The California Supreme Court has left intact a ruling that allows customers to sue Amazon.com for failing to warn buyers that some products it sells may contain hazardous substances such as mercury.

The court in its decision Wednesday denied a request by Amazon’s lawyers to review a lower court ruling that said Amazon violated the state’s Proposition 65, which requires companies to warn consumers about products they make or sell that contain chemicals known to cause cancer, reproductive harm or birth defects.

The case involved a lawsuit filed in Alameda County that said the online retail giant knowingly allowed skin-lightening creams to be sold on its website for years despite being aware of concerns about toxic mercury levels in such creams.

Mercury can harm pregnant women and their fetuses. The suit alleged that some of the products produced by third parties but sold on Amazon contained mercury levels that were thousands of times the U.S. federal legal limit.

Amazon said in a statement Thursday that safety is a top priority and that the products in question have long since been removed.

“We require that all products comply with applicable laws and regulations, and we have proactive measures in place to prevent suspicious or non-compliant products from being listed and we monitor the products sold in our stores for product safety concerns,” the statement said.

The Supreme Court’s action allows the previous court ruling to be used as precedent in state courts.

However, California has such a large market share that any actions Amazon takes to comply with Proposition 65 could have a much wider impact on consumers, said Rachel Doughty, a plaintiff’s attorney in the suit.