The city of San Francisco on Tuesday sued 10 major food companies, alleging that they marketed and sold ultraprocessed foods that they knew were harmful to human health and had been designed to be addictive.

The lawsuit argues that the foods have contributed to a public health crisis in San Francisco and across the nation, saddling cities and other governments with medical costs associated with the consequences of diets high in processed food. It’s a first-of-its-kind attempt to hold food conglomerates accountable for the proliferation of these foods and their established health risks.

“We have reached a tipping point in the scientific research about the harm of these products,” said David Chiu, the city attorney for San Francisco, in a news conference Tuesday morning. He added that “these products in our diets are deeply linked to serious health conditions, imposing enormous costs on millions of Americans and cities and states across our country.”

The term “ultraprocessed foods” generally includes items like flavored chips, sugary granola bars and soda, which contain synthetic compounds, preservatives and additives and are often high in saturated fat, sodium or sugar. Research has tied these foods to increased risk of obesity, diabetes and cardiovascular disease, among other conditions, as well as early death.

The suit, filed in San Francisco County Superior Court, alleges that the companies knew these foods were “dangerous for human consumption” and that they used “deceitful tactics” to market and sell their products.

The 10 defendants listed are Kraft Heinz Company, Mondelez International, Post Holdings, The Coca-Cola Company, PepsiCo, General Mills, Nestle USA, Kellogg, Mars Incorporated and ConAgra Brands.

NBC News asked each company for comment. None responded immediately to the requests.

Sarah Gallo, the senior vice president of product policy at the Consumer Brands Association, a trade organization for large food and beverage brands, said in a statement that the “makers of America’s trusted household brands support Americans in making healthier choices and enhancing product transparency.”

“There is currently no agreed upon scientific definition of ultra-processed foods and attempting to classify foods as unhealthy simply because they are processed, or demonizing food by ignoring its full nutrient content, misleads consumers and exacerbates health disparities,” Gallo wrote in a statement. “Companies adhere to the rigorous evidence-based safety standards established by the FDA to deliver safe, affordable and convenient products that consumers depend on every day. Americans deserve facts based on sound science in order to make the best choices for their health.”

The lawsuit comes amid increased scrutiny of ultraprocessed foods across both sides of the political aisle. Health Secretary Robert F. Kennedy Jr. has railed against these foods as a core tenet of his "Make America Healthy Again" agenda and plans to remove artificial food dyes from the food supply over the next year.

Now, an attorney in a California city known for its progressive politics is taking up the issue, too.

“For whatever reason, there is an alignment," said Laura Schmidt, a professor at the Institute for Health Policy Studies at University of California San Francisco, referring to the bipartisan pushback. "This is an area that was not really a political issue.”

She added: "Up until now, it has felt like watching a train wreck in slow motion. I've been talking about childhood diabetes for a couple decades now. The rates have continued to go up. Childhood fatty liver disease, childhood obesity — we've known for a long time there was something very wrong with this part of the food supply."

Schmidt disagreed with the trade association’s characterization that there is not a scientific definition of “ultraprocessed” foods.

She said the city attorney’s case reminds her of litigation against the tobacco industry.

"Anytime I see public actors like the city of San Francisco or state level attorneys interested in litigation, I'm encouraged, because that's how we got the attention of the tobacco companies back in the 1990s," Schmidt said. (The tobacco conglomerates Philip Morris and R.J. Reynolds even acquired several food companies in the 1980s. Philip Morris, for example, acquired Kraft Foods in 1988, then spun off the brand in 2007.)

Barry Popkin, a professor of nutrition at the University of North Carolina, said ultraprocessed foods began to penetrate the U.S. market in the 1980s and have since become ubiquitous. Researchers began to center on their negative health consequences about 10 to 15 years ago, he said.

“About 75% to 80% of what children eat comes from these ultraprocessed foods, and 55% to 60% of what adults consume come from them,” Popkin said. “You can’t compare how people ate during and right after World War II and in the decades before with how we’re eating now.”

Last month, the scientific journal The Lancet published a comprehensive review of the health effects of ultraprocessed foods that evaluated hundreds of studies and national food survey data.

The authors suggested that across the globe, ultraprocessed foods are worsening diets, driving overeating and exposing people to toxins. The overall effect is a rise in chronic disease, the studies suggested.

Popkin contributed to some of the research cited in the Lancet.

“We’re unhealthy. The diet has a huge amount to do with that. We stopped smoking, we’ve got cholesterol drugs, we’ve got drugs to handle heart disease, hypertension and so forth, but the food is killing us,” he said. “The most reputable, the most cited of all the medical journals out there felt that this was a subject worth presenting to the world.”

This article was originally published on NBCNews.com