A cottage industry that employed people, including many mothers, to extract poisonous lead from used car batteries has been blamed for the deaths of nearly 20 children in a Senegalese fishing town.

The World Health Organization pressed Tuesday for quick action to decontaminate the town of Thiaroye Sur Mer, where 18 children died mysteriously between October and February.

The rash of deaths concentrated in one neighborhood of Thiaroye Sur Mer prompted the Senegalese government to run blood tests on relatives of the dead children, said Dr. Hassan Yaradou, a Health Ministry official.

Mothers and siblings of the deceased were found to have lead levels of 1,000 micrograms per liter, according to a WHO team that last week conducted a follow-up investigation into the deaths.

A concentration of 100 micrograms per liter is enough to impair brain development in children and 700 micrograms is considered to require immediate treatment, the organization said.

Yaradou said the source is thought to be a local business that breaks down car batteries and extracts their lead to resell. The practice is common in developing countries, where many without electricity use car batteries to power lights and televisions, and where few hear health warnings about lead poisoning.

Many of those breaking apart the batteries were mothers who worked with young children strapped to their backs or playing nearby, said Joanna Tempowski, coordinator of the WHO’s investigation team.

Tempowski said the lead levels appeared to have gotten so concentrated in the town because the women took the extraction one step further _ sifting the dirt underneath their workspace to recover any lead that had fallen, with the side effect of filling the air with lead particles that people inhaled.

“People didn’t know the harm it could cause,” she said.

Thiaroye Sur Mer is a fishing town just outside Senegal’s capital, Dakar.

About 950 people have been “continuously exposed through ingestion and inhalation of lead-contaminated dust” in the neighborhood, a WHO statement said. It added that many of the local children showed signs of neurological damage but did not give specific details.

The Health Ministry’s Yaradou said the battery business was shut down soon after the contamination was discovered and the government has conducted a preliminary cleanup, but much remains to be done.

Tempowski said the WHO would work with the Senegalese government on cleanup and treatment and was seeking international donations for the project.