How Green is Your Pediatrician?

From: Robina Suwol
Date: 04 Sep 2003
Time: 23:59:45
Remote Name:


How Green is Your Pediatrician?
By Brian McKenna
Ask your pediatrician about lead, and she'll be able to tell you if your kids need to be tested, but ask her about pesticides from your lawn care company or if it's safe to use DEET insect repellant and she might not have much to tell you. If she's like most MDs she has received only three to
four hours of environmental education, and doesn't know about the many hazards that children face.
"There's absolute apathy in many parts of the U.S. medical system towards even thinking about the effects of the environment on health," says Dr. Ruth Etzel, a pediatrician and environmental epidemiologist. "The initial response to even raising the issue is to be laughed out of the room."
But that hasn't stopped Etzel and a team of environmentally conscious pediatricians from repeatedly dusting themselves off and re-entering the fray.
"All of us have encountered ridicule," she says, "but with any new discipline in medicine that usually happens for the first 25 years."
The Green Book Etzel's persistence is slowly paying off. In October 2003, under her editorship, the American Academy of Pediatrics will release the second edition of "Pediatric Environmental Health." The "Green Book," as it is known, is a groundbreaking clinical handbook that offers concise
summaries of the evidence that has been published in the scientific literature about environmental hazards to children, and provides guidance to pediatricians about how to diagnose, treat, and prevent childhood diseases linked to environmental exposures. The inaugural 1999 edition, initiated and
edited by Etzel while she served as Chair of the American Academy of Pediatrics Committee on Environmental Health, had 33 chapters with information on such topics as diesel emissions ("associated with asthma exacerbation"), pesticides (connected to "certain childhood cancers [including] brain cancers and leukemia"), and molds (linked to infant pulmonary hemorrhage and respiratory illnesses). The new edition has
expanded to 43 chapters and has sections on arsenic, gasoline, irradiation of food, and the potential effects of chemical and biological terrorism on children. Busy physicians want reference tools to answer questions quickly,
"and the Green Book is an attempt to put everything in one place," said Dr. William Weil, a Michigan-based contributor. He adds frankly, "but the majority of clinicians don't give a damn. It's very hard to get physicians excited about the issues."
The good news is that an increasing number of doctors are using the handbook. According to an Emory University survey of 266 practicing pediatricians in Georgia - published in the August 2002 Environmental Health Perspectives -
pediatricians' preferred source of environmental information is the American Academy of Pediatrics, including the Green Book.
Of course that doesn't mean they're applying the knowledge. Indeed, most respondents reported "low self-efficacy in taking and following up on environmental histories."
Still, Etzel is thrilled by the strong international support for the book and reports that the World Health Organization was so impressed that they are working with her and other members of the American Academy of Pediatrics to create their own international version, due for release in 2004.
"We'd like to see the Green Book become the one authoritative text for environmental health just like the Academy's Red Book has become for Infectious diseases," said Weil.
That will require a dramatic improvement in marketing. The Academy's approximate 48,000 pediatricians requested only about 20,000 copies of the 1999 edition even though copies are free for them.
"We're planning lots of media" for the 2003 release, said Etzel.
Against the grain Etzel and Weil are used to running against the grain. In 1999 they were the only two physicians invited to participate on former Governor Engler's seven-member Michigan Environmental Science Board to establish children's
environmental health standards in Michigan. Both vigorously dissented from the final 2000 report that recommended that nothing be changed to improve children's health.
Writing the minority opinion, Weil argued that, "the only prudent approach for protecting these especially vulnerable groups would require inclusion of an added factor." Weil was referring to a 10-fold safety factor against pesticides as is required by the 1996 U.S. Food Quality Protection Act.
Weil was a member of the National Academy of Sciences panel that recommended that level, which Congress adopted. The Detroit Free Press called it "a bitter irony"
when "pediatricians' call for proactive environmental standards [is] ignored."
But it's a safe bet that most Michigan medical students and pediatricians know little or nothing about their policy efforts.
"Do you have a basement?" Etzel notes the irony that pediatricians no longer visit the home and yet "we
now have a far better understanding that [home] exposures once thought to be innocuous, such as cigarette smoke, mercury and molds, may actually pose threats to children's health." To compensate, the Green Book provides a short "Home
Inventory Questionnaire," that pediatricians are encouraged to use at the first office visit.
Questions elicit knowledge about possible exposures and include, "Are you or your child involved in a hobby at home? Do you use pesticides on your lawn or in your home? Is your home located near a polluted lake or stream, industrial area, highway, dumpsite, farm, etc.? Do you have a basement?"
Basements are potentially quite toxic as Dr. Etzel herself discovered in 1994 when, as the lead investigator for a Centers for Disease Control and Prevention study, she concluded that a mold named Stachybotrys was the probable cause of infants' lung bleeding and sudden deaths in Cleveland. The mold grows
in areas where there has been standing water or flooding. For her efforts she won the prestigious Arthur Flemming award.
The cart before the horse By itself, the Green Book will likely have minimal impact. A sea change in medical education and practice is required. Fortunately, Green Book pediatricians and others are working on several fronts towards this end. A
centerpiece of this effort is the National Environmental Education & Training Foundation, chartered by Congress in 1990 "to advance environmental literacy in America."
In June 2003 more than 100 leaders in medicine, nursing, and environmental health met in Washington D.C. to establish a new pesticide education initiative with pediatricians. They are working to insert pesticide information into the medical curriculum and to educate physicians in the field. A point person in the initiative is Dr. James Roberts, Assistant
Professor of Medicine at the Medical University of South Carolina. Roberts was a major contributor to the Green Book's pesticide section. "Most of the time we look at a sick patient the possibility of pesticides doesn't come up
unless it's a known suicide," he said. Physicians need "a higher index of suspicion," to diagnose acute and chronic pesticide-related illness.
"There's a lot of animal data and epidemiological data, but little human data," he said. "We haven't looked at skin rashes, asthma, gastroenteritis (non-viral)" as pesticide-related. "Why has there been an increase in Attention deficit hyperactivity disorder? If you look at it from a neurological standpoint, there are lots of chemical effects on the nervous
Good advice When asked about DEET, for which the EPA has now required labels detailing their concentration because of concern about possible effects, Roberts said That the Academy recommends no higher than a 30% concentration. The 1999
Green Book edition goes further saying, "a cautious approach is to use 10% or less [concentration] on children."
Roberts cited a July 2002 New England Journal of Medicine study that compared the effectiveness of insect repellents against mosquito bites. Various concentrations of DEET were analyzed along with "natural" products like citronella and a relatively new soybean-based product called Bite Blocker. He agreed
with the study that DEET was the best protector available, over a long period of exposure." "I'd like to see information released to parents to gauge the time frame of outdoor activity for their children. If it's just an hour of T-Ball, use a
lesser concentration of DEET, but if it's an afternoon of fishing, use a Higher concentration." That's the kind of guidance I'd like to hear from a pediatrician. But is that the best advice available?
Parents as activists Roberts did not specifically mention Bite Blocker, which the NEJM article rated as better than a 4.75% DEET product (Off's Skintastic). In the study
Bite Blocker had a mean effective time of 94.6 minutes compared to just 88.4 Minutes for the Off product. Bite Blocker has become the "go to" protector for many consumers seeking a safer product, including Ontario municipal workers who ordered several cases.
Many activists are very critical of the use of DEET in any concentration. In making its case, Beyond Pesticides, a national group, reports that "researchers at Duke University Medical School led by Dr. Mohed Abou-Donia have published findings demonstrating in laboratory studies that frequent
and prolonged application of DEET cause neurons to die in regions of the brain responsible for muscle movements, learning, memory and concentration."
Bite Blocker will not be listed in the 2003 edition since the Academy "stays away from recommendations of any specific products," said Etzel.
If this discussion sounds like splitting hairs one must know that Etzel believes that "activists have taught pediatricians everything they know about working to prevent environmental hazards." She adds that that "parents drive pediatricians by sharing questions and concerns." Indeed, parents are
activists. One can begin to imagine a wide array of pediatric
interventions to prevent pesticide exposure. Will pediatricians get involved in primary prevention efforts against West Nile that eradicate mosquito larvae with non-toxic agents? Will they investigate organizations like Praxis, a Michigan-based company that uses bioremediation of pests? Fundamentally,
will they help lead the charge against corporations that freely, and unnecessarily, apply toxic agents to our food?
Clearly the feedback loop of activist - parent - pediatrician - activist will go on ad infinitum, as it must. It's heartening however when pediatricians like Etzel, Weil, and Roberts help lead the fight. They are among the movement's most important activists. And they - and their colleagues - are responsible for perhaps the biggest coup of late, according
to Etzel. She beamed when sharing the news that the Ambulatory Pediatric Association has created a three-year post-graduate Fellowship in pediatric environmental health. The program began in 2001 at three hospitals -- in Boston, New York, and Washington D.C. Fellows will be out Practicing in
two years. "We now have a seat at the table!" she explained. "In medicine you must get specialty training programs like this to become institutionalized."
Beyond the clinic How refreshing to have such enlightened pediatricians like Etzel, Weil, and Roberts fighting the good fight. One wonders how we can clone them? Etzel
provides a clue.
As a junior at the University of Minnesota Etzel was fortunate to do independent study in Zorzor, Liberia, in West Africa as part of her education. "I saw horrible disease and a lack of public health and sanitation. The needs were so great they called to me." As a result of that experience she
abandoned her academic interest in anthropology and chose medicine instead. Both elements, it appears, were crucial in her development. Third-World travel and anthropology shake up our complacency and make us question our assumptions about the world. Medical education, by itself, rarely does.
Its pathophysiological focus on the body obviates a wide-angle view of our social and environmental health."
Or, as Ruth Etzel puts it: "Good medicine requires ardent advocacy. You cannot be a good doctor without it. Health doesn't take place just in the clinic. You have to go out into the community."
Feel free to tell your pediatrician about the Green Book. Tell them that they can receive a free copy by calling 1-888-227-1770, or by e-mailing Dr. Ruth Etzel at:
Brian McKenna is a medical anthropologist who worked in medical education at Michigan State University for six years.

Tungsten Wire History

From: Robina Suwol
Date: 19 Dec 2005
Time: 19:07:14
Remote Name:


The word "Tungsten" was probably first used by A. F. Cronstedt in 1755, who applied it to the mineral subsequently known as "scheelite," which is the natural form of calcium tungstate. C. C. Leonhard named this mineral scheelite in 1821 in recognition of the discovery made by K. W. Scheele, in 1781, that the mineral was a compound of lime with a previously unknown acid, which he called "Tungstic Acid," a name by which it is still known. Before Scheele made his discovery, the mineral was generally regarded as containing tin. The word tungsten denotes a substance of high density and is derived from the Swedish language, "tung," meaning heavy, and "sten," meaning stone. In 1783 the Spanish brothers, J. J. and F. d'Elhujar, published the results of their investigations on wolframite carried out with the Swede, T. Bergmann, while they were working in his laboratory. They showed that this mineral contained the same tungstic acid, previously found in scheelite, but combined with iron and manganese, instead of calcium. They were also the first to record the preparation of elementary tungsten, which they made by reducing tungstic oxide with charcoal, and to which they gave the name "Wolfram." The origin of the word wolfram is obscure. Mennicke attributes it to the alchemists, who called the metal "spuma lupi," which means wolf spume or foam. Another suggestion is that the word is of German origin from wolf, meaning a beast of prey, and rabin or ram, which has several meanings, including dirt and soot. The word may also be derived from the Swedish word "Wolf rig," which means eating. All these meanings are assumed to be associated with the early difficulties of extracting tin from cassiterite when it was contaminated with wolframite; the two minerals are frequently found together, and the wolfram was thought to eat the tin as a wolf eats sheep. The common termination used in mineralogy, to give the name "wolframite" to the mineral, was used in 1820 by A. Breithaupt in his book, Kurze Charalderistik des Mineral Systems. The metal is known as tungsten in some countries and as wolfram in others, including Sweden, the country of origin of the name tungsten. The chemical symbol W, which is universally used to denote tungsten, suggests that wolfram was formerly the more generally accepted name for the element. In Britain the mineral wolframite is also known as wolfram. For many years tungsten remained one of the rare elements, and it was not until 1847, when Oxland took out a patent for the manufacture of sodium tungstate, tungstic acid, and tungsten from cassiterite (tinstone), that the element became of any industrial importance. Oxland's second patent, taken out in 1857, described the manufacture of the iron-tungsten alloys that form the basis of modem high-speed steels. The metal itself, however, found no application until nearly fifty years later, when it was first employed in the manufacture of filaments for electric incandescent lamps. From 1878, when Swan demonstrated his eight and sixteen-candle power carbon lamps at Newcastle, search was made for a more satisfactory filament material than carbon. The early carbon lamp had an efficiency of about 1.0 lumen per watt, which was improved during the next 20 years by modifications in methods of preparing the carbon, to about 2.5 lumens per watt. A further improvement was made in 1898 to about 3.0 lumens per watt by heating the filaments electrically in an atmosphere of petroleum vapor, which caused the deposition of carbon in the pores of the filament and gave it a bright metallic appearance. At the same time A. Von Welsbach produced the first successful metal filament was by using osmium; attempts had previously been made to use platinum, but its relatively low melting point of 1774C. prevented its successful development. Lamps using osmium filaments had an efficiency of about 6.0 lumens per watt. Since osmium is the rarest of the platinum metals it could never have been used on a large scale. Tantalum, with a melting point of 2996C., compared with osmium, 2700C., was extensively used as a drawn wire from 1903 to 1911, following work by Von Bolton of Siemens and Halske. Lamps with tantalum filaments had an efficiency of about 7.0 lumens per watt. Developments in the use of tungsten started about 1904, and it has been used exclusively since about 1911. The modern tungsten filament lamp used for general lighting purposes, which employs drawn wire, has an efficiency of about 12 lumens per watt, while lamps of high wattage have efficiencies up to about 22 lumens per watt. The modem fluorescent lamp, although it employs tungsten cathodes, does not depend upon tungsten for its much higher efficiency, which is of the order of 50 lumens per watt. In 1904 the Siemens-Halske Co. tried to apply the drawing process they had developed for tantalum to the production of filaments of the more refractory metals, tungsten, thorium, etc. The brittleness and lack of ductility of tungsten prevented their attaining success by this method, although later, in 1913-1914, it was demonstrated that fused tungsten could be rolled and drawn at very high temperatures, using very small reduction steps. By striking an arc between a tungsten rod and a partially sintered tungsten pellet in a graphite crucible, coated on the inside with tungsten metal powder and containing an atmosphere of hydrogen, small pieces of fused tungsten, about 10 mm. diameter and 20-30 mm. long, were produced, which could be worked with difficulty. It was found that working properties could be improved to some extent by the addition of thorium oxide, which reduces the tendency to develop a columnar type of structure during cooling of the fused mass. This process was never used commercially. In the same year Just and Hannaman patented a process for producing tungsten filaments by mixing the finely divided metal powder with an organic binder, extruding through dies, and heating in suitable gases to remove the binder, leaving a pure tungsten filament. During 1906-7, the well known extrusion process, which was the method by which the majority of tungsten filaments were made for the next four or five years, was developed. The process consisted in mixing very fine black tungsten powder with dextrin or starch in order to form a plastic mass, which was forced under hydraulic pressure through a fine diamond die. The thread produced in this way was sufficiently strong to be wound on cards and dried. The filament was then cut into "hairpins," which were heated in an inert gas to a red heat to drive out moisture and the lighter hydrocarbons. Each "hairpin" was then mounted in clips, and raised to bright incandescence by the passage of an electric current, whilst being surrounded by a gas, such as hydrogen, chosen to react with the binding material, so that pure tungsten only remained. At the highest temperature the fine particles of tungsten sintered together and formed a solid homogeneous metallic filament. These filaments, although elastic, were quite brittle, but could be formed to shape at a red heat. Just and Hannaman also developed another process at the same time. This was known as the "coating" process, and showed remarkable ingenuity. A carbon filament as small as 0.02 mm. in diameter was employed as the base, and this was coated with tungsten by raising it to incandescence in an atmosphere of hydrogen and tungsten hexachloride. The coated filament was then raised to bright incandescence in hydrogen at a pressure of about 20 mm. of mercury. The carbon core dissolved in the tungsten, forming tungsten carbide, the change being so complete that the resulting filament was tubular in cross-section, no carbon remaining in the core. The filament so obtained presented a glittering white appearance and was very fragile. The next step consisted in heating the filament in hydrogen containing steam, which oxidized the carbon and left a compact filament of pure tungsten. The filaments thus obtained were similar to those made by the extrusion process, except that they were tubular in cross-section. Many other processes for the production of tungsten filaments appeared in the following years, but the product obtained was in all cases of the same type, namely, an elastic but brittle tungsten filament. Amongst the more important may be mentioned the colloidal method of Kuzel, first developed in 1904. By this method a gelatinous pasty mass of metallic tungsten was prepared by striking an arc between tungsten electrodes under water. The material contained no binding medium, but was itself sufficiently plastic to be extruded into fine threads. On heating these to a high temperature in hydrogen by means of an electric current, the colloidal mass was converted into crystalline metal and the filaments were in all respects similar to those produced by the ordinary extrusion process. The method was largely used on the European Continent, and to some extent in the United States. Another method successfully developed in America in 1906 was the amalgam process. Finely divided tungsten powder was mechanically mixed with twice its weight of cadmium-mercury amalgam, from which filaments were formed by extrusion. The filaments were strong and exceedingly ductile. The amalgam was subsequently removed by volatilization at a high temperature and a pure tungsten filament was obtained. A method which achieved considerable success, and was used between 1908 and 1910 by the Siemens and Halske Co., was that of mixing tungsten metal powder with 6-10 percent of nickel, as nickel oxide, pressing the powder into ingots, and sintering in hydrogen at 1575 C. The ingots were first rolled to rod of 1 mm. diameter at 350 C., and then, with fre-quent anneals at 1500-1600 C., drawn cold to wire as fine as 0.03 mm. The drawn wire was quite ductile. The nickel was removed by heating the finished filaments in vacuo at 1500 C. A full account of this process has been given by M. Pirani. Other processes were also developed, such as drawing wires from tantalum tubes packed with tungsten powder. It was not, however, until 1909 that Coolidge, in America, was successful in making ductile tungsten from the metal powder by suitable heat treatment and mechanical working. In all previous processes some binding agent, either organic or metallic, had been employed to give the necessary plasticity, and was subsequently removed by chemical or thermal treatment. The filaments that resulted were pure tungsten as far as analysis could show, and yet the metal was in all cases completely brittle. Even these brittle filaments, however, could be bent and worked to some extent at a relatively low temperature, and even at temperatures below that at which oxidation takes place. The problem of making ductile tungsten did not, therefore, appear to be one of purifying the material, although it was realized that pure metal was probably essential if a ductile product was to be obtained. Rather, the problem was caused by the grain structure of the tungsten itself. By using a sufficiently high temperature initially, it was found that as the metal was subjected to mechanical work its ductility increased, until finally it became so ductile that it could be rolled, or drawn into wire, at room temperature. Although only a small percentage of the ore which comes on the market is used for the manufacture of lamp filaments and similar products, the great importance which tungsten has assumed scientifically and technically is the outcome of work directed to its production for this purpose. The knowledge gained has also been of inestimable value to workers in the newer fields of powder metallurgy, particularly in the manufacture of hard carbides. Consideration of the stages that have been passed in the development of modern processes gives some understanding of the difficulties that have been overcome.

Last changed: March 14, 2006