The Merriam-Webster medical dictionary defines a communicable disease as “an infectious disease transmissible (as from person to person) by direct contact with an affected individual or the individual’s discharges or by indirect means (as by a vector)”.  The listed conditions are indeed communicable (that is, their prevalence is a result of human interaction), but serve more as the vectors for diseases to become more prevalent in the population.  All of them occur as a result of peer and community influences, and can have positive or negative effects depending on the way in which they occur.

            If new foods are introduced to an area and become popular, they may eventually become less expensive than traditional sources of nutrition, thus pushing people with tight budgetary constraints to adopt them as their new sources of nutrition.  This can lead to disease if the new foods are less nutritious (often highly processed), or health benefits if they fill nutritional gaps (golden rice). 

            Physical activity (or lack thereof) often involves societal trends; if increases in technology or manufacturing abilities reduce the amount of jobs involving manual labor, the people affected may struggle with ways to replace the previous physical activity keeping them healthy.

            Automobile related issues are highly communicable.  If one person makes a reckless driving decision and gets into a crash, other innocent people could be involved and suffer ill effects.  Conversely, public health campaigns aiming to increase the usage of seatbelts could use person to person interactions to spread awareness and instigate change.

            Smoking, by its very nature, affects not just smokers but those around them.  People exposed to secondhand smoke also have an increased risk of developing health problems.

            As countries develop, I would imagine that the faster-paced lifestyles lead to a rise in stress among the population.  Stress levels can definitely be either increased or decreased via interactions with other people, making it communicable.

            Urbanization, in addition to causing positive and negative societal trends, has the effect of making people interact with others more frequently, thus promoting the spread of other communicable conditions.