Apparently it's not possible to be allergic to carbon, air or water. EXPLAIN..?

[Pete]

• Why another thread? What's wrong with the earlier one/s?
• From the latest articles I could find (2009 and 2010):
  http://dx.doi.org/10.1590/S0365-05962009000500015
  http://www.jiaci.org/issues/vol20issue7/vol20issue07-17.htm
  The pathogenesis of this form of urticaria has not been fully clarified; many mechanisms have been proposed. In 1964, Shelley and Rawnsley suggested that water interacted with components of the corneal strata or sebaceous glands to form a toxic substance that would be absorbed by the skin, resulting in degranulation of perifollicular mast cells and histamine release, which would result in urticarial lesions.1 Czarnetzki et al.11 suggested that there was a water-soluble antigen on the epidermis that, in contact with water, would diffuse throughout the dermis, causing mast cells to release histamine, which appears to be the chemical mediator in the pathogenesis of aquagenic urticaria. Other mediators, such as acetylcholine, serotonin, and bradikynin may also be involved in the pathogenesis of aquagenic urticaria.
• Exploring the pathophysiology is of questionable value, because there are so few people who suffer from it, and experimenting on them isn't nice. Eg see http://dx.doi.org//10.1034/j.1600-0536.2001.44020912.x:
  The sea water as is, the ultrafiltered seawater and the hypertonic saline solution elicited intense erythema, scattered with distinct small wheals, after 20 min of contact with the skin of the mandibular and submandibular region. Localized pruritus and discomfort were severe. The rash cleared spontaneously within 60 min. Tap water elicited patchy erythema and mild discomfort, while distilled water elicited only a tiny follicular wheal and no subjective symptoms. Control tests in the antecubital fossae were all negative. Sorbic acid 5% pet. caused intense erythema and a burning sensation, but no whealing. Petrolatum as is had no effect.
  
  It was not possible to investigate the urticant effect of ethanol, acetone or a hypertonic non-ionic water solution, such as a glucose solution, because the patient refused to undergo further testing.
• There's not necessarily a single answer. The specific cause might be different in different people.

 

[billvon]

They react with itchy hives all over their body if they come into contact with moisture. this includes fog, humidity in the air, showering (they can only shower 30secs each week.) or even a single drop of urine, sweat, tears or blood. this happens when they urinate as well. They are more likely to react to tap water but some also react to sterile distilled water. some can only eat dry foods and can only drink diet cola, milk or orange juice. the condition is diagnosed by putting tap water, then distilled water on the skin and observing the reaction. for some people, both types of water makes them break out. The human body is 70% water and h2o is too small to cause anything with antibodies and the immune system are made of water. This condition is mislabled in the press and I would like to know the actual cause/causes of this. esp. with the distilled water.

They're not allergic to water, they're allergic to electrons. Water has electrons in it.