With each day the repercussions of Brexit give pause for ominous thought. We know it threatens UK jobs in export industries. What should alarm us just as much are the awful implications for the health and safety of every one of us. As the Council of Europe rapporteur on the EU-US free trade deal TTIP (Transatlantic Trade and Investment Partnership) blocked by President Trump, and on the environmental audit committee, I have been talking to officials from the US chemical industry, the US Environmental Protection Agency (EPA), the American Federation of Labour (US TUC) and US members of Congress.

There is much jargon to be navigated, but put simply, if we leave the EU we step out of the protective umbrella of Reach, the EU directive that requires companies to prove their chemicals are safe to human health and the environment before they can be sold. The process works on the “precautionary principle” central to EU regulation: companies have to prove their products are safe. That basic approach simply isn’t recognised in the US.

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If the UK abandons the single market, it will start the negotiation of a US-UK trade deal without the protection of Reach. Instead we will be expected to adopt the US Toxic Substances Control Act (Tosca) – a toothless tiger measure from 1976 that even allows asbestos to be sold in the US as well as other chemicals long outlawed by the EU.

There is irony here. TTIP would have meant the US chemical giants having to accept European health and safety standards. That’s why last year they acted swiftly to hamper an amendment that would have obliged them to prove chemicals are safe before selling them. Instead, the onus has now been placed upon the EPA to prove each new chemical is hazardous within just 90 working days. This is a very tough call; now made much tougher by Donald Trump’s announcement that the EPA budget will be cut by 30%. The odds are already stacked against the protection agency. It is already obliged to spend eight years of testing and consultation before it can ban existing chemicals, even those that have safe substitutes but cause respiratory, neurological or life-shortening effects, such as asbestos.

Even if states decided to ban chemicals unilaterally to protect their citizens, their hands can be tied. California, New York and 10 other states have introduced laws to ban dangerous chemicals. However, just the referral of a chemical to the EPA for testing prevents a state from banning it.

So far, so bad, but what does this mean for us? It means a health and safety disaster if our UK-US trade deal has chemicals regulated under US rules. We should also think about our agriculture. If US rules prevail in respect of our food, hormone-impregnated and antibiotic-saturated US beef and chicken linked to premature puberty in children could find its way on to our supermarket shelves.

A few weeks before the EU referendum, I asked Boris Johnson to name any EU law applied in the UK to which he objected. After complaining about bananas, he named Reach. His ignorance would have been harmless had the referendum vote gone the other way.

Instead, the UK faces the prospect of US chemical standards and other lesser regulations. We know enough about their application and the risks they present to the public on the other side of the Atlantic to know we don’t want them here.