Hair Mn Concentrations Research Articles

Association between hair trace element and all-cause death in elderly people in Hainan

Objective: To explore the association between hair trace element and all-cause death in the elderly in Hainan Province. Methods: The subjects of the study were elderly people from China Hainan Centenarian Cohort Study, a total of 163 elderly were included. The association between hair trace element level and all-cause death was analyzed by using Cox proportional risk regression model. Results: After fully adjusting the covariates, the multiple Cox proportional hazards regression analyses showed that selenium (Se), manganese (Mn), strontium (Sr) concentrations in hair were significantly associated with all-cause mortality, the hazard ratio (HR) were 0.72 (95%CI: 0.54-0.98, P=0.035), 1.50 (95%CI: 1.07-2.11, P=0.020) and 0.54 (95%CI: 0.37-0.79, P=0.001), respectively. Subgroup and cross analysis showed that hair copper (Cu) were significant association with death in the people with anemia, the HR were 1.81 (95%CI: 1.13-2.88, P=0.013). And, hair Mn interacted with anemia, the HR was 0.46 (95%CI: 0.22-0.94, P=0.033). Conclusions: Se, Mn and Sr concentrations in hair were associated with the elevated risk for all-cause death in the elderly in Hainan. Se, Mn and Sr concentrations in hair can be used as a reference index for the prediction of the death risk of long-lived elderly in community, suggesting that the daily diet of elderly people are rich and diverse, in order to maintain normal and balanced trace element content in the body.

Ionomics-metabolome association analysis as a new approach to the impact of dietary copper levels in suckling piglets model

Ionomics-metabolomics association analysis is a novel method to elucidating the potential mechanisms underlying the effects of dietary copper on the overall health parameters of suckling piglets model. Few studies have elucidated the relationship between the changes of ionic and metabolic homeostasis responses to dietary copper level. The growth performance data was obtained from 180 suckling piglets which access to different copper levels: 6 (low copper diet, LC), 20 (control diet, CON), and 300 (high copper diet, HC) mg·kg−1 copper (based on diet, supplementation from CuSO4), and offered ad libitum from d 14 until weaning at 40 d of age. Dietary high level copper (300 mg·kg−1) increased the ADG and ADFI during d 14 to 28 of piglets. Six elements (Mg, Na, K, P, Cu, and Mn) concentrations significantly changes in hair among the three treatment diets. The significant increased concentrations of Na and K, and decreased concentration of Mg and Mn in 300 mg·kg−1 than 20 mg·kg−1 copper diet was observed. In current study, with the increase in copper level from 20 to 300 mg·kg−1 in diet, the correlation between hair Na, K and Cu, Mn, Zn vanish. Hair Na and K were positively correlated with serum total antioxidant capacity (T-AOC) and negatively correlated with tumor necrosis factor-α (TNF-α). The hair Cu was negatively correlated with serum malondialdehyde (MDA), total bile acid (TBA). The fecal Cu was positively correlated with serum growth hormone (GH). The results suggested that the average daily gain (ADG) in 6 mg·kg−1 copper diet and the average daily feed intake (ADFI) in 20 mg·kg−1 copper diet were decreased than 300 mg·kg−1 copper diet during d 14 to 28 and the ADG was decreased in 6 and 20 mg·kg−1 copper diets in d 29 to 40 of piglets. Dietary 20 mg·kg−1 copper maintain ion homeostasis due to increase the number of positive correlations between macroelements-microelements in hair and serum. Significantly changed Na, K, Mg, Mn and Cu concentrations in hair can reflect the adverse effects of dietary 300 mg·kg−1 copper of suckling piglets. We believe our results may benefit people to gain a better understanding of the ion interactions and metabolic homeostasis of heavy metal elements that are critical to human and animal health.

Manganese exposure and working memory-related brain activity in smallholder farmworkers in Costa Rica: Results from a pilot study

Main sources of manganese (Mn) in the general population are diet and drinking water. Mn is also found in ethylene bisdithiocarbamate (EBDC) fungicides used in agriculture or emitted into the air by ferromanganese plants and welding fumes, which can be additional environmental and occupational sources of exposure. High occupational Mn exposure has been linked with motor, behavioral, and cognitive impairment, but its effects on neural function remain poorly understood. We conducted a functional neuroimaging study in a sample of 48 farmworkers in Zarcero County, Costa Rica, an agricultural region where EBDC fungicides are sprayed. We measured Mn concentrations in farmworkers’ toenails (n = 40 farmworkers) and hair (n = 33 farmworkers), and recorded brain activity in the dorsolateral prefrontal cortex during a letter-retrieval working memory task using functional near-infrared spectroscopy (fNIRS). We estimated exposure-outcome associations using multivariable linear regression models adjusted for age and education level. Geometric mean (geometric standard deviation) toenail and hair Mn concentrations were 0.40 μg/g (3.52) and 0.24 μg/g (3.54), respectively. We did not find strong evidence that Mn concentrations were associated with working memory-related brain activity in this sample of farmworkers; we also found null associations between working memory task accuracy and brain activity. However, our small sample size may have limited our ability to detect small effect sizes with statistical precision. Our study demonstrates that fNIRS can be a useful and feasible tool in environmental epidemiology for examining the effects of toxicants, like Mn, on neural function. This may prove to be important for elucidating neuropathological pathways that underlie previously reported associations of elevated Mn exposure with neurotoxic effects.

Butyrylcholinesterase-a potential plasma biomarker in manganese-induced neurobehavioral changes.

Groundwater particularly drinking water contamination with metals has created an environmental disaster in Bangladesh. Manganese (Mn), an essential trace element, plays a key role in the development and function of the brain. Excess Mn exposure is reported to be associated with complex neurological disorders. Here, we have found a notably large extent of Mn above the permissive limit in the tube-well water of Rajshahi and Naogaon districts in Bangladesh. Higher levels of Mn in hair and nail samples, and a decreasing level of butyrylcholinesterase (BChE) activity were detected in plasma samples of the human subjects recruited from Naogaon district. Mn concentrations in water, hair, and nails were negatively correlated with the plasma BChE levels in Mn-exposed populations. To compare and validate these human studies, an animal model was used to determine the in vivo effects of Mn on neurobehavioral changes and blood BChE levels. In elevated plus maze, the time spent was significantly reduced in open arms and increased in closed arms of Mn-exposed mice compared to control group. The mean latency time to find the platform was declined significantly in control mice compared to Mn-treated group during 7days in Morris water maze test, and Mn-exposed group also spent significantly less time in the desired quadrant as compared to the control group in probe trial. BChE activity was significantly reduced in Mn-exposed mice compared to control mice. Taken together, these results suggest that plasma BChE levels may serve as reliable biomarker of Mn-induced neurotoxicity related to behavioral changes.

Pediatric Manganese Exposure and Neurocognition in Eastern Ohio

Manganese (Mn) is both an essential element and neurotoxicant. Two communities in eastern Ohio have the two of the highest ambient Mn concentrations in the nation. Our goal is to address the communities' primary research question: “Does Mn affect cognitive development of children?” Children ages 7-9 were enrolled in the Communities Actively Researching Exposure Study (CARES) from Marietta, Cambridge, and East Liverpool, Ohio. CARES has been conducted using community-based participatory research principles. We conducted neurocognitive assessment (child IQ). Blood was analyzed for Mn and lead (Pb); hair were analyzed for Mn, and serum was analyzed for cotinine, a measure of second hand tobacco smoke. We used penalized splines to assess potential non-linear associations between biological measures and child IQ scores, followed by multivariable regression models with categorical variables based on quartiles of the distribution for biological measures. Both low and high Mn concentrations in blood and hair were negatively associated with child IQ scores. There was a negative association between hair Mn and child IQ in East Liverpool children. Serum cotinine was also negatively associated with child cognitive function. Community engagement has enhanced the research process and the translation of study findings for these communities.

Prenatal Manganese and Behavioral Problems in 5-Year Old Children from the Infants' Environmental Health (ISA) Study

Background: Results from cross-sectional studies have shown excess manganese (Mn) may adversely affect children's neurodevelopment. However, data from prospective studies are limited. We examined whether prenatal manganese was associated with behavioral problems in children from the 'Infants' Environmental Health (ISA)' birth cohort study in Costa Rica, who live near banana plantations aerially sprayed with mancozeb, a Mn-containing fungicide.Methods: We interviewed mothers from 5-year old children (mean 5.7 ± 0.4 years) (n=292) about children’s behavior during the last two months using the Child Behavior Checklist (CBCL). We measured Mn concentrations in maternal blood (MnB) and hair (MnH) samples collected 1-2 times during pregnancy, and calculated mean MnB and mean MnH concentrations. We analyzed internal consistency of CBCL and only analyzed scales with Cronbach-alfa >0.7. We examined linear and nonlinear relationships for log10-MnH and MnB concentrations and CBCL scales (Internalizing, Externalizing, Aggressive, Withdrawn) in separate models. We adjusted models for children's age at assessment, parity, HOME score, maternal education and maternal depression. We also revised effect modification by child sex.Results: Median (P25-P75) mean MnB and mean MnH during pregnancy were 24.0 μg/L (20.3-28.3) and 1.6 μg/g (0.8-3.3), respectively. Higher MnB concentrations were associated with more internalizing problems for girls (β=0.21 95%CI: -0.02, 0.43) but not for boys (β=-0.02 95%CI: -0.25, 0.21). MnB was not associated with other CBCL scales. We observed null associations for log10-MnH, and did not find evidence for non-linear relationships for MnB or MnH.Conclusions: Further studies, which include maternal and cord blood concentrations, as well as other essential elements, such as iron, are needed to understand whether maternal excess Mn during pregnancy contributes to behavioral problems in young children. Effects of excess Mn may be different for boys and girls.

Prenatal Mancozeb Exposure, Excess Manganese, and Neurodevelopment at 1 Year of Age in the Infants' Environmental Health (ISA) Study.

Background:Although growing evidence suggests that early-life excess manganese (Mn) impairs neurodevelopment, data on the neurodevelopmental effects of mancozeb, a fungicide containing Mn, and its main metabolite ethylenethiourea (ETU) are limited.Objective:We examined whether prenatal mancozeb exposure and excess Mn were associated with neurodevelopment in 355 1-y-old infants living near banana plantations with frequent aerial mancozeb spraying in Costa Rica.Methods:We measured urinary ETU, hair Mn, and blood Mn concentrations in samples collected 1–3 times during pregnancy from mothers enrolled in the Infants’ Environmental Health (ISA) study. We then assessed neurodevelopment in their 1-y-old infants using the Bayley Scales of Infant and Toddler Development, 3rd edition (BSID-III). We estimated exposure–outcome associations using linear regression models adjusted for maternal education, parity, gestational age at birth, child age, Home Observation for Measurement of the Environment score, and location of neurodevelopmental assessment.Results:Median (P25–P75) urinary ETU, hair Mn, and blood Mn measured during pregnancy were (2.4–4.9; specific gravity–corrected), (0.9–4.1), and (20.3–28.0), respectively. Among girls, higher ETU was associated with lower social-emotional scores [ (95% CI: , 0.4)], whereas higher hair Mn was associated with lower cognitive scores [ (, 0.1)]. Among boys, higher hair Mn was associated with lower social-emotional scores [ (, )]. We observed null associations for blood Mn, language, and motor outcomes.Conclusions:Our findings indicate that maternal exposure to mancozeb and excess Mn during pregnancy may have adverse and sex-specific effects on infant neurodevelopment. https://doi.org/10.1289/EHP1955

Environmental manganese exposure and associations with memory, executive functions, and hyperactivity in Brazilian children

Manganese (Mn) is an essential element, however high levels of Mn have been associated with lower neuropsychological performance and behavioral problems in children. We investigated the associations between hair Mn concentrations and neuropsychological and behavioral performances among children with long-term exposure to airborne Mn aged between 7 and 12 years. Neuropsychological performance included tests of: verbal memory, inhibitory control, cognitive flexibility, verbal fluency, and motor function. We used the Conners Abbreviated Rating Scale for teachers to assess students’ behaviors of hyperactivity. Hair manganese (MnH) concentrations in children and exposure to airborne manganese from a ferro-manganese alloy plant were analyzed and correlated with tests scores. Multivariable linear models adjusting for potential confounders showed that elevated levels of MnH were associated with lower performance in verbal memory, as measured by the free recall after interference (β = – 1.8; 95% CI: – 3.4, – 0.2), which indicates susceptibility to interference, and Delayed Effect (β = –2.0; 95% CI: –3.7, – 0.2), representing a loss of information over time. Additionally, we found patterns of effect modification by sex in three subtests measuring verbal memory: the free recall after interference score, Interference Effect, and Delayed Effect (all at p < 0.10). Overall, the results suggest that long-term airborne Mn exposure may be associated with lower performance in verbal memory, and hyperactivity behaviors.

Impact of air manganese on child neurodevelopment in East Liverpool, Ohio

BackgroundEast Liverpool, Ohio, the site of a hazardous waste incinerator and a manganese (Mn) processor, has had air Mn concentrations exceeding United States Environmental Protection Agency reference levels for over a decade. Save Our County, Inc., a community organization, was formed to address community environmental health concerns related to local industry. Researchers from the University of Cincinnati partnered with Save Our County to determine if air Mn had an impact on the neurocognitive function of children in the community. MethodsChildren 7–9 years of age from East Liverpool and its surrounding communities, were enrolled (N=106) in the Communities Actively Researching Exposure Study from between March 2013–June 2014. Blood and hair were analyzed for Mn and lead, and serum was analyzed for cotinine. We used linear regression to assess associations between biological measures and IQ subscale scores. ResultsGeometric mean blood lead (n=67), blood Mn (n=66), hair Mn (n=98), and serum cotinine (n=69) concentrations were 1.13±1.96μg/dL, 10.06±1.30μg/L, and 360.22±2.17ng/g, 0.76±6.12μg/L respectively. After adjusting for potential confounders, hair Mn was negatively associated with Full Scale IQ. ConclusionsHair Mn was negatively associated with child IQ scores. Community partners were instrumental in the conception and implementation of this study.

Assessment of saliva, hair and toenails as biomarkers of low level exposure to manganese from drinking water in children

We evaluated hair, toenails, and saliva (whole and supernatant) as biomarkers of exposure to manganese (Mn) in 274 school age children (6–13 years) consuming well water in southeastern New Brunswick, Canada. Mn concentrations in tap water ranged from <0.03 to 1046μgL−1 (geometric mean 5.96μgL−1). The geometric mean of Mn intake resulting from the consumption of water was 0.25 (0–34.95) μg kg−1day−1. Both Mn concentration in water and Mn intake were significantly correlated with Mn in hair (r=0.60 and r=0.53, respectively), Mn in toenail (r=0.29 and r=0.37 respectively) and to a lesser extent with Mn in saliva supernatant (r=0.14 and r=0.18, respectively). Mn in whole saliva did not correlate with Mn in water or Mn intake. Both Mn in hair and Mn in toenail allowed to discriminate the most exposed group from the least exposed group, based on Mn in water and Mn intake from water. In this group of children with low level Mn exposure, Mn concentrations in hair, and toenails reflected reasonably well Mn exposure from drinking water, whereas Mn content in saliva correlated less strongly.

Manganese Exposure and Neurocognitive Outcomes in Rural School-Age Children: The Communities Actively Researching Exposure Study (Ohio, USA).

BackgroundManganese (Mn) plays a vital role in brain growth and development, yet excessive exposure can result in neurotoxicity. Marietta, Ohio, is home to the nation’s longest-operating ferromanganese refinery, and community concern about exposure led to the development of the research study.ObjectivesOur overall goal was to address the community’s primary research question: “Does Mn affect cognitive development of children?” We evaluated the relationships between Mn exposure as measured by blood and hair Mn, along with other neurotoxicants including blood lead (Pb) and serum cotinine, and child cognition.MethodsChildren 7–9 years of age were enrolled (n = 404) in the Communities Actively Researching Exposure Study (CARES) from Marietta and Cambridge, Ohio, and their surrounding communities from October 2008 through March 2013. Blood and hair were analyzed for Mn and Pb, and serum was analyzed for cotinine. We used penalized splines to assess potential nonlinear associations between biological measures and IQ subscale scores, followed by multivariable regression models with categorical variables based on quartiles of the distribution for biological measures with nonlinear associations and continuous variables for biological measures with linear associations.ResultsGeometric mean blood (n = 327) and hair Mn (n = 370) concentrations were 9.67 ± 1.27 μg/L and 416.51 ± 2.44 ng/g, respectively. After adjusting for potential confounders, both low and high blood and hair Mn concentrations were associated with lower Full Scale IQ and subscale scores, with significant negative associations between the highest quartile and middle two quartiles of blood Mn (β –3.51; 95% CI: –6.64, –0.38) and hair Mn (β –3.66; 95% CI: –6.9, –0.43%) and Full Scale IQ.ConclusionsBoth low and high Mn concentrations in blood and hair were negatively associated with child IQ scores. Serum cotinine was negatively associated with child cognitive function.CitationHaynes EN, Sucharew H, Kuhnell P, Alden J, Barnas M, Wright RO, Parsons PJ, Aldous KM, Praamsma ML, Beidler C, Dietrich KN. 2015. Manganese exposure and neurocognitive outcomes in rural school-age children: the Communities Actively Researching Exposure Study (Ohio, USA). Environ Health Perspect 123:1066–1071; http://dx.doi.org/10.1289/ehp.1408993

Maternal blood and hair manganese concentrations, fetal growth, and length of gestation in the ISA cohort in Costa Rica

BackgroundAnimal studies have shown that both deficiency and excess manganese (Mn) may result in decreased fetal size and weight, but human studies have reported inconsistent results. MethodsWe examined the association of blood and hair Mn concentrations measured at different times during pregnancy with fetal growth among term births and length of gestation in a cohort of 380 mother–infant pairs living near banana plantations aerially sprayed with Mn-containing fungicides in Costa Rica. We used linear regression and generalized additive models to test for linear and nonlinear associations ResultsMean (± SD) blood Mn concentration was 24.4±6.6μg/L and geometric mean (geometric SD) hair Mn concentration was 1.8 (3.2) μg/g. Hair Mn concentrations during the second and third trimesters of gestation were positively related to infant chest circumference (β for 10-fold increase=0.62cm; 95% CI: 0.16, 1.08; and β=0.55cm; 95% CI: −0.16, 1.26, respectively). Similarly, average maternal hair Mn concentrations during pregnancy were associated with increased chest circumference (β for 10-fold increase=1.19cm; 95% CI: 0.43, 1.95) in infants whose mothers did not have gestational anemia, but not in infants of mothers who had gestational anemia (β=0.39cm; 95% CI: −0.32, 1.10; pINT=0.14). All these associations were linear. Blood Mn concentrations did not show consistent linear nor nonlinear relationships with any of the birth outcomes ConclusionsMn plays an important role in fetal development, but the extent to which environmental exposures may cause adverse health effects to the developing fetus is not well understood. Among women living near banana plantations in Costa Rica, we did not observe linear or nonlinear associations of Mn concentrations with lowered birth weight or head circumference, as reported in previous studies. However, we did find positive linear associations between maternal hair Mn concentrations during pregnancy and infant chest circumference.

Blood and Hair Manganese Concentrations in Pregnant Women from the Infants’ Environmental Health Study (ISA) in Costa Rica

Manganese (Mn), an essential nutrient, is a neurotoxicant at high concentrations. We measured Mn concentrations in repeated blood and hair samples collected from 449 pregnant women living near banana plantations with extensive aerial spraying of Mn-containing fungicide mancozeb in Costa Rica, and examined environmental and lifestyle factors associated with these biomarkers. Mean blood Mn and geometric mean hair Mn concentrations were 24.4 μg/L (8.9–56.3) and 1.8 μg/g (0.05–53.3), respectively. Blood Mn concentrations were positively associated with gestational age at sampling (β = 0.2; 95% CI: 0.1 to 0.2), number of household members (β = 0.4; 95% CI: 0.1 to 0.6), and living in a house made of permeable and difficult-to-clean materials (β = 2.6; 95% CI: 1.3 to 4.0); and inversely related to smoking (β = −3.1; 95% CI: −5.8 to −0.3). Hair Mn concentrations were inversely associated with gestational age at sampling (% change = 0.8; 95% CI: −1.6 to 0.0); and positively associated with living within 50 m of a plantation (% change = 42.1; 95% CI: 14.2 to 76.9) and Mn concentrations in drinking water (% change = 17.5; 95% CI: 12.2 to 22.8). Our findings suggest that pregnant women living near banana plantations aerially sprayed with mancozeb may be environmentally exposed to Mn.

Associations Between Hair Manganese Levels and Cognitive, Language, and Motor Development in Preschool Children from Montevideo, Uruguay

ABSTRACT Environmental manganese (Mn) exposure in childhood has been associated with developmental deficits. This study investigated associations between low-level Mn exposure and developmental scores in children aged 14–45 months. Children's hair samples (n = 60) were analyzed for Mn and lead (Pb) using inductively coupled plasma mass spectrometry (ICP-MS). Children were assessed with the Bayley Scales of Infant Development III (BSID). Mean hair Mn and Pb concentrations were 0.98 ± 0.74 and 10.1 ± 10.5 μg/g, respectively. Unadjusted inverse associations were seen between Mn and BSID subscales, with girls having lower scores related to Mn than boys. No significant associations remained in covariate-adjusted models, although when stratified by sex boys had a positive association between hair Mn levels and language scores. This study does not show clear evidence of an association between hair Mn concentrations and children's developmental scores in a region of low-level Mn exposure.

Elevated manganese and cognitive performance in school-aged children and their mothers

Background Growing evidence suggests that excess manganese (Mn) in children is associated with neurobehavioral impairments. In Brazil, elevated hair Mn concentrations were reported in children living near a ferro-manganese alloy plant. Objectives We investigated these children’s and caregivers’ cognitive function in relation to bioindicators of Mn exposure. Methods In this cross-sectional study, the WISC-III was administered to 83 children aged between 6 and 12 years; the Raven Progressive Matrix was administered to the primary caregivers (94% mothers), who likewise responded to a questionnaire on socio demographics and birth history. Mn in hair (MnH) and blood (MnB) and blood lead (PbB) were measured by graphite furnace atomic absorption spectrometry (GFAAS). Results Children’s mean MnB and MnH were 8.2 μg/L (2.7–23.4) and 5.83 μg/g (0.1–86.68), respectively. Mean maternal MnH was 3.50 μg/g (0.10–77.45) and correlated to children’s MnH (rho=0.294, p=0.010). Children’s MnH was negatively related to Full-Scale Intelligence Quotient (IQ) and Verbal IQ; β coefficients for MnH were −5.78 (95% CI −10.71 to −0.21) and −6.72 (−11.81 to −0.63), adjusted for maternal education and nutritional status. Maternal MnH was negatively associated with performance on the Raven’s ( β=−2.69, 95% CI −5.43 to 0.05), adjusted for education years, family income and age. Conclusions These findings confirm that high MnH in children is associated with poorer cognitive performance, especially in the verbal domain. Primary caregiver’s IQ is likewise associated to Mn exposure, suggesting that, in this situation, children’s cognition may be affected directly and indirectly by Mn exposure.

Manganese exposure among smelting workers: blood manganese–iron ratio as a novel tool for manganese exposure assessment

Unexposed control subjects (n = 106), power distributing and office workers (n = 122), and manganese (Mn)-exposed ferroalloy smelter workers (n = 95) were recruited to the control, low and high groups, respectively. Mn concentrations in saliva, plasma, erythrocytes, urine and hair were significantly higher in both exposure groups than in the controls. The Fe concentration in plasma and erythrocytes, however, was significantly lower in Mn-exposed workers than in controls. The airborne Mn levels were significantly associated with Mn/Fe ratio (MIR) of erythrocytes (eMIR) (r = 0.77, p < 0.01) and plasma (pMIR) (r = 0.70, p < 0.01). The results suggest that the MIR may serve as a useful biomarker to distinguish Mn-exposed workers from the unexposed, control population.

A longitudinal follow-up of pulmonary function and respiratory symptoms in workers exposed to manganese.

The purpose of the investigation was to study the effects on the respiratory system in mine workers with long-term exposure to manganese (Mn) in the workplace. The study included a follow-up of pulmonary function and respiratory symptoms among 145 workers employed in a large Mn mine and 65 matched controls, and the assessment of Mn concentrations in environment and biological samples. Lung function was measured by recording spirometric parameters. The Mn-exposed workers reported more respiratory symptoms and a significantly higher prevalence of all grades of pulmonary function impairment. All predicted symptoms except for asthma increased significantly in the current smoking group compared with the non-smoking group. There was a significant decrease in FEV1, FVC, and FEV1% values in exposed workers compared with controls at stages 2 and 3, with an additive effect of the smoking habit. The Mn concentrations in blood, urine, and hair were significantly higher in the exposed workers than in the controls. The level of cumulative exposure index of workplace Mn was notable and did not change significantly over this study. The respiratory effects found in Mn-exposed workers were probably caused by the Mn in the workplace and the synergistic effect of smoking. These effects indicate a need for respiratory protection and improvements in the work environment.

Environmental and occupational exposure to manganese: a multimedia assessment

Methylcyclopentadienyl manganese tricarbonyl (MMT) is an organic additive used in Canada since 1976 as an anti-knock agent in unleaded gasoline. Its combustion leads to the emission of Mn oxides, especially Mn3O4. Since no study has assessed the potential risk of chronic exposure to low concentrations resulting from these emissions, the present investigation was undertaken to assess the level of environmental and occupational exposure of the human population. The multimedia exposure of two groups of workers (garage mechanics and blue-collar workers) potentially exposed to different levels of Mn from the combustion of MMT was assessed using personal air samplers, a dietary compilation, water samples at their places of residence, an epidemiological questionnaire and blood and hair samples. Results show that garage mechanics were exposed on average to higher atmospheric Mn at work (0.42 microgram/m3) than the blue-collar workers (0.04 microgram/m3). However, the contribution of atmospheric Mn to the total absorbed dose was less than 1%, and well below the standards established for occupational or environmental exposure; food contributes more than 95% of the multimedia dose. The average whole blood Mn concentrations were similar for the two groups (0.67-0.76 microgram/100 ml) and fall within the normal adult range. The average hair Mn concentrations were significantly higher for the garage mechanics (0.66 microgram/g) than for the blue-collar workers (0.39 microgram/g). The contribution of exogenous Mn versus endogenous Mn is questioned. As judged by the governmental standards or criteria for occupational and non-occupational environments, the current Mn levels in food, water and air may not cause any problems for the workers.

Possible health effects of high manganese concentration in drinking water.

Three areas in the same region of northwest Peloponnesos, Greece, that had varying concentrations of manganese (Mn) in drinking water were selected for study. The Mn concentrations in areas A, B, and C were 3.6-14.6 micrograms/l, 81.6-252.6 micrograms/l, and 1 800-2 300 micrograms/l, respectively. A random sample (62 in area A, 49 in area B, and 77 in area C) of males and females who were at least 50 y of age were submitted to a thorough neurological examination and their whole-blood Mn and hair Mn concentrations were determined. Although all areas were similar with respect to social and dietary characteristics, significant differences were observed for prevalence of chronic manganese poisoning (CMnP) symptoms and hair Mn concentration. The means (both sexes) of neurological scores were 2.7, 3.9, and 5.2, respectively, for areas A, B, and C (Kruskal-Wallis, chi 2 = 6.44, 2 df, p less than .05 for males; chi 2 = 7.8, 2 df, p less than .05 for females). Hair Mn concentrations were also significantly different, the means for which were 3.51, 4.49, and 10.99 micrograms/g dry weight, respectively (both sexes [p less than .001 for each sex separately]). These results indicate that progressive increases of Mn concentration in drinking water are associated with progressively higher prevalences of neurological signs of CMnP and Mn concentration in hair of older persons.

Hair manganese concentrations in newborns and their mothers

The study was designed to investigate the manganese (Mn) status of mothers and their offspring at delivery. Hair Mn concentrations in 31 full-term, 18 preterm and 12 newborn infants with congenital malformations and their mothers were determined by the flameless atomic absorption technique. Both in infants with congenital malformations and their mothers, hair Mn levels were significantly lower than the full-term and preterm infant-mother pairs. With the exception of mothers of infants with congenital malformations, hair Mn concentrations in mothers were significantly higher as compared with their infants. Low hair Mn concentrations of infants with congenital malformations and their mothers may possibly reflect a state of Mn deficiency in these women. These results imply that 1) Mn deficiency may play a role as one potential factor in intrauterine malformations, 2) Mn is supplied to the fetus by a homeostatic mechanism which is mainly dependent on the Mn status of the mother, 3) prenatal Mn analysis in maternal hair may prove to be a reliable indicator for the risk of intrauterine malformations.