Mahmood A. Khwaja
Khwaja@sdpi.org
DDT (Dichlorodiphenyltrichloroethane) is one of the most hazardous groups of chemicals called Persistent Organic Pollutants (POPs), also known as “ The Dirty Dozen.” These very toxic chemicals, including DDT are long lasting due to their non-degradability, can travel to distant places and being fat soluble, accumulate in animals and human bodies. Even in extremely small amounts, POPs cause adverse impacts on human health and environment. To save public health, especially the health of the children, the manufacturing and use of POPs has been banned in the world under the Stockholm Convention on Persistent Organic Pollutants (POPs), enacted in 2001. A number of national governments including Pakistan have signed the Stockholm Convention. The Convention has been ratified by over 120 countries thus far.
Due to the persistent nature of DDT, a persistent organic pollutant and its adverse environmental and health impacts, the present study was undertaken to examine the residual DDT in and around a DDT manufacturing factory in Amman Gharh, Nowshera, NWFP. The present study is one of many activities carried out under international POPs elimination project (IPEP) undertaken in eight regions of the world, including South Asia and supervised by international POPs elimination network (IPEN).
The factory was established in 1963 and remained in operation till 1994. The project team visited the factory site several times to carry out the survey, held meetings with the ex-employees of the abandoned factory and other stakeholders and took soil and water samples for chemical examination. Composite samples of soil, sediments and water were collected in and around the factory area, nearby DDT stores, main factory drain leading to river Kabul and nearby villages. Standard procedures were used for the collection, transportation and storage of samples for analyses. Physical parameters of the collected water samples measured were temperature, pH and conductance. Extraction of each sample for DDT analyses was carried out in triplicates using Soxhlet extraction apparatus. The extract was transferred to well washed, clean dry glass vial, sealed and put in the refrigerator. Gas Chromatograph with electron capture detector and capillary column was used for analysis. DDT in the samples were identified on the basis of their retention time and quantified on the basis of peak areas.
Soil samples from within the factory formulation unit showed residual DDT in the range of 242.28+/- 0.81 to 573.02 +/- 0.94 µg/gm. DDT levels in the soil samples at different points outside the factory compound were found to be in the range of 558.35+/-0.71 to 780.40+/-0.54 µg/gm. In the drain samples, DDT levels were found in the range of 388.57+/-0.48 to 1631.70+/-0.61 µg/gm. Highest DDT levels of 2822.08+/-0.88 and 2841.45+/-0.95 µg/gm were found in samples from the old, left-over bags in the formulation unit and in the stores. Soil samples taken from five yards outside the stores showed 1631.70+/- 0.61 µg/gm residual DDT. However, DDT was not detected in the soil samples taken from Azakhel, ten kilometers away from the DDT factory. Residual DDT levels in water samples from within the vicinity of DDT factory, nearby villages and drain leading to river Kabul showed little variation, most of the samples falling in the range of 0.20+/-0.23 to 0.31+/-0.03 µg/ml. Highest and lowest DDT levels were found to be 0.40+/-0.14 and 0.07+/-0.10, respectively.
It is evident from the analytical data obtained by the present study that both water and soil in and around the factory area are still contaminated with DDT, despite the closure of the factory twelve years ago. In view of the well established and known persistency, transportation, accumulative characteristics, environmental and health impacts of DDT, its contamination in and around the factory area poses threat to public health and environment and may have most serious consequences to ecosystem function, food safety and other aspects of human health, especially in Amman Gharh/Nowshera.
The abandoned DDT factory was there for over 12 years and nobody interested either to use, sell or buy it. However, on the last field visit to the DDT factory site, the project team was most surprised to see the factory almost demolished. It seems that a quick deal was struck by the owner(s), following the IPEP project team’s frequent visits to the site and the on-going interview/meetings with the city officials/stakeholders and ex-employees of the factory.
Whereas the health of the laborers working to demolish the factory and the spread of DDT contaminated bricks/construction material due to its transportation and further use in different near and far off localities are of grave concern, even more so is the likely sale of the land of the factory area (after all the construction material is sold and cleared away) and its further use as commercial or residential area, or as a school, playground, park etc. The area/soil may remain contaminated with DDT for quite some time and it is strongly recommended that the land of the factory area may not be sold or put to any use without prior approval gained after an environmental impact assessment (EIA) of the DDT factory site.
With immediate effect, the factory area may be declared as ‘dangerous’ and banned for any human activities. A barrier/wall may be constructed around the factory area to avoid entrance of children, animals, cattle, and chickens. The exposure’s potential risk to human health posed by hazardous wastes like DDT is known to be enhanced by a general lack of vegetation in the affected area, therefore, as an immediate measure, excessive vegetation may be grown in the area for effective minimization of the risk.
This study has indicated-alarming situation of DDT residue in soil samples. There is a need to look into the feasibility of employing the reported processes for decontamination of DDT from the soil in and around the factory area. A number of soil decontamination processes have been developed and reported. Some of these are referred to in Annex VI. The presence of DDT, a banned pesticide in the country, in the studied drinking water samples is a matter of grave concern, as usage of DDT contaminated water may cause serious impacts on human health. A study relevant to chronic water borne diseases and pesticide levels in water may be initiated in the contaminated areas. Control measures are also required to stop the smuggling of DDT/DDT mixed powder in the country under different trade names such as TOUP, ZOOM etc, from the neighboring countries.
In order to evaluate the risk associated with DDT contaminated site, studies using bio indicators like eggs, adipose tissues, milk, fish, birds, endocrine disruption and cholinesterase levels etc should be initiated in these areas. Soil is not just a mass of dead matter. Rather, it is a living entity. Pesticides residues in soil and their impact on beneficial macro and microorganisms should be elucidated.
