Potassium dichromate, toxicity

The primary routes of entry for animal exposure to chromium compounds are inhalation, ingestion, and, for hexavalent compounds, skin penetration. This last route is more important in industrial exposures. Most hexavalent chromium compounds are readily absorbed, are more soluble than trivalent chromium in the pH range 5 to 7, and react with cell membranes. Although hexavalent compounds are more toxic than those of Cr(III), an overexposure to compounds of either oxidation state may lead to inflammation and irritation of the eyes, skin, and the mucous membranes associated with the respiratory and gastrointestinal tracts. Skin ulcers and perforations of nasal septa have been observed in some industrial workers after prolonged exposure to certain hexavalent chromium compounds (108—110), ie, to chromic acid mist or sodium and potassium dichromate. 

Muller, H.G. 1980. Acute toxicity of potassium dichromate to Daphnia magna as a function of water quality. Bull. Environ. Contam. Toxicol. 25 113-117. 

Parker, W.R. Results of an Interlaboratory Study on the Toxicity of Potassium Dichromate to Daphnia EPS Report Environmental Protection Service, Environment Canada Canada, 1983. 

Potassium dichromate (K2Ct20 ) This is a strong oxidizer, but it only contains 16% oxygen by weight. It has a corrosive effect on the mucous membranes, and its toxicity and suspected carcinogenicity suggest the use of alternate oxidizers. 

Another type of nitrocellulose powder used for some time which eventually disappeared from the market was a semi-colloidal nitrocellulose powder containing inorganic salts such as potassium or barium nitrate (e.g. Poudre T in France, with 2% potassium nitrate) or with dichromates (e.g. Poudre J in France with 14% ammonium dichromate and 3% potassium dichromate). The dichromate powder was very sensitive to friction and its dust contained toxic dichromates. 

See Potassium Dichromate, Sodium Dichromate, and Sulfuric Acid. Very corrosive toxic. 

Several animal studies provide evidence that chromium(VI) is a developmental toxicant in rats and mice. A series of studies (Junaid et al. 1996a Kanojia et al. 1996, 1998) was conducted to assess whether premating exposure to potassium dichromate would result in developmental effects. In the first study, groups of 15 female Swiss albino mice were exposed to 0, 52, 98, or 169 mg chromium(VI)/kg/day as potassium dichromate in drinking water for 20 days (Junaid et al. 1996a) and then mated with untreated... 

Some chromium(VI) compounds, such as, chromium trioxide (chromic acid), potassium dichromate, potassium chromate, sodium dichromate, and sodium chromate, are very caustic and can cause bums upon dermal contact. These burns can facilitate the absorption of the compound and lead to systemic toxicity. 

Single-dose dermal LD50 values in New Zealand rabbits exposed to chromium(VI) as sodium chromate, sodium dichromate, potassium dichromate, and ammonium dichromate were determined by Gad et al. (1986). LD50 values ranged from 361 to 553 mg chromium(VI)/kg for females and from 336 to 763 mg chromium(VI)/kg for males. Signs of toxicity included dermal necrosis, eschar formation, dermal edema and erythema, and diarrhea and hypoactivity. The dermal LD50 value for chromium trioxide was 30 mg chromium(VI)/kg for combined sexes (American Chrome and Chemical 1989). The LD50 values are recorded in Table 2-3. 

The findings of toxic effects in the heart, stomach, blood, muscles, and kidneys of humans who were dermally exposed to chromium compounds is suggestive of distribution to these organs (see Section 2.2.3.2). Fourteen days after a salve containing potassium chromate(VI) was applied to the skin of an individual to treat scabies, appreciable amounts of chromium were found in the blood (2-5 mg/100 mL), urine (8 mg/L), feces (0.61 mg/100 g), and stomach contents (0.63 mg/100 mL) (Brieger 1920). The preexisting condition of scabies or the necrosis caused by the potassium chromate could have facilitated its absorption. A transient increase in the levels of total chromium in erythrocytes and plasma was observed in subjects immersed in a tank of chlorinated water containing potassium dichromate(VI) (Corbett et al. 1997). 

Gumbleton M, Nicholls PJ. 1988. Dose-response and time-response biochemical and histological study of potassium dichromate-induced nephrotoxicity in the rat. Food Chem Toxic 26(l) 37-44. 

NTP. 1996a. Final report on the reproductive toxicity of potassium dichromate (hexavalent) (CAS No. 7778-50-9) administered in diet to SD rats. National Institute of Environmental Health Sciences,... 

The impurities formed are mostly high oxides of nitrogen and are highly toxic. After the water is removed in a condenser, the gas is washed in a solution of potassium dichromate to remove nitric oxide, in caustic to remove nitric acid, and finally in water. 

SAFETY PROFILE An inhalation hazard. Mildly toxic by an unspecified route. An experimental teratogen. Experimental reproductive effects. A skin and eye irritant. Flammable in the form of dust when exposed to flame. The powdered metal may ignite on contact with air or oxidants (e.g., bromine pentafluoride, bromine, chlorine trifluoride, potassium perchlorate, potassium dichromate, nitryl fluoride, fluorine, oxygen difluoride, iodine pentafluoride, hydrogen sulfide, sodium peroxide, lead(IV) oxide). 

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