MILWAUKEE — The Milwaukee Health Department has no record it conducted environmental investigations at more than 100 homes where children had elevated lead levels in their blood, according to an audit released Monday.

The report is a response to the health agency’s revelation earlier this month that it could not say whether it sent follow-up letters to more than 6,000 families whose children tested positive for high lead levels.

The audit said the Childhood Lead Poisoning Prevention Program is “deficient in several areas,” citing staffing shortages, inadequate training, high turnover due to low morale and shoddy record-keeping. The agency’s troubles led to the Jan. 11 resignation of its commissioner, Bevan Baker. Mayor Tom Barrett ordered the audit.

“I think there is shared responsibility. Obviously as mayor, the buck stops at my desk and I understand that,” Barrett said at a news conference after the report’s release Monday night.

Lead is a powerful neurotoxin that causes significant harm, including speech and language delays, behavioral problems and death in rare cases.

The Centers for Disease Control and Prevention recommends taking action for blood lead levels above 5 micrograms per deciliter. From 2015 through 2017, the Milwaukee Health Department should have sent letters to 6,022 parents of children who tested above that level, but the agency’s electronic records document only 1,500 letters were sent.

Every year, about 25,000 children under 6 in Milwaukee are tested for lead, most of them by primary care physicians responsible for notifying them of the results, according to the audit. Nevertheless, the city also sends letters to parents of children who tested above the level set by the CDC, providing educational materials and prevention information.

The audit notes that the department has made “great progress” over the past 20 years with its mitigation efforts, reducing the number of children who tested at 10 micrograms per deciliter or more to 3.3 percent, compared to nearly 32 percent in 1997.

But there are still major causes of concern. State law requires investigations to determine the primary source of lead exposure at homes above 20 micrograms per deciliter. However, the audit found documentation for only 201 of the 320 homes that required investigations.

Children with levels higher than 45 micrograms per deciliter qualify for chelation therapy at home or a hospital to remove lead. In those cases, the city’s health department is supposed to ensure children are returning to a lead-safe environment, but the audit found that didn’t happen in at least two cases from 2015 through 2017. There were 32 cases requiring chelation therapy during that time.

Milwaukee Common Council members have expressed frustration with Barrett in recent weeks and last week refused to approve his nominee for interim commissioner of the department.

“These problems did not start overnight,” said Alderman Mark Borkowski, noting Barrett has been in office since 2004. “So the fair question is, how long has this been going on and who’s running the show? This is a dereliction of duty. You’ve got no leadership as far as that department is concerned.”