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The classic discussion is Mary Douglas's Purity and Danger: An Analysis of Concepts of Pollution and Taboo. There is also much useful analysis in The Guru Papers, which draws on Thought Reform and the Psychology of Totalism.
The purity obsession's harms are a narrowed scope of action, and various neuroses (avoidant-compulsive; superiority complex).
An effective antidote is deliberately playing with "impurity."