Early Postnatal Blood Manganese Levels and Children's Neurodevelopment

Abstract

Background Recent evidence suggests that low-level environmental exposure to manganese adversely affects child growth and neurodevelopment. Previous studies have addressed the effects of prenatal exposure, but little is known about developmental effects of early postnatal exposure. Methods We studied 448 children born in Mexico City from 1997 through 2000, using a longitudinal study to investigate neurotoxic effects of early life manganese exposure. Archived blood samples, collected from children at 12 and 24 months of age, were analyzed for manganese levels using inductively-coupled plasma mass spectrometry. Mental and psychomotor development were scored using Bayley Scales of Infant Development at 6-month intervals between 12 and 36 months of age. Results At 12 months of age, the mean (SD) blood manganese level was 24.3 (4.5) μg/l and the median was 23.7 μg/l; at 24 months, these values were 21.1 (6.2) μg/l and 20.3 μg/l, respectively. Twelve- and 24-month manganese concentrations were correlated (Spearman correlation = 0.55) and levels declined over time (β = −5.7 [95% CI = −6.2 to −5.1]). We observed an inverted U-shaped association between 12-month blood manganese and concurrent mental development scores (compared with the middle 3 manganese quintiles, for the lowest manganese quintile, β = −3.3 [−6.0 to −0.7] and for the highest manganese quintile, β = −2.8 [−5.5 to −0.2]). This 12-month manganese effect was apparent but diminished with mental development scores at later ages. The 24-month manganese levels were not associated with neurodevelopment. Conclusions These results suggest a possible biphasic dose-response relationship between early-life manganese exposure at lower exposure levels and infant neurodevelopment. The data are consistent with manganese as both an essential nutrient and a toxicant.

Scientific Opinion on Dietary Reference Values for manganese

“…Two studies were retrieved which investigated the relationship of manganese intake or whole blood concentrations with neurological and psychological functions (Finley et al, 2003;Henn et al, 2010). One small cross-over study in healthy young women, which used diets containing low or high amounts of manganese combined with two sources of fat (corn oil or cocoa butter) for eight weeks, reported a lack of response of neurological and psychological variables to changes in manganese intakes (Finley et al, 2003).…”

“…The relationship between manganese whole blood/serum concentrations, manganese concentration in toenails or hair and health outcomes has been examined in observational studies, where associations might be confounded by the effect of dietary, lifestyle, environmental or other factors on the outcomes investigated (Takser et al, 2004;Vigeh et al, 2008;Zota et al, 2009;Henn et al, 2010;Mordukhovich et al, 2012). The Panel notes that in none of these studies was manganese intake estimated, and that manganese blood/serum concentrations and manganese content of toenails or hair are not reliable and validated markers of manganese intake or status.…”

Is there a link between autism and glyphosate-formulated herbicides?

“…While excess manganese in the body is known to be toxic, a deficiency of manganese has been found to produce maldevelopment and mal-functioning of nerves and muscles [70,71]. Multiple studies have linked autism to manganese deficiency.…”

The Role of Heavy Metal Pollution in Neurobehavioral Disorders: a Focus on Autism

“…Though Mn cannot be considered an environmental pollutant, numerous evidence suggests the potential association between Mn exposure and intellectual impairment in school-aged children, who showed Prenatal cadmium exposure IQ deficits (4.5 years of age) Tian et al (2009) IQ deficits (5 years of age) Kippler et al (2012a) Postnatal cadmium exposure No significant effects on neurodevelopmental scores (2, 5, and 7 years of age) Cao et al (2009) Learning impairment (6-15 years of age) Ciesielski et al (2012);Yousef et al (2011) Social problems and attention deficits (7-16 years of age) Bao et al (2009) deficits in IQ and verbal domain (Bouchard et al 2007: Claus Henn et al 2010Bouchard et al 2011;Menezes-Filho et al 2011). Manganese exposure is further associated with an increased risk of behavioral disorders, including ADHD (Farias et al 2010;Yousef et al 2011).…”