It is possible, but I think, unlikely to be nearly as important as change in diets. The poor are much fatter than the wealthy. Do we really think its because they're exposed to more hormone disruptors? Or is it a terrible diet because they don't have the time and resources and knowledge and stress to eat healthier? Contaminants are probably a problem, and could accumulate non linearly into an even bigger problem. But obesity is almost certainly a diet problem. The poor are much more likely to eat high calorie, low nutrient food. Homeless people are increasingly both hungry and fat. I don't think its especially controversial to say that's the likely outcome if you were to just remove these chemicals back to 1800s levels.