Durham's lead problem

March 23

The Durham County Health Department learns that a routine blood test from a child contains high concentrations of lead.

April

Health officials launch an investigation to determine the contamination source.

Water from the kitchen faucet of the apartment in the Penrith Townhomes where the child had lived is found to contain lead at 837 parts per billion, nearly 60 times the federal limit considered safe.

Tap water samples from 32 other apartments in the complex are sent to the state lab in Raleigh. Nine are found to have high lead levels. Still, there is no public disclosure that a child was poisoned after drinking tap water.

May 19

The News & Observer reports about the lead poisoning and concerns about the toxic metal in the apartment complex's water.

May 30

Durham releases a statement stating that the "city's drinking water system and water supply system is safe." The problem with lead contamination is limited to lead-laced plumbing fixtures in the Penrith complex, the statement said. However, the city had not sampled homes outside the apartment complex to confirm this.

May 31

County health officials announce plans to screen homes within a one-mile radius of Penrith Townhomes for lead. Results released the following month show lead is found above the federal safety limit in more than 27 percent of the homes tested. City officials insist there is no evidence of a widespread problem.

June 13

State environmental health officials announce they will audit the city's program for detecting and preventing lead contamination. Of 70 samples collected by the county and sent to a state lab in Raleigh for testing, 37 percent contained lead above the federal limit. A more ambitious citywide study of 127 homes is launched.

June

Internal e-mail messages show state health officials officials consider issuing a public health advisory urging pregnant woman and children under 6 not to drink the city's water. The advisory is scrapped after Durham officials argue such a warning would not be fair because the city's test results had always complied with Safe Drinking Water Act.

June 30

Marc Edwards, a Virginia Tech engineering professor hired by the owner of the Penrith complex to study Durham's water, completes a report that suggests a chemical used in Durham's water treatment regime, ferric chloride, could be responsible for lead leaching. Durham had used ferric chloride at the larger of its two water treatment plants since 2003.

July 6

Durham ceases using ferric chloride, though officials continue to insist there is no conclusive link between their water and the lead contamination found in homes across the city. Other research suggests that a disinfectant still used in Durham, chloramine, can also dissolve lead in plumbing parts.

July-August

Durham conducts "special internal investigative sampling" of selected homes but does not share the results with state regulators.

Aug. 24

The Durham public school system disconnects selected drinking fountains at eight schools after tests find lead in the water. The concentration of lead in some fountains is as high as 118 times the federal safety limit of 15 parts per billion.