Excretion of chromium

There appears to be a chromium pool in individuals who are not chromium deficient (136). When there is an increase in level of cHculating insulin in response to a glucose load, an increase in circulating chromium occurs over a period of 0.5—2 h. This is foUowed by a decline and excretion of chromium in urine increases. Chromium deficiency is indicated when no increase or a small increase in blood chromium level or urine chromium occurs. 

Chromium compounds interact synergistically or antagonistically with many chemicals. For example, potassium dichromate administered by subcutaneous injection potentiated the effects of mercuric chloride, citrinin, and hexachloro-1,3-butadiene on rat kidneys (USPHS 1993). Chromium effects were lessened by ascorbic acid and Vitamin E, and N-acetyl cysteine was effective in increasing urinary excretion of chromium in rats (USPHS 1993)... 

Mean pooled urinary concentrations during the dosing periods were 2.4 pg chromium/g creatinine from exposure to chromium(VI) and 0.4 pg chromium/g creatinine from exposure to chromium(III) as compared to 0.23 pg chromium/g creatinine during the post-dosing time periods. The lower urinary excretion of chromium(III) after exposure to chromic oxide reflects the poorer absorption of inorganic chromium(III) compounds compared to inorganic chromium(VI) compounds. 

Daily urinary excretion levels of chromium were nearly identical in men and women (averages of 0.17 and 0.20 pg/L, respectively 0.18 pg/L combined) who ate normal dietary levels of chromium ( 60 pg chromium(III)/day). When the subjects normal diets were supplemented with 200 pg chromium(in)/day as chromium trichloride to provide intakes of 260 pg chromium(ni)/day, urinary excretion of chromium rose proportionately to an average of 0.98 pg/L combined. Thus a five-fold increase in oral intake resulted in about a five-fold increase in excretion, indicating absorption was proportional to the dose regardless of whether the source was food or supplement (Anderson et al. 1983). A group of 23 elderly subjects who received an average of 24.5 pg/day (0.00035 mg chromium(III)/kg/day) from their normal diets excreted 0.4 pg chromium/day in the urine (1.6%) and 23.9 pg chromium/day in the feces (97.6%), with a net retention of 0.2 pg/day (0.8%). Based on the 1980 daily requirement for absorbable chromium of 1 pg/day by the National Academy of Science Food and Nutrition Board, the retention was considered adequate for their requirements (Bunker et al. 1984). 

Measurement of the chromium content in 255 milk samples from 45 lactating American women revealed that most samples contained <0.4 pg/L with a mean value of 0.3 pg/L (Casey and Hambidge 1984). Another study (Anderson et al. 1993) measured chromium levels in the breast milk of 17 women 60 days postpartum, and reported mean levels of 0.2 pg/L. Lactation, therefore, represents a route of excretion of chromium and a potential route of exposure to the nursing infant. However, the precise relationship between maternal chromium levels and levels in breast milk is unclear, if such a relationship exists at all (Anderson et al. 1993 Engelhardt et al. 1990 Mohamedshah et al. 1998). 

Information regarding the excretion of chromium in humans after dermal exposure to chromium or its compounds is limited. Fourteen days after application of a salve containing potassium chromate(VI), which resulted in skin necrosis and sloughing at the application site, chromium was found at 8 mg/L in the urine and 0.61 mg/100 g in the feces of one individual (Brieger 1920). A slight increase (over background levels) in urinary chromium levels was observed in four subjects submersed in a tub of chlorinated water containing 22 mg chromium(VI)/L as potassium dichromate(VI) for 3 hours (Corbett et al. 1997). For three of the four subjects, the increase in urinary chromium excretion was less than 1 pg/day over the 5-day collection period. 

A number of factors have been shown to alter the rate of excretion of chromium in humans. Intravenous injection of calcium EDTA resulted in a rapid increase in the urinary excretion of chromium in metal workers (Sata et al. 1998). Both acute and chronic exercises have been shown to increase chromium excretion in the urine, though the increased excretion did not appear to be accompanied with decreased levels of total native chromium (Rubin et al. 1998). An increased rate of chromium excretion has been reported in women in the first 26 weeks of pregnancy (Morris et al. 1995b). Chromium supplementation did not appear to alter the rate of excretion into breast milk in postpartum women (Mohamedshah et al. 

One PBPK model for chromium has been published. The O Flaherty model (O Flaherty 1993a, 1996) simulates the absorption, distribution, metabolism, elimination, and excretion of chromium(III) and chromium(VI) compounds in the rat. Two kinetic models describing the distribution and clearance of chromium(III) compounds in humans are described at the end of this section. 

Gargas et al. (1994) employed a three compartment model describing the urinary excretion of chromium (Aitio et al. 1988) to estimate the bioavailability of chromium(III) from chromium(in) picolinate in volunteers ingesting capsules containing 400 pg. The model contained 3 compartments, a fast-exchange compartment receiving 40% of absorbed chromium with a half-life of 7 hours, a medium-exchange... 

A susceptible population will exhibit a different or enhanced response to chromium than will most persons exposed to the same level of chromium in the environment. Reasons may include genetic makeup, age, health and nutritional status, and exposure to other toxic substances (e.g., cigarette smoke). These parameters result in reduced detoxification or excretion of chromium, or compromised function of... 

An age-related difference in the extent of gastrointestinal absorption of chromium(III) was reported in one study (Sullivan et al. 1984) it is not known if a similar relationship would exist for chromium(VI). No other information is available which evaluated potential differences between adults and children. Toxicokinetic studies examining how aging can influence the absorption, distribution, and excretion of chromium, particularly chromium(VI) would be useful in assessing children s susceptibility to chromium toxicity. There are no data to determine whether there are age-specific biomarkers of exposure or effects or any interactions with other chemicals that would be specific for children. There is very little available information on methods for reducing chromium toxic effects or body burdens it is likely that research in adults would also be applicable to children. 

Donaldson DL, Smith CC, Yunice AA. 1984. Renal excretion of chromium-51 chloride in the dog. 

Gargas ML, Norton RL, Paustenbach DJ, et al. 1994. Urinary excretion of chromium by humans following ingestion of chromium picolinate Implications for biomonitoring. Drug Metab Dispos 22(4) 5 22-5 29. 

Kamath SM, Stoecker B J, Davis-Whitenack ML. 1997. Absorption, retention and urinary excretion of chromium-51 in rats pretreated with indomethacin and dosed with dimethylprostaglandin E2, misoprostaol or prostacyclin. J Nutr 127 478-482. 

Langard S. 1982. Absorption, transport and excretion of chromium in man and animals. In Langard, ed. Biological and environmental aspects of chromium. Elsevier Biomedical Press, 149-169. 

Manzo L, Di Nucci A, Edel J, et al. 1983. Biliary and gastrointestinal excretion of chromium after administration of Cr-III and Cr-VI in rats. Res Commun Chem Pathol Pharmacol 42( 1) 113-125. 

Mutti A, Cavatorta A, Borghi L, et al. 1979. Distribution and urinary excretion of chromium Studies on rats after administration of single and repeated doses of potassium dichromate. Med Lav 3 171-179. 

Norseth T, Alexander J, Aaseth J, et al. 1982. Biliary excretion of chromium in the rat A role of glutathione. Acta Pharmacol Toxicol 51 450-455. 

Uptake, Distribution, Metabolism, and Excretion of Chromium in Animals and Humans... 

Trivalent chromium is the most stable form in the food supply. Absorption estimates for chromium(III), based on metabolic balance studies or on urinary excretion from physiological intakes, range from 0.4 to 2.5% (Doisy et al. 1971 Bunker et al. 1984 Anderson and Kozlovsky 1985 Offenbacher etal. 1986 Anderson 1987). Because of analytical problems associated with the measurement of chromium absorption, several investigators have used the urinary excretion of chromium as an indicator of absorption. When dietary chromium intake was 10 pg per day, 2% of that amount was absorbed (estimated as urinary excretion), whereas at a chromium intake of 40 pg only 0.4-0.5% of the chromium was recovered in the urine (Anderson and Kozlovsky 1985). 

Bunker VW, Lawson MS, Delves HTand Ciayton B (1984) The uptake and excretion of chromium by the elderly. Am J Clin Nutr 39 797-802. 

A qualitative outline of chromium kinetic behavior emerges from these studies. Chromium(VI) is absorbed, distributed, and excreted substantially more readily than Cr(III). At the same time, reduction of Cr(VI) to Cr(III) occurs so rapidly in the lung, the gastrointestinal tract, and the body that to a large extent the kinetics of Cr(VI) have been thought of as the kinetics of Cr(III). This is not precisely correct. The rapidity with which Cr(VI) is reduced, compared to the rapidity of its absorption and excretion processes, controls a sensitive balance that determines overall absorption, distribution, and excretion of chromium as well as the amounts absorbed, distributed, and excreted as Cr(VI). In addition, the nature and rate of the reduction process itself appear to be linked with Cr(VI) pulmonary carcinogenicity. 

Excretion of chromium— The predominant route of excretion of endogenous chromium is the urine. The average daily loss is about 7 to 10 meg. 

A resent report (P) indicated that kombucha processes potent antioxidant and inununopotentiating activities. It helps in excretion of chromium from body tissues. The strong antioxidant activity decreases peroxidation, enhances antibody titers and delays hypersensitivity response in control (chromium treated) rat. However, there has been a lot of attention regarding the possible toxicity of kombucha tea. The presence of Bacillus anthrax in kombucha tea fermented in unhygienic conditions has been reported (IG). Gastrointestinal toxicity of kombucha has also occurred in four patients (ll). Recent FDA studies found no evidence of contamination in kombucha products fermented under sterile conditions. FDA and State of California inspections of the facilities of a major Kombucha tea supplier also found diat its product was being manufrictured under sanitary conditions. 

---