TOXICOLOGICAL PROFILE FOR CHROMIUM - Davidborowski.com

CHROMIUM 162. HEALTH EFFECTSuncertainties inherent in the application of the procedures to derive less than lifetime MRLs. As anexample, acute inhalation MRLs may not be protective for health effects that are delayed in developmentor are acquired following repeated acute insults, such as hypersensitivity reactions, asthma, or chronicbronchitis. As these kinds of health effects data become available and methods to assess levels ofsignificant human exposure improve, these MRLs will be revised.A User's Guide has been provided at the end of this profile (see Appendix B). This guide should aid inthe interpretation of the tables and figures for Levels of Significant Exposure and the MRLs.2.2.1 Inhalation ExposureDue to the extremely high boiling point of chromium, gaseous chromium is rarely encountered. Rather,chromium in the environment occurs as particle-bound chromium or chromium dissolved in droplets. Asdiscussed in this section, chromium(VI) trioxide (chromic acid) and soluble chromium(VI) salt aerosolsmay produce different health effects than insoluble particulate compounds. For example, exposure tochromium(VI) trioxide results in marked damage to the nasal mucosa and perforation of the nasal septum,whereas exposure to insoluble(VI) compounds results in damage to the lower respiratory tract.2.2.1.1 DeathNo studies were located regarding death in humans after acute inhalation of chromium or chromiumcompounds. An increased risk of death from noncancer respiratory disease was reported in retrospectivemortality studies of workers in a chrome plating plant (Sorahan et al. 1987) and chromate production(Davies et al. 1991; Taylor 1966) (see Section 2.2.1.2, Respiratory Effects). However, a number ofmethodological deficiencies in these studies prevent the establishment of a definitive cause-effectrelationship. Retrospective mortality studies associating chromium exposure with cancer are discussed inSection 2.2.1.8.Acute inhalation LC 50 values in rats for several chromium(VI) compounds (sodium chromate, sodiumdichromate, potassium dichromate, and ammonium dichromate) ranged from 29 to 45 mgchromium(VI)/m 3 for females and from 33 to 82 mg chromium(VI)/m 3 for males (Gad et al. 1986). Acuteinhalation LC 50 values for chromium trioxide were 87 and 137 mg chromium(VI)/m 3 for female and malerats, respectively (American Chrome and Chemicals 1989). Female rats were more sensitive than malesto the lethal effects of most chromium(VI) compounds except sodium chromate, which was equally toxic