Looks like Pinterest are doing a good job of removing harmful content from their plarform, removing over 500k pieces of content per day! The main tytpe of harmful content appears to be classified as Pornography or Sexualised content.

When reviewing individual instances of adult content removed, there isn't a great deal of information to be gleaned, othere than 'This Pin violates our Community Guidelines on adult content'. You can see an example here.