Vinland Map: Real or fake?
Good article on the Vinland Map, but the studies on the tracking of the yellow-outlined black lines seem unnecessarily complex (C&EN, Aug. 12, page 35). What evidence is there that the lines were required to be drawn separately?
Why could they not have been drawn at the same time, using a carbon-based ink in which the yellow contaminant was present? The carbon particles would not spread far from the drawn line, while the yellow contaminant could diffuse or otherwise move a small distance along the surface of the parchment.
||© 1965 YALE UNIVERSITY PRESS PHOTO
Unfortunately, this does not address the basic question of whether the map is real or fake. A contaminated solvent could have been used in 1440, or a carefully designed ink mixture could have been used in the past century.
Frederick G. Burton
The following is a quote by Robin H. Clark in "Real Or Fake?" by Stu Borman: "We are neutral about the double-inking suggestion, but to date no better one has been made." And what if the forger mixed anatase or some iron-based ink into carbon-based ink and maliciously counted on a slow phase separation? One should do the experiment.
I am sure this note will be one of many suggesting the same idea. As I read the article on Yale's Vineland Map, it came to me that the double-inking theory could be responsible for all the evidence reported, just not in the same way "double inking" has been considered to this point.
Is it possible that the map is truly ancient and was originally penned with a mixture of carbon- and iron-based ink? If this were true, it is then possible that everyone is right and no one is wrong in their findings/theories on the origin of the yellow and black nature of the lines.
Just my two cents' worth.
Robert L. Wolke's explanation of SPF (sun protection factor) might wow the readers of a popular press magazine, but C&EN's readers most likely understand the relationships among absorptance, transmittance, and dosage (C&EN, July 22, page 8).
Anyone who understands those relationships realizes that the dosage comes from the transmitted radiation. Sure enough, his numbers show that SPF 30 sunscreen transmits only half as much UV-B as does SPF 15 (3.3% versus 6.7%). That is the significant comparison, not the possibly confusing comparison of absorptance.
The answer to his question of whether you really need SPF greater than 15 is "no" if the assumptions in his example are correct. However, many users of high-SPF products either burn in far less than one hour, unprotected, or desire maximum protection against cumulative long-term effects of UV-B radiation.
I have been in sun care science long enough to accept many of the inaccuracies written about sunscreens (C&EN, June 24, page 38), but I still am perplexed by those, such as Wolke, who seek to correct with additional inaccuracies.
While his calculations on SPF were correct, his statements regarding the absorption of UV-B by sunscreen were misleading. Both UV-B (290 320 nm) and UV-A (320400 nm) contribute to sunburn. Sunscreens block both UV-B radiation, as pointed out by Wolke, and UV-A radiation. In fact, any sunscreen with an SPF greater than eight must be blocking some of the UV-A radiation.
I agree with Wolke that, at some point, the increase in SPF is not worth the gain. Unlike Wolke, I find much to be gained by using sunscreen products up to SPF 30. Because I burn in 12 minutes (Skin Type II) in the June 21 Memphis sun, an SPF of 15 allows me to remain in the sun for three hours (12 minutes x 15 = 180 minutes). However, an SPF 30 sunscreen will allow me to stay in the sun for six hours. To me, this often means the difference between burning or not.
Wolke's letter "Understanding SPF" wonders how much is actually gained by using higher SPF products, since in going from an SPF of 15 to an SPF of 30, only 3.4% more of the sun's rays are absorbed. He also asks who needs 15 hours of protection when the sun isn't out for that long? The answer is that we all do.
Dermatologists tell us that the harm done by exposure to UV radiation is cumulative. Therefore, what really counts is not how much is absorbed but how much is not. By going from an SPF of 15 to 30, our exposure is cut in half. It will thus take twice as many years for our inevitable skin cancers to develop. That's exactly what we want to know when choosing a sunscreen.
J. Thomas Denison
Editor's note: To resolve issues raised by these letters, C&EN asked FDA to put them through its filter.
Though their perspectives are different, Vinson and Wolke are both right about the value of sunscreens with an SPF of 15 versus an SPF of 30. The important thing, as FDA sees it, is that "SPF value represents a ratio that describes a relative measure of the attenuation of UV radiation that causes erythema of the skin."
Denison and Caswell suggest that some people require more protection than others to prevent sunburn, and FDA agrees. "There are many variables involved in sunscreen use--skin type, latitude, altitude, whether the consumer is at the beach or in a city, application rate, replication frequency, and spreading characteristics of the product," FDA says. "The SPF provides an individual consumer a means to evaluate and compare sunscreen drug products based upon that consumer's previous experience in the sun and previous use of products with an identified SPF value."
Caswell says Wolke ignores the impact of UV-A radiation. But UV-B is what matters most in the way FDA currently evaluates skin burn protection products. It is true that FDA's SPF test exposes subjects to "a continuous emission spectrum from 290 to 400 nm similar to sunlight at sea level from the sun at a zenith angle of 10º." However, FDA notes that "the specific amount and wavelengths of UV-A attenuated by two products with the same SPF value can vary significantly." The agency says it is "in the process of addressing active ingredients, labeling, and test methods for products intended to provide UV-A protection."
Getting OSHA out of academic labs
In June of 1992, a Rhône-Poulenc factory in Martinez, Calif., exploded. Sulfuric acid contaminated with flammable chemicals spilled and caught fire when it came in contact with hot machinery. Two workers were critically injured. One later died. That factory had inadequate emergency response on-site and had to be bailed out by a fire crew from a nearby Shell refinery.
Now, more recently, C&EN reports that, in what appears to be a similar facility owned by Motiva Enterprises LLC in Delaware City, Del., a corroded sulfuric acid tank leaking fumes from holes in its roof and shell exploded as a welder worked on a catwalk above the tank (C&EN, Sept. 16, page 20). His body was never found, and more than 1 million gal of sulfuric acid was spilled, with 100,000 gal going into the Delaware River. Over this 10-year period, the Occupational Safety & Health Administration has not included these tanks in their Protective Safety Management program despite the obvious hazard and demonstrated risks.
Motiva Refinery in Delaware PHOTO BY ROBERT CRAIG
It could be argued that, with only 2,200 employees to police an entire nation with millions of workers, OSHA has resources that are too limited to control activities at all hazardous sites. Experience in university laboratories suggests otherwise. While workers are being killed in dangerous industrial conditions, OSHA has fought to extend the sway of their few inspectors to include university chemistry laboratories.
In our research laboratory, one consequence has been to require professional chemists to write specific handling instructions for benzene. I argue that it is a waste of time for OSHA inspectors to involve themselves in regulation of environments which by definition have well-trained workers.
It is the height of stupidity to assume that if the university is not providing adequate training in specialty areas that piddling "safety" training and Standard Operating Procedures will do any better. In fact, the latter activities waste time better spent reducing real hazards and create an atmosphere of disrespect for safety.
It is time for all of us to write our congressional representatives and tell them to get OSHA out of academic labs and into nonprofessional environments where untrained workers are more likely to exist.
James W. Lewis
Santa Cruz, Calif.
I read with great disappointment C&EN's article on the symposium about noninvasive glucose monitoring held at the ACS national meeting in Boston (C&EN, Sept. 9, page 41). While devoting a significant portion of the article to near-infrared spectroscopy and the technological challenges this methodology faces, Celia Henry neglected to mention the landmark research presented by my group, and the fact that we have successfully overcome many of these issues.
Although other researchers continue to work with tissue phantoms and animals, we presented two sets of data from human clinical trials. The first set came from a six-center trial with over 100 subjects and 3,000 paired data points. While not perfect (mean absolute error of 22.4%), these data demonstrated that, in our case, near-IR diffuse reflectance spectroscopy could be used to measure glucose noninvasively in people diagnosed with diabetes.
The second study, with approximately 2,700 paired data points, showed significant improvement in accuracy (~15% mean absolute error). While impressive, the more important outcome of that study was the fact that a single calibration model was developed and used in conjunction with this second set of data. This is a monumental step toward the commercial viability of a noninvasive device based on near-IR spectroscopy.
The conclusion of our presentation listed the major technical areas of focus for our team as cost and consumer functionality with the expectation that we will be submitting our device to the Food & Drug Administration for approval within the next 24 months. While not wanting to raise the expectations of people living with diabetes, as groups have done in the past, I do want them to know that research exists that is beyond the tissue phantom and animal test stage.
Stephen L. Monfre
Sensys Medical Inc.
ACS ELECTION BALLOTS
Ballots for the American Chemical Society's fall national election were mailed to members on Sept. 30. If your ballot hasn't arrived yet, you may request that a duplicate ballot be sent to you by calling (800) 227-5558 by Nov. 4. Deadline for receipt of all marked ballots is Nov. 15. Election information on all candidates can be found on the ACS website at http://www.chemistry.org/election.
- Sept. 23, page 46: Multiple patents often apply to brand-name drugs. The patent expirations listed in the table refer to the year after which a generic version could be launched in the U.S., assuming that the generic company successfully challenges all later-expiring patents listed for the brand-name drug.