Project dates: 2019-2020
Number of people at risk: 1,000 residents
Source of pollution: Burial of obsolete pesticides, DDT
Project implementers: NGO “Peshsaf”, Environmental Protection Committee
Total cost: $16,000, the project was funded by European Commission, the assessment was co-funded by USAID and some travel costs were covered by Trust for Mutual Understanding.
The project was implemented in 2019-2020 by current EHPMI member CSO Peshsaf with the financial and organizational support of the EU/ Blacksmith Initiative UK and the Environmental Protection Committee under the Government of the Republic of TajikistanProject dates: 2019-2020Number of people at risk: 1,000 residentsSource of pollution: Burial of obsolete pesticides, DDTProject implementers: NGO “Peshsaf”, Environmental Protection CommitteeTotal cost: $16,000, the…
DDT – General Information
The term DDT refers to p,p’-dichlorodiphenyltrichloroethane. DDT, prepared by the reaction of chloral with chlorobenzene in the presence of sulfuric acid, was first made in 1874; and its insecticidal properties were discovered in 1939 by a Swiss chemist, Paul Hermann Müller. DDT (dichloro-diphenyl-trichloroethane) is considered one of the first of the modern synthetic insecticides.
DDT is applied as a dust or by spraying its aqueous suspension. The term DDT is also applied to commercial products consisting predominantly of p,p‘-DDT, but also containing smaller amounts of other compounds. All DDT isomers are tasteless, almost odorless solids.
DDT is a non-systemic contact insecticide with a broad spectrum of activity. Growers used DDT on a variety of food crops in the United States and worldwide. Some of the crops were beans, cotton, soybeans, sweet potatoes, peanuts, cabbage, tomatoes, cauliflower, brussel sprouts, corn, and other crops. DDT was also used in buildings for pest control.
It was banned in several countries in the early 1970s because of ecological considerations, and many other countries have more recently restricted or banned its use except when it is needed for the protection of human health. Despite a ban on sales, organochlorines may still be found in storage in many countries such as Tajikistan; thus, exposure is still possible. DDT is still used in some countries for the control of vectors that transmit yellow fever, sleeping sickness, typhus, malaria and other insect-transmitted diseases.
DDT was designated as a persistent organic pollutant (POP) in 1997 by the Governing Council of the United Nations Environment Programme. Pesticide applicators are exposed primarily to p,p‘-DDT, whereas it is the p,p‘-DDE metabolite to which the general population is exposed in the diet or drinking-water.
DDT and its metabolites are persistent in the environment and resistant to complete degradation by microorganisms, although photochemical degradation does occur. The persistence of DDT is substantially lower in tropical climates than in temperate ones (a few months compared with years). DDT and its metabolites are readily adsorbed onto sediments and soils, which can act both as sinks and as long-term sources of exposure. Because of its strong tendency to be adsorbed onto surfaces, most DDT that enters water is and remains firmly attached to soil particles. If it does find its way into water, it is gradually lost by adsorption onto surfaces.
In soils, DDT is immobile under aerobic conditions with a mean half-life ranging from 2 to 15 years. DDT is metabolized by microbial systems in soils and is broken down into DDE and DDD. Significant degradation has been demonstrated in soils under anaerobic conditions, while little or no degradation was observed under aerobic conditions. Biodegradation, however, is highly variable and influenced by the populations of required microorganisms. Various amendments to soils such as energy and carbon sources, were shown to increase degradation under anaerobic but not aerobic conditions. DDT has been shown to readily degrade in certain flooded soils. DDT is apparently co-metabolized by microorganisms and is not used as a sole carbon source. Products of biodegradation include DDD and DDE and occasionally DBP (4,4′-dichlorobenzophenone).
The physical and chemical properties of DDT and its metabolites enable these compounds to be taken up readily by organisms from the surrounding medium and from food. In aquatic organisms, uptake from water is generally more important, whereas food is the major source for terrestrial fauna. High lipid solubility and low water solubility lead to the retention of DDT and its stable metabolites in fatty tissue. In general, organisms at higher trophic levels tend to contain more DDT-type compounds than those at lower ones. These compounds can be transported around the world in the bodies of animals, as well as in ocean and air currents.
In the United States, populations of bald eagles and other raptors crashed when DDT thinned their eggs, killing their embryos. The pesticide, known for accumulating in food webs and persisting in soil and river sediment, was banned in the United States in 1972. Studies in animals have also shown that oral exposure to DDT can cause liver cancer.
DDT is classified as “moderately toxic” by the US National Toxicology Program (NTP) and “moderately hazardous” by WHO, based on the rat oral LD 50 of 113 mg/kg. Indirect exposure is considered relatively non-toxic for humans. The International Agency for Research on Cancer (IARC) classified DDT as Group 2A “possibly carcinogenic to humans”. EPA has determined that DDT, DDE, and DDD are probable human carcinogens as of January, 2015.
Current concerns surrounding DDT are that it is an endocrine disruptor. Endocrine disruptors are chemicals that can interfere with endocrine (or hormone) systems at certain doses. These disruptions can cause cancerous tumors, birth defects, and other developmental disorders. Any system in the body controlled by hormones can be derailed by hormone disruptors. A wide and varied range of substances are thought to cause endocrine disruption. Chemicals that are known endocrine disruptors include diethylstilbestrol (the synthetic estrogen DES), dioxin and dioxin-like compounds, polychlorinated biphenyls (PCBs), DDT, and some other pesticides.
Pesticides in Tajikistan
Before the collapse of the Soviet Union, pesticides and other chemicals were actively used in Tajikistan’s agriculture. The application of different pesticides was often done without proper adherence to the existing rules and standards and without consideration of the climatic conditions in different areas.
The range of pesticides used in Tajikistan included the following POPs: aldrin, dieldrin, heptachlorine, endrin, hexachlorinebenzene, toxaphene, chlordane, DDT, endosulphane, and lindane. On average, about 14 thousand tons of pesticides were brought to Tajikistan every year. The share of DDT constituted from 33 to 80% of the total volume of pesticides. About 90 thousand tons of DDT were brought to Tajikistan during the period of active use of this insecticide.
In 1970, by the decree of the Minister of Health of the Soviet Union, application of DDT was banned in agriculture and, in 1987. DDT was banned for use to control vector-borne diseases. In the 1980s and through the beginning of 1990s, the use of other pesticides-POPs was also banned. Despite the ban, the remaining pesticides were still used, though in much smaller volumes.
Currently, the threat of obsolete pesticides to the health of people and the environment in Tajikistan still exists. During the Soviet time, the amount of pesticides brought to Tajikistan exceeded actual application needs by 1.5-2 times. As a result, excessive volumes of pesticides were accumulating in multiple storages and distribution centers of “Tajikselkhozkhimiya” Republican Service. Because there were so large volumes of unused pesticides, various violations occurred: pesticides were distributed to individuals for uncontrolled use in their gardens, some pesticides were dumped in municipal landfills or secretly buried. In the 2000s and because of small supplies of pesticides to Tajikistan, the existing volumes of obsolete pesticides were used again in agriculture. People particularly preferred using DDT and excavated the waste chemical from the Vakhsh polygon, where more than 9 thousand tons of DDT were buried. The customs of Tajikistan registered some cases of illegal import of DDT, including the case of bringing 7 tonnes of DDT from Uzbekistan.
Today, agriculture is an important part of Tajikistan economy, generating about 24.2% of GDP (2015). The total area of land used for growing various crops exceeds 900 thousand hectares. Much attention was also paid to the agricultural sector while Tajikistan was part of the USSR. In Tajikistan there were significant areas of agricultural land for growing crops, especially cotton, and millions of rubles were spent on building infrastructure, as well as providing the industry with agrochemicals and pesticides. The development of agriculture, and, above all, cotton growing, in Tajikistan was closely linked to the widespread use of pesticides to control agricultural pests, plant diseases, and weeds.
The former pesticide storage is located in Darkat Village, Farhor District in Khaton Region, the most densely populated part of the Republic of Tajikistan.
During the Soviet era, this warehouse was a state property and it was used for storing 11 types of pesticides and mineral fertilizers. Now the warehouse is owned by a local farmer.
People built houses and moved into the area around the warehouse. There was easy access by children to the warehouse, and children sometimes played there. The residents gathered fruits in the garden that was planted around the warehouse. A portion of the warehouse was used by the owner to store hay. Within 400 meters from the warehouse, there is a school for 1,200 students and a kindergarten for 300 children. A small irrigation channel flows near the warehouse. The main pathways of exposure of people to pesticides are inhalation, direct dermal contact and eating fruits and animal products that may contain pesticides.
The site was initially assessed in October 2018. The project team found 3 drums with thiodan and 1 drum with DDT. These drums had labels and a distinctive chemical smell. More pesticides were stored on the property in piles.
The investigation team took samples and analyzed them in Institute of Chemistry of the Academy of Sciences of the Republic of Tajikistan. The concentration of DDT in soils exceeded the baseline values of Tajikistan (0.1 mg/kg) by 126 times. The USEPA regional soil level (RSL) for residential soil (1.9 mg/kg) was exceeded by 6.6 times, for industrial soil (8.5 mg/kg) – by 1.5 times.
In October 2018 the project team did the Detailed Site Assessment (DSA) of the site. More extensive soil sampling was conducted to estimate the volumes of contaminated materials and propose risk reduction alternatives.
Preparing for Remediation
The project team met with Head of District Administration (Hakim) and local administration to discuss the findings and feasibility of risk reduction activities. The local administration expressed support for the assessment activities and promised to help with the coordination and implementation of future risk reduction measures. The project team also interviewed residents to find out about the contamination distribution patterns and known health impacts.
The project team developed the alternatives analysis matrix to choose the best course of actions to reduce health risks at the site.
The following alternatives were considered:
A. No action.
B. Repackaging of obsolete pesticides and removal to Hazardous Waste Storage.
C. Repackaging and safeguarding obsolete pesticides on site.
D. In situ treatment of obsolete pesticides through biodegradation.
E. Biodegradation of pesticides in bioreactors (mobile plants)
F. In situ treatment of obsolete pesticides through destruction with special equipment (Burning pesticides in special modular plants).
G. The burning of pesticides in cement kilns.
The possibility of implementing of each alternative was assessed on a 5-point scale according to the following parameters: Risk reduction effectiveness; Sustainability; Logistical feasibility; Potential risks of work; Compliance with regulations and/or accepted practices; Stakeholder acceptance; Anticipated costs.
The cleanup started in October 2018. At the first day the Safety Manager Umijon Ulugov and Community Trainer Lyudmila Bobritskaya held a practical training for workers on handling hazardous materials.
The project team marked the site with a signal tape and prepared all the necessary equipment. The area of the warehouse was completely restricted to residents for the duration of the operation. The workers repackaged the contaminated soil and damaged bags with pesticides into UN Big Bags and plastic drums. A special metal funnel was used to bag the pesticides.
After the delivery of the contaminated soil and UN Big Bags to the facility the trucks were washed off there at a specially designated area in order to remove possible remaining contamination.
At the end of the remediation, a total of 31 metric tons of hazardous wastes were sent to the Vakhsh polygon.
A local resident Alimchon Bakaev, said: “I’m relieved and grateful that pesticides were removed from our community. For years, we witnessed the harmful effects of these chemicals on our environment and health. Removing the pesticides not only promotes a healthier ecosystem, but also protects the health of our families and animals. I believe that this is an important step towards our sustainable future. We must work together to keep our nature safe and healthy for future generations.”
Education and Awareness
In October 2018, Peshsaf conducted an information campaign for residents living near the contaminated area. The project team engaged in education and awareness activities to inform residents about the purpose of the action, about the risks of living next to obsolete pesticide warehouses, and about the health effects of pesticides. The project team explained to the residents how to minimize exposure to pesticides and answered questions.
The following educational materials were designed and printed:
- Booklets “What are pesticides?”, “How to protect yourself and your family?”.
- Wall Calendars for 2019-2020, with information about types of pesticides, their impacts on environment and negative effects on human health.
Local resident Sobir Qasimov said: “I participated in the training about the dangers of pesticides and I must say that now I’m more aware and concerned about the negative impacts of these chemicals on our health and the environment. Before the training I believed that pesticides were merely essential for pest control and crop protection. However, the training opened my eyes to the potential risks associated with the use of pesticides”.
Post Remediation Assessment
In order to control the quality of the cleanup, the project team took soil samples to analyse for organochlorine pesticides. The results indicated that in all samples the DDT concentrations did not exceed 1.9 mg/kg. It meant that DDT health risks for people in the area were reduced to internationally acceptable levels.
The Maximum Allowable Concentration adopted in Tajikistan is 0.1 mg/kg for DDT and in some samples the concentrations were above this value, though below 1.9 mg/kg. Since cleaning up the area to achieve compliance with MSA is impractical, the project team concluded that no further clean up action or long-term pollution controls system are necessary in the area.
The map of the DDT concentrations in soil before and after cleanup is shown below.
Link to project description at PE website: Two pesticide cleanups and a wedding in Tajikistan, near the Afghan border