The existing confusion (with regard to the effects of various tints) applies not only to matters relating to visible light, but seems to become even greater with regard to ultraviolet.

The fact that too much heat will produce a severe burn, and a little extra oxygen in the incubators of premature babies can cause blindness known as retrolen-tcdjibroplasia, does not necessarily mean that an environment of absolute zero temperature, totally devoid of oxygen, is indicated as desirable. However, this obviously irrational conclusion is being generally applied because of the known harmful effects of excessive exposure to ultraviolet.

The full spectrum of natural sunlight, including both the visible and invisible rays, under which life on this earth has evolved, is known to be of direct benefit to man. In reporting on the effects of exposure to ultraviolet. Dr. Ellinger, in his book Medical Radiation Biology (Charles C. Thomas) writes:

In 1967, at the meeting of the International Committee on Illumination (C.I.E.) in Washington, D.C., apaper by three Russian scientists, Dantsig, Lazarev and Sokolov, was presented which stated that:

An unnecessary degree of fear of ultraviolet exists, probably as a result of a general lack of understanding of the difference in the relative intensities of the near, or long, wavelength ultraviolet and the far, short-wave ultraviolet in natural sunlight at the surface of the earth. The atmosphere filters or stops virtually all of the far short wavelength ultraviolet except for a trace amount, but does allow the near long wavelength ultraviolet to pass through in amounts comparable to the intensity of visible light. Thus, life on earth has evolved under the balance of short wavelength ultraviolet comparable to the very low levels of general background radiation and much higher intensities of long wavelength ultraviolet comparable to that of visible outdoor natural sunlight.

Many artificial "sun" lamps manufactured today give off a peak of energy in the far short wavelength ultraviolet that is filtered from natural sunlight by the atmosphere. They are the same as germicidal lights, and these can produce severe bums and injury. This type of ultraviolet light has been used extensively in clinical experimental work and has shown beyond any doubt that over-exposure will produce harmful results, including skin cancer in laboratory animals.

The question then arises on how long an exposure and at what intensity, constitutes over-exposure. In view of the apparently extremely delicate biological responses to minor variations in energy levels in nature, it would seem that not very much of an increase of intensity of short wavelength ultraviolet over the trace amount in natural sunlight would be necessary to upset nature's biological balances. An actual measurement of the trace amount of short wavelength ultraviolet in sunlight is difficult to establish. The spectral energy chart of sunlight published by the U. S. Bureau of Standards totally ignores it, and shows an absolute cut-off in the ultraviolet range at approximately 2900A, as a result of the filtering effect of the atmosphere. My spectral chart shows the line representing sunlight energy continuing from 2900A on into the shorter wavelength at the very bottom of the chart in order to represent this trace amount of far, short-wave ultraviolet in a pictorial way. This trace amount of short wavelength ultraviolet might be compared to the so-calledtrace amounts in chemistry, which at one time were totally ignored but are now recognized as being of very great importance, especially in biochemistry. Yet many scientists seem to feel a sense of accomplishment in being able to direct a high intensity microbeam of short wavelength ultraviolet on a small part of a living cell and then studying the abnormal growth responses, which may frequently be the ultimate death of the cell.

In a chapter on The Absorption of Radiant Energy by the Ocular Tissues in Duke-Elder's Textbook of Ophthalmology (C. V. Mosby), it is stated that "the thermal lesion caused by infrared rays is frankly pathological... The chemical or abiotic lesion [caused by ultraviolet rays], on the other hand, is of a completely different nature. Since the reaction is directly dependent on the absorption of energy, a critical threshold of wavelength and of intensity of radiation must be employed to excite it. A certain amount of abiotic activity may be evident at 3,650 (Coblentz and Fulton, 1924), or 3,500 A. (Newcomer, 1917), if conditions are favorable and the exposure sufficiently intense; it is more readily seen at 3,050 (Hertel, 1903; and Henri, 1912), but it is found that for practical purposes only, rays below 3,000 may be considered abiotically active, and these must be used in an intensity of about 2,000,000 erg-seconds per square centimetre (Verhoeff and Bell, 1916; Duke-Elder, 1926)."

The text further states that:

Roughly 2,000,000 ergs is the equivalent of 19 minutes of full summer noon-day sunlight at Washington, D. C. Looking directly into the sun continuously for this amount of time would undoubtedly constitute over-exposure, even though almost all of the shortwave ultraviolet from sunlight is stopped by the atmosphere. However, 19 minutes of similar exposure to the equivalent intensity of an artificial light source rich in the shortwave ultraviolet is what is indicated as necessary to cause such abiotic lesions.

A paper presented by Dr. Frederic Urbach, et al, at a symposium held at the University of Oregon Medical School in 1965 states in the introduction that:

However, the following statement is included in the summary of the paper:

Certain ailments of the eye have also been related to excessive exposure to the ultraviolet in sunlight, and (as noted earlier) the practice of wearing sunglasses is becoming increasingly prevalent. It would be difficult to find an optician today who did not sell one brand or another of eyeglasses designed to filter out this so-another of eyeglasses designed to filter out this so-called "harmful" ultraviolet radiation and prevent it from entering the eyes. Yet the paradox of this theory about the harmful effects of ultraviolet from sunlight is that scientific studies relating a high rate of pterygium, an abnormal growth on the eyeball that destroys vision through exposure to high intensity sunlight in the tropics, did not take into consideration whether or not those people with pterygium wore any kind of eyeglasses or sunglasses which would protect the eye from the ultraviolet part of the sunlight spectrum. Even ordinary eyeglasses filter out much of the ultraviolet in sunlight.

One extensive study of this subject gave as a major exception to these findings a group of Cree Indians in northern Manitoba, Canada, who had an exceptionally high rate of pterygium, and this far north they would definitely be out of high intensity tropical sunlight. A personal investigation of the situation revealed that this same group of Cree Indians had been issued specially designed sunglasses, of the wraparound kind, trimmed with leather to prevent even the slightest bit of unfiltered sunlight from reaching the eyes, in connection with an earlier experiment designed to study problems of glare, etc., from the snow and ice.

Neither study indicated whether the rate of pterygium was greater in the cases of those wearing sunglasses or not. It would seem, however, that this question might be pertinent, and in view of the combined overall results of both experiments, might raise the question as to whether the high incidence of pterygium resulted from actual direct exposure of the eyes to high intensity sunlight, or might possibly indicate the need of further studies to determine if various unhealthy conditions of the eyes could result from being deprived of the complete spectrum, including the normal amount of ultra-violet in natural sunlight which might be essential to maintaining a healthy condition. In checking a limited number of individuals who had developed pterygium while on military duty in the tropics, it was found that all had constantly worn prescription sunglasses.

In studying the harmful effects of ultraviolet, it has been common practice to consider only the effects on the part of the skin or eye that has been directly exposed to the sunlight. However, the more recent knowledge of the existence of an oculo-endocrine system greatly expands the research possibilities of the effects of ultraviolet, or especially the lack of it, on the retinal-hypothalamic-endocrine system.

Could the lack of the normal amount of ultraviolet in sunlight received through the eyes possibly cause a condition of hormonal or chemical imbalance and in turn make the skin hyper-sensitive to sunlight as far as skin cancer is concerned? It is known that some drugs and certain ingredients in soaps and cosmetics make people more sensitive to light. The question of any possible connection between different conditions of light sensitivity and hormonal imbalance or malfunction of the endocrine system might well be worth further investigation.

The amount of light actually entering the eye depends on the size of the pupil which is controlled by the iris. Under bright light, the pupil is normally much smaller so that only a fraction of 10,000 foot candles of full sunlight gets through to the retina. The pupil enlarges to let in proportionally more light of lower intensities. Thus the iris compensates to a great extent for such extreme variations in tht intensity of the light entering the eyes but does not alter its wavelength distribution.

Tanning of the skin accomplishes essentially the same purpose of cutting down the intensity of the lightthat penetrates the outer surface and in this way helps prevent sunburn. The leaves of a plant respond in much the same way and can also be severely sunburned and will die if moved too suddenly from a shady location into full sunlight. Many species of plants that normally grow in shady locations never can fully adapt to bright sunlight.

In an article entitled Degeneration of the British Beef Breeds in the Tropics and Subtropics, by Jan C. Bonsma, Breeding Beef Cattle for Unfavorable Environments, p. 19, it is stated:

In 1969 an interesting experiment was conducted by Philip Salvatori, F.I.A.O. Mr. Salvatori is chairman of the Board of Directors of Obrig Laboratories, one of the largest manufacturers of contact lenses. He is also one of the trustees of the Environmental Health and Light Research Institute. The experiment consisted of fitting a patient with an ultraviolet transmitting contact lens for one eye and a non-ultraviolet transmitting lens over the other eye. Indoors, under artificial light containing no ultraviolet, the size of both pupils appeared the same, but outdoors, under natural sunlight, there was a marked difference. The pupil covered with the ultraviolet transmitting lens was considerably smaller. This would seem to indicate that the photoreceptor mechanism that controls the opening and closing of the iris responds to ultraviolet wavelengths as well as visible light.

When the ultraviolet wavelengths are blocked from entering the eye, the pupil remains larger than it would otherwise normally be and the visible part of the spectrum would then seem brighter. This could explain why some people feel a greater need for dark glasses.

The consistently better responses in all the experiments with both plants and animals to the full spectrum of natural sunlight, including its normal intensities of ultraviolet, and the effects on both the chloro-plasts and the pigment granules when a little ultraviolet was added to the ordinary incandescent light source of the phase-contrast microscope, started me thinking about the possibility of adding some black light ultraviolet to the light sources being used in the various compartments where some of the animals were being studied. As previously mentioned, the intensity of the ultraviolet used in the microscope experiments was arrived at through trial and error, and too much ultraviolet was found to kill the cells in the microscope slides.

As I did not want to give the living animals too much ultraviolet to start with, I was not certain just what intensity would be within a safe limit. While in process of trying to decide how much ultraviolet to give the animals, my wife and I had dinner one evening in a restaurant known as "Well of the Sea," in the basement of the Hotel Sherman in Chicago. As soon as we entered the restaurant I noticed that there were black light ultraviolet lights placed throughout the ceiling. They had been installed solely for ornamental purposes, to cause designs on the waiters' coats, as well as the menus, to fluoresce in the otherwise subdued light. The next morning I went back to the restaurant with a meter to measure the intensity of the ultraviolet at various distances from the ceiling, such as table level and the eye level of the waiters as they walked directly under the various light fixtures.

I also wanted to ask the captain of the waiters a number of questions. In view of the general concern, especially at that time, regarding danger of over-exposure to ultraviolet, I wondered how long the lights had been installed and whether he had experienced an unusually high turnover among the personnel working in the restaurant. I asked him if any of his men complained of any eye problem, skin cancer, or other difficulties, such as sterility, which might be attributable to working for long periods of time under the black light ultraviolet. The captain told me that he had essentially the same group of men working for him as he had when they had opened the restaurant 18 years before. He said that the ultraviolet lights had been in use continually during that time, and that the health record of his men had been so consistently excellent that the manager of the hotel had checked into the situation, with medical supervision, to try to determine why this particular group of men was always on the job, even during flu epidemics, when other departments in the hotel would be short-handed because of employees' illness.

I then talked to the manager of the hotel, who told me that these men working in the "Well of the Sea" seemed to be a particularly happy group—courteous and efficient, and all seemed to get along well together. He said no explanation had been found to explain this, and that, at the conclusion of the study, it was thought to be simply a coincidence that this particular group of men should be so healthy and content. I asked if the men had been given a health check-up at the time they were hired. The manager explained that this was not customary and that the men just happened to be at the head of the list when the waiters' union was called on to staff the restaurant. I went back again on several occasions to talk with the captain and his men, and also to check to see if any of them were wearing glasses that would block the ultraviolet from entering the eyes. Not one of them wore glasses, which is rather unusual in this day and age, and none had ever complained of any eye problems or discomfort as the result of the ultraviolet light. Therefore, the measurements I was able to make of the intensity of the ultraviolet at the "Well of the Sea" gave me a good clue as to a safe level of exposure to start with for the laboratory animals.

Several months later at the Seaquarium in Miami, Florida, I noticed a similar black light ultraviolet light over some of the fish aquariums. In discussing this with the curator. Dr. Warren Zeiller, his assistant, Mr. Bevan, and some of their staff, I learned that these lights had originally been placed over some of the aquariums for decorative purposes, to give the fish an eerie but attractive appearance. Dr. Zeiller told me that the added black light seemed to solve one of their main problems in keeping fish. This was a condition of exophthalmus, or pop-eye, recently identified as due to a virus. I was told that it is rare that any aquarium fish are troubled with exophthalmus when kept in an outdoor aquarium under natural daylight and nighttime conditions. Another problem of fin-nipping also disappeared under natural conditions. Dr. Zeiller and Mr. Bevan have since written a number of articles on this subject, and report that certain fish that could never before be kept in captivity thrive under this added black light ultraviolet. Similar reports have been received regarding reptiles, birds, and animals kept in a number of zoos throughout the country.

One report on reptiles came from Jozsef Laszlo of the Reptile Department at the Houston Zoological Gardens in Texas, and appeared in the 1969 International Zoo Year Book, published by the Zoological Society of London. Dr. Laszlo reported that a number of reptiles and amphibians became noticeably more active whenthe cool white and daylight white fluorescent tubes in their cages were replaced with full-spectrum lighting. He further mentioned that it was even more interesting to see that some long starving but otherwise healthy snakes accepted food only a few days after the new lights were installed. One very rare snake of a type notoriously difficult to keep alive for any length of time in captivity ate for the first time since arrival in the zoo six months earlier.

At the Bronx Zoo in New York City, according to an article in the November, 1971, issue of the American Cage-Bird Magazine, it took four years for the curator to find out how to make the tufted puffin feel at home. Although the shy sea birds' northern habitat had been faithfully duplicated—rocky-cliffs and a consistently cool temperature—the birds refused to breed. With the installation of a new full-spectrum lighting system, the puffins have since attained a more natural coloration and for the first time in captivity one pair produced a fertile egg.

Another noteworthy item comes from Syracuse, New York, where Charles T. Clift, Director of the Burnett Park Zoo, reports that new lights installed in an attempt to stop vandalism fooled many of the animals into thinking that spring had arrived. "The zoo has been turned into a veritable maternity ward. The cougars fell in love all over again and produced their fourth litter. We collected five goose eggs. At least eight lambs were born, and the deer population increased by twenty. Big Lizie gave birth to a bear cub. The wallaby produced a new mini-kangaroo and the chimpanzee is expecting in August."

A significant difference in the amount of voluntary activity in mice kept under different colored lights was reported in the April, 1969, issue of Laboratory Animal Care by J. F. Spalding. The activity was measured by the number of revolutions of a rotating activity wheel in which the mice were free to run.

All the mice tested, regardless of sex, age or color, exhibited activity related to six different color-environments, as follows: Group 1, red and dark; Group 2, yellow; and Group 3, blue, green and daylight. The groupings are given in order of their activity, with Group 1 showing the greatest. This response is interesting to compare with the results obtained in the zoos using red-lighted "night" rooms.

Dr. Spalding mentions that white albino mice responded to environmental lighting changes to a greater degree than black mice, and that there were further differences in activity due to age and sex. Of particular interest were findings reported of an earlier experiment indicating that different lighting conditions in the visible color spectrum had a strong influence on activity in normal mice, but that enucleated mice showed equal activity in the dark and in all color environments. Dr. Spalding further suggests that the results of these experiments may be pertinent to environmental lighting conditions not only of stock animals but also of the working man.

During the winter of 1968-1969 a serious outbreak of Hong Kong flu swept the country. Florida was no exception. The Health Department reported 5 per cent of Sarasota County—or 6,000 people—sick with the flu at one time. Employee illness caused the temporary closing of one supermarket, a social club, and the shutdown of two areas of the Sarasota Memorial Hospital because sixty-one nurses were out with the flu.

Obrig Laboratories, located just north of Sarasota, is one of the largest manufacturers of contact lenses and has approximately one hundred employees. During the entire flu epidemic not one employee was absent because of any flu type ailment, according to PhilipSalvatori, Chairman of the Board.

Obrig Laboratories was the first to design a new building using full-spectrum lighting and ultraviolet-transmitting plastic window panes throughout the entire office and factory areas. The added ultraviolet seemed to tie in closely with the results noted at the "Well of the Sea" restaurant in Chicago. Mr. Salvatori also mentioned that the Obrig employees had not been given any mass inoculation against the Hong Kong flu, although some individuals may have received shots from their private physicians. Mr. Salvatori also commented that everyone seemed happier and in better spirits under the new lighting, and that work production had increased by at least 25 per cent.

On another trip to Florida I gave a lecture to an advertising club, and after I had finished my talk, Mr. Richard L. Marsh, manager of radio station WILZ near St. Petersburg, told me of a similar situation. He said that some of the staff at the radio station had taken it upon themselves to try to brighten up their surroundings in both the studios and the control rooms by replacing the regular white fluorescent tubes with those of a deep pink color. About two months later, they began to have personnel problems. For example, announcers began performing poorly on the air. Everyone became irritable and consistently at odds with management decisions and generally difficult to control. Two resignations were received from employees without any known reason for their wishing to leave other than general dissatisfaction with themselves and the staff.

Then, one morning one of the men said, "If those pink bulbs aren't removed I'll go out of my mind." That sparked an immediate reaction, and that very day all of the pink tubes were removed and replaced with the white tubes. Within a week, as if by a miracle, tempers ceased to flare, congeniality and a spirit of working together began to redevelop and resignations were withdrawn. The airwork improved, with mistakes at a minimum.

These results seemed quite in line with the preliminary reports I had received from an experiment that I helped design to study the effects on mink kept behind different colored glass and plastic.

The experimental work with mink was carried on at the Northwood Mink Farms in Gary, Illinois, but unfortunately the project was suddenly interrupted due to the death by automobile accident of Mr. Bud Grosse, owner and operator of the farm. Immediately after his death the principal investigator and his two assistants all moved to other mink ranches in different parts of the country and no official paper was ever published. However, I was in close contact with Mr. Grosse while the experiment was under way and progress reports were given to me on the various results obtained.

The reports indicated that the mink exposed to natural daylight through a deep-pink glass became increasingly aggressive, difficult to manage and in many instances actually vicious. Ordinarily, mink are kept in open sheds with open window areas containing no glass. They are provided with a box-like shelter containing some straw, but the sheds are not heated as the natural habitat of mink is in north country, where the winters are long and cold.

However, mink normally are quite fierce and even without the pink glass it is customary for the animal caretakers to wear heavy leather gloves for protection, especially during the mating season. But when some of the mink were placed behind deep blue plastic they became friendly and docile, and in thirty days could be handled with bare hands like ordinary house pets.

The effect of the different colors on the animals'behavioral patterns was interesting, but the difference in the results of mating the animals under either pink glass or blue plastic was possibly of even greater interest.

When a female mink does not become pregnant after the first mating, it is common practice to give her an injection of a pregnant mare serum before attempting the second mating. This was not necessary with any of the female mink in the cages with the blue plastic, as all became pregnant after the first mating. Furthermore, to use the language of the mink industry, all the males were found to be "working males."

But the situation was quite different with both males and females in the cages behind pink glass. After three attempts at mating the females, which included two injections of the pregnant mare serum, only 87 per cent became pregnant and 90 per cent of the males were classified as "non-working."

The principal investigator of the project was Alex Ott (no relation), who also advised that four animals under the pink glass died during the experiment from a strange malady that he had never seen before. An autopsy of each animal indicated what appeared to be a cancerous condition of the abdominal area including a number of vital organs. Unfortunately, an actual biopsy was not performed due to the abrupt termination of the entire project. Approximately 500 female mink were used in each experiment.

Another interesting bit of information turned up as the result of a questionnaire given to a group of college students by a professor of psychology. In general, the questionnaire asked if the students wore glasses or contact lenses, and—in particular—if they wore tinted contact lenses or sunglasses and if so, what color. Questions were included asking how much time was spent out of doors and how many hours spent watching television. Roughly 300 students answered the questionnaire, but the overall replies clearly showed that either more detailed questions would be necessary or, better, a personal interview.

However, one rather clear relationship did show up. Although not statistically significant because only three cases were involved, three students did reply that they constantly wore "Hot Pink" glasses and a check with the faculty ratings indicated that these same three students also were considered to be the most psychologically disturbed students in the college.
More recently the following interesting letter was received: