IPPD (N-isopropyl-N’-phenyl-paraphenylenediamine)

IPPD is a PPD derivative, which is used as antioxidant/antiozonant mainly in rubber manufacture, less commonly as antioxidant in other products, such as mineral oils and foodstuffs.
Due to its staining property IPPD may only be used in black rubber items. These include not only heavy duty black rubber like tyres, conveyor belts, hoses and tubes, trush cushions, car bumpers, rubber boots, but also tool, machine and motorcycle handles, black rubber gloves, pneumatic handlers, elastic in clothes and underwear, diving suits and scuba face masks, leg dressings and orthopaedic bandages, braziers, squash balls, watch straps, spectacle chains, and others.
Although positive patch tests to IPPD are usually relevant (past or present relevance), some arguments are of special value.

1. Clinical arguments
   
   11. “Typical” clinical picture
       - hyperkeratotic palmar dermatitis
       - lichenoid dermatitis
       - PPPP syndrome (Purpuric Petechial Pruritic dermatitis due to PPD derivatives)
       - sub-acute foot and/or leg patchy dermatitis
       
   12. “Atypical” dermatitis
       - dermatitis of the trunk
       - flexural dermatitis
       - other dermatitis
   
   

2. Anamnestic arguments
   
   21. Known contact with common black rubber items, mainly in the transport industry
       
   22. Possible contact with less common black rubber items
       
   23. Unknown contact with black rubber – look for hidden sources (mineral oils, black felt hats, etc)
       

3. Patch tests arguments (beyond IPPD +)
   
   31. (+) Patch tests to black rubber items handled or contacted by the patient
       
   32. (+) PT to certain azo dyes
       
   33. (+) PT to PPD and/or other para substances
       

4. Investigative arguments (when available) – information from the manufacturer, safety data sheets, analytical investigations
   
   41. Positive investigation
       
   42. Negative