Dangerous toys, cars and household goods could "flood into the UK" after Brexit, a consumer group has warned.
There could be crucial delays to rooting out unsafe products if continued access to the European Safety Gate rapid warning system is not brokered, according to Which?.
EU member states warned of 2,257 dangerous products last year, which prompted responses such as recalls and goods being seized at the border.
In recent months alerts were issued over a toxic child's putty that could damage their reproductive systems and clothing that poses a strangulation risk.
Access to the system and other intelligence-sharing schemes must be negotiated in a post-Brexit deal.
Which? advocacy director Caroline Normand said: "If it is to make people's safety the number one priority, the government must secure access to the European alert and information sharing systems after Brexit, as well as introduce major domestic reforms to ensure consumers are properly protected from unsafe products."
The group also called for a "major shake-up" of the system because of rising numbers of alerts.
The system is under strain because it is "far too reliant" on "increasingly overstretched" trading standards officials, Which? said.
The Local Government Association said: "With the number of trading standards officers having more than halved since 2009 and budgets to this service having almost halved since 2011, the Government needs to use the forthcoming spending review to address the funding shortfall that councils face."
The Department for Business, Energy and Industrial Strategy said the Office for Product Safety and Standards (OPSS) was established to identify and deal with consumer risks.
"Ongoing data exchange with the EU about unsafe products remains subject to negotiation but, whatever the outcome, the Product Safety Database which OPSS is building will ensure regulators can access and exchange data securely and effectively," a spokesman said.