Food and the environment: Safety begins at the source
Food safety and environmental pollution are two of the most important issues of our time. Historically, the pollution of soil, air and water pollution have had an impact on food security, and pose serious threats to human health.
Many initiatives and activities are focused on the control of persistent organic pollutants (POPs). Among persistent organic pollutants, the greatest attention is given to organic substances that possess potentially harmful characteristics which can cause adverse human health or environmental effects. These pollutants are called persistent bioaccumulative toxic (PBT) substances.
Depending on their mobility in the environment, POPs may be of interest to local, regional or global level. The global extent of POP pollution became an important issue with their detection in remote areas of the globe such as the Arctic. Despite the fact that POPs have never been produced or used in these regions, they have been detected at levels that pose a risk to both wildlife (Barrie et al., 1992) and humans (Mulvad et al., 1996).
In recent decades, growing concern about the potential effects of some man-made chemical substances on human health and the environment has prompted action at many levels, from local authorities to global non-government organisations. Each country has defined rules and controls to ensure that POP levels are under control; official and private laboratories works on testing and risk assessment in this field.
POPs came into widespread use during the boom in industrial production after the Second World War, when thousands of chemicals were introduced into commercial use. Many of these substances have proven useful effects in disease control, agricultural production and industry. However, these same chemicals have had unexpected negative effects on human health and the environment.
Many people are familiar with some of the most well-known POPs used in agricultural, disease control, manufacturing or industrial processes. Examples include PCBs used in a variety of industrial applications (e.g., in electrical transformers and large capacitors, as hydraulic and heat exchange fluids, and as additives to paints and lubricants) and DDT, which is still used to control mosquitoes that carry malaria in some parts of the world.
Some POPs, such as dioxins, are produced inadvertently as a byproduct of some industrial processes and combustion. POP-producing activities include the incineration of municipal, industrial and medical waste, and even the simple backyard burning of trash.
The interrelationships among pollutants, sources, transport and transformation pathways, and environmental effects are complex. For example:
Emissions from various sources contribute to ozone, particle pollution, and acid rain formation in the atmosphere;
The photochemistry involved to form these pollutants is enhanced by sunlight;
Fires contribute to the build-up of particle pollution;
Winds disperse and transport pollution over large distances;
Rain washes particles out of the atmosphere into streams and lakes;
These processes and interrelationships create many pathways and feedback systems through which the ecosystems and human health are affected.
Figure 1: Air pollution sources, transport, transformations, removal and effects
POPs work their way through the food chain by accumulating in the body fat of living organisms and becoming more concentrated as they move from one creature to another. This process is known as "biomagnification." When contaminants found in small amounts at the bottom of the food chain biomagnify, they can pose a significant hazard to predators that feed at the top of the food chain. This means that even small releases of POPs can have significant impacts.
Let’s consider dioxins as just one example of this effect. Dioxin-like compounds in environment occur principally as a result of anthropogenic sources. These compounds are released to the environment in a variety of ways and in varying quantities depending upon the source. The ubiquitous nature of dioxins compounds suggests that multiple sources exist and that long range transport can occur. The major identified sources of environmental release have been grouped into four major categories as shown in Figure 2.
Figure 2: Dioxins release in the environment(Source: Elsevier Environmental International 34 (2008), pp. 139-153)
Many studies shows that over 90 percent of human exposure to dioxins is through food, with foods of animal origin accounting for 80 percent of that exposure. Figure 3 shows the results of one study that measured the food sources of dioxin ingestion in humans.
Figure 3: Food sources of dioxin exposure in humans
Unfortunately, the case with dioxin injestion is just one of many related to POPs in food, and illustrates the importance of working at the source to preserve the safety of food and ensure public health.
 “The Role of Monitoring Networks in the Management of the Nation’s Air Quality,” National Science and Technology Council, Committee on the Environment and Natural Resources, Air Quality Research Subcommittee, Executive Office of the President of the United States, 1999. Available here (as of 2 November 2015).
 “Dioxin sources and current remediation technologies—A Review,” Kulkami et.al., Environmental International, Volume 34, Issue 1, 2008, pp. 139-153. Abstract available here(as of 2 November 2015).
 “Intake of Dioxins and Related Compounds From Food in the U.S. Population,” Schecter et.al., Journal of Toxicology and Environmental Health, Part !, 63:1-18, 2001. Available here(as of 2 November 2015).