Although it is the responsibility of the Environmental Protection Agency in the USA to assess environmental risks for its population, this is a major task, and they are faced with dozens of new chemical products each year. This is in addition to still having to reassess a backlog of hundreds of complex organic molecules that now show evidence of possible toxic natures and require re-examination to new standards. Utilizing the analyses of urine samples from the US population in one large National Health and Nutrition Examination Survey a new methodology is in fact being suggested. This is permitting approximate unknown levels of exposure to be modeled for general types of anthropogenic chemicals utilizing observed distributions of others in the main database. As a result, it is becoming a concern that this potential body-burden of undesired chemicals that have to be purged from the body and brain are possibly playing some role in the spectrum of neurological illnesses now seen in the aged and moreover also in the young. Although a demanding task, it is therefore appropriate to critically review the almost overwhelming number of publications that have appeared in recent years addressing this topic.
The growth in analytical ability and its more widespread availability is an important advance, and now has spawned the acquisition of large medical databases of a more reliable nature. Moreover, more refined techniques of animal studies and isotopic labeling experiments have emerged. As a result, it is timely to pause and consider, in a more rigorous scientific manner, whether new insights are present particularly with emphasis on the current undeniable neurological epidemic evident particularly in the young. Although there is a rich literature on this subject and several excellent reviews, none have really examined the topic emphasizing the full chemical nature of the potential environmental species involved and how these have changed in recent decades in our diets.