The EU bases its policy on the precautionary principle, which means that when new processes or chemicals are invented they are not licensed until they can be proved to do no harm. This is in contrast to the policy process followed in the US, where a licence is granted until harm can be proved. The UK government has been objecting to the precautionary principle for some time and would be unlikely to maintain this risk-averse policy approach if we were to leave the EU.
An example of the precautionary principle in practice is the ban on GMOs (Genetically Modified Organisms) in the human food chain. The EU has resisted pressure from agribusiness corporations to permit GMOs into the European market, although this resistance has been unpicked to some extent as a result of pressure from the UK government. You can read more about the EU’s legislation on GMOs here.
The UK government is also working to ensure a new licence for the pesticide Glyphosate, in spite of concerns that it may cause cancer. The licensing process has been postponed because other countries’ governments blocked the process, another example of us gaining greater protection because of our membership of the EU.
There is a similar story with pesticides known as neonicotinoids, which have been shown to be damaging to bee populations. In 2013 a majority of EU member states voted to restrict the use of these pesticides, a decision that was opposed by the UK government.
It seems clear that other European governments are providing us with protection against dangerous pesticides and agricultural technologies and that we would lose this protection if we were to leave the EU.