13

Recently, my company started using fingerprint scanners to identify employees for access control and for attendance. Many employees have a concern about developing skin cancer from the IR fingerprint scanners.

The Saudi Gazette also has a warning

The dermatologist, whom the Makkah-based Arabic daily Al-Nadwah quoted spoke on the condition of anonymity, state these devices have a negative impact on the employees’ health, especially those who fingerprint their palms. He added that in the long run, exposure to infrared rays might cause cancer.

Is this plausible?

  • 1
    Have you heard any of the employees say why they have this concern? Have the heard this claim somewhere? – Flimzy Jan 3 '13 at 1:37
  • They say it is a "well known fact" but I did not ask them for a resource.. and I am talking about many many employees.. – user10938 Jan 3 '13 at 1:40
  • 1
    My google skills, so far, have only found IR scanners that detect skin cancer, not that are alleged to cause them... – Flimzy Jan 3 '13 at 1:43
  • 1
    @Oddthinking HaLaBi seems to be from Saudi Arabia so it is probably a culture specific belief. Hello, HaLaBi, welcome to Skeptics!! – Sam I Am Jan 3 '13 at 3:47
  • 1
    I am not aware of any link between infra-red radiation and cancer. Infra-red simply doesn't have the energy to cause damage to DNA, unlike ultra-violet and X-rays which do! – Nick Jan 3 '13 at 9:15
18

Sensor Technologies

Fingerprint scanners use one of two methods

  • optical (light)
  • capacitive

See HowStuffWorks and note that this manufacturer has both "E-Field" and "Active Cap" sensors.

Light

So not all fingerprint readers shine light on your fingers.

Also, patents such as this mention "light" and have no mention of "infra-red" so at first glance it seems that some sensors may be using wavelengths of light that are not infra-red.

Infra-red

Some Infra-red light is the same as radiant heat. I'm unsure this would be useful to shine on a warm object like a finger. It would be better to use a passive-IR detector to capture the IR-radiation (heat) emitted by the finger. This is how some night-vision cameras work. In this case there would be no additional IR received by your finger.

Compare with Passive Infra-Red (PIR) detectors used in automatic lights and burglar alarms.

Infra-Red light is commonly used in domestic heaters and in heaters used to raise chicks. Examples. Examples. So it would be surprising if these were a hitherto unknown cause of cancers.

Heating a finger could conceivably cause burns (though biometric scanners are unlikely to need high-powered IR emitters and so are probably unlikely to have circuits capable of carrying the electrical current needed to deliver a harmful heating effect).

The power emitted by a typical "high-powered IR emitter" is 20 mW (0.02 W). If this is all shone at a fingertip (area 0.0001 m²) with 100% efficiency (impossible) that gives 200 W/m². Compare this with the heat naturally emitted by your skin which is 40 to 800 W/m²

Cancer

When I search for "Infra-Red and Cancer" I only get results concerning the use of Infra-Red light to treat (i.e. attempt to cure) cancer! Example

Infra-red light is non-ionizing as pointed out by Nico in a comment below. This means it cannot cause the sort of damage to DNA molecules typically needed to cause cancers.

Skin cancer has been associated with UV-light (specifically UV-B), not IR light. Maybe there is some confusion.

See links referred to in Wikipedia

Health

To work out any health implications you'd need to know

  • does the specific fingerprint sensor used actually emit IR light
  • what frequency
  • what power
  • how long is the finger illuminated
  • how many time a day/week/month/year does each person use the sensor

I can't find any reference that IR light causes cancer. As explained above, this seems very unlikely.

Saudi Gazette

wrong about device

The article mentioned shows a picture, not of a fingerprint scanner but of a different device - a hand geometry scanner. I believe these scanners typically use visible light and cameras not Infra-Red.

The text of the article talks only about "fingerprint devices"

wrong about "exposure to infrared rays might cause cancer"

This seems to be an error - no references in the article.

other issues may be legitimate but grossly overstated

The anonymous dermatologist warns about transmission of "skin diseases" - this may be a legitimate concern (though the same concerns would presumably apply to doorknobs and banknotes, etc). Some respondents suggested the device is treated to reduce the chance of this.

irrelevant content

The article reports

In biochemistry, a fingerprint is defined as a pattern of fragments obtained when a protein is digested by a prototypic enzyme, usually observed following two-dimensional separation by chromatography and electrophoresis.”

The reporter or editor seems to be introducing information that is completely irrelevant to the operation of fingerprint scanners. At the very least they fail to explain how it can possibly be relevant. This casts some doubts on the reporters competence and impartiality.

wrong about X-rays

Physicians also said these devices emit X-rays directly at the hand

If the ridiculousness of this (in the context of fingerprint scanners) is not evident to anyone reading this, please say so in a comment.

Conclusion

(what follows is personal opinion - you can disregard it)

Whatever the hazards (if any) of fingerprint scanners - this article is, on the whole, not credible. It is probably a good example of the worst kind of journalism. It seems to deliberately stir up concern and even panic, prey on peoples natural apprehensions about new technologies and does not make any attempt to give the makers of the devices any opportunity to respond to the claims. For the sake of it's citizens, I hope it is untypical of journalism and science in Saudi Arabia.

| improve this answer | |
  • 1
    To work out any health implications you'd need to know : Does IR light cause cancer........ – Pieter B Jan 3 '13 at 9:15
  • @Pieter: Thanks, I have updated the answer to make that point a little more explicit. – RedGrittyBrick Jan 3 '13 at 9:40
  • You may want to add that infrared light is non-ionizing – nico Jan 3 '13 at 10:54
  • 4
    Infrared 'light' has less energy than visible light, so if you could get cancer from an IR fingerprint scanner, you should run away from lightbulbs and hide in completely dark rooms forever... – Shadur Sep 11 '14 at 4:41

You must log in to answer this question.