The warning came as waste company Viridor submitted a planning application to build an incinerator at New England Quarry, near Lee Mill. The site – along with Ernesettle and North Yard at Devonport – has been shortlisted for a £100million energy from waste (EfW) plant to handle domestic rubbish for Plymouth, Torbay and South Devon.
Viridor is in competition with MVV Umwelt, which wants to build on the Ernesettle and North Yard sites, but says it will go ahead at New England Quarry regardless of who wins.
The group STIFLE, which was set up to block attempts to build an incinerator at Ernesettle, has now widened its campaign to oppose building any incinerator at all.
In a letter to Mrs Pengelly, quoting information from the British Society for Ecological Medicine, they say: "There is now well researched scientific opinion over the dangers that waste incineration can offer.
"You must be aware that, as a councillor, you will be directly responsible for decisions you take that could adversely affect the health of Plymouth's citizens."
STIFLE says the pledge to reduce Plymouth's carbon footprint by 60 per cent by 2020 cannot be achieved by building a waste incinerator that will consume 240,000 tonnes of waste a year. They say that would force the city to keep recycling levels low.
STIFLE points out that Surrey County Council recently scrapped plans for two waste incinerators. They quote Surrey council leader Andrew Povey as saying: "It's a recognition that we have moved on, the technology has moved on, people are recycling more, the more we are recycling the more we avoid landfill."
"If investment could be put into businesses that focus on recycling and re-use this would create far more jobs than incineration and raise Plymouth's credentials as a forward-looking city," STIFLE said.
A council spokeswoman said: "There have been a number of well publicised withdrawals including Surrey, but these are based on a variety of factors such as the changes in the political administration of the councils proposing them, economic climate and deferring decisions until after the general election.
"Many projects, including Exeter, are still progressing.
"While we continue to make efforts to increase recycling and minimise waste production, this will not completely solve the problem. There is a limit to the waste that can be recycled."
In a statement issued yesterday, Viridor said it had submitted a planning application to Devon County Council for a resource recovery centre at New England, Lee Mill.
"Our environmental permit application will be submitted to the Environment Agency in the coming weeks," a spokesperson said.
"We will continue to engage with the local community."