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Products Carcinogenic effects |
Crystalline silica dust is listed by IARC in Group 1 as known to cause Lung cancer in humans, if inhaled Risk of cancer depends on duration And level of exposure.
A SILICOSIS The major concern is silicosis,caused by the inhalation And retention of respirable crystalline silica dust.Silicosis can exist in Several forms,chronic(or ordinary),accelerated,or acute.Chronic or Ordinary Silicosis (often referred to as Simple Silicosis) is the most Common form of silicosis ,and can occur after many years of exposure To relatively low levels of airborne respirable crystalline silica dust.It is Further defined as either simple of complicated silicosis.Simple silicosis Is characterized by lung lesions(shown as radiographic opacities) less
Than 1 centimeter in diameter,primarily in the upper lung zones.Often, Simple silicosis is not associated with symptoms,detectable changes in Lung function or disability.Simple silicosis may be progressive and may Develop into complicated silicosis or progressive massive fibrosis (PMF).Complicated silicosis or PMF is characterized by lung lesions (shown as radiographic opacities) grater than 1 centimeter in diameter Although there may be no symptoms associated with complicated
Silicosis or PMF , the symptoms, if present,are shortness of breath,
Wheezing,cough and sputum production Complicated silicosis or PMF may be associated with decreased lung Funcation and may be disabling.Advanced complicated silicosis or PMF May lead to death.Advanced complicated silicosis or PMF can result in Heart disease secondary to the lung disease(cor pumonale). Accelerated Silicosis can occur with exposure to high concentrations of Respirable crystalline silica over a relatively short period,the lung . Lesions can appear within five(5) years of the initial exposure.The
Progression can be rapid .Accelerated silicosis is similar to chronic or Ordinary silicosis,except that the lung lesions appear earlier and theProgession is more rapide Acute Silicosis can occur with exposures to very high concentrations of Respirable crystalline silica over a very short time period,sometimes as Short as a few months. The symptoms of acute silicosis includes Progressive shortness of breath,fever,cough and weight loss.Acute Silicosis is fatal.
B.CANCER IARC –The International Agency for Research on Cancer (‘’IARC”) concluded that there was “sufficient evidence in Humans for the carcinogenicity of crystalline silica in the forms of quartz Or cristobalite from occupational sources is Carcinogenic to human (Group1)”The IARC evaluation noted that “carcinogenicity was not dected in all industrial circumstances studies. Carcinogenicity may be dependent on inherent characteristics of the Crystalline silica or on external factors affecting its biological activity or Distribution of its polymorphs.” For further information on the IARC Evaluation,see IARC Monographs on the Evaluation of Carcinogenic
Araisks to Humans,Volume 68,”Silica,Some Silicates…..”(1997). NTP.The National Toxicology Program ,in its Ninth Annual Report on Carcinogens,classified” silica,crystalline (respirable)” as a known
Human carcinogen. OSHA-Crystalline silica (quartz) is not regulated by the U.S. Occupational Sfety and Health Administration as a carcinogen.There Have been many article published on the carcinogenicity of crystalline Silica,which the reader should consult for additional information,the Following are examples of recently published articles.
(1)”Crystalline Silica and Lung Cancer The Problem of Conflicting Evidence,” Indoor Built Environ,Volume 8,pp.121-126(1998);(2) Crystalline Silica and the risk of lung cancer on the potteries,” Occup Environ.Med,Volume 55,pp.779-785(1998); (3) “ Is Silicosis
Required for Silica –Associated Lung Cancer?”, American Journal of Industrial Medicine,Volume 37, pp. 252-259(2000);(4)” Silica Silicosis ,and Lung Cancer: A Risk Assessment,”American Journal of Industrial Medicine,Volume 38 pp. 8-18(2000); (5)”Silica ,Silicosis, And Lung Cancer: A Response to a Recent Working Group Report,” Journal of Occupational and Environmmental Medicine,Volume 42,pp. 704-702(2000).
C.AUTOIMMUNE DISEASES There is evidence that Exposure to respirable crystalline silica (Without silicosis) or that the Disease silicosis is associated with the increased incidence of several Autoimmune disorders,---scleroderma, systemic lupus erythematous, Rheumatoid arthritis and diseases affecting the kidneys.For a review of The subject the following may be consulted; “Occupational Exposure Crystalline Silica And Autoimmune Disease,” Environmental Health Perspectives,Volume 107, Supplement 5, pp.793-802 (1999): “Occupational Scleroderma,” Current Opinion In Rheumatology,Volum 11.pp.490-494 (1999),
D.TUBERCULOSIS Individuals with silicosis are at increased risk to Develop pulmonary tuberculosis,if exposed to persons with Tuberculosis.The following may be consulted for further information; Occupational Lung Disorders,Third Edition,Chapter 12, entitled “Silicosis and Related Diseases,” Parkes,W.Raymond (1994);”Risk of Pulmonary tuberculosis relative to silicosis and exposure to silica dust In South African gold miners,”Occup Environ Med,Volume 55,pp.496-502(1998)
E. KIDNEY DISEASE There is evidence that exposure to respirable
Crystalline silica (withoutsilicosis)or that the disease silicosis is End stage renal disease.For additional information on the subject,the Following may be consulted;”Kideny Disease and Silicosis” Nephron Volume 85,pp,14-19(2000). |