Food is very important to our lives. It provides the necessary nutrients we require to keep life moving on. The foods we eat are produced from the environment and are therefore subject to environmental pollution. There are varying types of pollutants and sources of pollution that affect our food.
Food is anything we eat to provide us the necessary ingredients the body require to keep alive. Food includes all sources of protein, vitamins, carbohydrates, essential minerals and trace elements. They come in different food types like yam, corn, cereals, vegetables etc.
Food is available for consumption either in their natural form or after being processed (cooked, heated, fried, chilled, roasted etc.) depending on the nature of the food.
Food is an important medium of pollutants and contaminants. The modern concept of food contamination/pollution include consideration of the production process e.g. the agrochemicals applied (fertilizers, pesticides, herbicides etc.), the site of cultivation, including the soil content and proximity of the farmland to sites of pollution.
These are essentially due to concerns of crop uptake of heavy metals in soil and other pollutants that can be picked and going through the food chain to harm consumers. During food preparation important considerations include the surfaces which the food comes into contact with and the ingredients added to the food and other likely sources of pollution. Unsafe food causes many acute and life- long diseases ranging from diarrhoeal diseases to various forms of cancer.
The Mechanism of Nutrient Uptake
All the nutrients with the exception of carbon are taken up by the plant through its roots. All those taken through the roots, with the exception of hydrogen which is derived from water, are taken up in the form of ions. Carbon, in the form of carbon dioxide, enters primarily through the stomata of the leaves and where the plant releases oxygen as a byproduct of photosynthesis.
All the hydrogen utilized by the plant originates from soil water and results in the release of further oxygen. Plants may have their nutrient needs supplemented by spraying a water solution of nutrients on their leaves, but nutrients are typically received through the roots by:
– Mass flow
– Root interception.
The nutrient needs of a plant may be carried to the plant by the movement of the soil solution of water in what is called mass flow. The absorption of nutrients by the roots from the water, with which it is in contact, causes the concentration of nutrients in that area to be depleted.
Nutrients then diffuse from area with higher concentration to lower concentration thereby bringing more nutrients to the roots of the plants. Plants also send out roots constantly to seek new sources of nutrients in a process called root interception.
Meanwhile, older less effective roots die back. Water is lifted to the leaves where it is lost by transpiration and in the process, it brings with it soil nutrients.
Persistent Organic Pollutants (POPs), heavy metals, dioxins etc., can find themselves (pollution) in the food of man through crop uptake. This all depends on the aggregate of inputs and the environment which food is produced.
Bacteria and illness can spread from the transporting of foods. New microbe strains of food related illnesses are evolving and becoming anti- biotic resistant.
Source or Points of Food Contamination
Slaughter: When healthy animals are slaughtered for food, there are bacterial microbes in their intestinal track. During the processing of these animals, the carcass can become contaminated by small amounts of these microbes.
Watering: Fruits and vegetables can become contaminated by unclean water during irrigation. The water can contain raw human sewage or animal manure.
Handling: People who handle fruits and vegetables can spread infection, if they are sick themselves. They can easily spread food related diseases by just touching the food.
Utensils: Using the same utensil in the kitchen can spread food related illness. If you use a knife to cut meat and then cut fruits and vegetables, it can contaminate the food.
Warm conditions: Leaving food out for a long period of time can cause contamination. Bacteria multiply in these conditions. Foods should always be refrigerated after a meal.
Raw foods: Heat kills most bacteria related to food contamination. Even fruits and vegetables are less likely to cause illness if they are cooked thoroughly.
In summary, Food contamination is a very important subject in environmental health control practices, especially at this era where most part of our days are spent outside homes and the necessity for us to rely on foods prepared for public sale. Environmental health officers have the professional responsibility to protect food meant for public consumption and ensuring their safety.
Food can also be contaminated by means of nutrient uptake from the soil. That underscores the importance of what we input (quality and quantity) during the production of the food crop, e.g. pesticides, fertilizers, etc. In the next unit we will delve into other issues that are of interest to pollution.
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