NATURALLY DANGEROUS: Surprising Facts About Food, Health, and the Environment.
By James P. Collman, Professor of Chemistry, Stanford University
Chapter 7. Natural and Unnatural Molecules in the Environment
© James P. Collman, 2003. All rights reserved
An important natural protein fiber, silk, was developed in China about 5,000 years ago. Made from a cultivated silkworm, the Bombyx mori silk moth, silk is a remarkable material. A single silkworm can produce between 600 and 900 meters (yards) of fiber. Recently scientists have been working on stronger and potentially more useful protein fibers produced by other insects, such as spiders! But it will be very challenging to make a practical silk from spiders. For example, a spider can produce no more than 130 meters of silk. It is also difficult to spin silk from spiders. The genes spiders use to make their silk are being introduced into bacteria, tobacco plants, and goats, so that larger quantities of spider silk can be produced. Other insects, such as bees, wasps, and ants are being investigated as sources of silk.
Spiders make several types of silk, which may be useful in producing exceptional
fibers. Spider silk is superstrong and supertough, so that is can support
tremendous weight and absorb a lot of kinetic energy before breaking. Spider
silk is tougher than the synthetic nylon, Kevlar or even steel. Silk from
silk worm caterpillars promote immune responses in people, precluding use
of this silk for sutures and other medical applications, but spider silk does
not appear to produce this immune response. Nevertheless, many problems remain
to be solved before spider silk becomes competitive with silk made from the
cultivated silk worms that were developed many years ago in ancient China.
(Science News, November 22, 2008, page 21)
Many people have reported experiencing intense euphoria after a vigorous
run. But is this" runner's high" real and if it is what is the science
behind the euphoric feeling? German researchers have recently verified the
runner's high hypothesis and shown that it comes from generating endorphins,
the brain's naturally occurring opiates. Recall from Chapter 1 that endorphins
are small proteins ("peptides") containing a few amino acids. By
using PET scans and studying opiod receptors in the limbic and prefrontal
areas of the brain these scientists showed that endorphins are generated by
vigorous exercise and that these molecules activate pleasure-giving regions
in the brain. Running may also affect pain perception and enhance pain tolerance;
that is currently being studied using these techniques. ( Gina Kolata, New
York Times, First Styles Page, March 27, 2008)
In Chapter 7 of Naturally Dangerous you learned that the poison found in livers of fugu (puffer fish) came from an unknown substance that the fish had eaten, perhaps a micro-organism. This toxin can cause paralysis, and heart failure. In small amounts it produces a numbing of the consumer's lips. Japanese have considered this a thrill!
Now that wild fugu fish are rare, constituting about 10% of the market in
Japan, non-poisonous puffer fish, which have been fed non-toxic feed, have
become readily available. The neurotoxin, called tetrodotoxin is concentrated
in the liver of wild puffer fish. For historic reasons the sale and consumption
of fugu livers has been illegal in Japan. Now that non-toxic fugu fish are
readily available, their tasty fish livers are a tempting delicacy. But, for
largely traditional reasons, such as protecting the jobs of licensed jugu
chefs and businesses, Japanese authorities are not permitting the sale of
non-toxic fugu fish livers. But unofficially, you can purchase these in several
Japanese restaurants. (New York Times, May 4, 2008, page 8)
More and more is being said about ethanol in gasoline, but at this time all the ethanol used as fuel is being produced from corn, but the severe problems derived from corn-based ethanol have not been discussed in the media. As the following facts show, this corn-based energy policy is political hot air, and it is costing consumers, who seem to be ignorant of these facts. According to an article in the Harvard Magazine the use of ethanol as a motor fuel is hopelessly expensive and has many disadvantages, unless you are a farmer, a politician or you own stock in Archer Daniel Midlands, a company that profits from corn-based ethanol. Ethanol is derived from corn (it can be made more cheaply from petroleum) because such ethanol comes from photosynthesis – the corn plant uses energy from sunlight to convert carbon dioxide in the air into carbohydrates, which are then converted into ethanol by fermentation. The same process is used to make alcoholic drinks from grain. Some sobering facts: ethanol contains less energy than gasoline because ethanol has been partially combusted. For this reason, one would need 1.5 gallons of ethanol to drive a car the same distance you would go on 1.0 gallon of ordinary gasoline. It is estimated that the gasoline savings in 2005 from adding ethanol amounted to only 1.9 percent of the total gasoline sold that year: 140 billion gallons. In 2006 ethanol production from corn is expected to be a mere 4.8 billion gallons and to increase only to 7.5 billion gallons in 2007. In spite of this small contribution, currently 12 percent of the U.S. corn crop is used to produce ethanol. By 2030 the U.S. Department of Energy (DOE) has a goal to displace 60 billion gallons of gasoline by ethanol, but that amount would have to come from other plant sources using the cellulose in switch grass and corn stalks. This will be very difficult because enzymes that can produce ethanol from such sources are inefficient and expensive, even though research to develop such enzymes has gone on for many years. Moreover this amount of cellulose would require at least 225 million acres to produce. As of 2004 23 percent of the nation’s total cultivated land, which amounts to 73.4 million acres were planted in corn. Land planted in corn is projected to increase to 25 percent in 2007. The demand for corn to be used to produce ethanol fuel is increasing corn prices so that more land is being planted in corn and less in soybeans – but both are used to feed livestock for food. Increased food prices are inevitable.
The price of ethanol to be used in gasoline is actually very high even though it is subsidized. In May 2006 the wholesale price of ethanol derived from corn was $2.65 a gallon, but if one adds in the subsidy of 51 cents authorized by Congress the price is actually $3.16. But in California in July 2006, the price of a gallon of ethanol derived from corn was $4.00. This additional cost derives from transportation – ethanol cannot be shipped through pipelines but must be transported by trucks or trains in special tanks. Because ethanol has less energy than gasoline, California motorists were actually paying $6.00 per gallon of ethanol to get the same energy (miles per gallon) as ordinary gasoline. Why doesn’t the U.S. buy plant derived ethanol from other countries such as Brazil , the World’s largest ethanol producer. As of 2004, the cost of ethanol from sugar cane in Brazil could be delivered to the U.S. at $1.01, which is 50 cents cheaper than the subsidized price of ethanol derived from corn in the U.S. To protect our farmers, and to keep their votes congress has imposed an import duty of 54 cents per gallon on imported ethanol (in addition to another import duty equal to 2.5 percent. Very few citizens know this, and the media have failed to tell the public about these tariffs, which raise gasoline and food prices.
What about the ecological gains from using plant derived ethanol as a fuel in terms of reducing carbon dioxide in the atmosphere. In Brazil, where ethanol is made more cheaply from sugar cane, much of the energy to make ethanol comes from burning the fibrous materials left over from harvesting the sugar. Any excess heat from burning this byproduct is used to generate electricity. The overall process is neutral in the consumption and emission of carbon dioxide, considering the petroleum that does not have to be burned as gasoline because the ethanol fuel replaces it. But the situation in the U.S. is at best marginal. The most favorable estimates claim that the energy captured in the corn-derived ethanol is greater than the fossil fuels that are required to produce the ethanol – such things as the natural gas used to make the fertilizer, the diesel fuel that propels the tractor, the fuel that is consumed transporting the crop to the refinery, and the energy consumed to distill water from the dilute ethanol solution coming from fermentation. Some academics have claimed this is an energy loss!! There is certainly some net savings in the use of liquid hydrocarbons, which must be imported and only these can be used to fuel cars, trucks, and especially airplanes. The latter cannot be run on coal or gaseous fuels. Another negative ecological effect is related to the potent greenhouse gas, nitrous oxide, which is produced as a byproduct during the manufacture of fertilizer. Thus the ecological benefits of legally mandating the use of corn-based ethanol as a fuel in the U.S. are very small if not negative and the real cost to consumers is quite high. The main-stream media’s job is to educate the public and they seem to have failed in the arena. Why? I do not know.
Your sense of smell depends on the nature of the molecules entering your
nose. Molecular shapes can influence odor. Since some of the odor detecting
centers are chiral or handed, differing as your hands do in a mirror image
relationship, your nose can distinguish pairs of isomeric, handed molecules.
In class I once asked students to sniff the two handed isomers of a plant
product, carvone. The "R" isomer has the odor of spearmint, whereas
the "S" isomer smells like caraway. There are many such examples
where the two handed isomers smell differently. But it is well known than
your nose cannot distinguish between molecule that differ only in having different
isotopes, for example where a hydrogen atom is replaced by its heavier isotope,
deuterium. Infrared spectrometers can distinguish molecules that possess different
isotopes, but your nose cannot do so, nor can your dog's nose. (see Chemistry
and Engineering News, May 10, 2004, page 8 for references)
A small, frisky female dog quickly spotted the forbidden fruit that had been
in my wife's purse in the Auckland N.Z. airport (my wife just ate the apple
and a banana). We are all familiar with drug-sniffing dogs, but canines are
used for many other activities based on their keen sense of smell. A dog named
Jada was rescued from a Florida pound because of her ability to detect bedbugs,
which infest some New York hotels. Dogs also are used to detect explosives,
people (both dead and alive) and recently to diagnose cancer. Other amazing
uses of dogs' acute sense of smell are: mercury, invasive weeds, and cows
in heat (for the dairy industry). There is a cottage industry training dogs
to detect whatever you might be interested in; an example being the Florida
Canine Academy in Safety Harbor, Florida, where Jada got her training. Dogs
have 20 to 40 times the number of nasal receptor cells that humans do, and
they work long hours at much lower rates, under poor working conditions. Who
ever heard of a dog belonging to a union and going on strike, but the human
trainer might do so. Dogs only have three wants: food, sex, and praise. Trainers
can provide two of these and that is sufficient. Some dogs such as Jada have
saved their lives by training to become a sniffer. (New York Times, June 13,
2006, page A1
In a letter to Chemistry and Engineering News Jeff Salzman writes the following (Chemistry & Engineering News, April 24,, 2006, page 4).
Archer Daniel Midlands (ADM) has been enjoying a large federal tax credit
for ethanol added to gasoline. For every gallon of gasoline doped with ethanol
the federal government hands over 5.4 cents. Over five years this has amounted
to more than $1.9 billion, not counting market share or a gain in gasoline
sales. Now all gasoline must be doped with ethanol since the other "oxygenate"
MTBE (refer to Chapter 7 in Naturally Dangerous) is being removed from the
market because of fears over law suits. Salzman points out, what is discussed
in Naturally Dangerous, that ethanol offers no emissions benefit to any car
with an oxygen sensor. Moreover, in 1996 AN Environmental Protection Agency
(EPA) found that a simple tune-up provides a greater improvement in emissions
compared with added ethanol. Finally, the general public does not realize
that ethanol contains less energy than gasoline so that the mileage of any
automobile using ethanol would be reduced! This unholy alliance between ADM,
environmentalists, and farmers is wasting federal tax money, wastes consumer's
money, and is contributing to the nation's energy problem.
A recent Swedish study reports that compared with heterosexual women, lesbians experience a distinctive brain reaction when exposed to sexual pheromones. Positron emission tomography (PET) scans of the anterior hypothalamus were used to monitor the response of diverse subjects upon exposure to two suspected sex pheromones. The brains of lesbian subjects showed a different response than heterosexual women, but the lesbian subjects did not show the same response when compared to heterosexual men. Two suspected sex pheromones, a progesterone derivative, 4,16-androstadien-3-one, dubbed AND, and an estrogen-like female pheromone, estra-1,3,5(10),16-tetra-3-ol, EST, were used. The male pheromone, AND, has been found in human sweat (10 times as much in men as in women). The female pheromone, EST is found in the urine of pregnant women. This small, recent study involved only 12 subjects, all said to be lesbians. This new study followed earlier research that showed activation of the same brain region, the anterior hypothalamus, upon exposure of both homosexual men and heterosexual women to the suspected male sex pheromone, AND. This same brain region was stimulated in heterosexual men upon exposure to the female pheromone, EST. These studies, although interesting, cannot be considered valid until a larger number of subjects are examined, including several ethnic and racial groups. Whether these effects are genetically determined or are the result of environmental conditioning is also being debated. (Forbes: Health Day News, May 9, 2006).
The detection of odors is still an active arena of exploration. New discoveries are being made about the odorant receptors in the olfactory system. Molecules that elicit distinctive odors seem to fit into an odorant receptor in the nose. It is well established that some handed molecules have distinct odors so that both left and right-handed odors fit into handed receptors. For example spearmint and caraway are left and right-handed forms of the same molecule; each has a distinctive odor – try smelling each. Now it has been discovered that mixtures of odorants can smell like a third odor, completely unlike the individual odors. And example is eugenol, and organic chemical that smells like clove and phenylethyl alcohol, which smells like roses, together smell like carnations. To elicit this effect the two must be sniffed simultaneously. In the mind the combination is transformed into a distinctive third odor. Using mouse models and a new technique for visualizing odors, other pairs of molecules were discovered in pairs to smell different from either odor alone. This strange phenomenon is still not well understood. (Chemistry & Engineering News, March 13, 2006 , page 12)
In the 1940s a snake-like fish from the ocean called lampreys invaded the Great Lakes and nearly wiped out native fish populations such as lake trout. An expensive 50-year program has restored some of these native fish populations, but now a cheaper, more effective method is on the horizon: the pheromones used by the lampreys to locate their spawning grounds have finally been identified by researchers at the University of Minnesota. These compounds are being synthesized and it is hoped they will be used to lead lampreys to their destruction. Extremely small quantities of pheromones are effective, as is described in Chapter 7. (Science News, November 12, 2005, Vol. 168, page 308)
Animal welfare groups have sued the EPA trying to prevent EPA from using data from animal tests to set exposure guidelines for children. These extreme animal rights groups: PETA (People for the Ethical Treatment of Animals, and the Physicians Committee for Responsible Medicine filed suit in federal court; the decision has not yet been rendered, but the behavior of these animal rights organizations is not unexpected. (Chemical & Engineering News, August 1, 2005, page 28)
A study conducted by OSHA and EPA has found a low level of incidence of illness among school children over the period from 1998 and 2002. More than 2,500 children were sickened, a low figure but the incidence increased over this five-year period. Part of the explanation is that more schools are located near farmland, where large amounts of insect repellents are used. It was suggested that buffer zones be set up around schools. These results show that substantial exposure to insecticides, insect repellants, and disinfectants can cause children to become ill. A major motivation for the consumption of organic foods is that residues of insecticides make non-organic foods dangerous. The amount of synthetic insecticides detected in food is so tiny and the absence of reports about serious illness from eating non-organic foods make this explanation specious. Nevertheless, this report about school children will give more ammunition to advocates of organic foods. (Chemical & Engineering News, August 1, 2005, page 26).
New synthetic compounds have been developed, which selectively block a cell receptor that is unique to insects. These substances may evolve into insecticides that immobilize and kill many insects, while not affecting man and other mammals. Different research groups (in DuPont, Germany, and Japan) have been working on this problem and all have achieved positive results. The Japanese group has developed a compound called flubendiamide that is lethal to several hard-to-kill, destructive insects, but doesn’t appear to harm rats, honeybees, spiders, or several beneficial insect species. Regulatory approval is pending in Japan. Keep tuned, these beneficial and selective insecticides based on molecular biology may soon become important weapons. (Science News, September, 2005, vol. 168, page 149)
If identical twins have identical DNA, why do they show slight variations in appearance and in their susceptibility to diseases? The answer to this interesting question appears to lie in environmental influences, which turn selective genes on or off. Two different chemical groups activate or silence genes by adding methyl groups or acetyl groups, respectively. This process, which biologists call epigenetic modification, can occur through environmental interactions, for example exposure to tobacco smoke and other chemicals. A recent study of DNA taken from 80 pairs of identical twins, ranging from 3 to 74 years old revealed three times greater epigenetic differences in 50 year old twins compared with 3 year olds, who showed very few differences. Larger epigenetic differences were found between twins who had lived apart for most of their lives, supporting the idea that environmental factors were involved. Arturas Petronis, a scientist who studies epigenetics at the Center for Addiction and Mental Health in Toronto has said: “About 90 percent of diseases don’t follow (simple) rules for inheritance.” Thus environmental factors can influence our health by altering genetic factors. (Science News, July 9, 2005)
Scientists have recently performed molecular tests on a group of people and found evidence for the effects of smoking and obesity on aging. Blood samples were taken from a group of 1,122 women in the U.K. whose body mass index (BMI) and smoking histories were determined. These scientists then analyzed telomeres from these subjects. Telomeres are structures similar to corn tassels that cap the ends of chromosomes in our cells and protect these pieces of DNA from damage. The length of a telomere is a measure of the age a cell can live. Every time a cell divides, its telomeres get shorter. (Cancer cells resist shortening their telomeres, which is one way they remain immortal)
These studies showed that telomere length did decrease with age, but the telomeres of obese women and smokers were much shorter than those of lean women and never-smokers. Each pack-year (number of cigarette packs smoked per day multiplied by the number of years smoking) was equivalent to a loss of an additional 18% shortening beyond the average annual shortening of telomeres. It is estimated that smoking corresponds to about 4.6 years of aging, but smoking a pack a day over 40 years corresponds to 7.4 years of aging. The difference between lean and obese individuals resulted on telomere lengths corresponding to 8.8 years of aging! These molecular results are consistent to many epidemiological studies relating cancer, heart disease and other health factors with obesity and smoking. (Health News, June 14, 2005, by W. Angelos reporting on an article in the medical journal, Lancet)
It is unusual that a synthetic drug intended for human use might improve the environment!! As mentioned on page 157 in Naturally Dangerous, Viagra was introduced in 1998, as a popular and effective drug for treating an all-too-common problem: impotence (specifically erectile dysfunction). From ancient times, traditional Chinese medicine has treated impotence with a variety of plant and animal products. Some of the animal species that have been sold by traditional Chinese shops for this purpose are: sea cucumbers, pipe fishes, seahorses, geckos, green turtles, and deer antlers. There is little double-blind evidence that these traditional medicines work. Nevertheless during the last few decades, the demand for traditional animal-potency products has become so great that some species have become threatened and yet the demand for these animal parts has continued through poaching. It has been suggested that because Viagra is effective and is relatively cheap ($8-10 per pill), it will take overmuch of this traditional market. These ancient folk remedies are more expensive and they are probably ineffective as well. Is there any evidence that Viagra is actually saving endangered animals? There is only a little. Because most of the endangered animal-potency products are sold on the black market there are no reliable figures as to the amounts sold, but deer antlers have been legally sold for this purpose and sales figures are available. Soon after Viagra appeared, sales for antlers fell by about 70%. Perhaps Viagra has become an inadvertent “green product”. (Environmental Conservation, 29, 3: 277-281, November 18, 2002)
You may not know that almost all humans and other animals such as polar bears and eagles have very stable compounds known as perfluorinated acids in their blood! The term perfluorinated means that all carbon-hydrogen groups have been transformed into carbon-fluorine groups. The concentrations of these unnatural chemicals in the blood is very low, but the biological or medical consequences of long term exposures are uncertain. Recently the Environment Protection Agency (EPA) has required the chemical industry to carry out research on these chemicals, although no human health effects have been determined. These chemicals are used in the manufacture of well known items that are found in most households, such as Teflon in no-stick fry pans and Gore-tex in breathable rain jackets as well as the original formulation of Scotchgard. These substances are chemically unreactive and are stable at the high temperatures encountered in a frying pan. Rats exposed to very high levels of these perfluorinated acids have experienced damage to their immune systems, brains, pituitary glands, thyroids and sexglands. More limited studies with monkeys have also shown evidence for damage and even death. However, these studies with lab animals were conducted at concentrations thousands of times greater than human exposure. It is not clear how these perfluorinated substances get into people or how they could have migrated thousands of miles ending up in the Arctic. These contaminations might have come from different but similar chemicals, perfluorinated alcohols that are used in shampoos, rug cleaners and food paper products. These alcohols are volatile and might have been carried long distances in the atmosphere and then transformed by reaction with oxygen into the perfluorinated acids.
This situation is reminiscent of the history of other persistent chemicals, such as the chlorofluorocarbons that have created the ozone hole (page 190) or DDT and PBC’s. These stable chemicals also initially appeared to be benign, and became widespread in people and animals over much of the earth (see page 162). DDT, which is oily, accumulates in fatty tissue, whereas the water-wetting perfluorinated acids accumulate in the blood. Recently, trace amounts of perfluorinated acids have also been found in several foods: green beans, bread, and ground beef and in some water supplies. Nearly all Red Cross blood samples show traces of these substances. It is unclear about how rapidly these chemicals are cleared from the body, which would be a factor in determining whether they build up in the blood over prolonged periods. An encouraging sign that these substances may not increase with time stems from the fact that the levels measured in the blood are similar among diverse age groups from adults to children. Probably fearing litigation, in 2000 Minnesota Manufacturing and Mining, 3M, stopped manufacturing a similar chemical, perfluorooctane sulfonate, PFOS and related compounds, which represented 2% of their sales. But DuPont is still be producing some of these very useful perfluorinated acids.
Two new competitors for Viagra, the drug for male impotence, are expected to be approved by the FDA this year. Cialis and Levitra (what an interesting name) are already on sale in Europe and some people in the U.S. are illegally purchasing these prescription drugs on the internet. The two new drugs are expected to be strong competition for “the little blue pill”, and to cut into its $1.7 billion annual U.S. sales. All three drugs work in the same way, by inhibiting the enzyme (PDE-5), thus sustaining an erection. There are significant differences in how rapidly these drugs take effect, and in how long they remain effective. Cialis works over a 24-hour period compared with about 5 hours for either Levita or Viagra. But all three drugs have side effects, such as headaches, flushing, and altered vision. The degree and nature of these side effects may vary among individual patients. (Wall Street Journal, March 27, 2003, D1)
Your brain can train your nostrils! Only about 30% of people can detect the odor of the putative pheromone, androstenone, but after repeated exposure to this substance, individuals can learn to detect its smell. When subjects were trained to detect the odor of androstenone with one nostril plugged, their other nostril learned to sense this substance, apparently from instructions coming from the brain. (Nature, October 24, 2002, p. 802)
There is new evidence that the red color in leaves is the result of antioxidant behavior in a living plant. The red pigments, called anthocyanins are thought to be produced in the plant during a period of vulnerability. When leaves are pricked with a fine needle, a burst of hydrogen peroxide occurs. This toxic compound is quickly degraded by the red pigment. Yellow leaf pigments are there all the time, hiding under green pigments such as chlorophyll; when the latter break down as the summer ends, the yellow color shines through. But the red color is produced by the plant to fight various kinds of stress. (Science News, October, 26, 2002, Vol. 162, p. 265).