Students may be consuming unsafe levels of mercury with their tuna fish sandwiches at the school lunch table, according to tests conducted in Massachusetts and 10 other states.

In a report called “Tuna Surprise,” a Vermont-based environmental group advises school officials and parents not to serve any albacore tuna to children and to limit consumption of light tuna to twice a month for most children and only once a month for those weighing under 55 pounds.

Researchers commissioned by the Mercury Policy Project, which works to lower mercury levels in the environment, found triple the amount of mercury in albacore compared with light tuna.

Mercury is a neurotoxin that can damage the developing brain of children and fetuses. Power plants and incinerators emit the metal into the air, and the pollutant can be carried thousands of miles before falling to the ground and washing into waterways. Fish then accumulate the mercury over time. In Massachusetts and many neighboring states, pregnant woman and children are urged not to eat fish from many waterways because of the mercury danger.

“It’s unfortunate that this otherwise healthy food is contaminated with toxic mercury and that parents and schools need to keep it from appearing too frequently on the menu,” said Elizabeth Saunders, Massachusetts legislative director for Clean Water Action, which co-released the report. She said there was good news in the study because it can be easy to reduce exposure.

The Mercury Policy Project tested the mercury content of 59 samples, representing eight brands of tuna sold to schools in 11 states, including Massachusetts. Mercury levels were consistent with levels found in tuna sold in grocery and seafood stores, but the report said the findings were troubling because American schoolchildren eat twice as much tuna as they do any other kind of fish; it is a staple in many school lunch programs.

Study sponsors were quick to point out that the research did not mean all children were at risk. “Most children are already consuming only modest amounts of tuna and are not at significant risk,” said Michael Bender, the project’s director. “So the focus really needs to be on kids who eat tuna often, to limit their mercury exposure by offering them lower-mercury seafood or other nutritious alternatives.”

The report recommends:

■  Children weighing more than 55 pounds should not eat more than two servings of light tuna per month. This amount of tuna (six ounces) is more than the average child currently consumes; the mercury dose it contains is acceptably low in risk.

■  Children up to 55 pounds should consume no more than one tuna meal per month. Because of their smaller body size, an added margin of caution is appropriate for younger children.

■ Parents and schools should offer children other seafood choices, such as shrimp and salmon, which are just as nutritious but contain far less mercury.

■  The US Department of Agriculture’s School Lunch Program should phase out commodity purchases of canned tuna and replace it with lower-mercury alterative seafood items.

■  Parents should monitor their children’s canned tuna consumption at school and ensure that the total consumed at home and at school does not exceed the recommendations for exposure.