**7. Degradation of endosulfan**

**Figure 2** shows the oxidation pathway of endosulfan; it has been reported that even though some hydrolysis takes place, at environmental conditions, the most common product is endosulfan sulfate [2, 16, 22]. After initial oxidation, four intermediates are detected until endosulfan lactone is reached. In further oxidation, the complete mineralization can be obtained. Endosulfan is relatively resistant to photodegradation but its metabolites, including endosulfan sulfate, are susceptible to photolysis [23]. **Figure 2** shows the main pathways of endosulfan degradation.

In aquatic systems, the α-isomer is converted more readily to endosulfan sulfate than the β-isomer. Various studies that have observed the degradation of endosulfan in aqueous phases identified hydrolysis as the dominating abiotic degradation process resulting in the

**Figure 2.** Degradation of isomers α- and β-endosulfan.

generated in India, but it had agreed to phase out its use in 2017. China produced approximately 5000 tons per year, and the remaining endosulfan was produced by Israel, Brazil, and South Korea [16]. Regarding the consumption of endosulfan, India was the main consumer 113,000 t from 1958 to 2000, followed by the United States with 26,000 t from 1954 to 2000. In China, annual use is estimated to average 2800 t/y during the period 1998–2004 [3]. Endosulfan is prohibited in 80 countries; some countries have registered only a few commercial products containing endosulfan, other countries have registered dozens of commercial products from various formulators. Endosulfan is now still produced and widely used in the crop fields in most of the developing countries, due to its effectiveness and low application cost [17].

Endosulfan is widely distributed in the environment and can be detected in all media, soil, sediments, air, water, and vegetation, over long distances from the application source. Levels of endosulfan in the air samples are very variable depending on the location. Recent measure-

Endosulfan is one of the most abundant organic pesticides in the atmosphere and is capable of reaching remote locations such as the Arctic. The presence of endosulfan in the Arctic at

obtained using an XD-based passive sampler with samples collected in monitoring stations. It has been suggested that the transport of endosulfan occurs when the compound volatilizes from warmer regions, experiences long-range atmospheric transport, and condenses again, permitting an accumulation of the substance in temperate regions, higher mountains, and the Arctic. Endosulfan residues in snow and ocean waters in the Artic indicate that atmospheric deposition of endosulfan is taking place, and it can promote bioaccumulation in zooplankton and various species of fish. For some biota, a biomagnification factor for α-endosulfan from

**Figure 2** shows the oxidation pathway of endosulfan; it has been reported that even though some hydrolysis takes place, at environmental conditions, the most common product is endosulfan sulfate [2, 16, 22]. After initial oxidation, four intermediates are detected until endosulfan lactone is reached. In further oxidation, the complete mineralization can be obtained. Endosulfan is relatively resistant to photodegradation but its metabolites, including endosulfan sulfate, are susceptible to photolysis [23]. **Figure 2** shows the main pathways

In aquatic systems, the α-isomer is converted more readily to endosulfan sulfate than the β-isomer. Various studies that have observed the degradation of endosulfan in aqueous phases identified hydrolysis as the dominating abiotic degradation process resulting in the

has been detected. Endosulfan concentration was

**6. Distribution of endosulfan in the environment**

concentrations between 3 and 8 pg m−<sup>3</sup>

8 Persistent Organic Pollutants

fish to seal is also occurring [3, 19–21].

**7. Degradation of endosulfan**

of endosulfan degradation.

ments indicate that around 320 d is the half-life in the atmosphere [18].

formation of endosulfan diol. A positive correlation between hydrolysis rate (khydro) and pH, with base-driven hydrolysis, a predominant degradation process in seawater conditions, allows a rapid degradation of endosulfan into endosulfan sulfate, whereas it takes longer in pure water.

Furthermore, hydrolysis of endosulfan sulfate to endosulfan diol is markedly slower compared to the hydrolysis of α-endosulfan.

The biodegradation of endosulfan has been reported in anaerobic conditions; these conditions predominate in sediments and the results can contradict the interpretation of the isomer deposition in freshwater sediments. At neutral pH and aerobic conditions, the degradation of endosulfan by biological oxidation has also been reported, being sulfate of endosulfan, the compound with the heaviest concentration.

It has been reported that the decomposition of endosulfan in aqueous solution can take place, but some natural environmental factors lead to the formation of sulfate indicating that some oxidation pathway is followed. The values are much lower than the persistence criteria designated for a POP, although in the colder marine waters at high latitudes, base-driven hydrolysis half-lives for endosulfan are likely to be greatly extended, compared to warmer waters in temperate or tropical regions [3, 15, 23].

There are relatively few studies that have examined the persistence of endosulfan in soil under field conditions. Degradation rates strongly depend on the soil conditions (particularly soil water content and ambient temperature).

the Conference of the Parties the inclusion of technical endosulfan, its α- and β-isomers as well as the main degradation product, the sulfate of endosulfan in Annex A of the Stockholm Convention for global elimination with possibility of specific and temporary

This exchange under the Rotterdam Convention on "prior informed consent" applies to banned or restricted chemicals and to the severely hazardous pesticide preparations listed in Annex III. Currently, there are more than 30 chemical products to which the PIC procedure applies. At the fifth meeting of the Conference of the Parties to the Rotterdam Convention that took place in Geneva, Switzerland, between June 21 and 24, 2011, it was agreed to include the

Previously, the seventh meeting of the Chemical Review Committee, held in Rome from March 28 to April 1, 2011, recommended the inclusion of a number of new chemicals in this Annex, including the pesticide endosulfan that had recently added to the list of the Stockholm

**11. Recent technologies to treat endosulfan present in water and soil**

Nowadays, there is a concern for the development of alternatives for the elimination of endosulfan in both water and soil. In this context, advanced oxidation processes (AOPs) are considered a highly competitive technology for the removal of those organic pollutants not treatable by conventional techniques. All AOPs produce •OH radicals, they are very reactive, attack most organic molecules, and are not highly selective. The generation of •OH radicals is through different reagent systems, which include photochemical degradation processes

/Fe2+), and electrooxidation (BDD electrodes) [27].

Others treatments for pesticides are biodegradation and bioremediation; both of these are based on the conversion or metabolism of pesticides by microorganisms. The difference between these two is that the biodegradation is a natural process, whereas bioremediation is a technology. One disadvantage of these processes is that they require a long time to degrade

One of the technologies most resorted to eliminate pesticides present in water is adsorption with activated carbon, as it can be applied at a large scale. Good characteristics of activated

**Table 2** shows some technologies that have been developed to degrade endosulfan present in

/UV, photo-Fenton reactives), chemical oxidation pro-

Dissemination of Endosulfan into the Environment http://dx.doi.org/10.5772/intechopen.81094 11

exceptions [15].

(UV/O<sup>3</sup>

cesses (O3

, UV/H<sup>2</sup>

, O3 /H<sup>2</sup> O2 , H<sup>2</sup> O2

the pesticide [28].

water and soil.

O2

**10. Rotterdam Convention**

endosulfan pesticide in Annex III of the Convention.

Convention of chemical substances that must be eliminated [26].

), photocatalysis (TiO<sup>2</sup>

carbon include large surface area and well distributed porosity [29].

The Environmental Protection Agency (EPA) indicates that concentrations above 0.22 μg L−<sup>1</sup> (acute) and 0.05 μg L−<sup>1</sup> (chronic) have adverse impacts on the health of aquatic organisms. To avoid intoxication from water consumption, fish or shellfish from water bodies near fields where the pesticide is used, concentration limits need to be established. For air concentrations, the limit recommended by the National Institute for Occupational Safety and Health (NIOSH) is 0.1 mg m−<sup>3</sup> [22, 24].
