The Food & Agricultural Organization AND The World Health Organization have categorized carrageenan under the best category for any food additive, so once and for all, my dear vegans, carrageenan is SAFE. That includes the one in your plant milk.
Read their review of countless studies and their final verdict here: http://apps.who.int/iris/bitstream/10665/43823/1/9789241660594_eng.pdf
In addition, as of 2014, they concluded that carrageenan IS also SAFE for infant formula use. See here: http://www.fao.org/3/a-at861e.pdf