Massachusetts made slight improvement over the past four years in its efforts to remove lead from school drinking water, and environmental advocates believe proposed legislation would send the Bay State soaring to the top of the class.

The U.S. PIRG Education Fund and Environment America Research & Policy Center published a new report Thursday grading all 50 states and Washington, D.C. on their work to protect students from lead-tainted water at school, the first time those groups have rolled out state-by-state assessments since 2019.

Massachusetts landed a D grade in the 2019 iteration and improved slightly to a C- in the latest version, which MASSPIRG Legislative Director Deirdre Cummings attributed to "incremental policy steps toward safer drinking water for kids at school."

That still put the Bay State on better footing than most other states. Twenty-seven states earned F grades for their lead prevention efforts in school water and eight received a D.

Washington, D.C., which authors said is "the only jurisdiction in the country to require installation of lead-removing filters at every drinking water tap in schools," led the pack with a B+.

Analysts praised Massachusetts for having "the most robust voluntary program in the nation" with more than seven in 10 districts participating. The state provides free comprehensive testing and technical assistance to help schools and child care centers identify lead levels in their drinking water, and although participants are not required to take action if they detect elevated lead presence, the Department of Environmental Protection "strongly recommends" steps such as replacing pipes, posting signage or shutting off taps in those cases, according to a state FAQ.

"The Commonwealth has also allocated $5 million in funding for installing filtered water stations and other solutions," authors wrote, noting that utilities such as the Massachusetts Water Resources Authority have also collectively committed more than $100 million toward replacing lead service lines.

Beacon Hill is grappling with major environmental policy questions, with efforts to clean the energy grid and slash greenhouse gas emissions on center stage in recent years. Some lawmakers — with the support of groups like MASSPIRG — are pushing to place new focus on the impact of pollutants, such as chemicals known as PFAS present in many manufactured goods.

Among tens of thousands of taps tested in more than 1,700 Bay State schools and child care centers since 2016, more than 80 percent had lead present, according to Department of Environmental Protection data cited by MASSPIRG. More than half of those had lead above the one part per billion level recommended by the American Academy of Pediatrics.

Experts warn that lead exposure can create a range of health problems for children. Alan Woolf, medical director of the Pediatric Environmental Health Center at Boston Children's Hospital, said in a statement provided by MASSPIRG that lead is "harmful to children's learning, their IQ, their behaviors, and their growth and development."

"We should eliminate ALL background sources of their possible exposure to lead, including drinking water fountains and bubblers at daycare centers, preschools and schools," Woolf said.

MASSPIRG and other environmental advocates on Thursday pitched legislation from Rep. Kate Lipper-Garabedian and Sen. Joan Lovely (H 851 / S 526) as a way to get a better handle on the impacts of lead in school drinking water.

The bill's provisions include a requirement for schools and child care centers to deploy lead-removal filters on faucets used for drinking and cooking, a call for districts to remove lead plumbing where feasible, and a mandate for any drinking water tap or faucet where lead is detected at a concentration greater than one part per billion to be shut off.

The legislation would allow the state to deploy funding from a water pollution abatement fund administered by the Massachusetts Clean Water Trust Fund to help offset costs.

Lovely said those changes would minimize exposure to a substance that can cause "debilitating and irreparable damage to [students'] developing brains and bodies."

"Massachusetts is a leader in public education on the cutting edge of student development and advancement. Despite these gains, many of our children attend school in older buildings, where outdated plumbing puts them at risk of lead ingestion," the Salem Democrat said in a statement. "This cannot continue."

Authors behind the state rankings pointed to the Lovely and Lipper-Garabedian bill as a major proposal, saying its passage would bump their grade of Massachusetts from a C- to an A.

"A key public health milestone included banning lead in gasoline and in paint," Cummings said. "It's long past time for us to 'get the lead out' of our water delivery systems -- especially where our kids go to learn and play each day."