Toxicity of cigarette filter leachates on <i>Hymenochirus curtipes</i> and <i>Clarias Gariepinus</i> in Nigeria

Abstract

Tobacco, Nicotana tabacum is grown in over 100 countries, 80% of it is used to produce cigarette which causes numerous harms to the man’s health. The process of converting tobacco seeds into package cigarettes is energy sapping and destructive to ecosystem yet tobacco smoking is indiscriminate in Nigeria. The toxicants in cigarette when flown to pond/lake/river expose aquatic wildlife and other zooplanktons to danger of leachate poison when consumed. Therefore, research is critical in determining the detrimental effects of littering cigarette-butts on aquatic life in Nigeria. An evaluation of the toxicity of smoked and unsmoked cigarette-filter leachates was carried out on Hymenochirus curtipes and Clarias gariepinus. The physio-chemical properties and heavy metals concentration of the cigarette leachates were determined. The smoked cigarette-filter leachates had smoky odour, light-brown colour and a pH of 4.5, while the unsmoked cigarette filter-leachate was odourless, colourless with a pH of 6.0. The concentration levels of lead, chromium, iron, cadium and zinc were higher with silver and zinc lower in the smoked than the unsmoked cigarette-filter leachate. Mortality rates of Hymenochirus curtipes and Clarias gariepinus in both leachates increased with corresponding increase in concentration and exposure time, showing significant differences only after 72h and 96h exposures (p<0.05). However there was no death in the control experiment. The lethal response of Hymenochirus curtipes and Clarias gariepinus to the smoked filter-leachate was six times higher than the unsmoked filter leachate after 24h of exposure with LC50 and values of 8.73g/l. After 96h exposure, LC50 of 1.92g/l and 4.8g/l were obtained for the smoke and unsmoked filter leachate respectively (p<0.05) in which the smoked filter-leachate was approximately 2.5 times more toxic to Hymenochirus curtipes and Clarias gariepinus than the unsmoked-filter leachate. The result indicated that smoked cigarette-filter leachate had higher toxicity in Hymenochirus curtipes and Clarias gariepinus than the unsmoked cigarette-filter leachate. The heavy metals (Cadmium, Copper, Lead and Chromium) in Cigarette leachates in high concentration of large number of butts are toxic to the aquatic life, affecting biochemical and physiological compositions of the organisms.

Keyword: smoked-filter and unsmoked-filter leachate, toxicants, Hymenochirus curtipes and Clarias gariepinus