Brain magnetic resonance imaging and manganese concentrations in red blood cells of smelting workers: Search for biomarkers of manganese exposure

Abstract

The MRI technique has been used in diagnosis of manganism in humans and non-human primates. This cross-sectional study was designed to explore whether the pallidal signal intensity in T1-weighted MRI correlated with Mn levels in the blood compartment among Mn-exposed workers and to understand to what extent the MRI signal could reflect Mn exposure. A group of 18 randomly selected male Mn-exposed workers of which 13 were smelting workers with high exposure (mean of airborne Mn in work place: 1.26 mg/m 3 ; range: 0.31-2.93 mg/m 3 ), and 5 power distribution control workers with low exposure (0.66 mg/m 3 and 0.23-0.77 mg/m 3 ) from a ferroalloy factory, and another group of 9 male subjects as controls from a non-smelting factory who were office or cafeteria workers (0.01 mg/m 3 and 0-0.03 mg/m 3 ) were recruited for neurological tests, MRI examination, and analysis of Mn in whole blood (MnB), plasma (MnP) or red blood cells (MnRBC). No clinical symptoms and signs of manganism were observed among these workers. MRI data showed average increases of 7.4% (p < 0.05) and 16.1% (p < 0.01) in pallidal index (PI) among low-and high-exposed workers, respectively, as compared to controls. Fourteen out of 18 Mn-exposed workers (78%) had intensified PI values, while this proportion was even higher (85%) among the high Mn-exposed workers. Among exposed workers, the PI values were significantly associated with MnRBC (r = 0.55, p = 0.02). Our data suggest that the workers exposed to airborne Mn, but without clinical symptoms, display an exposure-related, intensified MRI signal. The MRI, as well as MnRBC, may be useful in early diagnosis of Mn exposure.

Cerebrospinal fluid to brain transport of manganese in a non-human primate revealed by MRI

“…Studies addressing manganese overexposure in humans and non-human primates using MRI have described T 1 -weighted image enhancements in the basal ganglia, most notably in the globus pallidus and substantia nigra (Uchino et al, 2007;Pal et al, 1999;Jiang et al, 2007;Krieger et al, 1995;Dorman et al, 2006b;Shinotoh et al, 1995;Guilarte et al, 2006). In fact, T 1 -weighted hyperintesity in the basal ganglia is used as a biomarker for manganese poisoning in humans (Jiang et al, 2007). MRI is an important assay for manganese, since there is no histological stain for it and its accumulation must otherwise be measured in brain tissue samples with techniques such as mass spectrometry or with a 54 Mn radioactive tracer.…”

Short-term manganese inhalation decreases brain dopamine transporter levels without disrupting motor skills in rats

“…This can be converted to an equivalent human dose of 15 mg/m 3 over the same duration (Reagan-Shaw et al, 2008). Mn exposure in humans can originate from MMT emitted to the atmosphere during the combustion of gasoline, while high concentrations of Mn can also be detected in some working environments, where Mn concentrations of 0.093 mg/m 3 (Lucchini et al, 1997), 0.21 mg/m 3 (Myers et al, 2003), 0.948 mg/m 3 (Roels et al, 1992), 1.26 mg/m 3 (Jiang et al, 2007), 4.8 mg/m 3 , and even 35.7 mg/m 3 (Nakata et al, 2006) have been recorded.…”

“…Also, immediately dangerous to life and health concentration (IDLH) provided by NIOSH resources of occupational manganese exposure is 500 mg Mn/m 3 at work-related exposure fields. However, there were still some cases of Mn exposure that exceed the recommended limit, for example up to 2.93 mg/m 3 during ferroalloy manufacture in China (Jiang et al, 2007), up to 4.6 mg/m 3 in a heavy machinery plant in Russia (Ellingsen et al, 2006), 4.8 mg/m 3 in an air conditioner factory, and 35.7 mg/m 3 in a factory producing bridge parts in Korea (Nakata et al, 2006).…”

Early Primary Biliary Cholangitis is Characterised by Brain Abnormalities on Cerebral Magnetic Resonance Imaging

“…The basal ganglia and the globus pallidus in particular are key regions of the brain with associated pathophysiology in a variety of conditions ranging from movement disorders, such as Parkinson's disease 14 to chronic hepatitis C, and in manganese workers, who have been exposed to industrial pollution. [15][16][17] It has been previously hypothesised that disrupted activity in these areas of the brain leads to decreased motivation in these conditions, perceived by the individual as fatigue. 18 Furthermore, the basal ganglia and the globus pallidus in particular have been shown to be susceptible to manganese accumulation associated with cholestasis of any cirrhotic state, while patients with chronic liver disease exhibit pallidal hyperintensity on T 1 -weighted magnetic resonance imaging (MRI), similar to that seen in hypermanganesaemic states, such as chronic parenteral nutrition administration and manganese toxicity from industrial exposure.…”