It is believed that half the Byzantine Empire was destroyed in the 6th century, a total of 100 million deaths. Such large fluctuations in population size over long periods greatly compound the difficulty of estimating the number of people who have ever lived. By 1800, however, world population had passed the 1 billion mark, and it has continued to grow since then to the current 7 billion.
There are many steps during the process of preparing and serving food in which time and temperature must be controlled. Harmful microorganisms grow well in foods held between temperatures of 41 degrees Fahrenheit and 135 degrees Fahrenheit. This temperature range is also known as the Temperature Danger Zone (TDZ). The less time foods spend in the TDZ, the less time harmful microorganisms have to grow.
1 Keep hot food hot and cold food cold. Always use a thermometer to check food temperatures.  Potentially hazardous foods must pass through the temperature danger zone as quickly as possible.