It's not a symptom of being poor. It's more a symptom of growth transitioning away from being poor but not skipping the pollution stage. They could very well grow with modern technology now that it is available and proven --something countries which industrialized earlier didn't have. Not only technology but the knowledge of the effects. Nowadays people don't experiment with radioactive elements in their basement labs the way people did in the early 20th cent. because we know more about those substances and their effects on health.