MEDICINE CABINET OF CURIOSITIES CHAPTER 1 BY THE NUMBERS Doctors will have more lives to answer for in the next world than even we generals. --NAPOLEON I (1769-1821) What Little Boys, Little Girls, and All the Rest of Us Are Made Of H YDROGEN, MOSTLY. IN ELEMENTARY SCHOOL YOU HEARD that we are 65 percent water, or something like that, right? As usual, you didn't get the full story. In reality, your body is 62.91 percent hydrogen, 24.003 percent oxygen, and 11.97 percent carbon--that's a little more than 98.89 percent of you, and we've only accounted for three elements. You're 0.58 percent nitrogen, 0.24 percent calcium, 0.14 percent phosphorus, and 0.04 percent sulfur, so those four make up about another 1 percent. That leaves roughly 11 one-hundredths of 1 percent for everything else. You are about 0.0000000000000015259 percent radium. That's 80 billion atoms--not very many. Here's what a 155-pound man is made of, atom for atom: The Smallest Bone in the Human Body The stapes, one of three bones in the middle ear. It's also the lightest bone in the body and helps to transmit sound vibrations to the inner ear. The Biggest Bone in the Human Body The femur, or thighbone, which runs from hip to knee. It's also the longest bone in the body and, if it's in good health, could support about thirty times your weight. By a Hair's Breadth "Smaller than the width of a human hair" is the description people sometimes use when they're trying to describe something really, really small. But what exactly is the width of a human hair? It varies, for a number of reasons. Different people have different hair thicknesses. Dark hair tends to be thicker than light-colored hair. Babies have finer hair than adults. Age thickens some body hairs. And each hair varies in thickness from the root to the tip. So "the width of a human hair" is a pretty imprecise figure any way you look at it. How imprecise? Very. A good estimate is that a human hair can vary in thickness from about 15 microns (a micron is 39 one-millionths of an inch) to about 180 microns. So, big deal, we say: what's a few millionths of an inch between friends? Well, not much, but one hair can be twelve times thicker than another. If you simply mean that something is very thin, then "the width of a human hair" is probably good enough. But what if someone asked you how tall something is and you replied "It's about as tall as a ladder"? Do you mean a five-foot stepladder or a sixty-foot fire truck extension beam? In most everyday situations, a few microns one way or the other doesn't make much difference, but if you're designing the display coating for a TV screen, the circuitryfor an iPhone, or a lithium-ion battery for a laptop computer, you have to be a lot more precise than "the width of a human hair." Losing Our Hair Nonhuman primates, like most mammals, are covered with fur. So why is it that humans are the only (mostly) hairless ape? Darwin thought it was unlikely that hairlessness evolved by natural selection alone, since hair protects skin against the damaging rays of the tropical sun. Which makes it even more puzzling, as a matter of biology, when you consider where we do have hair--in our armpits, around our sexual organs, and on our heads. A 1981 paper suggested that the answer has to do with heat dissipation. As the ratio of surface area to volume decreases, the advantage of having lots of insulation decreases, too. A 450-pound gorilla has a mass a thousand times that of a half-pound marmoset, but an exposed surface only a hundred times as great. So the great ape needs less fur to keep the heat in. When humans emerged from the forest to explore the open savannah, they developed hairlessness to allow heat to escape, and then sweat glands to cool their bodies by evaporation. The evolution of sweat glands allowed even more extensive hairlessness to evolve. Presumably the evolution of darker skin happened for the same reason. None of this, of course, explains the persistence of armpit and pubic hair. A newer theory is that humans lost their hair to get rid of lice, fleas, and ticks and the diseases those animals carry, such as typhus, trench fever, and bubonic plague. This makes having less hair sexually attractive because it signals goodhealth. And sexual attractiveness gives the trait survival value. Do we think this explains why women, and now increasingly men, want to rid their bodies of hair? Maybe. And then again, maybe not. The Quick and the Dead Fingernails and toenails are made of a protein called keratin, and the nails have several different parts, most of them with names you've probably never heard of. The eponychium, better known as the cuticle, is the piece of skin where the finger meets the bottom of the nail. The skin around the edges is called the paronychium. The hyponychium is the skin that connects underneath the tip of the nail. The nail plate is the part on top that you see and polish, and the nail bed--sometimes called the quick--is the tissue that's under the nail. The white half-moon at the bottom of your fingernail is called the lunula. Fingernails grow about a tenth of an inch a month, toenails about three one-hundredths of an inch. They grow from the bottom out--the part that you file or clip is the oldest part, and it's dead. For some reason, nails grow faster in the summer than in the winter. They grow faster during pregnancy, but on the whole, men's grow faster than women's. And the nails on your dominant hand grow faster than those on the other hand. Nails lose their water content with age, which can make them crack or peel. Living in a cold, dry climate and washing your hands a lot can also dry them out and cause cracking and peeling. Nails can get fungal infections, which are more commonin the toenails than on the hands. Bacteria can infect the tissue around the nails, which often happens after an injury. Warts and tumors can appear around or under nails, and if a tumor is big enough, surgery may be required to remove it. The longitudinal ridges you see in your nails are the result of aging, and don't suggest any health problem. However, although no doctor would depend on examining them to make a diagnosis, fingernails and toenails can sometimes suggest certain other health problems. Those white spots you occasionally see usually mean nothing--they're often caused by minor trauma to the ends of your fingers--but sometimes they can indicate an infection. Psoriasis can cause flattening of the nails, and certain thyroid and lung conditions can cause brittleness. Dark spots on the nails have to be looked at by a dermatologist--they can be a sign of melanoma, a deadly skin cancer. But if you have a serious health problem, your fingernails are not the first place you'll notice it, and they're not the first place a doctor will look, either. The Smallest Surviving Baby Records are imperfect, so it's hard to say exactly who holds claim to the title of smallest baby ever, but Amillia Sonja Taylor, born at Baptist Children's Hospital in Miami, Florida, on October 24, 2006, is the smallest for whom there is a reliable record. She was nine and a half inches long and weighed just under ten ounces after a gestation that lasted a little less than twenty-two weeks. She went home in February 2007 weighing four and a half pounds. In July 2007, according to a report in People magazine, she was healthy, weighed fourteenpounds three ounces, and was able to hold up her head and sit with support. Vital Statistics We are sorry to note that the percentage of preterm births--those at less than thirty-seven weeks' gestation--increased by 20 percent between 1990 and 2005. The United States ranks just twenty-ninth in infant mortality, compared to twelfth in 1960, though the actual infant mortality rate has declined, to 6.9 deaths per one thousand live births. (Singapore ranks number one, with 2 deaths per one thousand births.) Congenital malformations, disorders related to low birth weight, and sudden infant death syndrome account for 43 percent of all infant deaths. In Black and White African Americans suffer more health problems than white Americans, and they often get poorer medical care. The problem is complicated, and racism and other prejudices are only sometimes a factor, but hundreds of studies have demonstrateda clear pattern in which white and black patients are treated differently. In any case, we consider the following highly disturbing: In New York City, black babies with very low birth weights (less than three pounds five ounces) are more likely to be born in hospitals with high risk-adjusted neonatal death rates. Only 11 percent of white very low birth weight (VLBW) babies were born at hospitals with high death rates, while 21 percent of black VLBW babies were born at such hospitals. Black patients get less opioid pain relief medicine than white people. According to Dr. Mark Pletcher of the University of California, San Francisco, this disparity was identified in the 1990s, and there was hope that a national campaign aimed "at improving pain management in emergency departments would shrink this disparity ... . Unfortunately, this is not the case." Black patients are less likely than white to receive various kinds of cancer therapy. A study finds that despite efforts in the last decade to mitigate cancer treatment disparities, black patients are significantly less likely than white patients to receive therapy for various types of cancer. Once again, efforts initiated in the 1990s to close treatment gaps appear to have had little impact. African Americans wait longer than white people to receive kidney transplants. There are many reasons why some patients get organs faster than others, but an important one is match by race. Black patients are less likely to receive mitral valve repairs, the treatment for mitral valve disease, a type of heart disease. African Americans present for mitral valve surgery at a significantly younger age than whites and with more risk factors, but they don't receive mitral valvuloplasty at the samerates, even though the operation can have an effect on long-term outcome. The reasons are not clear. Black patients are more likely to die from soft-tissue cancers than whites. This kind of cancer is rare, but it's very serious. Researchers studied 4,636 whites, 663 blacks, 696 Hispanics, and 411 Asians with the diagnosis. Blacks diagnosed with soft-tissue sarcomas in an arm or a leg were much less likely than other groups to receive certain limb-sparing treatments, and their overall survival was poorer. Blacks were 39 percent more likely to die from the disease, even when other factors are taken into account. Black patients are less likely than whites to undergo thorough examination and surgery for treatable lung cancer, even when they have equal access to specialized medical care. Blacks with chronic obstructive pulmonary disorder are less likely to undergo lung transplants than whites, even after controlling for age, lung function, pulmonary hypertension, obesity, and diabetes. Insurance, cardiovascular risk factors, and poverty explained part--but not all--of the differences in treatment. Black smokers are less likely to be screened for tobacco use and less likely to be advised to quit. During visits to health care providers in 2007, 63 percent of white smokers were advised to quit smoking, while 55 percent of black smokers got the same recommendation. And it wasn't because the black smokers were poorer or had worse insurance factors--the researchers statistically accounted for those variables in their study. When Medicare began paying for women to undergo preventive mammograms in 1991, doctors expected breast cancer mortality rates to drop. Breast cancer deaths did decrease, but not as quickly for African American women as agroup--though breast cancer death rates for black and white women used to be nearly identical. And while breast cancer death rates are decreasing for white women in every U.S. state, for African American women, death rates are decreasing in only eleven of the thirty-seven states with sufficient numbers for analysis and in the District of Columbia. In the rest, death rates are either flat (twenty-four states) or increasing (in Arkansas and Mississippi). Black patients are less likely to receive chemotherapy or radiation therapy for rectal cancer, though black patients and white patients see rectal cancer specialists at similar rates. African Americans were 23 percent less likely to receive chemotherapy for rectal cancer, and 12 percent less likely to receive radiation therapy, than whites. "We knew that African Americans were not receiving chemotherapy for rectal cancer at the same rates as white Americans and it was contributing to their increased mortality. Now we have a better idea of where the problem lies: somewhere between the visit with the oncologist and the actual initiation of chemotherapy," says Dr. Arden Morris of the University of Michigan Medical School and the Veterans Administration Ann Arbor Health-care System. Black patients are more likely to die in the early stages of chronic kidney disease. Individual physicians achieve less favorable outcomes among their black diabetes patients than among their white patients. One factor is socioeconomic: poorer people have poorer outcomes, regardless of the seriousness of the disease. But there were still racial disparities in outcomes, and they were attributable not to differences between physicians or between health plans, but to individual physicians. Accordingto this study, physicians treat black and white patients differently, and whites get better care. Black males have the highest death rate--and a higher death rate across most of the leading causes of death. Copyright (c) 2009 by Nicholas Bakalar Excerpted from The Medicine Cabinet of Curiosities: An Unconventional Compendium of Health Facts and Oddities from Asthmatic Mice to Plants That Can Kill by Nick Bakalar All rights reserved by the original copyright owners. Excerpts are provided for display purposes only and may not be reproduced, reprinted or distributed without the written permission of the publisher.
