The reality is that bamboo itself is one of the most eco-friendly plants on earth. Remember, while bamboo can be made into fibers, it is a plant, and that is what makes it natural. However, there needs to be somewhat of an asterisk added to this section, and here is why.
While bamboo itself is eco-friendly, the process of actually making bamboo fabrics (and this would include socks) is going to require a lot of chemicals. These chemicals can harm the environment but do not worry as engineers have an answer for it. Many companies will recycle these chemicals to lower the impact they have on the environment.