Cambridge can claim some enviable statistics when it comes to lead contamination in water and lead levels in children’s blood: residential and school drinking water well below government limits, and only 24 children – around 1 percent of those tested – with worrisome levels last year.

But the city has a disturbing gap. Around 20 percent of children under the age of 4 are not being tested at all for the metal, which can cause permanent deficits in thinking, behavior and academic achievement. This is true despite state law requiring that all kids be tested at least three times between the ages of 9 months and 4 years, and a requirement that parents provide evidence of testing before a child enters kindergarten.

The Cambridge Public Health Department was asked in April about the testing figures. Four months later, after repeated requests, the department was finalizing a response, a spokeswoman said.

Scott Zoback, then spokesman for the state Department of Public Health, said in June that the state enforces the requirement that kids be tested by investigating every “late reporting event” by doctors and possibly referring physicians with repeated violations to regulators. But Zoback didn’t address how the state handles instances when no test is performed.

The current agency spokesman, Omar Cabrera, did not respond to questions about how the state is trying to increase the percentage of children tested.

In good company

Cambridge isn’t alone in reporting lapses in child lead testing, and it does better than many other communities and the state as a whole – 76 percent of kids tested last year – though Massachusetts tests more kids than many other states and the nation. The most recent national figures posted by the U.S. Centers for Disease Control and Prevention and based on state reports show that in 2010, testing peaked at 17.7 percent of children under age 6, declining to 10 percent last year.  The agency says its data have limitations, though, such as not including all states.

And in general, public health officials appear unconcerned about the number of kids who aren’t tested. The CDC says on its website that state and local health officials focus their lead testing and prevention efforts on places where kids are likely to be exposed to lead: low-income neighborhoods with lots of old housing.

Testing, tract by tract

In Cambridge, the percentage of kids tested for lead varies by geographic area, and those areas with the most kids tested are not always the poorest.

A map showing testing percentages by census tract, provided by the state health department, shows that a sliver of land including the Massachusetts Institute of Technology and bordering the Charles River has the highest proportion of children tested: more than 99 percent of children between 9 months and 4 years old. Other census tracts with testing levels above 90 percent include the Mid-Cambridge neighborhood near the high school; Porter Square; a section of Area IV/The Port that includes part of two public housing projects; and a North Cambridge tract that includes part of Rindge Avenue, but not the portion near Alewife where there are several low-income housing developments.

A small East Cambridge tract near the Star Market shopping plaza had the lowest percentage of kids tested: 41 percent.

No safe level

Children absorb lead from old paint, contaminated soil, industrial effluent – even from their mothers while they’re in the womb. Since the 1960s, researchers have found effects of the metal at lower and lower blood levels.

In 1960, the CDC recommended that doctors act when the level was 60 micrograms per deciliter (µg/dL) or more. The standard dropped steadily, ending at 25 µg/dL in 1990. A year later it descended to 15 µg/dL, with the federal agency recommending that community officials act to reduce exposure in an area where children’s blood levels were 10 µg/dL.

Four years ago, the federal government adopted an even lower “reference value” of 5 µg/dL, based on findings that only 2.5 percent of American children tested for lead had levels above that value. In addition, the agency reiterated that “there is no safe level” of lead. The CDC recommended that test results at or above 5 µg/dL be reported to parents and that local officials try to reduce lead exposure in the community – for example, by removing lead paint from housing.

No federal money

Massachusetts followed suit and said it would add children with the lower level to a case management program that offers services such as retesting and advice about lead paint testing in the child’s home. But in a letter to doctors in 2012 announcing the 5 µg/dL level, former Gov. Deval Patrick said federal funding for the case management program had ended and asked physicians to provide the advice.

Cambridge results for last year show that 22 children had blood lead levels from 5 µg/dL to 9 µg/dL, and four had levels from 10 µg/dL to 24 µg/dL; none had levels at or above 25 µg/dL. The numbers above the abnormally high value of 5 µg/dL total 26 children, but the city reported 24 kids with “confirmed” levels above the reference value. One sample drawn from a vein, or two samples drawn from capillaries, produce a confirmed result, the state says.

Screening children for lead at an early age is important because an elevated result – even if it’ not high enough to require medical treatment – can alert doctors and parents to take steps to prevent further exposure to the metal. Doctors and public health officials recommend actions such as testing homes for lead paint and, if it’s found, keeping kids away from peeling and chipping paint; cleaning regularly; having children wash their hands before eating; and feeding kids a diet high in calcium and iron. Parents shouldn’t allow children to play in dirt near a home where lead paint was used – more commonly, houses built before 1978.

Drinking water

Lead contamination of drinking water has been in the news recently since scientists and residents of Flint, Mich., discovered extraordinarily high lead levels in city water caused by a decision to switch to cheaper water from the Flint River. The city’s water treatment plant didn’t add recommended chemicals to treat the more acidic water from the river. As a result, lead leached from old pipes and solder. It flowed through residents’ faucets, raising kids’ blood lead levels.

The Environmental Protection Agency estimates that drinking water can contribute as much as 20 percent of total exposure to lead in an adult, but 40 percent to 60 percent for infants drinking formula.

Cambridge drinking water is virtually free of lead when it leaves the water treatment plant at Fresh Pond; the metal can still get into water at the faucet because some homes have old, lead-lined service pipes connecting from the water main, and lead from solder joining interior pipes can leach into the water.

Homes and schools

Federal and state rules require the city to sample water at the faucet for lead. Large systems such as Cambridge must test the water at 100 homes, or 50 homes if they qualify for a reduced testing requirement by repeatedly meeting standards. Cambridge has met the qualifications for fewer tests and is also allowed to test water for lead every three years instead of six months, because of its performance.

In 2014, the most recent year when homes were tested, the highest lead level measured was 9 parts per billion; the government says 90 percent of samples must be 15 ppb or less.

The city also tests water at every public school once a year. The most recent tests last September showed only three schools where the metal was detected – Cambridgeport, Amigos and Tobin – with the highest level of 7 ppb, well below the limit.

---

This story was updated Oct. 13, 2016, to change several incorrect identifications of “parts per billion” of reported blood lead levels to the correct term: micrograms per deciliter, or µg/dL.