First phase of the environmental assessment on the site had already been done. The investigation was done to complete a cursory assessment of the abandoned industrial site so as to determine its conditions which indicate the prospects of environmental liability.
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The purpose of the environmental risk assessment of the site was to identify the actual and potential sources of environmental risk posed by the hazardous waste site which resulted form the past industrial activities on the land and propose measures for managing the environmental risks.
Scope and Limitations
This report provides a summary of the site’s potential environmental concerns. The environmental risk assessment process involved reviewing the historical and the present documentation concerning the site, a reconnaissance inspection as well as interviews with people who have some knowledge about the site. The report includes a description of the toxicants common routes of exposure, mechanisms of toxicity and the exposure limits for the toxicants. The assessment process will involve the steps of risk assessment which are; hazard identification of the hazards, dose responsive assessment of the hazardous wastes, exposure assessment as well as risk characterization. Finally, the report proposes recommendations for managing the subject site.
The environmental assessment of the site is limited by inadequate information available during the assessment process. There is a possibility that unreported disposal of wastes causing serious harm to the environmental status of the area may have occurred but could not be identified.
Description of the Site
Several issues were identified after the visual inspection of the subject site and the areas adjoining it. There are 100 unmarked drums buried on the site. Many of the drums are rusting and showing signs of cracking. There is a general strong smell of pungent chemicals in the air near the drums. A general overview of the drums indicted the past usage of PCBs in the electrical equipment such as capacitors, fluorescent lamp ballasts as well as transformers. The site is located approximately one mile upstream of a residential area and a surface water withdrawal point for the local water supply. Water is also withdrawn downstream from the site for irrigation purposes. One stream, which is a popular fishing stream, runs through the site.
Historical review of the site from the records available from the municipal council showed that the subject site had been an industrial site for the past sixty years. The records also showed that there were two companies which utilized the subject site. The two companies are now defunct and the information from the regulatory agencies showed that subject site is listed as closed.
An interview with people knowledgeable about the subject site discovered that the industrial wastes in the unmarked drums buried in the soil included; Poly Chlorinated Biphenyls (PCBs), chromium waste, acrylamide and toluene diisocyanate (TDI). The information found at the regulatory agencies also showed that the subject site had been PCB storage facilities.
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Mechanisms of Toxicity
The major routes of exposure of Poly Chlorinated Biphenyls PCBs are through ingestion and inhalation. The common exposure pathways are through consumption of PCB-contaminated sportfish as well as drinking PCB-contaminated water from wells. PCBs may also enter the bodies of human beings through breathing indoor air. The common exposure pathways of acrylamides are through inhalation or through consumption of food products like fish that have been contaminated by acrylamides (Becker, & McCartor, 2010). Skin absorption is a key route of exposure of acrylamide. The common exposure pathways for Chromium are through inhalation, ingestion or dermal contact (Becker, & McCartor, 2010). TDI’s exposure routes include, inhalation, dermal and ingestion may also occur.
Although PCBs dissolve poorly in water, but the physical presence PCB equipment and the manifestation of clinical abnormalities among those living around the site may be used to determine the level of exposure. PCBs are chemically stable and are therefore resistant to biodegradation. The fish in the stream that passes through the subject site are bound to take up PCBs into their bodies. Exposure to PCBs may cause dermal effects which include thickening of the skin, swelling of eye lids; edema, abdominal pain, jaundice, dizziness, nausea, depression, lymphoid depletion, liver damage among many others. PCBs also pose the risk of cancer infection on human beings.
Acrylamide is usually present in the soil, air, surface water and ground water in such industrial wastes sites such as the subject site. Health risk analysis reveals that acrylamide is toxic to kidneys and may cause eye and skin irritation, fatigue, chest pain and even general body weakness (Becker, & McCartor, 2010). Inhalation of acrylamides such as mercury may cause stomach, intestinal and lung, brain damage. Acrylamides such as mercury may cause miscarriages in women. It also causes respiratory failure which could eventually lead to death. Sampling and testing is likely to reveal that Chromium exists in air, soil groundwater and surface water in the subject site. Chromium is a potential human carcinogen and is also toxic to kidney. Chromium also damages the immunological, reproductive and respiratory systems (Becker, & McCartor, 2010).
Toluene may depress the central nervous system and hence may cause decrease in alertness and even loss of consciousness. PCBs are toxic to the liver and may also cause various skin ailments such as chloracne (National Industrial Chemical Notification and Assessment Scheme, 2002). PCBs are also carcinogenic to animals. Toluene diisocyanate (TDI) causes asthma to human beings. Exposure to toluene diisocyanate is likely to cause irritative skin, upper respiratory tract. Chronic exposure to TDI may cause pulmonary and bronchitis edema (National Industrial Chemical Notification and Assessment Scheme, 2002).
Steps of Risk Assessment
Toxicity identification is done to characterize the classes of toxicants in the subject site. Wastes are classified according to their chemical and biological profiles. During the toxicity identification, solid-phase extraction is done by removing the hydrophobic compounds from the buried drums. Ion exchange extraction is done by removing cations from the water samples. Leachate sample is also prepared for toxicity test. Toxicity tests are done on water and soil in replicates. A diffusion leaching test is also done to determine whether toxicity was from the enclosed metal layers in the drums. Other important laboratory tests such as blood gases, chest roentgenogram are also done.
The environmental risk assessment involved sampling and testing of the soil, air, surface water of the river passing through the site, groundwater and the materials found in the tanks. This is to investigate leaks, spills and even contaminant discharge into the stream passing through the site.
Calculation of groundwater mobility is done to determine the mobility of PCBs in groundwater. Generally, PCBs have low groundwater mobility are the degrade sediments of PCBs are usually found in the surface water which in this case is the stream. The effect of water vapour on the toluene diisocyanate, chromium and acrylamide in the air is determined quantitatively.
Dose-Response Assessment for PCBs focuses on dioxin-like health effects of the various PCBs which might be available in the subject site. The evaluation and analysis is done using toxic equivalent factors and by carrying out the actual measures of the PCB body implications on the people living around the site. Series of long-term studies are done to determine the exposure to a mixture of PCBs on the surrounding population. Laboratory animals may be used in the study to carry out the risk assessment of PCBs. Information on toxicity, environmental process as well as disposition is used to evaluate the health risks of the surrounding population (National Center for Environmental Assessment, 1996). Dose-response assessment of acrylamide, chromium wastes and toluene diisocyanate involves biological monitoring of human exposure to these chemical elements.
Risk characterization of the hazardous waste in the subject site involves environmental risk which include analyzing the aquatic risk to the aquatic life in the stream passing through the subject site, risks to terrestrial organisms in the surrounding environment, risks to surface water and wastewater treatment; public health risk which is risks to the surrounding population; occupational health risks which includes risks estimates, areas of concern, occupational exposures and critical health effects.
Exposure assessment will involve testing of the chemicals in the samples (soil, air, surface water and groundwater) extracted from the subject site to determine the volatility of the chemicals; chromium, acrylamide and TDI. Priority pollutants are defined according to their toxicity, bioaccumulation, mobility as well as their environmental persistence. Biological and chemical assessments are done to characterize the exposure as well as ecological effects of the industrial waste elements ( Azizian, Nelson, Thayumanavan, & Williamson, 2005). Potential ecological risks that are posed by the industrial waste constituents are also determined.
After categorizing the wastes according to their chemical and biological profiles, composting biodegradable elements in the drums to an anaerobic and biological degradation process should be applied to manage some wastes (Rushton, 2010). Another method for the hazardous wastes management would be to relocate the wastes to a landfill where the wastes would be deposited in specially designated areas that consist of pre-constructed cells which are lined with impermeable layers which are able to effectively control emissions from the chemical elements in the wastes (Rushton, 2010).
Bioremediation and volatilization should be applied to remove contaminants from the soil. The soils around the region can also be treated by saturating them with chemical solutions to reduce the chemical contamination of the soils. Air emissions from the subject site should treated by biofiltration. In this case, the pollutants are degraded and also mineralized through the use of heterotrophic aerobic microorganisms.
The subject site is poses a health hazard to the ecological and aquatic environment and the human population. It is therefore important that quick recovery and treatment measures are implemented before the situation becomes more dangerous to the environment.
Azizian M. F, Nelson, P.O, Thayumanavan, P, & Williamson, K. J. (2005). Evaluation methodology for environmental impact assessment of industrial wastes used as highway materials: An overview with respect to U.S. EPA’s environmental risk assessment framework. The Handbook of Environmental Chemistry, 5(271-291). Berlin: Springer.
Becker, D. & McCartor, A. (2010). World’s worst pollution problems report 2010. New York: Blacksmith Institute.
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National Center for Environmental Assessment. (1996). PCBs: Cancer dose- response assessment and application to environmental mixtures. Washington D. C.: U.S. Environmental Protection Agency.
National Industrial Chemical Notification and Assessment Scheme (NICNAS). (2002).Acrylamide: Priority existing chemical assessment report no. 23. Sydney: Info Access.
Rushton, L. (2010). Health hazards and waste management. British Medical Bulletin 96 (1), pp. 183-197. Leceister: Institute for Environment and Health
Takeuchi, Y. (2004). Health effects from exposure to chronic levels of industrial chemicals. Oxford: Eolss Publishers.