being breastfed and were fed at least an hour before the procedure. They were randomized into two groups, one of which received expressed breast milk (from the infant’s mother) and one of which received a solution of glucose. (Glucose is a type of sugar; it’s exceedingly common in nature and in food, but is only about 70% as sweet as table sugar. Sugar solutions have been well established as a method of delivering pain relief to neonates [2]). The researchers found that infants given glucose displayed significantly less discomfort during and after the procedure compared to those given expressed breast milk. Interesting though these results are, they don’t particularly excite me. They can be taken to mean oral glucose is a superior analgesic to oral breast milk in late preterm newborns, but they can’t be taken to mean oral glucose is a superior analgesic to breastfeeding in late preterm newborns. This is because breastfeeding consists of more than simply oral administration of breast milk.

I’m more interested in the findings of a second study, also conducted on late preterm infants undergoing heel stick [3]. In this study, breastfed infants were randomized to one of three conditions: oral sucrose (table sugar) solution, expressed breast milk, or breastfeeding. Infants were fed or given sucrose during the heel stick procedure. Those being breastfed were held in their mother’s arms, while those receiving expressed breast milk or sucrose were held by a nurse. As in the first study, the researchers measured crying and pain response via PIPP. There was no significant difference in PIPP score for infants receiving breast milk versus those receiving sucrose. Interestingly enough, this was true for both the expressed breast milk group AND the group being breastfed. I have to admit to being surprised by the results; I would have guessed that there would be no difference between sucrose and expressed breast milk (or possibly that sucrose would be more effective), but that breastfeeding would provide superior analgesia!

Note that these results apply only to neonates (and, to be rigorous, only to late preterm neonates). It’s entirely possible that the establishment of a solid breastfeeding relationship over the course of the first weeks or months of life would change the relative efficacy of sugar solution versus expressed breast milk versus breastfeeding as analgesics (follow-up post on this issue forthcoming).

One final note — in the discussion portion of the second study (where the researchers talk about what their results mean and what they noticed while doing the study), there was a line that jumped out at me. The researchers were apparently, like me, surprised that they didn’t discover that breast milk was a superior analgesic. They suggested that one reason could have been that preterm infants have an “immature competence for sucking,” which could have reduced their ability to take enough milk to make a difference. Further, they noted (and this is what caught my eye), “We observed that these [preterm] newborns are more easily annoyed than term neonates…” Alrighty then!


Science Bottom Line:* In late preterm newborns, sugar solutions provide pain relief for procedures such as a heel lance. Breast milk, either expressed or obtained via breastfeeding, may provide similar pain relief, though some evidence suggests that breast milk is not as effective as sugar.


Do you think breast milk helps relieve pain?



1) Bueno et al. Breast milk and glucose for pain relief in preterm infants: a noninferiority randomized controlled trial. Pediatrics. 2012 Apr;129(4):664-70. Epub 2012 Mar 5.

2) Harrison et al. Efficacy of sweet solutions for analgesia in infants between 1 and 12 months of age: a systematic review. Arch Dis Child. 2010 Jun;95(6):406-13. Epub 2010 May 12.

3) Simonse et al. Analgesic effect of breast milk versus sucrose for analgesia during heel lance in late preterm infants. Pediatrics. 2012 Apr;129(4):657-63. Epub 2012 Mar 5.

When Is The Best Time To Introduce Solids?

The decision to start solids is both an exciting one (your baby is growing up!) and a difficult one for many parents. The latter is because there’s so much conflicting information floating around (“Starting solids sooner will make your baby sleep better!” “Starting solids too soon will give your baby allergies!”). The purpose of this post is to summarize the research that addresses when to start solids in a baby that is breast- and/or formula-fed.

If you’re confused by all the seemingly conflicting information out there regarding when to start solids, you’re in good company; the American Academy of Pediatrics (AAP) is split on this issue. The AAP’s Breastfeeding Initiatives state that it’s best to wait until an infant is 6 months of age, while the AAP’s nutrition division suggests that it’s fine to introduce solids around 4 months of age. There is no research to suggest that there’s any benefit associated with introducing solids before 4 months of age, and there is quite a bit of research suggesting that such early introduction of solids is associated with increased risk of allergies and eczema (see, for instance, Greer et al, Tarini et al, Zutavern et al). Waiting until 6 months of age to introduce solids decreases the risk of atopic diseases (allergies, eczema, and asthma). Researchers are split on introduction of the most allergenic foods (including eggs, shellfish, and nuts). Some studies (including Filipiak et al) suggest that there’s no benefit associated with waiting beyond the sixth month to introduce these foods (in non-chokable form), while other studies (such as Fiocchi et al) suggest waiting to introduce dairy, egg, nuts, and seafood. Given the split nature of research findings on delayed introduction of highly allergenic foods, it may be worth delaying such foods in families with a history of atopic disease. Highly allergenic foods aside, the preponderance of evidence suggests that the best time to introduce first solid foods falls somewhere between 4 and 6 months of age. The question, then, is whether to shoot for closer to the beginning of that window, or closer to the end.

There are several arguments often made for adding solids to the diet earlier, rather than later. None of these, however, are supported by science. Perhaps the most common assertion is that adding solids will improve infant sleep. Several studies have examined this issue, and have found no sleep improvement with added solids (see, for instance, Macknin et al, Oberlander et al.) The Oberlander study looked at newborns, comparing sleep after a randomly assigned meal of water, carbohydrate, or formula. Water-fed infants slept less than formula-fed infants, while carbohydrate-fed infants (contrary to the common maxim) didn’t sleep as well as formula-fed infants. The Macknin study examined the effects of adding infant cereal to the nighttime bottle (a common practice thought by some to promote sleep) of 5-week-old and 4-month-old infants. The sleep durations of the infants given cereal were compared to the sleep durations of same-age infants given formula with no cereal; the researchers found no increased quantity or quality of sleep with cereal. There is no research support for beginning solids as a means of improving sleep.

Another argument used to support introducing solids at closer to 4 months than 6 months of age is that the older infants are (according to their caregivers) no longer satisfied by breast milk or formula alone. Because 4- to 6-month-olds have very limited communication ability, this is largely based upon speculation. For instance, some caregivers interpret a 4-month-old’s sudden interest in the food on an adult’s plate (or silverware) as an interest in eating. Given the opportunity, many 4-month-olds will grab food off an adult’s plate and place it in their own mouth, interpreted by some caregivers to mean the baby wants to (and/or is ready to) eat solids. However (and I recognize this is not a scientific statement), 4-month-olds also put rocks, garbage, and anything else they can find into their mouths. Around 4 months of age, an infant’s attention begins to turn to the outside world. The infant also increasingly possesses the ability to control his hands, allowing him to grasp objects of interest and bring them to his mouth for exploration. Infants don’t differentiate “food” from “non-food” with regard to what they taste; they simply use oral investigation as one of their means of gaining information about the world. It is a misattribution of intent to suggest that a 4-month-old who grabs food off his mother’s plate wants to eat solids. More scientifically, there is no evidence to suggest that an infant younger than 6 months of age needs anything more than breast milk (with supplemental vitamin D if indicated, see this article for more information) or formula. Further, there is ample scientific evidence showing that infants thrive on nothing but breast milk for the first 6 months (see, for instance, Carruth et al, Dewey, Nielsen et al). There is also evidence showing that introducing solids after 4, but before 6 months of age doesn’t positively affect growth (Cohen et al), because infants fed solids consume less milk or formula. Even infants given as many nursings (this study was conducted on breastfed infants) as they’d been given prior to introduction of solids consumed less milk per nursing when given supplemental solids. This demonstrates that a 4-month-old can’t be made to increase his caloric intake by giving him solids, as he’ll take less milk in response. Of particular concern is the case of the breastfed infant; there is no substance as nutritionally complete or suited to the digestive tract of the young infant as breast milk. Thus, since the breastfed infant responds to solids by decreasing milk consumption, supplementing with solids prior to 6 months of age actually decreases the quality of the breastfed infant’s diet. Given that formula is designed to mirror the nutritional qualities of breast milk as much as possible, we can reasonably extrapolate that it is the best second choice for feeding a non-breastfed infant (or supplementing an infant whose mother is not exclusively breastfeeding) until 6 months of age, and that introduction of complementary solids displaces a higher-quality source of nutrition.

If waiting until 6 months to introduce solids is good, then, is waiting longer than 6 months even better? Apparently not. There’s research that suggests rather strongly that delaying the introduction of solids beyond the 6-month point does not further decrease the risk of allergies (see, for instance, Filipiak et al, Greer et al, Zutavern et al), and may even increase the risk (Nwaru et al). Further, breast milk and formula are no longer sufficient to support increasing nutrient needs beyond 6 months of age (Dewey). As an isolated (but not unique) example, breast milk is quite low in iron (there is a great article about this at Science of Mom), and complementary foods can be used to increase iron in the diet (there’s another great article from Science of Mom here). The most nutritionally-complete diet for a 6-month-old (or older) infant should consist of mainly breast milk (or formula), with carefully-selected complementary solid foods.


Science Bottom Line:* There is ample research to support waiting until after 4 months of age to begin complementary solids, and there is a modest amount of research to support waiting until 6 months of age, particularly in the case of a breastfed infant. There is no evidence of any nutritional or behavioral benefit conferred by solids between 4 and 6 months of age. Research does not support (and, in fact, opposes) waiting beyond 6 months of age to introduce complementary solids.


When did you/will you introduce solids, and why?



Carruth et al. Addition of supplementary foods and infant growth (2 to 24 months). J Am Coll Nutr. 2000 Jun;19(3):405-12.

Cohen et al. Effects of age of introduction of complementary foods on infant breast milk intake, total energy intake, and growth: a randomised intervention study in Honduras. Lancet. 1994 Jul 30;344(8918):288-93.

Dewey, K. Nutrition, Growth, and Complementary Feeding of The Brestfed InfantPediatr Clin North Am. 2001 Feb;48(1):87-104.

Filipiak et al. Solid food introduction in relation to eczema: results from a four-year prospective birth cohort study. J Pediatr. 2007 Oct;151(4):352-8. Epub 2007 Aug 23.

Fiocchi et al. Food allergy and the introduction of solid foods to infants: a consensus document. Ann Allergy Asthma Immunol. 2006 Jul;97(1):10-20; quiz 21, 77.

Greer et al. Effects of Early Nutritional Interventions on the Development of Atopic Disease in Infants and Children: The Role of Maternal Dietary Restriction, Breastfeeding, Timing of Introduction of Complementary Foods, and Hydrolyzed Formulas. Pediatrics. 2008 Jan;121(1):183-91.

Macknin et al. Infant sleep and bedtime cereal. Am J Dis Child. 1989 Sep;143(9):1066-8.

Nielsen et al. Adequacy of Milk Intake During Exclusive Breastfeeding: A Longitudinal Study. Pediatrics. 2011 Oct;128(4):e907-14. Epub 2011 Sep 19.

Nwaru et al. Age at the Introduction of Solid Foods During the First Year and Allergic Sensitization at Age 5 Years. Pediatrics. 2010 Jan;125(1):50-9. Epub 2009 Dec 7.

Oberlander et al. Short-term effects of feed composition on sleeping and crying in newborns. Pediatrics. 1992 Nov;90(5):733-40.

Tarini et al. Systematic Review of the Relationship Between Early Introduction of Solid Foods to Infants and the Development of Allergic Disease. Arch Pediatr Adolesc Med. 2006 May;160(5):502-7.

Options, Ethics, and Moral Imperatives

Vaccinations. Circumcisions. Birthing interventions. These are among the parenting topics that stir up strong feelings and can lead to the exchange of strong words. The recent heated debate over a circumcision post I wrote is one example of this, but there are countless others in fora and on blogs all over the web. In any case, all of this has gotten me thinking about differences in parenting styles. When do philosophical differences become true cases of “right” versus “wrong”?

To illustrate, while discipline styles fall along a continuum, involved parents can generally be classified as authoritarian (strict disciplinarians who don’t display much affection), authoritative (moderate disciplinarians with a warm parenting style), or permissive (non-disciplinarians who display significant affection). Several studies have demonstrated that authoritative parents raise the most well-adjusted, competent children (see, for instance, Lamborn et al, Steinberg et al, Dombusch et al). Furthermore, a recently published study on the topic suggests that authoritarian parenting is associated with future delinquent behavior (Trinkner et al). Still, though the evidence is mounting that children of authoritative parents do best in school and are least likely to engage in risky behaviors of various sorts later in life, parenting style is considered a matter of philosophy, and is left up to the parent (provided the child is not being neglected or abused). Abuse and neglect aside, the overarching social philosophy regarding discipline is that the parent(s) know the child best, and will act in the best interest of the child.

Let’s take another example. As I’ve pointed out here and here, there is neither scientific evidence to support routine infant circumcision, nor is there scientific evidence proving it is harmful in any way. As such, while it’s possible to debate circumcision on moral/ethical grounds (and to feel very strongly about it), the overarching social philosophy is that it’s up to the parent(s) to make the decision regarding circumcision. While there are some who feel very strongly about circumcision (including both those who think circumcision is a violation of the infant’s rights AND those who think that to forgo circumcision is an affront to god), the procedure is not legislated in the United States. Neither is it either supported or opposed by large medical organizations in this country (at this time, at least; there are stirrings that the American Academy of Pediatrics might support circumcision to some extent in the coming years).

Moving on. Vaccination gets a bit trickier, as both camps that feel strongly about the vaccination issue think that there is actual, physical harm being visited upon the child being (or not being) vaccinated. Anti-vaccination advocates think that vaccinating parents are exposing their children to unsafe substances, while proponents of vaccination worry about the children of the anti-vaxers AND about their own children (because the higher the percent of vaccinated individuals in a population, the better EVERYONE, including the vaccinated individuals, is protected). Vaccinations are legislated to some extent; the U.S. Centers for Disease Control and Prevention keeps a database of which vaccinations are required for entry into public school by state. The legislation of vaccinations helps improve compliance among those parents who don’t feel strongly either way about immunizing children, but parents who are fervently anti-vaccination can get an exemption on any one of a number of grounds (philosophical, religious, etc). Nevertheless, some pediatricians feel strongly enough about the dangers associated with children remaining unvaccinated that they won’t accept unvaccinated children into their practice (both to avoid exposing patients to unvaccinated children and to try to motivate parents to vaccinate). Other pediatricians feel that this exclusion of unvaccinated children is unethical. Given that the scientific evidence unequivocally supports childhood vaccination (more articles on this topic archived here), is it ethical to allow a parent who claims that vaccinations are harmful to make a potentially dangerous decision for their child? Is being wrong about the science the same thing as being wrong about the parenting?

Here’s yet another example. There was an ethical discussion written up in the medical journal Pediatrics last year about a case in which parents refused antibiotics and hospitalization for a septic (that is to say, bacterially-infected) newborn (Simpson et al). The mother had been trying for a home birth with a midwife, but had developed a fever and was brought to the hospital. The parents refused fetal monitoring and wanted to continue with their natural birth plan, despite concerns on the part of the medical team that both the mother and newborn had a bacterial infection. The mother eventually accepted IV antibiotics. She refused any treatment for her newborn, however, and asked to be discharged same-day. She and her husband wanted to leave against medical advice because they felt the newborn “didn’t look sick.” The medical team ended up contacting CPS, and the parents agreed to an antibiotic treatment for the newborn. Medical protocol would have been for the newborn to remain in the hospital for 48 hours of monitoring. Instead, however, the parents found another doctor who had privileges at the hospital and who agreed to discharge the baby early. The purpose of the article was to discuss what had been done and what should have been done. The authors of the article, all medical practitioners, agreed that the parents were doing what they (the parents) thought (in the absence of any medical knowledge) was in the best interest of the baby. This was not a case of purposeful abuse or neglect. However, the parents refused to allow the majority opinion of medical experts to guide their decision-making, and instead found a rogue practitioner willing to do what they wanted. Everyone agreed that, given the parents clearly loved the child, it was a shame to have had to bring CPS into the equation Still, the authors further agreed that when it comes to medical decisions, there’s a line between a parent exercising a parental right…and a parent simply being wrong.

With regard to some parenting issues, there’s no clear right or wrong answer. For instance, a few real sticklers on either side of the fence might butt heads over whether a 22-month-old should be allowed to watch TV, but there’s no rational argument that can be made for legislating this issue either way. There are other parenting issues that are clear-cut cases of moral imperative. For instance, it is wrong to keep a child in a kennel. No discussion, no ifs, ands, or buts. It’s wrong. And it’s illegal. Unfortunately, though, the waters are pretty muddy with regard to many other parenting decisions. Sure, the science supports breastfeeding, but what if mama hates it? What if she has to return to work and can’t pump? What if…whatever? Even when science comes down (either weakly or strongly) on one side of an argument, there’s often room for different philosophies. But then again, sometimes there isn’t.

Isaac Asimov, ca 1965

I guess the real question is how do we know what delineates a difference of philosophy and what’s simply a case of right and wrong? Should a set of parents be allowed to feed their newborn nothing but raw vegetable juice — because, say, they’re vegans who further happen to believe that soy is unhealthy due to…whatever — given that this diet would result in massive malnutrition (and eventually death)? Is it the right of a parent who wants a “natural birth experience” to leave the hospital against medical advice with a neonate that the medical staff feel needs antibiotics? If the parents leave and the infant lives, does that make them any less negligent than if they had left and the infant had died? Where’s the line between persevering in a philosophy…and perseverating? When does adherence become obstinance? The availability of free information (much of it erroneous) on the Internet has made many of us feel like armchair Experts In Everything. We tend to turn to the Internet rather than true experts, or we choose to trust only those experts who agree with our preformed, Interwebs-derived conclusions. Further, somehow it has become acceptable — in some circles, even admirable — to defy the medical and scientific establishments, and to refuse to acknowledge the validity of well-performed, oft-repeated, well-accepted research. How did this happen? In the words of Isaac Asimov, who said it so gracefully, “Anti-intellectualism has been a constant thread winding its way through our political and cultural life, nurtured by the false notion that democracy means that ‘my ignorance is just as good as your knowledge.’


What do you think a parent should — or should not — be able to choose for their child?



Dombusch et al. The relation of parenting style to adolescent school performance. Child Dev. 1987 Oct;58(5):1244-57.

Lamborn et al. Patterns of competence and adjustment among adolescents from authoritative, authoritarian, indulgent, and neglectful families. Child Dev. 1991 Oct;62(5):1049-65.

Simpson et al. When parents refuse a septic workup for a newborn. Pediatrics. 2011 Nov;128(5):966-9. Epub 2011 Oct 24.

Steinberg et al. Over‐time changes in adjustment and competence among adolescents from authoritative, authoritarian, indulgent, and neglectful families. Child Dev. 1994 Jun;65(3):754-70.

Trinkner et al. Don’t trust anyone over 30: parental legitimacy as a mediator between parenting style and changes in delinquent behavior over time. J Adolesc. 2012 Feb;35(1):119-32. Epub 2011 Jun 12.


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