Other plants may also contain the allergen in poison ivy. For example, contact exposure to the shells and the wood (but not the nutmeats) of the cashew tree can cause the same kind of allergic reaction as poison ivy. Mah-jongg tiles from China were often made of cashew wood and during the 1920's there was such a rage for this game that the makers ran out of seasoned wood for manufacturing and began to use inadequately aged wood, which resulted in an epidemic of finger dermatitis among mah-jongg players. Ah, the wages of indolence.