San Francisco officials have called for investigations of a city health department employee who helped a powerful developer sell homes on land reclaimed from a toxic Superfund site.

Four current or incoming members of the Board of Supervisors said this week they want to know if Amy Brownell, an environmental engineer, should have been directly involved in individual home sales at the former Hunters Point Naval Shipyard — the city’s biggest redevelopment project in a century.

The officials said they plan to investigate and possibly hold a hearing.

“It seems like something broke down here,” said District Eight Supervisor Rafael Mandelman. “We need to figure out whether this was one person acting outside her authority, or if, in fact, there are just no rules at all about this, which suggests a larger problem.”

Supervisors Jane Kim and Hillary Ronen agreed, along with Supervisor-elect Matt Haney, who will begin representing District Six in January.

The vice chair of the city’s Ethics Commission, Quentin Kopp, also said he would ask the commission staff to investigate — and possibly consider a new rule to ban interactions like Brownell’s.

The inquiries come after The Chronicle reported that Brownell, one of the city’s top health and safety watchdogs on the shipyard project, was aiding the company she is supposed to be regulating.

From 2014 until this spring, records show, Brownell talked with several potential home buyers at the request of mega-developer Lennar Corp. Buyers were nervous about their health and safety and the future of the development.

The home area is on a hilltop adjacent to America’s largest Superfund site — hundreds of acres tainted with long-lasting radioactive substances spread by the Navy during the Cold War. In 2014, whistle-blowers came forward with startling allegations, saying that tests for radioactivity had been falsified to make the site seem cleaner than it really is.

Since then, the scandal has snowballed, bringing the cleanup to a halt and delaying future development. Two former supervisors with Tetra Tech, a key cleanup contractor, have been sentenced to prison for faking soil samples, and the U.S. Environmental Protection Agency now suspects that nearly all of the company’s data may be bogus. And although agencies declared the home parcel safe back in 2004, whistle-blowers said the area had never been rigorously checked, suggesting harmful radioactivity could exist there too.

Lennar asked Brownell to discuss the situation with wavering buyers, and she did. But instead of providing house-hunters with all relevant information, she gave them a series of assurances, failing to disclose documents in her possession that pointed to uncertainties about the shipyard’s safety.

Since The Chronicle’s report appeared, two more shipyard homeowners have come forward to share their experiences with Brownell. Like the others, they said that Brownell painted an optimistic picture of the shipyard and minimized concerns about falsified cleanup tests.

Those actions may have crossed an ethical line, experts told The Chronicle. Brownell’s job is to protect residents and workers during the transformation of the shipyard, monitoring the site’s cleanup and policing the developer to make sure people aren’t exposed to hazardous substances.

“There is an appearance that public dollars are being utilized to promote the private sales of these homes,” said Kim, who is leaving office next month. “It is the duty of our health officials to advocate for the public, not the bottom line of the developer.”

Kopp said Brownell also could have put the city in a precarious legal situation if home buyers later felt misled.

“Jesus, if I were the director of public health, I would not allow anyone in the health department to participate in this fashion,” said Kopp, a former city supervisor, state senator and Superior Court judge.

The city attorney’s office did not respond to questions about whether Brownell’s actions may have violated any current laws or rules. The health department and Amy Brownell did not respond to questions in time for publication.

Brownell previously declined to comment. Health department spokeswoman Rachael Kagan has defended Brownell’s interactions with shipyard home buyers, saying that Brownell provided accurate and objective information in response to questions from the public. “We fail to see how that is improper,” Kagan said.

Mayor London Breed did not answer questions about Brownell’s actions. Her spokesman, Jeff Cretan, said in a statement that the health department’s duty is “to respond to questions from any member of the public regarding public health issues regardless of how that inquiry comes in.”

Supervisor Malia Cohen, who represents District 10, which includes the shipyard, declined to comment on Brownell’s exchanges with Lennar and its home buyers. Cohen also is leaving office next month.

Her successor, Shamann Walton, also declined comment.

Walton is the executive director of Young Community Developers, a nonprofit that has received about $650,000 in grants from Lennar and its spinoff, FivePoint Holdings, since 2011, according to city documents. Lennar also contributed a $10 million subsidy to a joint venture involving the nonprofit. Walton told The Chronicle that the grants and subsidies have strengthened Bayview-Hunters Point, funding education and employment programs and building affordable housing for residents who otherwise would be forced to leave because of high costs. His last day at the nonprofit is Jan. 4.

The shipyard development has been marketed as San Francisco’s next great neighborhood, part of a vast new waterfront community of 12,000 homes rising on the mothballed naval base and nearby Candlestick Point in the city’s southeast. About 450 housing units have been built so far on the hilltop outcropping known as Parcel A.

Over the past few years, as news about the cleanup darkened, the fallout stretched to Parcel A. At least six shipyard home buyers broke their contracts due to health and safety concerns, according to 2017 city documents.

And with some potential home buyers wobbling, Brownell entered the picture, records show.

At least four sets of potential home buyers were sent to Brownell by Lennar agents. Three of those families had already put down deposits on shipyard homes when they spoke to her, and all three ended up completing their purchases. They told the newspaper that Brownell struck them as knowledgeable, responsive and reassuring.

But she didn’t give the buyers the full story. Internal city emails and project reports showed that Brownell painted an overly optimistic picture of the shipyard cleanup, withholding key public documents that pointed to serious problems and uncertainties.

Two other homeowners said this week that Brownell also helped persuade them to buy a shipyard condo. Paloma, 29, and Melissa, 31, are sisters who asked to be identified only by their first names. Paloma works for the Hearst Corp., which owns The Chronicle.

The women said that in 2014, they were living in the Sunset District and getting priced out when they discovered the shipyard, where Lennar agents were pre-selling homes that hadn’t yet been built. Views of the city skyline were stunning, and a new two-bedroom condo cost $562,000 — a lot of money, but within reach, they said.

Visiting a Lennar sales office that summer, the sisters noticed a series of massive binders, each one stuffed with hundreds of pages of documents about the Superfund site next to the home area. Months later, after paying an initial deposit to reserve the condo, the sisters saw a television report by NBC Bay Area about the cleanup contractor Tetra Tech. It showed that the company had botched a series of radioactivity tests, submitting false data. A whistle-blower told the network that the data had been faked.

At that point, the sisters asked their Lennar saleswoman for more information about the cleanup. They were mainly concerned for their health, but the condo “was also a huge investment,” Melissa said. “We were putting all of our savings into it.”

The saleswoman pointed them to Brownell.

“She is great and will make you feel a lot better,” the Lennar agent emailed them in November 2014, attaching a snapshot of Brownell’s contact information.

The sisters spoke to Brownell on the phone and by email and, as promised, she quelled their fears about buying a shipyard condo. Brownell dismissed the news story, telling Melissa and Paloma in an email that it was based on “old data” and that any problems had already been fixed.

In fact, the news report relied on the Navy’s own documents, as well as interviews with whistle-blowers whose claims have since been bolstered by independent findings from the Navy, the EPA and the U.S. Department of Justice.

At the time, though, the Navy was characterizing the false samples as a minor glitch, and Brownell agreed.

“I’ve been working on this project for 21 years,” she emailed Melissa, “and the Navy has spent hundreds of millions of dollars and had Regulatory Agency scrutiny of their work so that you and all the other new residents can help make this the last ‘new’ neighborhood of SF! It is very exciting.”

Convinced that the shipyard was safe, Paloma and her sister bought the condo and moved there in December 2015.

“She represented the city (as) the authority on the cleanup, so I felt she was a trusted and reliable source,” Paloma said.

The sisters enjoyed living at the shipyard, but as months went on and new allegations emerged about misconduct by Tetra Tech and faked radiation tests, they began to get scared and went back to Brownell.

“We were like, ‘What’s going on Amy?’” Melissa said. “We thought everything was fine.”

Again, Brownell blamed the media, essentially characterizing investigative reports on the shipyard as fake news.

“I just wanted to reassure you that, as I’m sure you are aware, the news organizations are in the business of making headlines and selling news,” Brownell wrote to the sisters on Sept. 29, 2016. In the same email, she spoke in glowing terms about the development, writing, “Every time I see the buildings, views and open space areas it makes me so excited for this new neighborhood that is being created.”

In hindsight, Paloma told The Chronicle, it’s clear to her that Brownell was communicating a distorted and unrealistic view of the shipyard.

“I feel like she was anchored as a closer for the developer, and I think that was really inappropriate,” Paloma said. “They should have just been honest and told people the facts.”

The sisters have recently joined about 20 other shipyard homeowners who are suing Lennar/FivePoint and Tetra Tech, alleging that the companies failed to disclose facts about contamination. The companies have said the lawsuits are baseless.

Although the city is not a defendant in the lawsuits, the sisters said they also felt misled by Brownell.

“Not only were we putting our trust in the future of this new development, but we were putting our trust in the city to take care of us,” Melissa said. “So it is just really frustrating all around.”

Reacting to The Chronicle’s recent investigation, Supervisor Ronen said that Brownell appeared to have “curated” documents and arguments for home buyers, stressing positive information while withholding evidence of problems.

“That is what I found particularly upsetting,” Ronen said. “If she is picking and choosing information in a biased fashion, that is a major problem. And then, if that is done in coordination with the developer of the property, that is without a doubt, a major ethical problem and completely inappropriate.”

Ronen and other supervisors said that, depending on the outcome of their investigation, they may ask the health department to clarify that its role is not to help Lennar/FivePoint sell homes. The supervisors could also pursue a legislative fix, altering the city code to prohibit health regulators like Brownell from participating in the marketing and sales machinery of private developers, while also making sure that the public can still get information from city officials.

“Perception matters,” said Haney, the supervisor-elect. “Trust is important, especially when we are talking about people’s lives and their health and well-being.”

Jason Fagone and Cynthia Dizikes are San Francisco Chronicle staff writers. Email: jason.fagone@sfchronicle.com, cdizikes@sfchronicle.com Twitter:@jfagone, @cdizikes