Exposure chromium

Chromium Exposure Levels and U.S. Government Regulations. The level of exposure to chromium compounds for employees in industry and for the general population via waste disposal and industrial emissions is the subject of much regulation, research, and controversy. Some U.S. Government regulations, such as the Comprehensive Environmental Response, Compensation, and LiabiUty Act (CERCLA), also known as the Superfund Act, make no distinction as to the oxidation state of chromium (144). However, there is valence distinction in other regulations. 

Biomarkers that demonstrate chromium exposure under field conditions is under active investigation. Laboratory studies with Prussian carp (Carassius auratus gibelio) exposed for 3 to 9 days to 25 to 100 pg Cr /L or 50 to 200 pg Cr+3/L show a dose-dependent increase in the frequency of micronuclei in erythrocytes, and this increase is considered indicative of increasing DNA damage (Al-Sabti et al. 1994). Similar increases in micronuclei were observed in Prussian carp from the River Ljubjanica near chromium-containing outfalls from leather waste products in the Republic of Slovenia (Al-Sabti et al. 1994). 

Khangarot, B.S. and D.M. Tripathi. 1992. The stereoscan observations of the skin of catfish, Saccobranchus fossilis, following chromium exposure. Jour. Environ. Sci. Health 27A 1141-1148. 

Sastry, K.V. and K. Sunita. 1983. Enzymological and biochemical changes produced by chronic chromium exposure in a teleost fish, Channa punctatus. Toxicol. Lett. 16 9-15. 

Norseth, T. 1980. Cancer hazards caused by nickel and chromium exposure. Jour. Toxicol. Environ. Health 6 1219-1227. 

Occupational sources of chromium exposure (with chemical forms of interest shown in brackets) may occur in the following industries ... 

Examples of other occupations that may involve chromium exposure include these ... 

In addition, you may be exposed to higher levels of chromium if you use tobacco products, since tobacco contains chromium. For additional information about chromium exposure, see Chapter 5. 

However, since chromium(III) is an essential nutrient, low levels of chromium are normally found in body tissues and urine. Tests for chromium exposure are most useful for people exposed to high levels. These tests cannot determine the exact levels of chromium you may have been exposed to or predict whether or not health effects will occur. High chromium levels in the urine and red blood cells indicate exposure to chromium(VT) or chromium(III) compounds. 

These changes were more pronounced in the workers with respiratory disorders due to chromium exposure than in the workers with chromium-induced gastrointestinal effects. The changes in the myocardium could be secondary to pulmonary effects and/or to a direct effect on the blood vessels and myocardium (Kleiner et al. 1970). 

Yet, other studies involving electroplaters and welders report a higher incidence of chromosomal aberrations or sister chromatid exchanges in lymphocytes of workers than in controls. In one study, a causal relationship between chromium exposure and the observed effects could not be established... 

Biological monitoring has been used to relate serum and urine chromium levels to occupational exposure levels. A statistically significant (r=0.95, p<0.001) relationship between total chromium exposure and urinary chromium concentrations at the end of the workday were observed in five welders exposed to chromium(VI) compounds. The urinary chromium concentrations of 40-50 pg/L immediately after work... 

Acute inhalation LC50 and oral and dermal LD50 studies suggest that female animals are more sensitive to the lethal effects of chromium(VI) compounds (see Sections 2.2.1.1, 2.2.2.1, and 2.2.3.1). Whether human females are more sensitive than males to toxic effects of chromium or its compounds is not known. Other information identifying possible susceptible populations was not located. Some individuals who are sensitive to chromium may develop asthma as an anaphylactic response to inhaled chromium. Also, some individuals have less ability than others to reduce chromium(VI) in the bloodstream and are more likely to be affected by the adverse effects of chromium exposure (Korallus 1986a, 1986b). The ability to reduce chromium(VI) in the bloodstream may be related to the ascorbic levels in the plasma. 

Additional studies in workers with known levels of chromium exposure that control for confounding factors would be useful for defining levels at which chromosomal aberrations occur in humans exposed to chromium(VI) in the workplace. Also, better dose-response relationships would be useful for the various genotoxic and regulatory effects observed with chromium to better determine which end points are the most sensitive and dominant at exposures near environmental levels. 

There are sufficient data to determine that chromium or its compounds affect the immune system. More sensitive tests of the immune function after inhalation, oral, or dermal exposure to chromium or its compounds would be useful to determine the threshold levels for effects in humans. Additional studies that explore changes in cytokine levels (Snyder et al. 1996) caused by chromium exposure should prove helpful since they may provide mechanistic information as to how chromium may affect immune function. 

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