Investigation of Toxicity of Cigarette Butts Collected in Addis Ababa to Swiss Albino Mice

Bekele, Tigist Tefera (2016) Investigation of Toxicity of Cigarette Butts Collected in Addis Ababa to Swiss Albino Mice. Masters thesis, Addis Ababa University.

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Abstract

Background: Cigarette butts are the most common form of litter in the world; approximately 5.6 trillion cigarettes are smoked yearly worldwide. Over 7000 chemicals may be introduced to the environment in cigarette butts and smoke constituents. These include chemicals such as nicotine, carbon monoxide, hydrogen cyanide, polycyclic aromatic hydrocarbons, heavy metal ions, nitrosamines, ammonia, acetaldehyde, formaldehyde, benzene, phenol and acetone, over 70 of which are carcinogenic to humans. Environmental cigarette butts are toxic to microorganisms, fish, other marine organisms and birds, but no studies have been done on their toxicity to mammals. Methods: In this study the toxicity of cigarette butt leachates to Swiss albino mice was investigated, and the effects of cigarette butts with and without associated tobacco were compared. Cigarette butt leachates were made by soaking different numbers of cigarette butts in 250 mL of tap water overnight, and leachates were given to mice to drink. The weights of mice as well as amounts of food and fluids consumed were followed over time. Necropsies were performed and tissues were weighed and evaluated by histological staining with eosin and hematoxylin. Blood glucose and liver function tests (ALT, AST and ALP) were also measured. Results: Mice given high-concentration cigarette butt leachates during their growth from 6 weeks to 16 weeks preferred water over any of the leachates, whereas mice given lower butt concentrations of leachates representative of the relative frequencies of butt types in the environment drank butt leachates as well as water. Food intake was not affected by cigarette butt leachates. Mean fasting blood glucose and activities of serum liver enzymes were not different between mice given leachates or water to drink. The weights of the mice, as well as tissues (liver, lung, spleen, heart, kidney, epididymal fat pads) were significantly lower in mice that drank leachates with associated tobacco than in mice that drank water alone or leachates made from butts without associated tobacco. This suggests that a component(s) of tobacco is/ are responsible for reducing weight gain during mouse growth. Cigarette butt leachates had no effect on histopathology of liver, heart and kidney, whereas lung tissue of the mice that drank leachates made with tobaccoassociated butts showed increased air space volumes and alveolar fibrosis, compatible with pulmonary emphysema. Conclusions: Cigarette butts are toxic to laboratory mice, causing reduced weight gain during growth, reduced mass and size of tissues and organs, and pulmonary emphysematous changes. An average cigarette butt thrown into the environment contains 1.5 mg of nicotine, enough to potentially kill 15 mice. The implications of these studies to environmental animals in Ethiopia and elsewhere are discussed.

Item Type:	Thesis (Masters)
Subjects:	Q Science > QD Chemistry Q Science > QH Natural history > QH301 Biology R Medicine > R Medicine (General)
Divisions:	Africana
Depositing User:	Emmanuel Ndorimana
Date Deposited:	27 Jul 2018 12:57
Last Modified:	27 Jul 2018 12:57
URI:	http://thesisbank.jhia.ac.ke/id/eprint/8290

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