Mn Exposures & ADHD

Manganese Exposures Being Associated with ADHD


JUN 2001 – University of California Irvine, Irvine, CA

Baby Teeth Measure Link between Heavy Metal & Hyperactivity

“Infants and fetuses are at particular risk from exposure to manganese. Manganese is an essential human nutrient in appropriate amounts, but toxic at higher levels”

“Because they have not yet developed the ability to metabolize it as adults do, infants exposed to manganese accumulate it in the blood, bone and soft tissue, including the brain.”

Since the 1970’s in studies led by Dr. Louis Gottschalk, UCI professor emeritus of psychiatry and human behavior, at UCI and elsewhere, high concentrations of manganese have been associated with neurological disorders such as hyperactivity in children and Parkinson’s disease in adults, as well as lowered threshold for aggression and violence and compromised respiratory and reproductive processes.”

Summary statement: “Our findings, while preliminary, demonstrate for the first time that manganese can be measured in tooth enamel. With a biological indicator, or biomarker, to determine the history of manganese exposure, we can identify critical windows of exposure and eventually a cause-and-effect relationship between manganese and neurological problems such as ADHD.”


OCT 2001 – Office of Environmental Health Hazard Assessment, State of California

Children’s Environmental Health Protection Act – Manganese and Compounds

“There is evidence from human studies and animal experiments that manganese exposure can lead to neurodevelopmental and behavioral effects. Neurotoxicity and developmental toxicity are two of the key toxicological endpoints of concern to infants and children.”

Summary statement: “Human studies show that hyperactive children and children with learning disabilities may have higher hair levels of manganese than normal children. This suggests that manganese may act as a neurodevelopmental toxicant on young children. Animal studies show that newborn animals are unable to maintain homeostasis of manganese and that as a result, manganese accumulates in the brains of animals exposed at young ages.”


NOV 2001 – University of California, Davis, CA & University of California, Irvine, CA

Effect of High Dietary Manganese Intake of Neonatal Rats on Tissue Mineral Accumulation, Striatal Dopamine Levels, and Neurodevelopmental Status

“Recent reports of high Mn levels in hair of children with neurodevelopmental deficits suggest that these deficits could be due to Mn-induced neurotoxic effects on brain dopamine systems, although the mechanism is not well understood.”

“Infants are of particular concern since they are exposed to diets with highly variable Mn content in addition to ambient environmental sources.”

“It has been suggested that high Mn intake is associated with attention deficit hyperactivity disorder (ADHD) since elevated hair Mn levels have been found in children with ADHD.”

Summary statement: “In conclusion, exposure to modest amounts of Mn during early life led to (1) increased tissue concentrations of Mn, (2) no decrease in tissue Fe, (3) a dose-response depletion of striatal dopamine, and (4) adverse effects on motor development and behavior.”


DEC 2001 – Science and Environmental Health Network, Boston, MA

Toxic Threats to Neurologic Development of Children

“More recently, the developmental neurotoxicity of manganese has emerged as a significant public health concern.”

“Available data indicate that the brain is vulnerable to long-lasting effects from developmental exposures to manganese.”

“In several small epidemiologic studies of children, manganese hair levels are associated with ADHD.”

“Compared to adults, children and immature animals absorb more and excrete less manganese. Moreover, in infants, manganese easily gains access to the developing brain because of an immature blood-brain barrier.”

“These observations raise questions about the wisdom of supplementing infant formula with manganese and the widespread use of infant soy formula containing naturally high concentrations of manganese.”

Summary statement: “Regulatory agencies have generally failed to require neurodevelopmental testing of chemicals before they are marketed. None of the voluntary testing programs proposed by the chemical industry in the United States includes neurodevelopmental testing.”


OCT 2002 – University of California Davis, Davis, CA

Effects of Neonatal Dietary Manganese Exposure on Brain Dopamine Levels and Neurocognitive Functions

“Neonatal exposure to high levels of manganese has been indirectly implicated as a causal agent in attention deficit hyperactivity disorder (ADHD), since manganese toxicity and ADHD both involve dysfunction in brain dopamine systems.”

“This study was undertaken to examine this putative relationship in an animal model by determining if levels of neonatal dietary manganese exposure were related to brain dopamine levels and/or behavioral tests of executive function when the animals reached maturity.”

Summary statement: “These results lend support to the hypothesis that neonatal manganese exposure is related to brain dopamine levels and neurocognitive deficit in the rodent.”


OCT 2006 – University of Quebec Montreal, Quebec, Canada and Harvard Medical School, Boston, MA

Hair Manganese and Hyperactive Behaviors: Pilot Study of School-Age Children Exposed through Tap Water

“Neurotoxic effects are known to occur with inhalation of manganese particulates, but very few data are available on exposure to Mn in water.”

“The present pilot study shows that children living in the houses connected to the well with higher Mn levels displayed higher concentrations of Mn in hair, pointing to tap water use as a source of Mn exposure in this community. In turn, Mn was associated with increased hyperactive and oppositional behaviors in the classroom.”

Summary statement: It is notable that all of the children with elevated scores for CTRS-R Oppositional and Hyperactivity subscales, had elevated Mn [in hair] above the normal range. The findings of this pilot study are sufficiently compelling to warrant more extensive investigations into the risks of Mn exposure in drinking water.”


MAR 2007 – Neurotoxicol Teratol, Ericson JE, Crinella FM

Prenatal Manganese Levels Linked to Childhood Behavioral Disinhibition

“Animal research suggests that exposure to high levels of manganese during infancy may deplete dopamine in areas of a child’s brain that are linked to impulsivity and ADHD.”

Summary statements:Iron deficiency in the mother during pregnancy can cause over-exposure to manganese in the infant. Also, soy infant formula may be a source of over-exposure after birth. Soy formula can contain 80 times the amount of manganese that normally occurs in breast milk.”