ƒÆ’-¡ƒ”š‚ M.A.C.S. Jayasumana Department of Pharmacology, Faculty of Medicine and Allied Sciences, Rajarata University of Sri Lanka
P.A. Paranagama Department of Chemistry, Faculty of Science, University of Kelaniya, Kelaniya, Sri Lanka.
M.Amarasinghe & S.I. Fonseka Department of Botany, Faculty of Science, University of Kelaniya, Kelaniya, Sri Lanka. and
D.V.K.Wijekoon Water Resources Board, Colombo 07, Sri Lanka

Abstract

World Health Organization classifies pesticides with arsenic compounds as active ingredients to be highly hazardous. Arsenic (As)-containing pesticides are thus banned in Sri Lanka since 1995 and it has been officially notified in the extraordinary gazette notification no 1190/24 of the Democratic Republic of Sri Lanka of 6th June, 2001. Arsenic is not even prescribed to include as an inert ingredient, except for six types of pesticides in which it is allowed (within limits) as an impurity and in Sri Lanka, copper- based pesticides only are legally allowed to contain (within limits) arsenic.

Present study is an attempt to test the pesticides available in the Sri Lankan market for presence of arsenic. Despite the fact that importation of As- containing pesticides is illegal, results of the present study revealed that twenty nine (29) out of the 31 available pesticide brands belong to 20 active ingredients in the local market tested, contained As in the range of 180ƒÆ’-¡ƒ”š‚±14 – 2586ƒÆ’-¡ƒ”š‚±58 ƒÆ’…½ƒ”š‚¼g/kg and it varied depending on the type of active ingredient, brand, batch of pesticides, importer and the area that it is used.

Using arsenicals in augmenting toxicity of pesticides is speculated a potential means through which As enters the natural environment, especially in the areas where rice cultivation is predominant. Chemical waste produced by a variety of industries is a cheap and a readily available source of arsenic. Results of the present study therefore highlight the potential magnitude of an environmental pollution issue that has not been hitherto received due attention. It is an urgent need therefore to divert more resources to consolidate these findings and to plan and implement strategies to prevent/ abate pollution of Sri Lankan environment with arsenic derived from agrochemicals. Chronic arsenic poisoning evidently leads to many health hazards and it has been proved beyond doubt that the entry of minute quantities of As to human body in microgram levels over several years can cause many non communicable diseases.

A multipronged approach with input from different specialties will be needed to make inroads into this national problem.

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Introduction

Arsenic compounds have been used as pesticides for centuries. The oldest records indicate use of arsenic sulfide in China as early as AD 900 (Shepard 1939). The poisonous properties of arsenic trioxide were well known during the middle ages and it was a favorite instrument of murder as practiced by the Borgias. This knowledge of the poisonous properties of arsenic compounds probably led to their use as insecticides. The first insecticidal use of arsenic in recent times has been reported in 1867 in Colorado potato beetle in the USA (Peryea 1998). In that occasion, copper aceto arsenite (Paris green) was used as an insecticide. Thereafter, Paris green has been used in many countries for mosquito abatement. Lead arsenate was the most extensively used arsenical insecticide which has been introduced in 1892 for use against gypsy moth in Massachusetts, USA. Lead arsenate initially was prepared by farmers at home by reacting soluble lead salts with sodium arsenate. Lead arsenate was the principle pesticide used in Western world until Dichloro Diphenyl Trichloroethane (DDT) was introduced by Paul Muller in 1939 (Benson et al., 1969).

Arsenic trioxide, As2O3 is a white crystalline material sometimes referred to as white or gray arsenic. It is the starting material in the commercial manufacture of arsenical compounds used as insecticides and weedicides. The calcium arsenate that was sold commercially as an insecticide is a complex mixture of several calcium arsenates and an excess of calcium hydroxide. Commercial calcium arsenate generally is colored pink and is alkaline in reaction. It is a finely divided powder. It has been used extensively against certain insects affecting field crops, especially cotton.

Following the use of arsenical pesticides for 2-3 decades several ill effects of human exposure to arsenic has been identified. As arsenic is accumulated in environment and in biological systems there were many serious concerns of continuation of arsenical pesticides. With the time more serious health impact has been detected due to chronic arsenic poisoning (Kapaj et al., 2006). This not only affects the user of pesticides but also the population in general by entering the food chain and polluting the water table and surface water. It has serious environmental impacts like the destruction of fish, bird wildlife and the quality of the habitat. The increase of cancer, chronic kidney disease, diabetes mellitus, heart diseases suppression of the immune system, sterility among males and females, neurological and behavioral disorders, especially among children, have been attributed to chronic arsenic poisoning.( Tchounwou et al., 2003. Tseng et al., 2003; Rahaman et al., 2003; Meliker et al., 2007; Kozul et al., 2009; Vahter, 2009). These effects probably extend to farm and other animals. With the expansion of knowledge about the fate of arsenic in environment and adverse health effect of chronic arsenic poisoning, many countries have restricted or banned the usages of arsenic containing pesticides.

Termination of lead arsenate use in USA, started in state of Washington in 1948 was declared on 1st of August 1988 and all insecticidal uses of lead arsenate were officially banned in USA. Due to harmful effects on human health, physical removal of arsenic contaminated topsoil by excavation has been carried out in USA (Peryea, 1998). Arsenical pesticide use in Germany was banned in 1974 (Nagy, 1974). Calcium arsenate, lead arsenate, copper arsenate and sodium arsenite have been classified as highly hazardous (class 1b) technical grade active ingredients according to the classification introduced by WHO in 2009 (WHO guidelines of pesticides, 2009).

Arsenic in drinking water, usually in its inorganic form, is known as the silent, slow killer because its presence is not revealed by taste, odour or colour of the water. Groundwater is the main source of drinking water in many countries around the world. In rural areas of Bangladesh and India (West Bengal), the presence of arsenic in groundwater has endangered tens of millions of people (Chakrabortiet al., 2010). Apart from ground water, elevated arsenic levels in rice have been identified as a significant source of inorganic arsenic in south east Asian region (Abedin et al., 2002; Meharg, 2004). Rice is particularly susceptible to arsenic accumulation compared to other cereals. There are many controversies over the primary source of arsenic in ground water and rice in the south east Asian region. Some scientists are arguing this is naturally occurring while some are showing pesticides as the main source (Jamal, 2000).

Although presence of arsenic in locally-grown rice has been reported from Sri Lanka (Jayasekara and Freitas, 2004; Yamily et al., 2008 and Chandrajith et al., 2010) presence of arsenic in pesticides has hitherto not been investigated. The Control of Pesticides Act No. 33 of 1980 in Sri Lanka regulates imports, licensing, packing, labeling, storage, formulation, transport, sale, use thereof and other concerns of pesticides. The Registrar of Pesticides (ROP) is the sole authority implementing the laws and regulations under this Act. The Pesticides Technical Advisory Committee advises Registrar of Pesticides on policy and technical matters. The use of WHO class 1a and 1b pesticides for pest control in Sri Lanka was banned since 1995 and it has been officially notified in the extraordinary gazette notification no 1190/24 of the democratic republic of Sri Lanka of 6 th June 2001 which states that use of pesticides containing arsenic or arsenic compounds as the active ingredient, is banned within Sri Lanka.

Jayasumana et al. (2011) reported the presence of arsenic in drinking water, rice grown in the area, hair and urine of patients of Chronic Kindney Disease of unidentified etiology (CKDu) as well as in body parts of diseased CKDu patients from Sri LankaƒÆ’‚¢ƒ¢-¡‚¬ƒ¢-¾‚¢s largest rice cultivation areas in the North-Central Province. This led to the hypothesis that presence of arsenic compounds in drinking water and food may be a potential cause of CKDu and the pesticides containing arsenicals may be the potential source of it.

Objective of the present study therefore is to determine presence of arsenic in pesticides imported and used within the country.

Full Paper in pdf format

ƒÆ’-¡ƒ”š‚ http://www.lankaweb.com/news/items11/Arsenic-Paper.pdf

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