Endosulfans Added to Stockholm Convention POPs

Endosulfan is an organochlorine pesticide with a highly chlorinated cyclodiene structure, similar to other banned pesticides such as aldrin, chlordane, and heptachlor. Developed in the United States in the 1950s, technical endosulfan is found as a mixture of conformational stereoisomers, typically in a roughly 70:30 mix of α-: β- isomers. The α- isomer, or endosulfan-I, is more thermally stable, and the β- isomer, endosulfan-II, will irreversibly convert to the α- isomer, though the process is slow. The primary degradation product of endosulfan is endosulfan sulfate¹. 

Endosulfan is used primarily for pest control in crops such as cotton, coffee, and tea, with highest usage in India, Brazil, and China, and significant use in the US and Argentina. Due to its demonstrated persistence, bioaccumulation, potential for long-range transport, and adverse (health) effects², endosulfan was added to Annex A of the Stockholm Convention during the 5th Conference of the Parties (COP5) held in April 2011 in Geneva, Switzerland. This action puts it on course for elimination from the global market by mid-2012. However, the listing does allow for specific exemptions; for example, endosulfan can be used on cotton crops for the control of bollworms³.  The US EPA issued a mandatory phase-out of endosulfan in November 2010, with final termination of use by July 31, 2016. The United States is not currently a member of the Stockholm Convention.

The application of isotope dilution mass spectrometry (IDMS) techniques has proven a valuable upgrade to the analysis of endosulfans, allowing for the accurate detection and quantification of these compounds at trace levels in both environmental and biological samples. Cambridge Isotope Laboratories, Inc. has developed not only endosulfan-I and endosulfan-II labeled and unlabeled standards, but also standards for endosulfan sulfate. In addition, CIL now offers comprehensive mixtures of all Stockholm Convention POPs pesticides, including endosulfan-I and endosulfan-II, chlordecone (kepone), α-, β-, and γ- (lindane) hexachlorocyclohexane (HCH), and pentachlorobenzene. Offerings include a full calibration series as well a sampling, cleanup, syringe, and native PAR spiking solutions. First-time users can contact CIL to learn more about our expanded POPs Pesticides Starter Kit. 

^[1]Wikipedia: Endosulfan

^[2] Pesticide Action Network International:Endosulfan Meets the POPs Screening Criteria

^[3]Chemical and Engineering News: Endosulfan Banned Worldwide