According to a Center for Disease Control (CDC) report released late last week, bullet fragments can be a source of lead poisoning in Americans. When someone is shot, fragments from the round remain in their body, which can expose them to high doses of lead.

“An estimated 115,000 firearm injuries occur annually in the United States, and approximately 70% are nonfatal,” the report reads. “Retained bullet fragments (RBFs) are an infrequently reported, but important, cause of lead toxicity; symptoms are often nonspecific and can appear years after suffering a gunshot wound.”

Testing for lead exposure is frequently done based on a person’s job industry and their likelihood of being exposed to lead. Those who have sustained gunshot wounds, however, rarely receive testing for lead exposure, meaning they don’t know the full extent of harm to their body. The report mentions that “…routine testing of adults with RBFs is infrequent.”

Some states participate in the Adult Blood Lead Epidemiology and Surveillance (ABLES) program, which require healthcare providers and labs to report blood lead levels (BLL) test results to the state health department. The information provided to ABLES is also used by the CDC for these types of studies.

CNN spoke with those at the CDC who conducted the research:

The Centers for Disease Control and Prevention found that, overall, fewer than 1% of cases of adults with elevated blood lead levels were caused by retained bullet fragments. However, for those with the highest blood lead levels, nearly 5% of cases could be linked to bullets.

“There are no safe levels of lead in the human body,” said Debora Weiss, lead author of the report and an Epidemic Intelligence Service officer at the CDC. She added that exposure to lead can have both short- and long-term effects, ranging from a small change in organ function to symptomatic life-threatening toxicity.

“Current evidence shows that lead exposure even at very low levels — and we’re talking about (blood lead levels) around 5 micrograms per deciliter and lower — have been associated with decreased renal (kidney) function,” Weiss said.