Analytical Methods for the Quantification of Persistent Organic Pollutants in Serum and Nicotine Enantiomers in Electronic Cigarettes

Abstract

Obesity and tobacco use are two major risk factors for non-communicable diseases in Lebanon. In this thesis, studies focused on understanding the role and determining the levels of certain components that contribute to these health risks. One of the factors leading to obesity is the exposure to persistent organic pollutants (POPs), especially during fetal development. POPs, such as polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs), are known to be endocrine disrupting chemicals that interfere with metabolism and disrupt normal homeostatic controls over adipogenesis and energy balance. In this study, a gas chromatography method that can be used to measure POPs in serum samples collected from the cord blood and maternal blood is developed. In addition, a systematic review and meta-analysis is performed to analyze the associations between prenatal exposure to POPs and childhood obesity. Results obtained from the systematic review and meta-analysis indicated that prenatal exposure to DDE, but not PCBs, was significantly associated with an increase in BMI z-score and overweight risk in childhood.

Tobacco use, on the other hand, is associated with various health effects. For this reason, the Tobacco Control Act provided the Food and Drug Administration authority to regulate all tobacco products. As a result, manufacturers of electronic cigarettes (ECIGs) started using synthetic nicotine instead of tobacco-derived nicotine, since synthetic nicotine was not mentioned as part of the regulation. Thus, high interest in discerning between tobacco-derived and synthetic nicotine has emerged. Tobacco-derived nicotine is mainly found as (S)-nicotine (>99%), while synthetic nicotine usually contains a racemic mixture 50:50 of (R) and (S) enantiomers. In addition, nicotine enantiomers are known to be pharmacologically and toxicologically different. (R)-nicotine being less toxic than the (S) enantiomer, might be used as therapeutic agent for neurodegenerative diseases and tobacco smoking addiction. In this study, a liquid chromatography method that can be used to quantify (R) and (S) enantiomers of nicotine in e-liquid and aerosol samples from ECIGs is developed. Results obtained from the analysis of nicotine enantiomers indicated that (R)/(S) interconversion does not take place during vaping and the form of nicotine, whether (R) or (S), that enters the body will be the same as that initially present in the e-liquid.