Pollution from one of Scotland's major glass recycling operations has provoked a storm of protest from the surrounding community who fear for their health.

The worries of residents living near a glass-crushing plant at Bonnyrigg in Midlothian have been backed by their local MSP, and prompted investigations by the Scottish Environment Protection Agency (Sepa). But the UK waste company that runs the plant, Viridor, insisted that the pollution was harmless and that incidents had been "sporadic".

However, concerns about the company's operations on the site have been accentuated by the fact that it has been using mobile glass-crushing machines for two years without planning consent. An application for retrospective permission is now being considered by Midlothian Council.

The latest pollution incident took place less than two weeks ago, when woodland and plants outside the site were coated with white powder. Earlier incidents were recorded by residents in September and October last year.

"It looks like a fall of snow," said a spokesperson for the Cockpen Association, which represents the local community. "But we are very concerned and angry that it is toxic and carcinogenic and could harm not only the local residents and their families but employees on the site."

Analysis of the deposits by Edinburgh Council's scientific laboratory last September concluded that it was powdered glass. The association is worried that this could include silica, which experts say can cause cancer.

The pollution had reached a field and covered bramble bushes from which local people pick fruit every year, claimed the association. The Esk Valley waterways could also be contaminated.

Rhona Brankin, the former communities minister who was re-elected as Labour MSP for Midlothian last Thursday, told the Sunday Herald that she was "hugely concerned" about the plant.

She has taken up the issue with Sepa, Midlothian Council and Scottish Natural Heritage. Sepa said that inspectors had visited the site in Dalhousie Business Park in April. Dust had escaped from glass not covered by the dust suppression system.

Viridor agreed to remove the stockpile and adjust its sprinklers. Sepa hadn't carried out tests to determine the composition of the pollution.

The company said that its crushing operations had not been given planning consent because of a two-year delay by the authority. The company strongly defended its environmental record, insisting that its operations caused "no unacceptable impact".

Viridor's external affairs manager, Dan Cooke, said the company is planning to set up a local liaison group.

Midlothian Council said it was "very aware" of the concerns of the local community and that Viridor's application for the glass crusher would be considered "in due course".