Poison Ivy If Scratching Doesn’T Spread It, What Does? Itchy Myths Shattered! 4

October 1990 Poison Ivy If scratching doesn’t spread it, what does? Itchy myths shattered! 4 MysteryMatters The Fox River Fish Kill 6 Thousands of fish were dead. The neighbors were raising a stink. The scientists investigating it were stumped. Light Your Candy Get some wintergreen candies...put a little sparkle in your mouth! 10 The Phantom Flame A chemistry student transforms a common assignment into a metaphor for science. 13 The Back Burner Friedrich Wöhler’s Lost Aluminum 14 Shiny, cheap, useful aluminum is around us, everywhere. Wasn’t it always? The Puzzle Page The Margarine Puzzle 16 What common substance is added to margarine to lower the calorie count? pOisoN IVY By Eric Witzel Dormant, not dead Urushiol is actually a mixture of four It was a pleasant sunny afternoon, different but similar phenolic com and I was helping my father stack pounds called catechols, which con firewood. Some of the logs had con sist of a benzene ring with two venient handle-like vines that had hydroxyl (-OH) groups on grown firmly onto the tree. I grasped adjacent carbons them to carry the logs, blithely igno and a 15-carbon side rant of the type of vines they were. I chain (Figure 1). The paid for that ignorance. The next day catechols in urushiol are rela- I developed the red, itching rash that tively small, stable organic~~ ...~· comes from touching poison ivy compounds. Because vines-and so learned that the irritat they are stable, any ing agent in poison ivy remains active article that becomes con- '. long·after the plant is dead. In fact, I taminated with urushiol later learned that even 100-year-old should be washed to specimens in botanical collections make sure that it doesn't can cause a rash. spread the irritant. Poison ivy belongs to the Picking up a rake two I. Anacardiaceae or cashew family, months after it was which includes many other rash used to rid a garden of poison ivy can causing plants such as poison oak cause a rash. Contaminated articles and poison sumac. Poison ivy is should be washed thoroughly native to North America and unfortu because the amount of urushiol on a nately is widespread. Equally unfortu pinhead would be enough to cause nate, the plant defies easy identifica rashes in 500 people. tion. The leaves do appear in groups Urushiol is one of the most com of three, which gave rise to the mon causes of allergic reactions in woodsman's old warning: "When the United States. The rash is leaves are three, let it be." However, caused by the immune system, the surface of the leaves may be whose normal function is to destroy either hairy or shiny, and their edges p9tentially lethal microbes such as may be either toothed or smooth. bacteria, fungi, and viruses. The sys All parts of the poison ivy plant tem recognizes the microbes in part produce the oily irritating agent, because they contain very large urushiol (OR-oo-shee-ol). To elicit a molecules. The catechols in urushiol rash, urushiol must touch the skin do not, by themselves, trigger the directly. Luckily, the irritant is not immune system because their volatile (and so does not evaporate molecules are so small. readily) and is released only when the plant is disturbed. Unluckily, it Ten-minute warning does not take much of a disturbance You can avoid getting a rash by to release the oil. Simply brushing washing your skin soon after expo against the plant is enough. It is also sure with lots of plain, cold water. possible for droplets of urushiol to be Avoid using soap because it removes carried through the air on particles of natural oils that help protect the skin, smoke. Inhaling urushiol smoke can and warm water only spreads the severely damage breathing pas urushiol further. Gasoline and other sages. My older sister was once hos organic solvents are not recommend pitalized after walking downwind of a ed because they also spread the oil. brush fire in an area where poison ivy Ten minutes after exposure, this fat grew. soluble irritant penetrates the outer TINAMION 4 CHEM MAnERS, OCTOBER 1990 BenadrylTM) reduce the itching, and calamine lotion and hydrogen perox ide dry out oozing blisters. The popu lar CaladrylTM combines calamine and Benadryl. For severe rashes, doctors may prescribe cortisone, giv ing it in pills or injections. The only certain way of avoiding poison ivy rash is to avoid the plant. 3-n-Pentadecadienyicatecllo! However, this is impossible for peo ple who must venture into poison ivy OH infested areas, and the U.S. Forest Service estimates that at any given time about 10% of its employees are Figure 1. several compounds are pre on sick leave because of exposure to sent in urushiol, the irritating oil exud poison ivy or poison oak (in general, ed by polson ivy. poison ivy grows in the eastern layer of skin and binds to proteins on states, poison oak in the western the surface of cells in deeper layers. states). Soon there may be ways of The combined urushiol-protein protecting people against urushiol. molecules are large enough to trigger For instance, researchers have found the immune system. The deep skin that swallowing small amounts of cells internalize and modify the urushiol makes people less sensitive urushiol-protein complexes (for to the irritant, and their allergic reac example, enzymes cut pieces off the tions are milder and less frequent. protein), and then the modified com Also, people may soon be able to plex returns to the surface of the cell. protect themselves against urushiol There, an urushiol complex is bound by using an aerosol spray called Ivy by an immune system cell called a Block. Developed for the Forest helper T cell, which then divides Service, Ivy-Block contains activated rapidly and produces many copies of bentonite clay, a mineral used in itself. These T-cells release proteins antiperspirants that can absorb called Iymphokines that attract anoth enough water to increase its volume er type of immune system cell called several fold. Besides forming a pro macrophages, which in turn cause an tective barrier between skin and inflammatory syndrome that includes urushiol, bentonite binds the oily irri swelling, redness, itching and, in tant so it can't penetrate the skin. severe cases, a rash of oozing blis FDA approval of Ivy-Block is pend ters. Contrary to popular belief, these ing. blisters do not contain urushiol, so The next time I stacked firewood scratching them will not make the at my parents' home, you can be rash spread. However, scratching sure I was on the lookout for suspi does increase the likelihood of infec cious vines. I also wore gloves and tion and should be avoided. washed my hands. This time, I escaped getting that awful itchy rash. Itching for treatment Although there is no way to cure a Eric Witzel is a former high school chem poison ivy rash, you can ease the istry teacher and former editorial intern at discomfort. Ice packs soothe the Chern Matters. He now works as a research assistant at the University of inflamed skin, over-the-counter medi Maryland's Center ofMarine cations (such as hydrocortisone Biotechnology in Baltimore where he is creams and the antihistamine studying chemotaxis in marine bacteria. CHEM MATIERS, OCTOBER 1990 5 Fox River Fish Kill oxygen, which is commonly found as Dead wrong a cause of a fish kill." Could it be pesticides and herbicides By Harvey Black Usually low levels of dissolved washing into the river from a nearby oxygen can be recognized just golf course? The section of the city The fish were dying, by the tens, before sunrise. "The reason is," said bordering the river is a filled-in wet hundreds, thousands. No one knew Ball, ''there is plenty of dissolved oxy land. Could some long-forgotten toxic why. Experts at the Wisconsin gen during the day, when algae are material, used as part of the fill, now Department of Natural Resources busy using sunlight in photosynthe be leaking into the river? Were there (DNR) were scratching their heads, sis. At night the plants are taking barrels rusting on the river bottom, unable to explain why the dead stur back the oxygen (emitted during pho 20 or so feet below the surface, with geon, white bass, walleye, and other tosynthesis), and threatening the fish poisons oozing into the water? In fish were floating on a three-mile with suffocation." But the scientific fact, Ball said, recently a barrel con stretch of the Fox River that flows sleuths discovered no lack of dis taining chemical residue had been through the city of Oshkosh. This solved oxygen in the water. found floating in the river. stretch of river links Lake Winnebago 'We had no idea what to look for," A number of storm sewers dis and Lake Butte des Morts. said Ball. "Any of a thousand things charge into the river. Had a "midnight Solving the mystery would mean might be doing it." countless hours of tracking down, and "finally discarding, all the plausi ble explanations and eventually set tling on an explanation that the scien tific literature seemed to rule out. According to Joe Ball, a DNR water resources specialist, there had been fish kills on that stretch of river for about 30 years. One or two major kills had occurred annually. Ball explained that fish kills are not terri bly unusual. They're often the result of natural causes, such as the stress of spawning or a lack of dissolved oxygen in the water; the latter can be caused by an overabundance of algae or decaying plants.

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