Manganese, urinary excretion

Dithiocarbamates are chemically characterized by the presence of metals in the molecule (iron, manganese, zinc, etc.) therefore, the measurement of these metals in urine has been proposed as an alternative approach to monitor exposure. For instance, increased urinary excretion of manganese has been reported in workers exposed to mancozeb (Canossa et al., 1993). Available data are at present insufficient to confirm the possibility of using metals as biomarkers of human exposure to DTC. 

As shown in Table VI, urinary excretion of manganese did not differ significantly among the four dietary treatment periods. No explanation can be offered for the high urinary manganese losses that occurred during the pre-period. 

Gregus and Klaassen carried out a comparative study of fecal and urinary excretion and tissue distribution of eighteen metals in rats after intravenous injection. Total (fecal + urinary) excretion was relatively rapid (over 50% of the dose in 4 days) for cobalt, silver and manganese between 50 and 20% for copper, thallium, bismuth, lead, cesium, gold, zinc, mercury, selenium and chromium and below 20% for arsenic, cadmium, iron, methylmercury and tin. Feces was the predominant route of excretion for silver, manganese, copper, thallium, lead, zinc, cadmium, iron and methylmercury whereas urine was the predominant route of excretion of cobalt, cesium, gold, selenium, arsenic and tin. Most of the metals reached the highest concentration in liver and kidney. However, there was no... 

Edetic acid is a metal chelator. The effect of an intravenous dose of 1 g of calcium disodium edetate on the urinary excretion on the elements aluminium, boron, barium, calcium, copper, iron, lead, magnesium, manganese, phosphorus, potassium, sihcon, sodium, strontium, sulphur, and zinc was measured in healthy volunteers. The ratio of the increase of urinary elimination was about two for iron, five for aluminium, lead, and manganese, and 15 for zinc (1). 

Small amounts of manganese can also be found in urine, sweat, and milk (EPA 1993b). Urinary excretion of manganese by healthy males was 7.0 nmole/g creatinine (7.0 nmole = 385 ng = 0.385 pg) (Greger et al. 

Measurement of altered levels of dopamine and other neurotransmitters in the basal ganglia has proven to be a useful means of evaluating central nervous system effects in animals (e.g., Bonilla and Prasad 1984 Eriksson et al. 1987a, 1987b), and these changes are often observed before any behavioral or motor effects are apparent (Bird et al. 1984). No noninvasive methods are currently available to determine whether there are decreased dopamine levels in the brain of exposed humans, but decreased urinary excretion of dopamine and its metabolites has been noted in groups of manganese-exposed workers (Bernheimer et al. 1973 ... 

Greger JL, Davis CD, Suttie JW, Lyle BJ. 1990. Intake, serum concentrations and urinary excretion of manganese by adult males. Am J Clin Nutr 54 457-161. 

Table VI. Mean Urinary Manganese Excretion (yg/day), Manganese Balance (mg/day) and Whole Blood Manganese (yg/dl) in Humans Fed Varying Levels of Manganese and Fat...

The absorption of dietary Mn by humans is low, about 6,0%, and can range frorn 1 to 16%. About 99% of the body s losses of Mn ate fecal, with about 0.7% lost via the skin and 0.1 % via the urine. The primary route of excretion of the body s Mn is the bile, which cemtributes to the fecal rnanganese. Plasma Mn levels vary from 0.015 to 0.030 pM. Plasma Mn can vary within this range from day to day in an individual. Ked blood cell manganese is about 20 ng/ml of packed cells. Urinary Mn is fairly constant at about 7.0 nmol/g of creatinine. Plasma and urinary Mn levels seem not to be closely correlated with Mn intake. 

The average daily excretion of manganese in sweat amounts to between 30 and 120 jg, assuming a daily sweat volume of 0.5 - 2.0 L, and this corresponds to 0.7-2.8% of the total daily manganese intake. Thus, integu-mental losses may contribute more to total balance than do urinary losses and should... 

It can be seen from equation (2) that when the constant b approaches 0, no correction is required, i.e., the observed concentration is independent of urinary flow rate. This, however, does not seem to be true for any chemical studied (including, especially, creatinine) (Araki et al., 1990). When b approaches 1, the corrected concentration is proportional to urine flow rate, and correction to relative density is rather accurate. This is the case for mercury (Araki et al., 1990), and nickel in some circumstances (Nieboer et al., 1992). On the other hand, when b approaches 0.67, the b constant for creatinine (Araki et al., 1990), correction to creatinine excretion would seem most appropriate in routine biological monitoring. Manganese and cadmium are candidates for this approach. Chro-... 

Dang et al. (2000) increased the sensitivity of NAA for Th by separating the indicator radionuclide, Pa, using co-predpitations with manganese dioxide and barium sulfate and determined Th in total diet samples. A similar postirradiation procedure was coupled to the following pre-irradiation separation and concentration of Th (PC-RNAA) by H5llriegl et al. (2005) to increase the sensitivity of the method for the determination of urinary Th excretions. The pre-concentration procedure consisted of phosphate and caldum oxalate coprecipitations. The detection limit of Th in the urine sample was about 10 pg (0.04 jiBq). 

For the majority of inorganic compounds the most important route of excretion is via the urine, and urinary concentrations may be used to monitor exposure. Some metals (manganese is an example) are excreted predominantly into the bile and then excreted into the gut to appear finally in the faeces. Toxicologists seldom rely on faecal analysis to monitor exposure, for reasons which should be apparent to all. 

---