Contaminated foods and drinks are common sources of infection. Among the more common infections that one can get from contaminated foods and drinks are typhoid fever Escherichia coli infections, shigellosis or bacillary dysentery, giardiasis, cryptosporidiosis, other salmonelloses, cholera, rotavirus infections, also a variety of worm infestations. Many of the infectious diseases transmitted in food and water can also be acquired directly through the faecal-oral route.
Food adulteration is the act of intentionally debasing the quality of food offered for sale either by the admixture or substitution of inferior substances or by the removal of some valuable ingredient. Food is declared adulterated if:
- a substance is added which depreciates or injuriously affects it
- cheaper or inferior substances are substituted wholly or in part
- any valuable or necessary constituent has been wholly or in part abstracted
- it is an imitation
- it is coloured or otherwise treated, to improve its appearance or if it contains any added substance injurious to health
Food-preservatives have a very extensive use, which often constitutes adulteration. Salt is the classic preservative, but is seldom classified as an adulterant. Salicylic, benzoic, and boric acids, and their sodium salts, formaldehyde, ammonium fluoride, sulphurous acid and its salts are among the principal preservatives. Many of these appear to be innocuous, but there is danger that the continued use of food preserved by these agents may be injurious. Some preservatives have been conclusively shown to be injurious when used for long periods.
Coal-tar colours are employed a great deal, pickles and canned vegetables are sometimes coloured green with copper salts; butter is made more yellow by anatta; turmeric is used in mustard and some cereal preparations. Apples are the basis for many jellies, which are coloured so as to simulate finer ones. In confectionery, dangerous colours, such as chrome yellow, prussian blue, copper and arsenic compounds are employed. Yellow and orange-coloured sweets are to be suspected. Artificial flavouring compounds are employed in the concoction of fruit syrups, especially those used for soda water. Milk is adulterated with water, and indirectly by removing the cream. The addition of water may introduce disease germs. Cream is adulterated with gelatin, and formaldehyde is employed as a preservative for it. Butter is adulterated to an enormous extent with oleomargarine, a product of beef fat. Brick dust in chilli powder, coloured chalk powder in turmeric, injectable dyes in watermelon, peas, capsicum, brinjal, papaya seeds in black pepper etc.
To avoid illness, one is advised to select foods with care. All raw foods must be checked for contamination particularly in areas where hygiene and sanitation are inadequate. One is advised to avoid salads, uncooked vegetables, and unpasteurised milk and milk products such as cheese, and to eat only food that has been cooked and is still hot. Undercooked and raw meat, fish, and shellfish can carry various intestinal pathogens. Cooked food that has been allowed to stand for several hours at ambient temperature can provide a fertile medium for bacterial growth and should be thoroughly reheated before serving. Consumption of food and beverages obtained from street food vendors has been associated with an increased risk of illness.
Water that has been adequately chlorinated, by using the minimum recommended water treatment standard provide protection against viral and bacterial waterborne diseases. However, chlorine treatment alone, as used in the routine disinfection of water, might not kill some enteric viruses and the parasitic organisms that cause giardiasis, amoebiasis, and cryptosporidiosis. In areas where chlorinated tap water is not available or where hygiene and sanitation are poor, one is advised that only the following might be safe to drink:
- Beverages, such as tea and coffee, made with boiled water
- Beer and wine
- The safety of canned or bottled carbonated beverages, including carbonated bottled water and soft drinks is questionable nowadays.
Where water might be contaminated, one is advised that ice should also be considered contaminated and should not be used in beverages. If ice has been in contact with containers used for drinking, one should thoroughly clean the containers, preferably with soap and hot water, after the ice has been discarded.
It is safer to drink a beverage directly from the can or bottle than from a questionable container. However, water on the outside of beverage cans or bottles might also be contaminated. Therefore, one should be advised to dry wet cans or bottles before they are opened and to wipe clean surfaces with which the mouth will have direct contact. Where water might be contaminated, one is advised to avoid brushing their teeth with tap water. The following methods may be used for treating water to make it safe for drinking and other purposes.
- Chemical disinfection (for eg. chlorine tablets)
- Water filters
Proper selection, operation, care, and maintenance of water filters are essential to producing safe water. If no source of safe drinking water is available or can be obtained, tap water that is uncomfortably hot to touch might be safer than cold tap water; however, proper disinfection, filtering, or boiling is still advised.