Search

Objectives: To determine the association between blood metal mixture and HUA risk., Methods: A cross-sectional study was performed based on the populations from Kailuan cohort trial in China. Inductively coupled plasma mass spectrometry was utilized to detect the blood concentrations of iron (Fe), lead (Pb), calcium (Ca), copper (Cu), magnesium (Mg), zinc (Zn), selenium (Se), and manganese (Mn). Multivariate logistic regression (MLR) models and weighted quantile sum (WQS) regression models were employed to assess the relationships., Results: There were 3706 participants included in this study, and 464 (12.52%) were with HUA. The mean level of uric acid was 485.60 μmol/L in the subjects with HUA, which was remarkably increased compared to those without HUA (293.10 μmol/L). The multivariate-adjusted odds ratios (95% confidence intervals) of HUA were 2.15 (1.40, 3.29) for Pb, 3.42 (2.24, 5.23) for Fe, 1.61 (1.15, 2.25) for Ca, 3.06 (2.04, 4.59) for Mg, and 1.69 (1.26, 2.28) for Zn by comparing the highest and lowest metal quartiles using the single-metal logistic regression model. Meanwhile, the WQS regression models demonstrated a positive association between metal mixtures and HUA risk, to which, Fe, Mg, Pb, and Zn were the major contributors. Pb, Fe, and Zn were still robust in multiple-metal models. Age, gender, weight, smoking, and drinking status could modify these relationships with significant interactions., Conclusions: Co-exposure to Fe, Pb, Ca, Cu, Zn, Mg, Se, and Mn were related to increased HUA risk in Chinese adults, of with, Pb, Fe, and Zn appeared to have greater impacts. These relationships were more obvious in adults aged < 60 years, or women, or overweight, or non-smoking, or drinking with significant interactions. Key Points • Increased Fe, Pb, Mg, Ca, and Zn were related to increased HUA risk in dose-response fashion among Chinese adults. • The metal mixture dominated by Fe, Mg, Pb, and Zn was positively associated with HUA risk. Fe, Pb, and Zn were still robust in MM model. • Such association was stronger showed in adults aged < 60 years, or women, or overweight, or non-smoking, or drinking with significant interactions., Competing Interests: Declarations. Ethical approval and consent to participate: This study was approved by the Ethics Committee of the Kailuan Medical Group and the Chinese Academy of Medical Sciences (Approval No. 2018ZX10715005). All participants were signed informed consent. Consent for publication: All the authors have read and approved the final manuscript. Competing interests: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to International League of Associations for Rheumatology (ILAR).)

Objective: To compare the mineral levels in umbilical vein and artery serum and to analyze the relationship between newborn birth weight and the mineral levels in umbilical vein and artery serum by measuring the mineral levels in umbilical vein and artery serum., Methods: A cross-sectional study was conducted to recruit 101 pairs of maternal and newborn who were hospitalized in Danyang People&apos;s Hospital, Jiangsu Province from June to September 2021 as the participants. After delivery, umbilical vein and artery blood were collected, and the levels of manganese(Mn), iron(Fe), cobalt(Co), copper(Cu), zinc(Zn), selenium(Se), magnesium(Mg) and calcium(Ca) in umbilical vein and artery serum were detected by inductively coupled plasma mass spectrum(ICP-MS). The serum mineral levels of umbilical artery and vein were compared by matching method, and logistic regression analysis was used to explore the relationship between birth weight and mineral levels in umbilical artery and vein serum., Results: The levels of Se, Mg and Ca in umbilical vein were higher than those in umbilical artery, but the levels of Mn and Fe were lower(P&lt;0.05). After adjusting serum albumin, the level of Ca in umbilical vein was higher than that in umbilical artery and the levels of Mn, Fe and Zn were lower(P&lt;0.05). Compared among different birth weight groups, the levels of Zn and Ca in umbilical vein serum in the small for gestational age(SGA) group were lower than those in the appropriate for gestational age(AGA) group and the larger for gestational age(LGA) group(P&lt;0.05), and the level of Cu in umbilical artery serum was higher in the LGA group(P=0.059). The result of multivariate analysis showed that compared with the AGA group, high levels of Mn in umbilical artery serum were negatively correlated with LGA(OR=0.15, P=0.040), while other minerals were not statistically correlated with birth weight., Conclusion: There are differences in mineral content between umbilical vein and umbilical artery. Mineral levels in umbilical arterial/venous serum were correlated with birth weight.

Manganese (Mn) is an essential element. However, Mn overexposure is associated with motor dysfunction. This cross-sectional study assessed the association between bone Mn (BnMn) and whole blood Mn (BMn) with motor function in 59 Chinese workers. BnMn and BMn were measured using a transportable in vivo neutron activation analysis system and inductively coupled plasma mass spectrometry, respectively. Motor function (manual coordination, postural sway, postural hand tremor, and fine motor function) was assessed using the Coordination Ability Test System (CATSYS) and the Purdue Pegboard. Relationships between Mn biomarkers and motor test scores were analyzed with linear regression models adjusted for age, education, current employment, and current alcohol consumption. BMn was significantly inversely associated with hand tremor intensity (dominant hand (β=-0.04, 95 % confidence interval (CI):-0.07, -0.01; non-dominant hand β=-0.05, 95 % CI:-0.08, -0.01) hand tremor center frequency (non-dominant hand β=-1.61, 95 % CI:-3.03, -0.19) and positively associated with the Purdue Pegboard Assembly Score (β = 4.58, 95 % CI:1.08, 8.07). BnMn was significantly inversely associated with finger-tapping performance (non-dominant hand β=-0.02, 95 % CI:-0.04,-0.004), mean sway (eyes closed and foam β=-0.68, 95 % CI:-1.31,-0.04), and positively associated with hand tremor center frequency (dominant hand, β = 0.40, 95 % CI:0.002, 0.80). These results suggest BMn is related to better postural hand tremor and fine motor control and BnMn is related to worse motor coordination and postural hand tremor but better (i.e., less) postural sway. The unexpected positive results might be explained by choice of biomarker or confounding by work-related motor activities. Larger, longitudinal studies in this area are recommended., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Background: Manganese (Mn) ions play a crucial role in the immune response. The immunotoxicity of Mn is rarely reported compared with the neurotoxicity of Mn., Objectives: The purpose of this study was to investigate the associations between chronic Mn exposure and immunological parameters in occupational Mn-exposed workers., Methods: A total of 538 workers were selected from the follow-up of manganese-exposed workers healthy cohort (MEWHC) in 2017. We divided the workers into the low-exposure group and the high-exposure group by the cutoff of the manganese-time weighted average (Mn-TWA) setting at 0.15 mg/m 3 . We examined serum immunological parameters by the immunoturbidimetric method and leukocyte counts and ratios in blood routine. Then we used the generalized linear model analyses and spline analyses to explore the associations between external exposure of Mn and multiple immunological parameters adjusted for variables. Based on the epidemiological analyses, we used Elisa (enzyme-linked immune sorbent assay) to detect plasma complement C3 of Mn-exposed rats., Results: In male workers, the mean value of complement C3 was 1.20 ± 0.16 g/L in the high-exposure group, which was significantly lower as compared to the low-exposure group (1.25 ± 0.18 g/L, P = 0.023). The generalize linear models' analyses showed that complement C3 value had a significantly negative association with external exposure of Mn included adjustment for variables (β = -0.04, P = 0.035). Moreover, in male rats, the high-exposure group also had a lower level of complement C3 compared with the low-exposure group (P < 0.001). None significant association was observed in immunological parameters among female workers and rats (all P > 0.05)., Conclusions: Mn exposure from inhalable dust was associated with decreased complement C3 among occupationally Mn-exposed male individuals but not in female workers, which was further confirmed by the rat model. Further research into the possible mechanism of C3 reduction is needed in the future., Competing Interests: Declaration of Competing Interest The authors declare no competing financial interests., (Copyright © 2020 Elsevier GmbH. All rights reserved.)

Occupational manganese (Mn) exposure has been associated with cognitive and olfactory dysfunction; however, few studies have incorporated cumulative biomarkers of Mn exposure such as bone Mn (BnMn). Our goal was to assess the cross-sectional association between BnMn, blood Mn (BMn), and fingernail Mn (FMn) with cognitive and olfactory function among Mn-exposed workers. A transportable in vivo neutron activation analysis (IVNAA) system was designed and utilized to assess BnMn among 60 Chinese workers. BMn and FMn were measured using inductively coupled plasma mass spectrometry. Cognitive and olfactory function was assessed using Animal and Fruit Naming tests, World Health Organization/University of California-Los Angeles Auditory Verbal Learning Test (AVLT) and the University of Pennsylvania Smell Identification Test (UPSIT). Additional data were obtained via questionnaire. Regression models adjusted for age, education, factory of employment, and smoking status (UPSIT only), were used to assess the relationship between Mn biomarkers and test scores. In adjusted models, increasing BnMn was significantly associated with decreased performance on average AVLT scores [β (95% confidence interval (CI)) = -0.65 (-1.21, -0.09)] and Animal Naming scores [β (95% CI) = -1.54 (-3.00, -0.07)]. Increasing FMn was significantly associated with reduced performance measured by the average AVLT [β (95% CI) = -0.35 (-0.70, -0.006)] and the difference in AVLT scores [β (95% CI) = -0.40 (-0.77, -0.03)]. BMn was not significantly associated with any test scores; no significant associations were observed with Fruit Naming or UPSIT tests. BnMn and FMn, but not BMn, are associated with cognitive function in Mn-exposed workers. None of the biomarkers were significantly associated with olfactory function., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Previous studies have shown that toxic metal exposure can have adverse effects on the nervous system of children, but the toxicology of metal co-exposure on neurodevelopment remains to be clarified. Brain derived neurotrophic factor (BDNF) plays an important role in nervous system development, but the possible effects of metal co-exposure on the serum BDNF concentrations of children remain unknown. A total of 561 children living in Taizhou City, China were recruited to participate in our cross-sectional multicenter survey. We measured their blood Pb, Hg, Al and Mn levels and serum BDNF concentrations as well as determined their associations in the total and within sex subgroups. The geometric means of the blood Pb, Hg, Al and Mn levels in all the participants were 67.18 μg/L, 1.01 μg/L, 52.03 μg/L and 18.26 μg/L, respectively. The serum BDNF concentration in children was 19.45 ng/mL. After adjusting for confounders, the blood Pb levels were significantly negatively associated with the serum BDNF concentrations in all the subjects and boys but not in girls. In addition, a significantly negative interaction between blood Pb and blood Hg and a positive interaction between blood Pb and blood Al on serum BDNF concentrations were also observed in boys but not in girls. Our findings highlight the toxic effects of metal co-exposure on serum BDNF levels in pre-school children and indicate that these effects might differ by gender, which suggest that special attention should be paid to the sex-specific effects of metal exposure., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The purpose of this study was to investigate the associations between levels of lead (Pb), cadmium (Cd), chromium (Cr), and manganese (Mn) in the PM 2.5 and blood and physical growth, and development parameters including birth length and weight, height, weight, body mass index (BMI), head circumference, and chest circumference in preschool children from Guiyu (e-waste exposure area) and Haojiang (the reference area). A total of 470 preschool children from Guiyu and Haojiang located in southeast coast of China were recruited and required to undergo physical examination and blood tests during the study period. Birth length and weight were obtained by birth records and questionnaire. Pb and Cd in both PM 2.5 and blood were significantly higher in Guiyu than Haojiang. Remarkably, the children of Guiyu had significantly lower birth weight and length, BMI, and chest circumference when compare to their peers from the reference area (all p value < 0.05). Spearman correlation analyses showed that blood Pb was negatively correlated with height (r = -0.130, p < 0.001), weight (r = -0.169, p < 0.001), BMI (r = -0.100, p < 0.05), head circumference (r = -0.095, p < 0.05), and chest circumference (r = -0.112, p < 0.05). After adjustment for the potential confounders in further linear regression analyses, blood Pb was negatively associated with height (β = -0.066, p < 0.05), weight (β = -0.119, p < 0.001), head circumference (β = -0.123, p < 0.01), and chest circumference (β = -0.104, p < 0.05), respectively. No significant association between blood Cd, Cr, or Mn was found with any of our developmental outcomes. Taken together, lead exposure limits or delays the growth and development of preschool children.

Background: Although manganese (Mn)-induced neurotoxicity effects are well known among occupational Mn exposure, few reports have investigated the effects on endocrine systems among welders and smelters., Objective: To determine the effect of high level occupational manganese (Mn) exposure on neuropsychological parameters and hormonal status., Methods: We used a cross-sectional design with 52 welders, 48 smelters and 43 age-matched office workers from the same factory in China. We analyzed serum endocrine hormones level and airborne Mn concentrations. Erythrocyte and urine Mn levels were quantified using inductively-coupled plasma atomic emission spectroscopy., Results: The geometric mean of air Mn concentrations for the welders and smelters were 19.7 and 273.1 μg/m 3 , respectively. Mn concentrations in erythrocytes of smelters were markedly greater than those in controls and welders, but there was no difference between the erythrocytes Mn levels of Control and welders. We also found an increase of Mn levels in the urine of both welders and smelters vs. controls; Mn levels in urine of smelters were higher than in welders. Self-reported neurobehavioral symptoms were higher in welders and smelters than in controls. Finally, thyroid-stimulating hormone (TSH) levels of welders were significantly lower than in controls, whereas smelters had lower prolactin (PRL), testosterone (TST) and follicle-stimulating hormone (FSH) concentrations than either controls or welders., Conclusions: These results show that smelters have higher Mn exposure than do welders, and that Mn levels in erythrocytes or urine can be a marker for exposure. Moreover, high level occupational Mn exposure increases adverse neurobehavioral effects, and also may disrupt endocrine systems., (Copyright © 2018 Elsevier GmbH. All rights reserved.)

Background: The effects of low-level prenatal manganese (Mn) exposure on neonatal growth remain unclear. The level of fetal Mn that may be considered "safe" has never been examined., Methods: A multicenter study including 1377 mother-infant pairs was conducted from 2008 through 2009 in Shanghai. Mn concentrations were determined for both the cord and maternal serum, as well as neonatal birth weight and birth length. The ponderal index (PI) was calculated as (birth weight g/birth length cm(3))×100, and a ponderal index ≥3.17 was defined as a high ponderal index (HPI)., Results: The median serum Mn concentration was 4.0μg/L in the cord blood, and was 2.8μg/L in maternal blood. Of 1377 infants, 135 (9.8%) had a HPI. After adjusting for potential confounders, cord serum Mn was not associated with birth weight. However, there was a linear relationship between the cord serum Mn and the birth length (adjusted ß=-0.5, 95% CI=-0.7 to -0.2, p<0.0001). Additionally, a nonlinear relationship was observed between the cord serum Mn and the ponderal index, and between the cord serum Mn and HPI. The ponderal index and the prevalence of HPI increased with Mn levels above 5.0μg/L (Log Mn ≥0.7). A high level of Mn in the cord (≥5.0μg/L) was associated with a higher ponderal index (adjusted ß=0.2, 95% CI=0.1 to 0.2, p<0.001) and a high risk of HPI (adjusted OR=3.3, 95% CI=1.8-6.0, p<0.001)., Conclusions: Higher prenatal Mn exposure, even at a low level, is associated with a higher prevalence of HPI in a nonlinear pattern. Cord serum Mn levels less than 5.0μg/L may be considered safe with respect to neonatal ponderal index assessment., (Copyright © 2012 Elsevier Inc. All rights reserved.)

The Occupational Medicine Forum is prepared by the ACOEM Occupational and Environmental Medical Practice Committee and does not necessarily represent an official ACOEM position. The Forum is intended for health professionals and is not intended to provide medical or legal advice, including illness prevention, diagnosis or treatment, or regulatory compliance. Such advice should be obtained directly from a physician and/or attorney.

Background: Manganese (Mn) is an essential element in humans but its effect on semen quality is unclear. This study therefore aimed to assess the effects of Mn on semen quality in healthy men with no occupational exposure to Mn., Methods: Semen samples were obtained from healthy Chinese men 20-59 years old who were recruited from six provinces in China. Individuals with urogenital tract diseases, tuberculosis, or occupational exposure to heavy metals were excluded. A questionnaire survey was conducted, and the external genitalia, semen quality, and serum Mn levels were examined., Results: A total of 1,179 volunteers were enrolled in this study. The median serum Mn concentration was 8.2 μg/L (25th percentile (P25)=3.7 μg/L, P75=16.2 μg/L). After adjusted area (six provinces), abstinence interval, season, registered residence, age of subjects, education level, income, smoking, and drinking, the risk of teratospermia was increased at serum Mn concentrations >19.40 μg/L (P80) group, with an adjusted odds ratio of 2.27 (95% confidence interval: 1.18-4.37)., Conclusion: High serum Mn levels appeared to have harmful effects on sperm morphology and motility among healthy men with no occupational exposure to Mn.

Objective: To investigate the levels and differences of plasma selenium, manganese, iron, copper, zinc among oldest elderly in longevity areas in China., Methods: 446 oldest elderly including 208 centenarians, 238 aged 90 and over, who lived in Xiayi county of Henan province (110 persons), Zhongxiang city of Hubei province (111 persons), Mayang county of Hunan province (60 persons), Sanshui district of Guangdong province (113 persons), Yongfu county of Guangxi Zhuang autonomous region (52 persons) in China, were selected. The contents of plasma selenium, manganese, iron, copper, zinc were detected and compared among these elderly who were classified into different genders, different regions and different age groups., Results: In oldest elderly, the median (inter-quartile range) of content of plasma selenium was 1.44 (0.91) micromol/L, content of manganese was 0.54 (0.94) micromol/L, content of iron was 69.17 (102.85) micromol/L, content of copper was 20.19 (8.73) micromol/L, content of zinc was 31.66 (32.51) micromol/L. Contents of plasma selenium of oldest elderly in Xiayi, Zhongxiang, Mayang, Sanshui, Yongfu region were 1.46 (0.66), 1.30 (0.80), 1.06 (0.51), 2.39 (1.53) and 1.35(0.55) micromol/L; contents of plasma manganese were 0.56 (0.51), 1.40 (1.11), 0.35 (0.71), 0.44 (0.55) and 0.15 (0.21) micromol/L; contents of plasma iron were 86.77 (86.87), 141.42 (101.83), 38.88 (36.28), 31.38 (46.19) and 79.64 (75.34) micromol/L; contents of plasma copper were 22.16 (8.11), 19.46 (9.26), 21.36 (12.38), 18.12 (6.74) and 21.47 (7.85) micromol/L; contents of plasma zinc were 36.85 (26.18), 36.59 (35.94), 39.98 (56.91), 25.05 (24.92) and 16.74 (16.81) micromol/L. Contents of plasma trace elements among oldest elderly in different longevity areas were significantly different (F values were 29.76, 38.75, 47.18, 11.51 and 13.47, P values were all less than 0.05). Contents of plasma trace elements in different gender groups (contents of plasma selenium were 1.38 (0.83) micromol/L in male and 1.45 (0.91) micromol/L in female; contents of plasma manganese were 0.52 (0.95) and 0.54 (0.91) micromol/L; contents of plasma iron were 69.23 (104.06) and 69.11 (101.05) micromol/L; contents of plasma copper were 20.28 (8.72) and 20.06 (8.76) micromol/L; contents of plasma zinc were 28.39 (32.58) and 31.85 (34.26) micromol/L) were not significantly different (t(Se) = -1.82, P = 0.07; t(Mn) = 0.64, P = 0.52; t(Fe) = 0.65, P = 0.52; t(Cu) = -1.90, P = 0.06; t(Zn) = -0.96, P = 0.34). The contents of plasma selenium, iron, copper in centenarians were higher than those aged 90 and over (contents of plasma selenium were 1.63 (0.94) micromol/L and 1.30 (0.82) micromol/L, contents of plasma iron were 112.63 (119.78) and 60.13 (58.43) micromol/L, contents of plasma copper were 21.07 (9.03) and 18.81 (8.86) micromol/L, F value were 41.99, 27.32, 24.45, P values were less than 0.01). Content of plasma manganese in centenarians was lower than those aged 90 and over (0.44 (0.76) and 0.64 (0.93) micromol/L, F = 10.76, P < 0.01). No significant differences were detected in plasma zinc between concentration and those aged 90 and over (31.78 (34.06) and 31.11 (33.85) micromol/L; F = 1.32, P = 0.25)., Conclusion: The concentrations of plasma selenium, manganese, iron, copper and zinc were high in oldest elderly in the longevity areas. The contents of plasma selenium, iron, copper increased with age.

Background: Idiopathic Parkinson's disease (PD) and the Parkinsonian syndrome caused by manganese (Mn) poisoning are known to be indistinguishable in terms of symptoms. We thus suspect that many patients who have accumulated Mn in the body in daily life are diagnosed as having idiopathic PD. We examined the relationship between PD and blood levels of heavy metals, and the influence of intake from food in a general population., Methods: The subjects comprised PD patients and sex- and age-matched controls recruited from the outpatient clinic of Xiangfan No. 1 People's Hospital in Hubei, China, between 2006 and 2008. Information was obtained on previous eating habits before diagnosis of PD and other factors. Morning blood samples were collected before breakfast and were used to measure concentrations of metals., Results: The whole-blood Mn and serum iron (Fe) levels were significantly higher in PD patients than in controls. However, no differences in intake of each metal from food or experience of Mn poisoning were seen between the groups., Conclusions: In China, accumulation of Mn and Fe via unknown routes might be involved in the etiology of PD in the general population., (2009 S. Karger AG, Basel.)

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.

Human saliva offers a unique noninvasive approach for populational study. Purposes of this study were to investigate the feasibility of using saliva manganese (Mn) concentration as a biomarker of Mn exposure among career welders and to study the variations of Mn, copper (Cu), zinc (Zn), cadmium (Cd), and lead (Pb) in saliva as affected by the welding profession. Forty-nine male welders, of whom 28 were in the low exposed group and 21 in the high exposed group, were recruited. Control subjects were 33 military soldiers without metal exposure. Ambient Mn levels in breathing zones were 0.01, 0.24 and 2.21mg/m(3) for control, low, and high exposed groups, respectively. Saliva samples were collected to quantify metals by inductive coupled plasma mass spectrometer (ICP-MS). Saliva concentrations of Mn and Cu were significantly higher in welders than in controls (p<0.01); the variation in saliva levels appeared likely to be associated with airborne Mn levels among study populations. Saliva levels of Zn were significantly lower in welders than in controls (p<0.05), while Cd and Pb levels in saliva were unchanged. Significant associations were observed between saliva and serum for Mn (r=0.575, p<0.05) and Cu (r=0.50, p<0.05). Moreover, saliva Mn concentrations were higher among welders with 5-10years of employment than those with less than 5years of employment. Linear regression analysis revealed a significant correlation between saliva Mn and Cu and between saliva Mn and Zn. Taken together, these data suggest that Mn concentrations in saliva appear reflective of welders' exposure to airborne Mn and their years of welding experience, respectively. Elevated Mn levels among welders may alter the homeostasis of Cu and Zn.

The neurotoxicity of manganese (Mn) is well known, however, the neurochemical effect caused by this metal is less well investigated. In this study, urinary homovanillic acid (HVA) and vanillymandelic acid (VMA), two end products of catecholamine metabolism, were measured in 39 workers chronically exposed to Mn in a manganese smelting plant. The average duration of Mn exposure was 17.4 yr. Nineteen nonexposed workers were also studied. Concentrations of Mn in serum (MnS) and in urine (MnU) were measured by Zeeman graphite furnace atomic absorption spectrophotometry (ZAAS), and HVA and VMA determined by high performance liquid chromatography (HPLC). For Mn-exposed workers, the concentration of MnS was nearly 2.8 times (1.61 +/- 0.16 mg/L vs 0.56 +/- 0.16 mg/L) and MnU about 4.5 times higher (7.62 +/- 0.17 mg/L vs 1.69 +/- 0.16 mg/L) than the nonexposed. Although the geometric mean concentration of HVA in exposed workers was similar to that of the nonexposed (3.09 +/- 1.39 mg/g cre. vs 2.99 +/- 1.40 mg/g cre.), the VMA concentration was significantly higher (3.02 +/- 1.43 mg/g cre. vs 2.49 +/- 1.58 mg/g cre., p = 0.033). Multiple regression analysis showed that although there were no correlations between any of these parameters with the duration of exposure to Mn, both HVA and VMA showed significant correlations with increase in MnS and MnU. These data provide evidence that exposure to Mn was associated with measurable increase in catecholamine metabolites. This finding is compatible with recent observations in laboratory animals that Mn interferes with neurochemical metabolism.