U.S. businesses with COVID-19 outbreaks are facing an emerging legal threat from claims that workers brought coronavirus home and infected relatives, which one risk analysis firm said could cost employers billions of dollars.

The daughter of Esperanza Ugalde of Illinois filed in August what lawyers believe is the first wrongful death “take home” lawsuit, alleging her mother died of COVID-19 that her father contracted at Aurora Packing Co’s meat processing plant.

The cases borrow elements from “take home” asbestos litigation and avoid caps on liability for workplace injuries, exposing business to costly pain and suffering damages, even though the plaintiff never set foot on their premises.

“Businesses should be very concerned about these cases,” said labor and employment attorney Tom Gies of Crowell & Moring, which defends employers.

The lawsuit against Aurora alleges that Ricardo Ugalde worked “shoulder to shoulder” on the company’s processing line in April when Aurora knew it had a coronavirus outbreak at its facility and failed to warn employees or adopt any infection prevention measures.

Aurora did not respond to a request for comment.

Between 7% and 9% of the roughly 200,000 U.S. COVID-19 deaths so far are believed to stem from take-home infections and the lawsuits could cost businesses up to $21 billion if the number of Americans fatalities reaches 300,000, according to Praedicat, a firm that evaluates risks for insurers.

Rob Reville, Praedicat’s chief executive, cautions that is a worst-case scenario and said the cases might cost far less, depending on how judges view the lawsuits.

The U.S. workers compensation system generally makes it difficult for workers to sue for COVID-19. The system caps liability for businesses and bars costly lawsuits in return for quick payments to employees, who do not need to prove fault.

But Esperanza Ugalde was not an employee of Aurora, so her family can sue the company. Depending on the circumstances, a successful wrongful death case can top $1 million in damages.

Take-home cases have been around for decades in asbestos litigation and courts have split on whether a business has an obligation to members of the public who have never been on their premises.

In 2013, a California jury awarded Rose-Marie Griggs $27.3 million in compensatory and punitive damages after she contracted mesothelioma that her lawyers argued was caused by asbestos fibers carried home in the 1950s on the work clothes of her then-husband, who installed insulation for an affiliate of Owens-Illinios Inc.

The company appealed and two sides reached a private settlement before the appeal was heard.