Complex sentence: Despite support by public health organizations and authorities, efforts to introduce water fluoridation have met considerable opposition, opposition that is "often based on Internet resources or published books that present a highly misleading picture of water fluoridation".
Split into simpler sentences: Despite support by public health organizations and authorities, efforts to introduce water fluoridation have met considerable opposition. Antifluoridation arguments are, "often based on Internet resources or books that present a highly misleading picture of water fluoridation".