Bacterial growth occurs in four phases: lag, log (exponential), stationary, and death. Bacteria multiply most rapidly during the log phase. The six conditions that influence bacterial growth are: food, acidity, temperature, time, oxygen, and moisture. There are three main types of food hazards - biological, chemical, and physical. Biological hazards include bacteria, viruses, parasites, and toxins. Chemical hazards stem from toxic metals, pesticides, and cleaning chemicals. Physical hazards are foreign objects that contaminate food such as glass or metal shards. Proper food handling and sanitation can help reduce these food safety risks.