Friday, September 23, 2011
KCAL 9 Reporter Needs an Atlas
Tonight in the 9 pm KCAL 9 News, reporter Juan Fernandez was a interviewing E.C. Krupp, Director of the Griffith Observatory. The observatory has a piece of a Delta 2 rocket that fell to Earth in Mongolia. Juan asked Dr. Krupp if it fell in the ocean. Somebody should buy Juan an atlas.
Dr. Oz has an apple in his As.
On September 14, Dr. Oz claimed on his TV show that apple juice has dangerous levels of arsenic (chemical symbol As). The Federal Drug Administration (FDA), in what has to be an unprecedented move, wrote a letter to Dr. Oz explaining to him that testing for inorganic arsenic (the dangerous form) is much more complicated than testing for total arsenic (which Dr. Oz tested for.) In a second letter, the FDA showed the results from its own tests that demonstrate that Dr. Oz's results were "erroneously high."
In both letters, the FDA states that "it would be irresponsible and misleading for the Dr. Oz Show to suggest that apple juice is unsafe based on tests for total arsenic."
Now for the science.
Arsenic comes in two predominate types: pentavalent As(+5) and trivalent As(+3). Pentavalent arsenic is also referred to as organic arsenic while trivalent arsenic is called inorganic arsenic. An article on Wikipedia claims that organic arsenic is 500 times less toxic than the inorganic form, but I couldn't verify that in a trusted source. What I did find from the Environmental Protection Agency (EPA) is that the EPA and the Center for Disease Control (CDC) is most concerned with exposure to inorganic arsenic.
Inorganic arsenic is nasty stuff. A lethal dose of inorganic arsenic is about 100 to 200 mg (milligrams) for a 150 lb person. Roughly speaking, that is about 1/50 of a teaspoon. Dissolved in a quart of water gives a concentration of about 200,000 ppb. How much arsenic are you exposed to? So the EPA has set the limit for drinking water at 0.01 mg/L or 10 ppb (parts per billion). What does this mean? Imagine taking a quart of water (about one liter) and then dissolving 1 teaspoon of sugar. That would be about 4,000,000 ppb. To get down to 10 ppb, take your sugar water and pour in 400,000 quarts of water. That's one hundred thousand gallons.
The EPA sets such a stringent limit, because our country's water supply must be safe. No water on Earth is as safe as city tap water. Many cases of arsenic poisoning occurs in the Third World where the drinking water is contaminated with inorganic arsenic.
What about other sources of arsenic like apple juice, rice, and carrots? Dr. Oz claims that the samples of apple juice he tested had levels 36 ppb while the EPA measurements were between 2.0 and 6.0 ppb. Furthermore, Dr. Oz tested for total arsenic not inorganic arsenic. The EPA did the same, but the agency's policy is that when the total arsenic level is above 23 ppb, they will run additional tests for inorganic arsenic. The implication here is that nearly all the arsenic found in food is organic arsenic, and not nearly the concern that inorganic arsenic is.
Rice has arsenic in it in concentrations anywhere from 100 ppb to 800 ppb depending on where it's grown. Compare that to the apple juice. By the way, Texas and Louisiana rice tends to be higher in arsenic; California's rice is among the lowest. Carrots have about half the amount of rice.
End notes:
1. During the Chosun dynasty in Korea, arsenic was used as a form of capital punishment.
2. In the play Arsenic and Old Lace, the old ladies killed by spiking their home made elderberry wine with arsenic. I'll stick to Pinot Noir.
3. Political statement - I know that in certain political quarters it is quite fashionable to question federal oversight and the money spent in doing so, but I thank our federal officials who make my life healthier, longer, and more enjoyable, because they are monitoring our country's food, water, and drugs.
Sunday, September 11, 2011
Is Your Cell Phone Killing You?
It could, if you're texting while driving.
My least favorite TV physician, Dr. Oz, says on his website that "experts have grown concerned about the health implications of heavy exposure—specifically, the radiation that the devices emit." Dr. Oz often offers misleading advice, but this is just plain wrong. Experts know that there is no danger from cell phones.
The World Health Organization (WHO) reports that "[a} large number of studies have been performed over the last two decades to assess whether mobile phones pose a potential health risk. To date, no adverse health effects have been established as being caused by mobile phone use."
The National Cancer Institute at the National Institutes of Health says "there is no evidence from studies of cells, animals, or humans that radiofrequency energy can cause cancer."
What is it about cell phones? Cell phones use microwaves - a form of electromagnetic radiation. The history of this issue goes back at least to an article in the New Yorker in 1989. Paul Brodeur alarmed the country when some epidemiological studies supposedly showed an increase in cancer in homes near power lines. [More about epidemiology later.] The power lines as all electrical currents generate magnetic fields - extremely low frequency radiowaves. Scientists never found any causal link. In fact, when more careful epidemiological studies were conducted, the correlation between exposure to electromagnetic fields and cancer disappeared.
Now for the science lesson. Cancer is an example of a biochemical reaction gone horribly wrong. While not well understood in many types of cancer, whatever happens causes the uncontrolled growth of abnormal cells. Documented cancer-causing agents are perchloroethylene (used in dry cleaning), tobacco smoke, ultraviolet light, viruses, and environmental toxins like aflatoxin in peanut butter.
How can light (electromagnetic radiation) cause these biochemical changes? Each particle of light called a photon has an energy that depends on the color of the light. As one can see from the diagram, light comes in more colors than just red. orange, yellow, green, blue, indigo, and violet. The photon can be absorbed by an atom or molecule. The energy then is used to excite an electron. If the energy is large enough, the electron can be stripped from the atom.
Now I like to tell my physics students that chemistry is the science of electrons. When chemical bonds are rearranged or broken in a chemical reaction, it's the electrons that are being exchanged between the atoms. So when the photon is absorbed, this can cause a chemical reaction - if the energy is large enough.
What colors of light have enough energy and can cause biochemical effects? Roughly speaking, you need ultraviolet light. This is why I wear sunscreen when I golf. What about microwaves? A microwave photon has about 1/100,000 the energy of a UV photon. No chemical reactions here.
You may be wondering about your microwave oven. That certainly cause some chemical reactions, right? Yes, but not through the mechanism described above. In this case, the microwave photon is absorbed by a water molecule, and this makes the water molecule rotate. This added motion translate as added energy to the water making the water hotter.
So can a cell phone cook your brain? No. Through evolution, mammals have a wonderful mechanism for ridding the body of excess heat - the circulatory system. However, we can calculate how much cooking is going on. A typical cell phone emits about 1 Watt of power. In a five minute phone call, this could cause an increase in temperature of 0.1ºC in the brain tissues near your ear.
Yak away.
A Note Regarding Epidemiology: This is an important field in science-based medicine. Epidemiology aims to find relationships between exposure to agents and mortality (death) and morbidity (disease). The link between cigarette smoking and lung cancer was first found by epidemiologists, long before any understanding of the physical causes.
A good study is difficult. The most serious threat to a good study is bias. Bias comes in three forms: 1. Selection bias in which subjects are taking part because of an unknown factor that happens to be associated with the exposure and the effect. 2. Information bias where the information gathered is flawed. A typical source of information bias example is when subjects are asked to remember information. 3. Confounders are variables that correlate with both the exposure and the effect. For example , a confounder in the power line study may have been the neighborhoods where the subjects lived.
My least favorite TV physician, Dr. Oz, says on his website that "experts have grown concerned about the health implications of heavy exposure—specifically, the radiation that the devices emit." Dr. Oz often offers misleading advice, but this is just plain wrong. Experts know that there is no danger from cell phones.
The World Health Organization (WHO) reports that "[a} large number of studies have been performed over the last two decades to assess whether mobile phones pose a potential health risk. To date, no adverse health effects have been established as being caused by mobile phone use."
The National Cancer Institute at the National Institutes of Health says "there is no evidence from studies of cells, animals, or humans that radiofrequency energy can cause cancer."
What is it about cell phones? Cell phones use microwaves - a form of electromagnetic radiation. The history of this issue goes back at least to an article in the New Yorker in 1989. Paul Brodeur alarmed the country when some epidemiological studies supposedly showed an increase in cancer in homes near power lines. [More about epidemiology later.] The power lines as all electrical currents generate magnetic fields - extremely low frequency radiowaves. Scientists never found any causal link. In fact, when more careful epidemiological studies were conducted, the correlation between exposure to electromagnetic fields and cancer disappeared.
Now for the science lesson. Cancer is an example of a biochemical reaction gone horribly wrong. While not well understood in many types of cancer, whatever happens causes the uncontrolled growth of abnormal cells. Documented cancer-causing agents are perchloroethylene (used in dry cleaning), tobacco smoke, ultraviolet light, viruses, and environmental toxins like aflatoxin in peanut butter.
How can light (electromagnetic radiation) cause these biochemical changes? Each particle of light called a photon has an energy that depends on the color of the light. As one can see from the diagram, light comes in more colors than just red. orange, yellow, green, blue, indigo, and violet. The photon can be absorbed by an atom or molecule. The energy then is used to excite an electron. If the energy is large enough, the electron can be stripped from the atom.
Now I like to tell my physics students that chemistry is the science of electrons. When chemical bonds are rearranged or broken in a chemical reaction, it's the electrons that are being exchanged between the atoms. So when the photon is absorbed, this can cause a chemical reaction - if the energy is large enough.
What colors of light have enough energy and can cause biochemical effects? Roughly speaking, you need ultraviolet light. This is why I wear sunscreen when I golf. What about microwaves? A microwave photon has about 1/100,000 the energy of a UV photon. No chemical reactions here.
You may be wondering about your microwave oven. That certainly cause some chemical reactions, right? Yes, but not through the mechanism described above. In this case, the microwave photon is absorbed by a water molecule, and this makes the water molecule rotate. This added motion translate as added energy to the water making the water hotter.
So can a cell phone cook your brain? No. Through evolution, mammals have a wonderful mechanism for ridding the body of excess heat - the circulatory system. However, we can calculate how much cooking is going on. A typical cell phone emits about 1 Watt of power. In a five minute phone call, this could cause an increase in temperature of 0.1ºC in the brain tissues near your ear.
Yak away.
A Note Regarding Epidemiology: This is an important field in science-based medicine. Epidemiology aims to find relationships between exposure to agents and mortality (death) and morbidity (disease). The link between cigarette smoking and lung cancer was first found by epidemiologists, long before any understanding of the physical causes.
A good study is difficult. The most serious threat to a good study is bias. Bias comes in three forms: 1. Selection bias in which subjects are taking part because of an unknown factor that happens to be associated with the exposure and the effect. 2. Information bias where the information gathered is flawed. A typical source of information bias example is when subjects are asked to remember information. 3. Confounders are variables that correlate with both the exposure and the effect. For example , a confounder in the power line study may have been the neighborhoods where the subjects lived.
Friday, September 2, 2011
Maxwell's Silver Magnet (apologies to the Beatles)
In the post on wine swirling, i didn't bring up one of of Ralph de Amicis' incorrect comments, because there were so many that were wrong. This one though, deserves it's own post.
A frequent mistake that people make is to mix up the electric charge with the magnetic pole. Both are basic characteristics of matter, just as mass is, but they're not interchangeable. Incredibly, I've even heard one of my science colleagues make this mistake in his class.
When I rub a balloon on my sweater, the balloon rips electrons from the fibers. When I put the balloon near the wall, those extra electrons on the balloon repel the electrons near the surface of the wall leaving a slight deficit of electrons (or a slight surplus of protons). Now notice those little plus (+) signs and negative (-) signs. Benjamin Franklin realized that electric charge comes in two types. He named them positive and negative. I think those are rather apt names, because in mathematics a negative sign can mean 'opposite.'
Now let's play with a magnet. When I place a magnet near a compass which is just a small magnet, I notice that the one end of the compass (white in the figure) is attracted to the red end of the magnet and vice-versa. I also notice that the red end of the compass is repelled by the red end of the magnet. When I take the compass outside, I see that the red end always points North. Historical note: The Chinese invented the compass 4500 years ago.
Since not all magnets have red and white ends, we need to name the two ends. I guess that since the red end points toward the North Pole, some ancient people (probably either the Chinese or the Greeks) called that end the north pole and the other end the south pole. Now look at the figure with the Earth. Since the north pole of the compass (the red end) points toward the North Pole of the Earth, the North Pole is really a magnetic south pole. Every semester when I teach this, I wish we used the terms red end and white end.
Two separate characteristics, two different phenomena. Charges created static electricity. Poles create magnetism.
What's really cool though is that although charge and pole are different characteristics of matter, they are related. Scientists like Faraday and Maxwell realized in the 19th century that by moving charges (like in electrical currents), we can create an electromagnet and by moving magnets we can create electrical current. These are the principles that give us electrical motors and generators.
The positive pole is more highly charged, just like the North Pole of the Earth,…
A frequent mistake that people make is to mix up the electric charge with the magnetic pole. Both are basic characteristics of matter, just as mass is, but they're not interchangeable. Incredibly, I've even heard one of my science colleagues make this mistake in his class.
Now let's play with a magnet. When I place a magnet near a compass which is just a small magnet, I notice that the one end of the compass (white in the figure) is attracted to the red end of the magnet and vice-versa. I also notice that the red end of the compass is repelled by the red end of the magnet. When I take the compass outside, I see that the red end always points North. Historical note: The Chinese invented the compass 4500 years ago.
Since not all magnets have red and white ends, we need to name the two ends. I guess that since the red end points toward the North Pole, some ancient people (probably either the Chinese or the Greeks) called that end the north pole and the other end the south pole. Now look at the figure with the Earth. Since the north pole of the compass (the red end) points toward the North Pole of the Earth, the North Pole is really a magnetic south pole. Every semester when I teach this, I wish we used the terms red end and white end.
Two separate characteristics, two different phenomena. Charges created static electricity. Poles create magnetism.
What's really cool though is that although charge and pole are different characteristics of matter, they are related. Scientists like Faraday and Maxwell realized in the 19th century that by moving charges (like in electrical currents), we can create an electromagnet and by moving magnets we can create electrical current. These are the principles that give us electrical motors and generators.
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