Environmental impact of POPs

POPs are a global problem. Contamination is becoming universal: pesticides contaminate soil and plants, industrial sewage pollutes waters, burning of waste impacts the atmosphere.

Through soil, water and air POPs are absorbed by plants, water and incects that serve as food to birds, fish and mammals. People absorb POPs through foodstuffs, air, water and skin.

Once released in the environment chemicals can travel to the most remote regions of the planet. There is a trend of air travel of POPs from warmer areas to colder regions. Having reached these regions POPs, as a rule, are condensed and fall down on the surface of the Earth in the polar areas, Arctic and Antarctic. The travel distance varies depending on the volatility of chemicals. For instance, DDT is less volatile than hexachlorocyclohexane, therefore its range of distribution is smaller.�

It is quite difficult to examine the impact of a certain POP on ecosystems as usually ecosystems and wildlife are affected by several POPs simultaneously. The effects of a particular POP on animals vary depending on the type of animal, its age and sex, as well as the level, degree and duration of exposure. The effects on a particular living organism also depend on the duration of exposure in relation to the life circle of the organism. Besides, defects can appear only in the second or third generation.�

In wildlife such serious defects associated with POPs exposure as crossed beaks, clubfoot, tumors and injuries have been well documented. On the other hand, a number of other disorders associated with low exposure to POPs are difficult to detect on an individual level but they have serious repercussions for the entire population.� For instance, disruption of the immune system caused by POPs is sometimes difficult to find in an individual amphibia, fish, bird or mammal, but it can lead to infectious diseases, epidemics and extinction of their population. Reproductive disorders are also better seen at the population level. There are well-known examples of bird populations exposed to POPs with reduced or slow egg production, increased embryo mortality, thinner egg shells, embryonic defects, slow egg growth and hatching.

POPs cause ecosystem imbalances. POP-based pesticides do not only exterminate pests but also kill useful insects, birds, fish and other organisms. Extensive use of pesticides disrupts ecological balance and jeopardizes habitat and survivals of endangered species, including amphibias, Pacific salmons, sea turtles and American eagles.

POPs stockpiling has also a negative impact on the environment. For example, in the 1960s-80s thousands of tonnes of POP-based pesticides were brought to Africa from the developed world for pest control. The imported amount of pesticides was far greater than it was needed and therefore they were stocked in warehouses. According to FAO, now Africa has 50,000 tonnes of obsolete pesticides in warehouses and thousands of tonnes of contaminated soil that pose serious threat to human health and environment. According to estimates, POPs account for one third of these pesticides. The total obsolete pesticide stocks in the world are estimated at 150,000 tonnes.

The problem of persistent organic pollutants is that a great number of these substances continue to be released into the atmosphere. The reduction in the level of contamination by the POPs that have been banned in some countries is not a reason for optimism as the level of contamination by other POPs remains extremely high. In this connection the potential danger of POPs both for human health and wildlife remains high. Due to their toxic properties the only way to eliminate this danger is to stop using POPs and modernize technological processes accompanied by the release of POPs.