I have not finished this article but your title here seems a bit misleading actually.
What this article seems to be saying, is that this plastic chemical stuff can cause the symptoms of ADHD.
There are over 400 organic measurable physical disorders that manifest both in the ADHD symptoms and in the realm of physical organic reality as well that can produce ADHD symptoms. It is only ADHD when there is no link between the physical world and the behaviors. If you can point to something and say "This is what is causing the ADHD" then in point of fact according to the criteria set forth in the DSM you are not dealing with ADHD.
ADHD is a disorder. (a disorder rather than a disease due to a lack of physically measurable organic evidence for it's existence in the brain. This means a brain with ADHD is completely consistent in all appearance and functionality as far as we can detect through the use of science at this time with a normal and regular healthy brain.) ADHD has a bunch of loosely stated behaviors attached to it in the DSM. The diagnosis procedure adheres to no methodologies set out by the hard sciences. Upon which a subjective diagnosis is made when all other physical and organic possible contributors to the problem have been ruled out.
So you are misrepresenting what this article is saying.