The endocrine and nervous systems are intimately intertwined. For example, the brain stimulates the thyroid gland and thyroid hormone production, which play a key role in neurological development. Neurological function is affected by melatonin and cortisol, hormones that regulate sleep and stress. Normal neurological development and behavior rely on these hormone balances.
Unfortunately, the brain is highly vulnerable to endocrine disrupting chemicals (EDCs), which can cause widespread disruption of hormone receptors, enzymes, and nerve signals. The renewal, maintenance, and death of neurons are also highly hormone-sensitive.
The World Health Organization, the United Nations and the US National Toxicology Program are just a few of the leading agencies concluding that EDCs may cause a variety of neuroendocrine dysfunction that negatively effects the brain and behavior. EDC exposures have been linked to decreased IQ, increased neurodevelopmental problems, and other neurocognitive conditions.
The danger extends to places once thought to be chemically pristine such as remote communities near the Arctic. It turns out that these areas are actually where polychlorinated biphenyls (PCBs) and other persistent pollutants are concentrating to some of the highest levels on Earth. Researchers are now seeing increasing neurological problems in residents of these communities such as impaired neurodevelopment, lower IQ, and problems with attention, memory, and fine motor skills.
Which EDCs are the culprits? PCBs, present in products from hydraulic fluids to electronic components, have the strongest associations with neurological disorders. Meanwhile, animal and cellular research indicates that DDT also modifies neuroendocrine systems. More research is being done on DDT and other EDCs. This research is sorely needed because right now we have very little information on the neurodevelopmental effects of many common EDCs.
Understanding how and when these neuroendocrine disruptions take place is of great importance because the effects can be passed on to future generations. For instance, women directly exposed to industrial contamination or dioxins gave birth to children with neurocognitive impairments.
Human neural system processes are similar to those of other species. As a result, many EDCs designed to harm pest neurological systems can also damage these systems in people.
Studies have linked pesticide exposure with depressive behaviors and neurodegenerative disorders such as Parkinson’s disease. Other studies have suggested links between pesticides—as well as chemicals in fire retardants and foam—and ADHD, ASD, and related learning disabilities.
Chlorpyrifos, once one of the world’s most common insecticides, is an EDC. Prenatal and childhood exposure has been linked to ADHD and impaired mental and motor skills. Extensive studies in animals suggest neurotoxicity.
Researchers also have connected deficits in concentration, fine motor coordination and cognition to PBDE exposure during early development. A study of prenatal and childhood exposure in a California migrant community associated a 10-fold increase in PBDE exposure to an average IQ reduction of five points. Similar effects were seen in children exposed to lead and PCBs.
Knowing the effects of EDCs is an important first step. Here are a few resources to learn more: