In Canada, if a Full Blooded native woman marries a non native man, she looses native status. So in practice, if very few native men are being born compared to native women, there is the very real chance that within a few generations there won't be anyone left on the reservation recognized as a native since native status follows the male line and no males means no native status.

So I really don't expect any Government would do anything about it even if it is confirmed to be from toxins. The Canadian Government has an interest in this happening.