Para-phenylenediamine is a strong sensitizer.
Sensitizer means that every body is naturally allergic to PPD to some degree, and every time the PPD is used, the body will react more violently to it. Some people have PPD tattoos once or twice without reaction. But on the 3rd or 4th time, that same person could end up with permanent scarring or end up in the hospital in a life threatening reaction. There can also be sensitization to other products. So after having a PPD tattoo without reaction, you could a week later react severely to: cosmetics, lotions, sunscreen, medications, black clothing, ink, dark leather, etc..

PPD is carcinogenic & causes many other health problems!
Within seconds the toxins from PPD ‘henna’ enter the blood stream and can cause: Cancer, liver tumors, asthma, angioneurotic edema, renal failure, mutated cells, muscle necrosis causing death, permanent scarring, chronic skin conditions, eye & face irritation, bronchitis, etc…
When PPD breaks down in the body, the metabolic residue is more damaging than the actual PPD molecule.

PPD has a delayed reaction:
Typically, a person won’t react until 3 – 10 days after having a PPD tattoo applied. Usually by this time the negligent artist has moved on, unaccountable to the damage caused & the person fails to make the connection between the PPD and reaction.

How to tell if it’s PPD ‘Black Henna’
1. If you can watch first & see that the paste is black & stains the skin right away, it’s PPD.
2. Ask how long the paste needs to stay on. If they say less than 1 hr, it’s not real henna.
3. Ask them what colour it will stain. If they say black instead of red-brown, it’s not henna.
4. Ask the artist what’s in the paste. If they can’t tell you, don’t trust them.
For your safety & the health of others, please report anyone using illegal PPD “Black Henna”

If you are ever tempted to get a henna tattoo from a street vendor, consider two things: ask them what’s in their henna mix, and how long it will take the design to develop. If they can’t tell you what’s in their mix, walk away. It’s a good bet they use a pre-made henna mix from India that could have who-knows-what in it. (Pre-made mixes from India often do not have ingredient lists, and the industry is fairly unregulated so they can put anything they want in the mix from essential oils to urine to gasoline.) If they say it only needs to be on the skin for 5 to 20 minutes and you’ll have the design for up to three weeks, walk away. Chances are they’re using black henna and you want none of it. Real henna should be on the skin for a minimum of 4 hours and kept warm for a decent stain to form. (Yes, I’m a henna artist. Can you tell?)

Also, the people in the article shouldn’t have had their 3-year-old hennaed anyway. In children under 6-years-old, there can sometimes be a reaction even with natural, unadulterated henna. It has to do with a genetic condition called G6PD Deficiency. It’s rare, but it’s still something a responsible henna artist should be aware of. There’s more info about this on the site http://www.hennapage.com.