For the past 30 or so years, there have always been flashlights under our Christmas trees. Every child, every year, and sometimes one for me as well. Very early on in our family life, my dear husband decided that each child needed his own flashlight, with the ostensible goal of protecting his personal flashlights from the children. (Do they never learn? Do not ask whom I mean by they.) Of course, they were almost always the cheapie flashlights that don’t last long, so we don’t actually have kid flashlights all over creation, which is fortunate. Unfortunately, the same cannot be said about Aaron’s flashlights, which do seem to be everywhere.
This year, I decided to get in on the act and gift a few flashlights of my own. Of course, they had to be practical. No fluff from me.
Enter the blacklight flashlight.
I bought one for the medical kit a few years back. And I thought I’d discussed them on the blog, but a diligent search revealed only one passing reference. So it was time to remedy the situation with a dedicated blog article. Naturally, I couldn’t publish it before Christmas, because the kids, if they read the blog, would know what they were getting. Couldn’t have that happen.
So why did I decide they needed a blacklight? And do you want one for yourself? Thought you’d never ask.
Of course, most people are somewhat familiar with blacklights. They were all the rage in the 1960s and early 1970s for casting a groovy blue-violet hue on objects as well as revealing some things hidden to the naked eye. CSI drama fans recognize their use in highlighting body fluids at crime scenes. When combined with black light-activated invisible ink, they’re commonly used by security teams to identify who is authorized to enter paid venues and other events.
The conventional blacklight is a step down from a Wood’s light (or lamp), which was developed by Robert Wood in 1903 and subsequently used to identify fungal infections in the 1920s. An official Wood’s lamp has a shorter wavelength of ultraviolet light that makes identification of microbes and other small objects easier.[1] However, a conventional blacklight works nearly just as well and is cost effective at around $15.[2] And it’s really easy to use, just like any other flashlight.
Health & Hygiene
- Check lodgings for cleanliness.[3] (This is how we use our blacklight most frequently.) You’ll see whether the hotel room was cleaned well. (Fair warning: We’re usually disappointed.) With all the outbreaks of bed bugs all over the country, we check hotel room beds every single time we visit.
- At home, you can quickly check for where pets may have urinated, like after returning from vacation and finding your pet sitters weren’t so reliable.[4]
- After applying sunscreen, go into the bathroom and turn the lights off to verify whether sunscreen coverage is complete.[5] [6]
Medicine
- Bed bugs fluoresce red[7]
- Corneal abrasion[8]
- Ethylene glycol (anti-freeze) poisoning patients will produce urine that fluoresces blue-green. Traces may also be found on the skin or clothing. Doctors warn, however, that the presence of fluorescence in the urine or on clothing doesn’t necessarily confirm or refute anti-freeze poisoning.[9]
- Jaundice in newborns can be managed with a blacklight.[10]
- Lice fluoresce as blue dots near the scalp or skin.
- Pseudomonas aeruginosa infections of the skin fluoresce green.[11]
- Psoriasis patients can use a blacklight to create vitamin D that helps correct the condition. [12]
- Scabies tunnels, tunnel borders, and mites fluoresce very well, white or green.[13] [14]
- Skin cancer, specifically basal cell carcinoma, fluoresces bright red.[15]
- Tetracycline compliance is revealed by shining a blacklight on the patient’s toenails, which will fluoresce yellow.[16] [17]
- Vitiligo is visible to the naked eye; however, a blacklight confirms the condition is vitiligo (fluoresces bright blue-white).[18] [19] [20]
- Some use a blacklight to check for aflatoxin mold in feed grain. Unfortunately, it is not 100% accurate. While the absence of glowing bits in the grain indicates that there is no mold, the presence of glowing bits does not mean there is mold. The glow bits could be due to something else.[21]
- Tomato worms glow green under a blacklight.[22]
Household
- Use a blacklight to identify vehicle leaks of coolant and oils.[23]
- Reveal leaks from household appliances, sinks, and toilets.[24]
- Mark important documents and property with an invisible ink pen. A blacklight will highlight the markings.
- Counterfeit currency is easily identified with a blacklight.[25]
What substances or actions can affect fluorescence results?
- Recent showering/bathing. (Though article doesn’t define recent, I surmise that it’s within a few hours based on the fact that tetracycline compliance is verified by looking at the patient’s toenails, rather than the fingernails which have hopefully been recently washed.)[26]
- Certain medications, detergents, and fibers.[27]
- Highlighters, dried soap, and laundry detergent.[28]
- Lemon juice, lint, saliva, syrup, milk, semen, sunscreens, ointments, cosmetics, hair dyes, and wet ear wax. [29]
Caution. Researchers disagree on the safety of using a Wood’s lamp and regular black lights. Some say all people should wear protective eyewear; others say that only children’s eyes need to be protected.[30]
If you aren’t sure about getting blacklights for everyone, here’s another option likely to work for you: your smartphone.[31]
Here’s how:
- Use a search engine to locate a “blue image” and download it.
- Maximize the smartphone brightness level.
- Turn off the screen timeout setting.
- Then proceed as if using a Wood’s lamp or blacklight.
- Darken the room.
- Hold the phone 4-5 inches away from the skin (or other object).[32]
References:
https://bedbugsos.ca/blogs/edu/how-to-find-bed-bugs-with-black-light
https://centralohiobedbugs.org/can-you-see-bed-bugs-with-a-black-light/
https://www.theimpatientgardener.com/hornworm/
Links to related posts:
[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9239119/
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9239119/
[3] https://www.lightbulbs.com/blog/what-are-black-lights-used-for
[4] https://www.oillampman.com/what-are-uv-flashlights-used-for/
[5] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9239119/
[6] https://onlinelibrary.wiley.com/doi/10.1111/phpp.12138
[7] https://bedbug.ninja/what-do-bed-bugs-look-like-under-uv-light/
[9] https://casereports.bmj.com/content/2017/bcr-2017-221373
[10] https://www.lightbulbs.com/blog/what-are-black-lights-used-for
[11] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9239119/
[12] https://www.lightbulbs.com/blog/what-are-black-lights-used-for
[13] https://pubmed.ncbi.nlm.nih.gov/37702268/
[14] https://pubmed.ncbi.nlm.nih.gov/36548678/
[15] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9239119/
[16] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9239119/
[18] https://www.lightbulbs.com/blog/what-are-black-lights-used-for
[20] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9239119/
[21] https://vetmed.iastate.edu/sites/default/files/vdl/disease-topics/SamplingMycotoxins.pdf
[25] https://www.lightbulbs.com/blog/what-are-black-lights-used-for
[26] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9239119/
[27] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9239119/
[28] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9239119/
[29] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9239119/
[30] https://pubmed.ncbi.nlm.nih.gov/15502661/
[31] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9239119/
[32] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9239119/
Never thought of this. Thanks
ReplyDeleteThose living in the Southwest can see scorpions outside with a black light--creepy, or satisfying depending on what you do next!
ReplyDeleteWhat is tetracycline compliance? Why would you check toenails for it, or lack of it?
ReplyDeleteWhether the patient is taking tetracycline as prescribed. Some people don't take their antibiotics, after all, putting others at risk in the case of communicable diseases like brucellosis or STDs. As to why toenails would be checked, I couldn't find an answer. My guess is that (hopefully) frequent handwashing would prevent the fingernails from fluorescing, while toenails don't get washed as often, so they would fluoresce.
Delete