الفهرس Only 14 pages are availabe for public view
 |  | from | 165 |  |  |
| | | from | 165 | | |
Abstract
Polyvinyl alcohol (synonyms, vinyl alcohol polymer, PVA, ethenolhomopolymer) is a water-soluble synthetic resin, prepared by the polymerization of vinyl acetate, followed by partial or complete catalysed hydrolysis. In this study , the effect of thermal degradation products of PVA was studied in Clarias gariepinius. The half lethal concentration of thermally decomposed PVA was 1.1 g/l. Fish were categorized into 4 groups : the first act as control , the second exposed to 1/2 half lethal concentration for 1 w ( short term intoxicated group) , while the third and the fourth exposed to 1/5 and 1/10 half lethal concentration for 6 w( long term intoxicated groups). The PVA exposed fish showed nervous manifestations, abnormal swimming behaviour in the form of erratic swimming and/or circling was also noticed beside abnormal skin disclouration in few cases and darkness in the others. The postmortem findings revealed, congestion and haemorrhages in all internal organs in addition to pale anaemic gills. Mortality rate was 50 % in short term PVA exposed group while was about 40 % and 30 % in fish groups exposed to 1/5 and 1/10 half lethal concentration of PVA during long term exposure.