Evaluation of a cement dust generation and exposure chamber for rodents: blood heavy metal status, haematological variables and gastrointestinal motility in rats

Abstract

Exposure to cement dust has been documented to cause various occupational and long-term health complications both in human and animal. However, investigations on the extent of toxicity associated with cement dust exposure have been limited by lack of suitable model for controlled laboratory exposures. In this study, a glass house animal exposure chamber was fabricated using a plexi-glass and a blowing fan of adjustable revolution. Model simulations were validated using experimental data showing the effects of cement dust exposure on haematological indices, trace element status and gastrointestinal motility in rats. Thirty male Wistar rats were randomly divided into three groups. The unexposed group (n = 10) served as control while the other groups were exposed for five hours daily to cement dust (200g) at a revolution of 2400-3000rpm. Blood collected was analysed for some haematological variables as well as plasma concentrations of cadmium, lead, silicon, aluminium, manganese, calcium, iron and magnesium. Organ weights were measured and histopathological features of the kidney, lungs stomach and liver were assessed to determine the degree of tissue damage. Intestinal motility was assessed in vivo using the Charcoal meal method while colonic motility was studied by measuring the distance travelled by beads inserted 2cm into the distal colon through the anal opening. Data were expressed as Mean ± SEM, analysed using one-way ANOVA and p<0.05 was significant. Blood analysis from exposed rats on days 14 and 28 showed significant increase in concentrations of Calcium, Silicon, Manganese, Iron, Lead, Cadmium, Aluminium and magnesium compared with unexposed animals. Significant reductions were observed in haematocrit values, red and white blood cell counts after cement dust exposure. Also, significant increases were observed in the neutrophil-lymphocyte ratio and erythrocyte sedimentation rate in exposed rats compared with control. There was a significant decrease in organ weights - stomach, lungs, kidney when compared with control. Rats exposed to cement dust had significantly decreased small intestinal motility but increased colonic transit time. Histopathological examination from exposed rats revealed peribronchiolar infiltration by lymphocytes in the lungs while gastric gland was severely infiltrated by inflammatory cells. The results from this study are comparable to data obtained from earlier reported on haematological and heavy metals in humans occupationally exposed to cement.

Keywords: Cement dust, fabricated chamber, haematological indices and gastric motility

Afr. J. Biomed. Res. Vol. 22 (January, 2019); 79- 87