Viruses and Chemicals

Viruses

Viruses are microscopic. They are not live cells but need to combine with a live cell, where they act like a sort of parasite, taking over the cell and changing its nature and function to something harmful. They are likely to get into food in similar ways to bacteria and can affect any food type. They don't multiply in food they just use the food as a vehicle to get around.

Some of the viruses common to food-borne illness in New Zealand include:

• Rotavirus: these can cause fever, vomiting and watery diarrhoea starting one to three days after consumption and lasting four to six days.
• Norwalk: these can cause nausea, vomiting, diarrhoea, abdominal pain, muscle pain and headache, fever and general malaise starting 10-50 hours after consumption and lasting 24-48 hours.
• Hepatitis A: Viral illness tends to show itself faster than illness caused by bacteria. It tends to last longer and is more severe. It is believed food-borne viral illnesses go unidentified and so viral contamination of food is becoming more prevalent than it used to be. Frequent and stringent cleaning and personal hygiene measures are vital to ensuring the prevention of viral illness in the workplace.

Chemical Contaminants

Metallic compounds are naturally present in many foods in low concentrations and are not harmful. However, excessive amounts can get into foods via herbicidal, antifungal and insecticidal sprays of fruit and vegetables, plumbing pipes for drinking water reticulation, or from ceramic glazing, tin can coatings or trade waste contaminated waters in which seafood are harvested.

Metals that can become food contaminants in these ways include copper, lead, zinc, antimony and cadmium, aluminium and mercury.

Some other food-borne chemical contaminations include arsenic, selenium sodium nitrite from meat pickling, algae toxins and pesticides. Local Health Protection Officers from the Ministry of Health will periodically sample foods at the point of processing and recreational waters to test for harmful levels of these contaminants to ensure the Food Regulations (or new ANZFA regulations) are not breached.

To help prevent illness from chemicals and metals:

• thoroughly wash all fruit and vegetables prior to use.
• ensure all metal cookware and utensils are of high quality and in good condition.
• use a Council-supplied water source (as opposed to a private one) so that the water is tested for chemical and metals.
• do not use crockery that has been imported without customs and MAF checking to ensure the glazes are safe to eat from.
• store acidic foods cafefully as these can cause leach metal from the container.
• ensure any shellfish have been harvested from proven safe waters.
• pickled meats must come from licensed butchers to ensure that their pickling solutions are of the correct concentrations.

There is no excuse for contamination. What is not already there naturally must not be allowed to get there, and what is there naturally must be controlled. Knowledge of the risks associated with different food types will help you decide how to treat each food item you deal with and prevent the different types of contamination at all times.