الفهرس 
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Abstract
Chromium is a generally abundant element in the earth’s crust and occurs in oxidation states ranging from Cr+2 to Cr +6, but only trivalent and hexavalent fonns are of biological sif:,rnificance . Trivalent chromium is the more common form found in nature and in biolob~cal material, and it is believed to be the essential form of the metal, serving as a component of a low-molecular weight organic complex called the glucose tolerance factor. Trivalent chromium and its compounds are considerably less toxic than the hexavalent compounds and neither corrosive nor irritating. However, hexavalent forms of chromate compounds are of greater industrial importance. Sodium and potassium chromate and dichromate are the principal substances for production of all chromium chemicals. The known hannful effects of chromium in human have been attributed to the hexavalent fonn, and it has been speculated that the biological effect of hexavalent chromium may be related to the reduction to trivalent chromium and the fonnation of complexes with intracellular macromolecules. Hexavalent chromium is locally irritating and corrosive due to its acidity and oxidizing potential and it causes chronic ulceration and perforation of the nasal septum and also causes chronic ulceration of other skill surfaces which is independent of hypersensitivity reaction on skin. Allergic chromium skin reaction readily occurs with exposure and is independent of dose. Exposure to dust or mist containing hexavalent chromium may cause chemical irritation of bronchial mucous membrane resulting in bronchospasm and in some rare cases may lead to asthma due to sensitization . Nowadays, chromium and its compounds are so extensively used and a fowing awareness of the effects of the chronic low level exposure to hexavalent and trivalent chromium and its compounds on the health of the workers has been developed, especially their dermatological, bronchopulmonary and carcinogenic effects. Therefore, the present study has been carried out in a trial to assess the health status of the workers occupationally exposed to chromimn and its compounds to suggest recommendations for proper preplacement and periodic medical workers examination for occupationally exposed to chromium and its compounds. The present cross-sectional study involved 200 male workers who were selected as follows: an exposed bTfOUP (n= 100) composed of 50 workers from El-Nasr tanning company, 50 workers from electroplating workshops and a control group of 100 workers who were selected from Edfina and I\~psi-Cola companies with the same demographic characterstics: age, edllcational.statlls and socioeconomic status as the exposed workers. All the participants were interviewed usmg a questionnaire (appendix) including occupational, family and smoking history, as well as history of any present or past systemic disease. The interview was followed by clinical examination for all exposed and control subjects with special emphasis on dermatology. Pulmonary functions were measured for all subjects usmg portable vitalograph R. model spirometer. The selected parameters were forced expiratory volume in the first second (FEV 1.0) and forced vital capacity (FVC) and, FEV 1.0/ FVC ratio. Patch test was applied for all exposed workers diagnosed to have contact dennatitis, their total number was 10 chromium plating workers. Blood samples were collected from each of the examined subjects I and half of the sample( 1.5 ml) was heparinized for the hematological analysis( i.e. complete blood picture) while the other half was allowed 10 clot at room temperature and the serum was separated and analyzed for nt:atinine, (test for renal function) gamma glutamyl transferase ( test fix liver function) as well as to assess chromium concentration. Spot urine samples were also collected from each participant to exclude diseased cases. The data were coded and transfered to special coding sheet and were statistically analyzed using the appropriate statistical methods. It has been found that the chromium plating workers showed si!,rnificantly higher prevalence of chronic bronchitis than tannery workers and than control subjects. However, no statistical significant difference was observed regarding other respiratory complaints. Chromium plating workers showed as well significantly higher prevalence of contact dermatitis than tmmery workers and control subjects. Meanwhile, no cases of chrome hole or skin ulcer have been detected among the studied exposed subjects. No statistical significant differences were observed regarding I circulatory, gastrointestinal, nervous, urinary or eye manifestation. The chromium plating workers also showed significantly lower mean hemoglobin levels than control group. On the other hand, both exposed groups showed a statistically sibrnificant higher mean concentrations of chromium in their plasma than control subjects. However no statistical significant difference has been elicited regarding the other hematological parameters. Regarding the pulmonary functions, a statistically significant reduction in FEY 1.0 among tannery workers and chromium plating workers was observed as compared to control groups. No significant differences have been elicited regarding FYC predicted between tannery workers, chromium plating workers and control groups. It has been concluded from the present study that chromium plating workers were more affected and suffered from occupational exposure to chromium and its compounds than tannery workers as well as chromium hexavalent but not chromium trivalent represents the most hazardous source of chromium exposure due to its oxidizing and acidic properties and its ability to cross cell membranes as well as its well known primary irritant and corrosive properties.^leng