Authorities were scrambling to address the situation yesterday with several letterbox drops and doorknocks from industry and government representatives.

Deliveries included a government information sheet delivered about 8pm yesterday warning of a potential health risk to the community and advising on ways to reduce contamination.

Plumes of hexavalent chromium, the chemical that came to public awareness through public campaigning in the US by Erin Brockovich, wafted past 70 homes for half an hour on Monday from about 6.15pm.

But residents in neighbouring Stockton were not immediately told about their exposure to emissions from the Orica ammonium nitrate production plant at Kooragang Island.

Up to 20 workers at the Orica mining explosives plant were exposed during Monday’s incident.

The Newcastle Herald reported yesterday that the Electrical Trades Union expressed concern that a warning alarm was not tripped when workers at the plant were exposed to a dangerous chemical.

An Orica spokeswoman said that when the leak was detected work stopped immediately and emergency procedures were enacted.

But it was little consolation for the plant’s closest residential neighbours in Fullerton Street, who were still left wondering last night about the chemical exposure’s effects.

Fullerton Street resident Debbie Davies said she did not know until she heard about the incident in the news and was shocked.

‘‘Why didn’t they tell us?’’ she said.

‘‘I feel betrayed, totally betrayed. How would you feel? I’ve got an 11-year-old daughter.’’

Ms Davies said she did not mind living alongside industry, provided it was controlled, and companies were responsible for their actions.

The news of the Orica incident and lack of information following it has shaken her faith.

‘‘You’re not safe anywhere,’’ Ms Davis said.

Health concerns were foremost in her mind.

‘‘What danger is it to us?’’ Ms Davies said.

Jeffrey, Casey and David Parsons, who live in Fullerton Street, also felt the response to Monday night’s fallout at Orica was too slow.

‘‘It’s bloody late,’’ Jeffrey Parsons said.

The Parsons were handed a letter from officials late last night that contained information from NSW Health.

One of the government-issued letters said that to date, no health effects had been identified as a result of the chromium release from Orica.

The government was working to verify information that indicated a low health risk to the community.

‘‘This factsheet suggests ways you and your family can reduce your exposure in the interim,’’ the letter said.

Advice included washing outdoor items with tap water onto grassy areas to reduce contamination. The letter said the chromium would degrade to a safer form within 10 days on contact with soil.

Residents said environmental officers had visited their homes and collected samples from the soil, parked cars and outdoor equipment.