Environmental epidemiology is a branch of epidemiology that is related to determining how environmental risks affect human health. This area tries to understand how different external risk factors can prevent or prevent disease, illness, injury, developmental abnormalities or death.

Genetic epidemiology is concerned with understanding heritable aspects of disease risk, individual susceptibility to disease, and ultimately with contributing to a comprehensive molecular understanding of pathogenesis. The massive investment and expansion of human genetics, if it is to return value for the common good, must be integrated into public health functions. The human genome epidemiology network has been established to promote the use of genetic knowledge in terms of genetic tests and services for disease prevention and health promotion.

Cancer Epidemiology represents the investigation of elements in responsible of the inception, metastasis and guess of different sorts of malignant growth. Epidemiological research discoveries on disease can encourage the detailing of appropriate helpful treatment techniques and preventive medicines for cancer. It is the exposure to specific chemical and physical agents is potentially one of the most important ways in which analytical epidemiologic methods can contribute to the knowledge of cancer etiology.

Nutritional epidemiology is one of the younger disciplines in epidemiology. This may be partially due to the difficulties in measuring diet as an exposure. Diet and physical activity are arguably the most difficult exposures to assess in observational research and are plagued by considerable measurement error. Hence we are all exposed, and the variation may be more subtle than with other, more distinct exposures such as smoking or use of hormone replacement therapy.

Molecular epidemiology is a multidisciplinary field combining molecular biology methods and epidemiological design embracing also such fields as cell biology, biochemistry and statistics. It aims at developing molecular markers to aid in revealing exposures, setting diagnosis, detection of early disease, follow-up of treatment and individual susceptibility of diseases. In molecular epidemiology, research is done in many cases among healthy people with one of the main aims being to reveal individual risk, and studies are often genetic by nature. Consequently, there are important ethical aspects to consider on one hand to protect people, and on the other hand, to increase understanding of the positive implications

Cardiovascular disease (CVD) is a major cause of morbidity and mortality worldwide, with the lifetime risk exceeding 60%. Major advances in cardiovascular epidemiology over the last 4 decades have improved our understanding of the pathogenesis of CVD, with the identification and treatment of several major risk factors. Thus, cardiovascular epidemiology is confronted by a dualism: unprecedented opportunities for new research directions amid a growing uncertainty about its potential value and a pressure to do more and be more accountable.

The Psychiatric epidemiology has done little to illuminate either the etiology or the environmental factors that create mental illnesses. Because of the limits of its knowledge base, the policies stemming from epidemiological studies have served to justify the predominant ideological and administrative interests of psychiatrists, researchers, and policymakers. The lack of an adequate system of classification of mental illnesses has been the primary factor limiting the development of Psychiatric epidemiology and, consequently, its usefulness for developing effective public policy toward mental illnesses.

Epidemiology has provided a scientific foundation for public health and disease prevention. Epidemiology has contributed to major scientific discoveries such as the relationship between cigarette smoking and common diseases. Yet, the observational nature of much of epidemiologic research has attracted criticism including excess expense, repudiated findings, that offer small incremental, knowledge, inability to innovate at reasonable cost, and failure to identify research questions with the greatest merit.

The recent research shows that cumulative neighbourhood socioeconomic disadvantage was associated with increase in the odds of developing diabetes at middle age, with a dose-response association; those exposed to neighbourhood socioeconomic disadvantage for a shorter duration showed a less increased risk. The association remained after controlling for individual socioeconomic status. The results show that the effect of neighbourhood disadvantage becomes visible in childhood (poor diet), adolescence (low physical activity, increased prevalence of daily smoking) and early adulthood.