HEALTH EFFECT OF ASH FROM COAL GASIFICATION AND INTERACTION WITH CADMIUM IN RATS
T. MALJKOVIC M. BLANUSA K. KOSTIAL Institute for Medical Research and Occupational Health, MoSa Pijade 158, 41000 Zagreb, Yugoslavia
ABSTRACT The scope of this work was t o determine the health effect of ash from coal gasification plant in conditions of continuous oral exposure to this ash in food, and toxic heavy metal - cadmium in drinking water to evaluate the potential interaction in their health effects. The experiment was performed on albino rats of both sexes. T h e y received ash (5%) in the diet and cadmium as chloride (100 p p m Cd) in drinking water. The diets (with or without addition of ash) and drinking water (with or without cadmium) were given ad libitum during the 16 weeks (experimental period). A t the end of the exposure period the body weights, organ weights and trace elements (cadmium, zinc and iron) in kidneys and liver were measured. Trace elements were determined by flame atomic absorption spectrophotometry (Beckman) after wet ashing of the organs with nitric acid. From the results obtained it is evident that feeding the rats with food containing ash decreased body weights of animals of both sexes and lowered the concentration of iron in liver and kidneys, It does not affected relative organ weights and concentration of zinc in liver and kidneys. W h e n cadmium was given in drinking water with normal food the body weights o f animals were lower especially in males, and relative organ weights were not affected. Concentrations of essential elements were changed - zinc was significantly elevated and iron seemed to be lower. Simultaneous feeding ash in food and cadmium in drinking water resulted in additional effect on observed parameters: body weights were lower, relative organ weights were higher, cadmium concentration in organs was higher and iron concentration in kidneys and liver were lower. Eowever, this simultaneous exposure did not affect morbidity and mortality of animals.
1. INTRODUCTION The ash (slag) is the unburnable coal residue left over after the coal gasification process. This ash is a complex mixture of inorganic substances which could cause a health hazard and might also interact with other toxic metals already present in the environment. Our earlier results with rats showed that the ash itself from a Lurgi coal gasification plant at Kosovo near Pristina in Yugoslavia given t o the animals in the diet does not present a health hazard [l,21 although it contains many toxic elements. In this work we investigated possible interaction of gasifier ash with cadmium, since both are likely to occur in increased concentrations in the human environment.
The experiment was performed on six-week-old albino rats (of both sexes) from the Institute’s breeding farm. The rats were housed in plastic cages, and divided into two groups: the group on standard diet (diet A) and the group with the addition of 5.0% of the coal ash to the standard diet (diet B). The standard diet was prepared by ‘Pliva” Pharmaceutical Works in Zagreb. The nutritional composition of the diet, and the analytical data, as well as the sampling and treatment of the ash have already been reported 11, 21. Each group was again divided into four subgroups each consisting of males and females (6-19 in each group) given deionised drinking water with or without addition of 100 ppm of cadmium as chloride. The diets and drinking water were given, ad libitam, during the 16 week experimental period. A t the end of exposure period body weights, organ weights, and trace elements (cadmium, zinc and iron) in kidneys and liver were measured. Trace elements were determined by flame atomic absorption spectrophotometry (Beckman) after wet ashing of the organs with nitric acid. Details of the methods used were already described [3, 41.
Tab. 1. Organ concentrations of cadmium (pg/g wet weight) of rats fed the standard diet with or without 5% ash and exposed to cadmium in drinking water
49.7f2.9 (10) 27.1f1.6 70.3*4.4 (10) 32.9f1.4
51.0f1.8 (16) 42.1 zk
77.2f5.4 (16) 53.0
Results are presented as arithmetic means f SEM.Number of animals in brackets Diet A - standard laboratory diet Diet B - standard laboratory diet which contained 5% gasifier ash Values obtained on diet B were compared with values on diet A ( x x P < 0.001)
3. RESULTS AND DISCUSSION Body weights of rats fed the 5% ash diet (diet B) was about 16% lower in males and about 12% in females compared with controls (diet A). Cadmium given alone in drinking water decreased body weights by about 5%. In groups fed diet B and cadmium the effect on growth was additive. This effect was more pronounced in males (28%) than in females (20%). Relative wet kidney and liver weights (percentage of body weights) were significantly increased in male and female rats fed diet B and cadmium in drinking water. Ash in diet or cadmium in drinking water given alone, did not change relative organ weights. Organ concentrations of cadmium in cadmium exposed groups (Tab. 1) were from 50-77 pg/g wet weight in kidneys and about 27-33 pg/g in liver. The addition of ash in diet did not change the concentration of cadmium in kidney. However, in the liver of animals fed diet B the level of cadmium was significantly higher (42-53) than in animals fed diet A (27-33). Organ concentrations of zinc (Tab. 2) in cadmium exposed animals were significantly higher (about a factor of 2). The addition of ash in diet caused almost no Tab. 2. Organ concentrations of zinc ( p g / g wet weight) in rats fed the standard diet with or without 5% ash and with or without addition of cadmium to drinking water Controls Diet
Drinking water with
cadmium (100 ppm) Kidneys
70.6f 5.4** 60.6f0.8**
M 34.6f3.3 (7) 116.9 f 20.2** (7) F 33.0f1.6 62.6 =k 4.6*' (6) (7) Res ts are presented as arithmetic means f SEM. Number of animals in brackets Diet A - standard laboratory diet Diet B - standard laboratory diet which contained 5% gasifier ash Control animals on diet B were compared with control animals on diet A ("P < 0.01) Animals exposed to cadmium in drinking water were compared with respective controls on diet A or diet B ('*P < 0.001) Diet B
54 Tab. 3. Organ concentrations of iron (pg/g wet weight) in rats fed the standard diet with or without 5% ash and with or without addition of cadmium to drinking water
Drinking water with
cadmium (100 ppm) Kidneys
184f15”” (7) 178*17”” (15) (7) 326523”” (17) 412f67” Results are presented as arithmetic means SEM. Number of animals in brackets Diet A - standard laboratory diet Diet B - standard laboratory diet which contained 5% gasifier ash Control animals on diet B were compared with control animals on diet A (“P < 0.01, Diet B
P < 0.001)
Animals exposed to cadmium in drinking water were compared with respective controls on diet A or diet B (**P< 0.001)
change in zinc concentrations of organs. Organ concentrations of iron in cadmium exposed groups (Tab. 3) were always lower but significantly lower only in the liver of male and female rats on diet A. Ash in diet given alone caused significantly lower iron concentration in both organs and in both sexes. When cadmium in water and ash in diet were given simultaneously, lowest iron concentrations were observed in both organs i.e. the effect was additive.
From the results obtained it is evident that feeding the rats with food which contains 5% ash from a coal gasification plant during 16 weeks results in significantly lower body weights in rats of both sexes. It does not affect relative organ weights, the concentration of zinc in organs, but it lowers significantly the concentration of iron in kidneys and liver which is in agreement with our previous findings [Z]. When cadmium was given t o animals in drinking water with normal food during the same period of time, the body weights of animals were lower especially in males.
55 Relative organ weights were not affected. Concentrations of essential elements were changed: zinc was significantly elevated and iron seemed to be lower. These changes are in general agreement with results published by other authors [5, 61. Feeding both, ash in food and cadmium in drinking water resulted in additional effect on almost all parameters: lower body weights, higher relative organ weights, higher cadmium concentrations in liver and lower iron concentration in kidney and liver. Simultaneous oral exposure t o rather high levels of ash and cadmium caused, however, no additional effect on morbidity and mortality of animals.
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