Multiple studies have determined that consumption of hot dogs can be a risk factor for childhood cancer.
Peters et al studied the relationship between the intake of certain foods and the risk of leukemia in children from birth to age 10 in Los Angeles County between 1980 and 1987. The study found that children who ate more than twelve hot dogs per month had nine times the normal risk of developing childhood leukemia. 
Researchers Sarusua and Savitz studied childhood cancer in Denver and found that children born to mothers who consumed hot dogs one or more times per week during pregnancy had about double the risk of developing brain tumors. Children who ate hot dogs one or more times per week were also at higher risk of brain cancer.  Curing the Incurable: ... Best Price: $9.83 Buy New $18.89 (as of 01:20 EST - Details)
Bunin et al also found that children of mothers who consumed hot dogs during pregnancy had an increased risk of childhood brain tumors. 
How Do Hot Dogs Cause Cancer?
Most hot dogs contain preservatives called nitrites. During the cooking process, nitrites combine with amines naturally present in meat to form carcinogenic N-nitroso compounds. It is also suspected that nitrites combine with amines in the human stomach to form N-nitroso compounds. These compounds are carcinogens and have been associated with cancer of the oral cavity, bladder, esophagus, stomach, and brain. 
What About Vegetables That Contain Nitrites?
It is true that nitrites are commonly found in many green vegetables, especially spinach, celery, and green lettuce. However, the consumption of vegetables appears to be effective in reducing the risk of cancer. How is this possible? The explanation lies in the formation of N-nitroso compounds from nitrites and amines. Nitrite containing vegetables also have vitamins C and D, which help inhibit the formation of N-nitroso compounds.
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