Out of the darkness that covered Orlando this weekend there emerged a spot of light: blood banks filled to capacity with donors, lines winding out the door with more. But notably absent from the ranks of donors were members of Orlando’s gay and bisexual community, whom the US Food and Drug Administration effectively bars from donating blood, even as their community was targeted at Sunday’s shooting at a gay nightclub.

Now, several Massachusetts politicians and researchers have joined voices nationwide, calling on the FDA to revisit its donation regulations, which mandate that any man who has had sex with another man in the past year cannot give blood. Advocates of a policy change say technological advances have rendered such a deferral obsolete.

Nine members of the Massachusetts congressional delegation have signed on to a letter urging the FDA to reconsider the 12-month waiting period. Stephen Kerrigan, who ran for lieutenant governor in Massachusetts in 2014, said he will lobby elected officials and health care experts for a policy change.

And the Broad Institute of MIT and Harvard, a biomedical research institute, announced this week it will sponsor a working group to study alternatives to the current waiting period and potentially propose changes to the FDA. Within 24 hours of the announcement, 42 members of the Broad community had volunteered to participate, said Broad Institute president Eric Lander.

“It’s clear from the information we have that there are no scientific studies that really can support the ban,’’ said US Representative Bill Keating, a Democrat whose district includes the Shore Shore and Cape Cod. “So for no reason that even is connected with safety, there are donations that [blood banks] aren’t getting.’’

In a statement to the Globe, US Representative Niki Tsongas called the policy “archaic’’ and “out of touch’’ and said it hinders the fight for LGBT equality.

“The issue has been highlighted in the days following the tragic events in Orlando and driven home even more poignantly by the fact that many gay and bisexual men could procure a gun more easily than they could donate life-saving blood,’’ said Tsongas, a Democrat whose district includes parts of the Merrimack Valley and north-central Massachusetts.

The 12-month waiting period is already a significant reduction from the FDA’s previous lifetime ban on donations from gay and bisexual men, which was instituted amid the HIV crisis of the 1980s and relaxed last December. But advocates of further policy change say the current one-year deferral is still at odds with the FDA’s acknowledgment that HIV infection can now be detected within nine days.

Replacing a blanket hold on all donations from gay and bisexual men — the majority of whom do not have HIV but who are still ineligible to donate — with risk-based screening of individuals would end unnecessary discrimination and expand the pool of potential donors without endangering the safety of the blood supply, said Sean Cahill, director of health policy research at The Fenway Institute, a Boston research and policy center on LGBT health.

Risk-based screening would help eliminate high-risk heterosexual donors, too, many of whom are not barred from donating blood, Cahill said.

“We can ask people about the actual activity that increases the risk for HIV transmission,’’ said Uri Ben-David, a researcher at the Broad Institute. “We should base policy on what we know about sexually transmitted diseases, rather than on whether you’re a gay man or not.’’

Much of the FDA’s rationale for its caution surrounding gay donors stems from a lack of evidence about alternative, individualized approaches, evidence Lander said the Broad Institute’s working group can provide.

“I wouldn’t call it activism,’’ Lander said. “I would call it a science-based response to an important question,’’ he said. “If you read the FDA’s guidance for industry associated with its policy change in December . . . it seems clear that there are opportunities for a much more inclusive policy.’’

While Kerrigan acknowledged that politicians — and Massachusetts politicians in particular, especially Senator Elizabeth Warren — have pushed for changes to the FDA regulations in the past, he said he is hopeful the Orlando tragedy will lend those efforts more momentum.

“I hope it’s a watershed moment,’’ he said. “I mean, look, Orlando was so horrifying and tragic, and I think it’s incumbent on us and particularly public officials to see what sense we can make of it and what change we can make in our own lives.’’

Vivian Wang can be reached at vivian.wang@globe.com.