A no-deal Brexit threatens billions of pounds of chemical imports, the head of the Chemical Industries Association, Stephen Elliott, has warned, reports BBC.
He says secondary legislation, needed to copy EU regulations into UK law, contains "significant gaps".
The loophole could halt UK imports of chemicals by EU-registered companies from countries outside the EU, he says.
"Put simply, the drugs don't work, the cars don't run and the planes don't fly without chemicals and chemistry."
Unless the law is changed, he says, the import of "billions of pounds worth of chemicals," used across UK manufacturing, would have to come to a sudden halt if the UK left the EU with no deal on 29 March.
Defra said the government was working closely with industry stakeholders to ensure they are prepared in the event of a no-deal Brexit.
"As you would expect, the Government is working closely with industry stakeholders to ensure they are prepared in the event of a no-deal Brexit. "Our approach will maintain regulatory standards, provide continuity for business and reduce the risk of interruption in supply chains," it said.
The UK imports roughly £33bn of chemicals from the EU every year, and about £27bn from the rest of the world.
Part of the problem is the huge amount of work that needs to be done, and the speed with which legislation is being pushed through parliament as a result.
"I think the average politician is not one hundred per cent across all the details of where the gaps are, so it's left to business to pick up the pieces," says Allie Renison, who heads Europe and Trade Policy at the Institute of Directors.
There is plenty of expertise in the system, Ms Renison adds, but civil servants are trying to create entire regulatory systems that have not existed before.
