Staying in the European Union will be the best option for the British public's wellbeing, according to public health experts.
A report by the Faculty of Public Health (FPH) found the EU's free movement rules benefited the UK, with 10% of the health and social care workforce from European Economic Area countries.
European legislation on the environment, consumer safety, food quality and human rights had also contributed to better UK health and wellbeing, the report said.
But the document acknowledged that the process of making decisions within the 28-member bloc was cumbersome and slow and a post-Brexit UK could act in a more streamlined and efficient way.
The report said "a decision to remain in the EU would ensure continued protection for health, notably from legislation on clean air, water, safe food and consumer products, a flow of qualified workers for the NHS and funded opportunities for researchers to thrive in a dynamic scientific community".
It added: "In contrast, leaving the EU would, on balance, be likely to be detrimental to the health of the UK population, impede effective public health practice and act as a barrier to UK research."
FPH president Professor John Ashton said: "Just as our economy and society have become international, so have the threats to our health. Pandemics like flu, or water and airborne diseases and pollution, do not respect border controls. Our food and economic security, as well as the impact of climate change, cannot be controlled from within the UK alone.
"The UK has a strong leadership role for public health in Europe, for example on resistance to antibiotics. We all benefit from a pan-European approach to such a vital issue. Our analysis is that is better for the UK to remain a team player within Europe, where we benefit from shared intelligence, response and action.
"We agree that reform is needed within the EU to improve existing legislation. With a seat at the table, FPH believes that the UK has stronger, bloc wide, negotiating power.
"The UK is a net beneficiary from EU funding, including our excellent public health practice and research, which protects and improves health and helps make best use of the NHS's resources.
"Our analysis suggests that it would almost certainly be detrimental to people's health in the UK for us to leave the EU. Remaining in the EU would be in the best interests of everyone's health and wellbeing."
Brexit could mean NHS spending would be £135 a head lower, according to analysis by the Economist Intelligence Unit (EIU).
The analysis said: "Any resulting dip in the UK economy would bring a matching drop in the UK's health budget. Even if savings from the UK's net contribution to EU budgets are reallocated to health, there would still be a spending gap that would impact health services."
Some 10,000 doctors and 19,000 nurses from the European Economic Area working in the NHS could be affected by Brexit, the EIU said.
"Although it is not certain that EEA workers would be asked to leave if the UK votes for Brexit, their tenure would become more uncertain," the report said. "They would also become harder to replace if they did leave."
Without free movement rules after Brexit, "recruiting new staff would become more difficult and more expensive", the report said.