The U.K.’s National Society for the Prevention of Cruelty to Children (NSPCC) canceled a live event after users from popular parenting website Mumsnet flooded them with questions about their support of transgender children joining Girl Guides.

Many were concerned about girls who were born male sharing the same changing rooms, showers, and dorms with girls that were born female. The website has been known to fixate on trans issues, with some users coming across as transphobic. Mumsnet founder Justine Roberts said discussions about trans rights have tested the site to “the absolute limit,” making it harder to have “civilized discussion,” Telegraph reported.

The NSPCC pointed out in a statement to Mumsnet that they “don’t consider there to be specific child protection concerns in relation to trans-inclusive policies,” and reminded them that “Trans young people are at particular risk.”

The Girl Guides’ 2017 policy said that members are free to use the facilities of their self-identified gender.