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

BACKGROUND: Neurotoxic effects are known to occur with inhalation of manganese particulates, but very few data are available on exposure to Mn in water. We undertook a pilot study in a community in Québec (Canada) where naturally occurring high Mn levels were present in the public water system. Our objective was to test the hypothesis that greater exposure to Mn via drinking water would be reflected in higher Mn content in hair which, in turn, would be associated with increased level of hyperactive behaviors. METHODS: Forty-six children participated in the study, 24 boys and 22 girls, 6–15 years of age (median, 11 years). Their homes received water from one of two wells (W) with different Mn concentrations: W1: mean 610 μg/L; W2: mean 160 μg/L. The Revised Conners’ Rating Scale for parents (CPRS-R) and for teachers (CTRS-R) were administered, providing T-scores on the following subscales: Oppositional, Hyperactivity, Cognitive Problems/Inattention, and ADHD Index. RESULTS: Children whose houses were supplied by W1 had higher hair Mn (MnH) than those supplied by W2 (mean 6.2 ± 4.7 μg/g vs. 3.3 ± 3.0 μg/g, p = 0.025). MnH was significantly associated with T-scores on the CTRS-R Oppositional (p = 0.020) and Hyperactivity (p = 0.002) subscales, after adjustment for age, sex, and income. All children with Oppositional and Hyperactivity T-scores ≥ 65 had MnH > 3.0 μg/g. CONCLUSIONS: The findings of this pilot study are sufficiently compelling to warrant more extensive investigations into the risks of Mn exposure in drinking water

Brain Uptake, Retention, and Efflux of Aluminum and Manganese

My colleagues and I investigated the sites and mechanisms of aluminum (Al) and manganese (Mn) distribution through the blood-brain barrier (BBB). Microdialysis was used to sample non-protein-bound Al in the extracellular fluid (ECF) of blood (plasma) and brain. Brain ECF Al appearance after intravenous Al citrate injection was too rapid to attribute to diffusion or to transferrin-receptor-mediated endocytosis, suggesting another carrier-mediated process. The brain:blood ECF Al concentration ratio was 0.15 at constant blood and brain ECF Al concentrations, suggesting carrier-mediated brain Al efflux. Pharmacological manipulations suggested the efflux carrier might be a monocarboxylate transporter (MCT). However, the lack of Al 14C-citrate uptake into rat erythrocytes suggested it is not a good substrate for isoform MCT1 or for the band 3 anion exchanger. Al 14C-citrate uptake into murine-derived brain endothelial cells appeared to be carrier mediated, Na independent, pH independent, and energy dependent. Uptake was inhibited by substrate/inhibitors of the MCT and organic anion transporter families. Determination of 26Al in rat brain at various times after intravenous 26Al suggested a prolonged brain 26Al half-life. It appears that Al transferrin and Al citrate cross the BBB by different mechanisms, that much of the Al entering brain ECF is rapidly effluxed, probably as Al citrate, but that some Al is retained for quite some time. Brain influx of the Mn2+ ion and Mn citrate, determined with the in situ brain perfusion technique, was greater than that attributable to diffusion, suggesting carrier-mediated uptake. Mn citrate uptake was approximately 3-fold greater than the Mn2+ ion, suggesting it is a primary Mn species entering the brain. After Mn2+ ion, Mn citrate, or Mn transferrin injection into the brain, brain Mn efflux was not more rapid than that predicted from diffusion. The BBB permeation of Al and Mn is mediated by carriers that may help regulate their brain concentrations

Exponering för flingformat aluminiumpulver Effekter på nervsystemet

Exposure to aluminium flake powder: Effects on the nervous system. A small group of aluminium flake powder producers was studied with psychological and neurophysiological tests and with symptom questionnaires. The flake powder producers were compared to groups with varying degrees of aluminium exposure, i.e. welders, potroom workers, and foundry workers. Comparisons were also made to a group of welders with no exposure to aluminium. The exposure was measured by blood and urine samples as well as questionnaires. The flake powder producers had considerably higher levels of aluminium in urine compared to the other groups, possibly indicating an increased body burden. In spite of this finding, no aluminium related effects on the CNS were observed in any of the tests or questionnaires. However, the high aluminium levels observed in urine indicate a possible risk for negative effects when exposure is prolonged. Therefore, the aluminium exposure should be reduced by improvements in the work environment.Undersökningen avsåg att med hjälp av psykologiska och neurofysiologiska test samt symptomformulär undersöka nervsystemets funktion hos personer med yrkesmässig exponering för flingformat aluminiumpulver. Exponeringen kartlades med mätningar av metallhalter i blod och urin, samt frågeformulär. Den pulverexponerade gruppen jämfördes med svetsare, gjutare och smältverksarbetare, vilka exponerats för aluminium i olika grad, samt med en kontrollgrupp bestående av svetsare utan exponering för aluminium. De pulverexponerade uppvisade högre halter av aluminium i urin än samtliga andra grupper. Trots dessa höga halter av aluminium kunde inga effekter av aluminium på nervsystemet påvisas. De höga halterna innebär att det inte kan uteslutas att en längre tids exponering skulle kunna påverka nervsystemets funktion även hos de pulverexponerade. Det är därför motiverat att se över arbetsmiljön, och att vidta arbetsmiljöförbättrande åtgärder för att sänka aluminiumexponeringen

Diamond-like carbon coating of alternative metal alloys for medical and surgical applications

The effectiveness of a plasma-deposited, diamond-like carbon (DLC) coating on aluminium alloy based surgical instruments is investigated. Surgical instruments must satisfy a number of important criteria including biocompatibility, functional performance, sterility and cleanability, structural integrity, and fatigue resistance. The integrity of the DLC layer and the diffusion barrier properties are of paramount importance due to biocompatibility considerations of the underlying aluminium metal. We investigate optimisation of the coating with incorporation of silicon and variation in negative self bias, and highlight the design and manufacture of a lightweight laparoscopic assist instrument from aluminium alloy coated with diamond-like carbon, which has been used successfully in the clinical environment to improve operations such as cholecystectomy (gall bladder removal) and exploratory techniques for the diagnosis of cancer