Comparative cancer potency for silica from extrapolations of human and animal findings.
Goldsmith-DF; Ruble-RP; O'Klein-C
Scand J Work, Environ & Health 1995 Sep; 21(Suppl 2):104-107
An analysis of the cancer risk associated with silica (14808607) dust exposure based on extrapolations of laboratory animal and epidemiological data was performed. Data were taken from three laboratory animal studies in which F344-rats inhaled Min-U-Sil-5 quartz or DQ12 quartz dusts for 24 months in which induction of lung tumors was the outcome of interest and two epidemiological studies conducted in South African gold miners and California diatomaceous- earth workers which found a clear dose response for lung cancer caused by silica dust exposure. Cancer potency slopes (CPSs) and inhalation cancer potency slopes (ICPs) were calculated from both the experimental animal and epidemiological data using the computer program GLOBAL 86, which fit linearized multistage models to the experimental data. The CPSs obtained by extrapolating the laboratory animal data varied from 0.08 to 20.89mg/kg/day. The corresponding ICPs after normalizing to an inhaled quartz concentration of 1 microgram per cubic meter (microg/m3) varied from 2.9x10(-5) to 6.0x10(-3)microg/m3. The CPSs obtained by extrapolating the epidemiological data varied from 3.09x10(-4) to 1.16x10(-2)mg/kg/day assuming a working lifetime of 40 years (yr). The corresponding ICPs varied from 1.83x10(-7) to 6.75x10(-5)microg/m3 for a working lifetime of 40yr after normalizing to an inhaled quartz concentration of 1microg/m3. The authors conclude that based on extrapolations of laboratory animal and epidemiological data, continuous inhalation of 1microg/m3 silica dust by humans will yield a lung cancer risk characterized by ICPs of 2.9x10(-5) to 6.0x10(-3) and 1.8x10(-7) to 6.8x10(-5), respectively.
NIOSH-Publication; NIOSH-Grant; Pulmonary-system-disorders; Risk-analysis; Lung-cancer; Silica-dusts; Occupational-exposure; Computer-models; Epidemiology; In-vivo-studies; Laboratory-animals; Inhalation-studies;
Author Keywords: cancer risk assessment; comparing rat and human extrapolations; cristobalite; dose-response findings
Dr DF Goldsmith, Western Consortium for Public Health, 2001 Addison Street, Suite 200, Berkeley, CA, 94704, USA
Scandinavian Journal of Work, Environment and Health
University of California Davis, Davis, California