Recently the prevalence of obesity has increased dramatically across much of the world. Obesity, as a complex, multifactorial disease, and its health consequences probably result from the interplay of environmental, genetic, and behavioral factors. Several lines of evidence support the theory that obesity is programmed during early development and that environmental exposures can play a key role. We therefore hypothesize that the current epidemic might associated with the influence of chemical exposures upon genetically controlled developmental pathways, leading to metabolic disorders. Some environmental chemicals, such as PCBs and pesticide residues, are widespread in food, drinking water, soil, and they exert multiple effects including estrogenic on cellular processes; some have been shown to affect the development of obesity, insulin resistance, type 2 diabetes, and metabolic syndrome. To bring these lines of evidence together and address an important health problem, this narrative review has been primarily designed to address PCBs exposures that have linked with human disease, obesity in particular, and to assess the effects of PCBs on gene expression in a highlyexposed population. The results strongly suggest that further research into the specific mechanisms of PCBs-associated diseases is warranted.

The epidemic of type 2 diabetes mellitus (T2DM) and the possibility of it contributing to the risk of Alzheimer’s disease (AD) have become important health concerns worldwide and in Pakistan, where the co-occurrence of T2DM and AD is becoming more frequent. To gain insights on this phenomenon, a cross-sectional study was initiated. We recruited and interviewed 820 research participants from four cities in Pakistan: 250 controls, 450 T2DM, 100 AD, and 20 with both diseases. Significant differences between groups were observed for age (p < 0.0001), urban vs. rural locality (p = 0.0472) and residing near industrial areas. The average HbA1c (%) level was 10.68 ± 2.34 in the T2DM group, and females had a lower level than males (p = 0.003). In the AD group, significant relationships existed between education and family history. Overall, the results suggest that T2DM and AD were associated with both socio-demographic and environmental factors in Pakistani participants. Detailed molecular investigations are underway in our laboratory to decipher the differential genetic pathways of the two diseases to address their increasing prevalence in this developing nation.