A new investigative report suggests that recently recorded lead poisoning rates in over 3,000 areas in the U.S. were twice as high when compared to Flint, Michigan, during the peak of that city’s drinking water contamination crisis.

The Flint water crisis occurred after the city switched its water supply in 2014. In September 2015, scientific studies showed that around 4-5 percent of children screened there had high blood lead levels.

In the latest investigative report, Reuters found vulnerable neighborhoods where testing showed the highest rates of children with elevated levels of lead in their blood. By relying on data obtained from state health departments and the U.S. Centers for Disease Control and Prevention spanning about a decade, Reuters found about 1,100 communities that had rates of lead blood levels that were at least four times higher than that found in Michigan.

According to the study, pockets within cities such as Baltimore, Cleveland and Philadelphia saw an increase of 40 to 50 percent in blood lead levels in the last decade.

In all, Reuters found 2,606 census tracts, and another 278 zip code areas, with a prevalence of lead poisoning at least twice Flint’s rate. Census tracts have an average of about 4,000 residents apiece, while zip codes average populations of 7,500.

Though requests for data records were placed in all 50 states, due to lack of data or inadequate responses, the Reuters map has limitations: the available data includes roughly 61 percent of the U.S. population in 21 states.

Exposure to lead, a heavy metal neurotoxin, can cause anemia, hypertension, renal impairment, immunotoxicity and toxicity to reproductive organs. Subjection to high levels can also cause coma, convulsions and even death, according to the WHO.

Elevated lead levels in children are particularly dangerous and can result  in a variety of symptoms like headaches, stomach pains and irreversible neurological and behavioral problems such as A.D.H.D and others. Several reports have also suggested that chronic lead exposure resulted in a measurable drop in IQ scores and some studies have even found a link between lead and increasing violent crime rates. 

As per the Centers for Disease Control and Prevention threshold, elevated lead levels were defined at any test result at or above 5 micrograms per deciliter, the same parameter adopted in the methodology of this study. The study also claimed that in several areas, children also go untested, which makes the tracking of poisoned children even harder.

Though the cause of lead poisoning is the same in Flint as it is for the other regions — crumbling paint, plumbing or industrial waste as well as remnants of the clean-up operation that began after the phasing out of lead from paint and gasoline in the late 1970s — areas other than Flint are not receiving the same kind of attention.

Almost $170 million, which is 10 times the CDC’s budget for assisting states with lead poisoning,  was directed for aid to Flint by Congress, according to Reuters.

And, while it is true that children’s average blood lead levels have dropped by more than 90 percent since the phasing out of lead from gasoline and paint, CDC still estimates that at least 4 million children in U.S. households are exposed to high levels of lead.