jm + hair   2

TIL you shouldn’t use conditioner if you get nuked
If you shower carefully with soap and shampoo, Karam says [Andrew Karam, radiation expert], the radioactive dust should wash right out. But hair conditioner has particular compounds called cationic surfactants and polymers. If radioactive particles have drifted underneath damaged scales of hair protein, these compounds can pull those scales down to create a smooth strand of hair. "That can trap particles of contamination inside of the scale," Karam says.

These conditioner compounds are also oily and have a positive charge on one end that will make them stick to negatively charged sections of a strand of hair, says Perry Romanowski, a cosmetics chemist who has developed personal hygiene formulas and now hosts "The Beauty Brains" podcast on cosmetics chemistry.

"Unlike shampoo, conditioners are meant to stay behind on your hair," Romanowski says. If the conditioner comes into contact with radioactive material, these sticky, oily compounds can gum radioactive dust into your hair, he says.
factoids  conditioner  surfactants  nuclear-bombs  fallout  hair  bizarre  til  via:boingboing 
august 2017 by jm
FBI admits flaws in hair analysis over decades
Wow, this is staggering.
The Justice Department and FBI have formally acknowledged that nearly every examiner in an elite FBI forensic unit gave flawed testimony in almost all trials in which they offered evidence against criminal defendants over more than a two-decade period before 2000. [....]

The review confirmed that FBI experts systematically testified to the near-certainty of “matches” of crime-scene hairs to defendants, backing their claims by citing incomplete or misleading statistics drawn from their case work. In reality, there is no accepted research on how often hair from different people may appear the same. Since 2000, the lab has used visual hair comparison to rule out someone as a possible source of hair or in combination with more accurate DNA testing. Warnings about the problem have been mounting. In 2002, the FBI reported that its own DNA testing found that examiners reported false hair matches more than 11 percent of the time.
fbi  false-positives  hair  dna  biometrics  trials  justice  experts  crime  forensics  inaccuracy  csi 
april 2015 by jm

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