Okay, so there is a decent amount of scientific evidence suggesting there could be a link. I mentioned in my comment that she treats the subject very gingerly, rightly so, because people will respond the way you are likely to respond.

However, saying that it is dangerous is a very good way to shut down the conversation completely, or demonize those trying to gather an honest understanding of reality. Consider the case that there really is a link. Is it better to wall off the conversation completely instead of investigating? Is it possible to discuss the topic at all? ever?

I mean, read the book, it is backed by real science it is not political at all, not some alt-right hateful thing.

That's the thing -- there isn't. At best, it's a working theory that is equal to any other theory.

Saying that something is dangerous means that we should err on the side of caution, it does not mean that we should not discuss it. Plenty of scientific topics are dangerous and require a close cooperation with an ethics board to advance.

To name a few theories that are ongoing: genetics, endocrine disruptors (doesn't single phtalates), childhood experience, parasites, neurodevelopmental disorders, relationship with autism spectrum, etc.

None of the above is winning the race. The current leading theory is that the gender identity, including cisgender identities, is complex and a mix of genetic, biological, environmental, and cultural factors.

The WHO describes a disease as "any harmful deviation from the normal structural or functional state of an organism, generally associated with certain signs and symptoms and differing in nature from physical injury".

The trans identity is not a disease, it is not something to be fixed. In the same way that homosexuality is not a disease. Both have been on a road of depathologization, they are not harmful but regular variations of the human experience.

I'll close with a question: how can phtalates be the cause of gender incongruence and gender diversity when communities that falls under that umbrella exist since before the use of plastics? See: "Hijra", "Mukhannath", "Mahu", "Two-spirit", "Fa'afafine", "Muxe", "Bangala", "Mamluk", "Xanith", etc.

Gender dysphoria is a condition in which a person experiences distress, anxiety, and/or discomfort due to a discrepancy between their gender identity and the sex they were assigned at birth. This can include feeling like one’s body does not match one’s gender identity, feeling disconnected from one’s body, or feeling that one’s gender identity is not accepted or respected by others. People with gender dysphoria may experience a range of emotions, including depression, anxiety, and anger. They may also experience physical symptoms such as insomnia, fatigue, and changes in appetite. Treatment for gender dysphoria may include counseling, hormone therapy, and other medical interventions.

But if it is true it could be dangerous to them for us not to discuss the possibility. If they are people with a medical problem rather than a perfectly naturally occurring identity then we may not be giving them the treatments that will help them most while causing them the least harm. What if there were treatments that would mitigate or reverse the effects of environmental exposure and allow them to feel normal with the gender expression typical of their sex?

Being transgender is not a medical problem.