As hundreds of New Brunswickers prepare to return to their homes in the flood-ravaged areas of the province, they must remain conscious of health and safety issues, a provincial medical officer is warning.

With the waters receding in many areas, the health and safety concerns left in the wake of the flooding St. John River will become more apparent, Dr. Eilish Cleary, deputy chief medical officer, said on Saturday.

New Brunswickers impacted by the flood need to exercise caution with their drinking water and food, Cleary said.

Boil-water orders have been enacted in several communities, and any residents using wells should ensure their water source has not been contaminated, Cleary said.

People should also discard any food that has been touched by the flood waters, including any packaged products, she said. Any homes that had their power disconnected should also not consume food that was left in freezers or refrigerators, she added.

"Err on the side of caution," Cleary said. "It is essential that affected residents take the precautions necessary to reduce possible risks to their health and that of their family."

The flood waters are full of debris and may have been contaminated as they travelled down the 673-kilometre St. John River, she said.

Some sewer facilities became flooded from the rising waters, and the flood water also spread across agricultural fields and properties that might have contained chemicals.

Andy Morton, deputy director of the province's Emergency Measures Organization, said that there are no major concerns about environmental contamination that might have been caused by the flooding.

"The volume of water is so huge that in most instances, it dilutes the product so much it doesn't present much of a hazard," Morton said Saturday.

Morton said EMO has no reason to be concerned that any significant amount of hazardous materials has been flowing down the river.

Mould and mildew a threat

The New Brunswick Health Department is still recommending that in areas impacted by flood water, residents clean their homes thoroughly while wearing protective clothing and wash their hands after being exposed to the water.

The growth of mildew or mould in homes may also be an issue in some areas, Cleary said, and it's important that water-soaked insulation be dried.

Dick Isabelle, the executive director of police, fire and emergency services for the provincial Department of Public Safety, said people should not return to their homes just yet. Local authorities will inform communities when it is safe to return, he said.

All homes that have been disconnected from the power grid will have to undergo an electrical inspection before they can be reconnected, he said.

Prime Minister Stephen Harper toured the flooded areas of New Brunswick on Friday. Both Harper and Premier Shawn Graham have said there will be a disaster assistance for those impacted by the flooding, but neither has provided specifics. Some of the details of the financial aid package will be released on Sunday, Isabelle said, as the province initiates its recovery operations.

Cleaning up after the St. John River fully recedes could take months, Cleary said.

"Floods can be very, very stressful on people," she said, adding that it can be even more so when the destruction wrought by the water is assessed and the cleanup begins.

Cleary said communities and neighbours must remain diligent and helpful in the weeks to come.