If consumers frequently eat foods that are preserved with formalin, it will over time can cause irritation to the stomach so the blood can cause vomiting, or diarrhea mixed with blood, urine or blood and could also potentially cause death. But this rarely happens, because it required a large dose of formalin.The most common is chronic poisoning due to eating foods that are often preserved with formalin, is usually damaged kidneys or can cause cancer in the future.