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Еnvirоnmеntаl Risk Аssеssmеnt


Risk-based approach is a phenomenon that most people use in their daily lives. When there is a presumed risk, the idea is to identify the risk and ascertain its presence before assessing and analyzing the risk. Any analysis of risk is expected to lead to a comprehensive management of the risk.

The approach involves weighing up risks and hazards against rewards and benefits. The environment t is one entity in life that is always faced with the danger of having risky and hazardous activities affecting it. This in turn affects the safety of the environment, putting the life forms under risk. Environmental risk assessment is necessary in order to identify the risky activities, classify the intensity of the risk and also device methods and approaches to defend life from the dangers posed by these risks.

Environmental Impact Assessments (EIA) should be a general forum for the socio-environmental part of the risk assessment. This kind of assessment is responsible for most of the governmental responses and management of environmental risks and uncertainties. The objective of this paper is to identify and analyze the risks to the environment from a case study. This identification and analysis will lead to a comprehensive risk assessment and guide the risk management process.

The case study on which this paper is based is Dredging the Hudson River, an environmental risk assessment case study by the McGraw-Hill Companies. The case study deals with the government’s efforts to clear Hudson River, a project that is expected to be the most expensive clean-up project in history. The clean-up follows previous reckless discharge of PCBs into the river by General Electrical in a process that during this time was considered legal.

This implies that the company cannot be held liable. Since the government banned the production distribution and procession of PCBs in the year 1976, after the company had already discharged enough of these products into the environment especially from its factories in Hudson Falls and Fort Edward, the government has the responsibility to clear the mess. However, the clean-up exercise took place more than 25 years after the actual disposal of the risky products into the environment. This means that much of the risk was already in the environment.

Perceived Risks

The perceived risk associated with exposure to PCB products from the analysis by scientists are;

  1. The products are carcinogenic and will cause cancer to exposed human beings.

Environmental concentration beyond the safe level will cause increased exposure to a larger population within the area. This will in turn cause an exacerbation of the adverse effects in the long run. Since the PCBs are proven to be carcinogenic, many people who will be exposed are likely to suffer.

  1. Contamination of the rivers increases the turbidity of the water affecting the aquatic life.

Accumulation of the PCBs in the water will affect the aquatic life. Without any safety data on this ecosystem, there is a possibility that this accumulation may have negative effects on the aquatic life both physically and genetically through accumulation.

  1. The products are also related to other health conditions such as thyroid disease, autoimmune disorders and skin diseases.

Chronic exposure to the population will cause massive accumulation of the toxins inside the bodies of the affected. The chemicals have been linked with other diseases

The identified risks are all important for consideration due to the impact they have on the lives human beings, plants and animals living in the affected ecosystem. However, the risk of causing cancer to human beings represent the worst case scenario effect of the chemicals. This is because the exposure to the water, as determined from the case study, is highly unlikely to cause an immediate hazard to the aquatic life owing to the low solubility of the chemicals in the water. The chemicals, therefore, will only sediment, and the little seepage into the water will take time to affect the aquatic life. However, prolonged exposure of these chemicals in the environment are likely to cause chronic damage to aquatic live forms, as well as the health of other water users in the populations.

These risks are measurable and assessable through research and surveys. However, the research indication is that to obtain clear data on mortality rates, reproduction and other demographic parameters that can be used to measure the risk is unrealistic. This, therefore, means that the measurement has to depend on the experimentations and inference data from scientific findings.

Risk ranking

Student’s Name These risks can be ranked in a likelihood vs consequences matrix as shown in the matrix below.





Almost certain A

The risk of causing cancer to human beings

Risk to the pelagic and benthic aquatic ecosystem

Possible C

Diseases related to chronic exposure

Unlikely D

Unknown E

Risk Measurement

Risk assessment involves a serious measurement of the exact possibility for the risk. In this case, laboratory measurements of the contamination levels of the river and the effects of the PCBs were used to identify the exact risk. The laboratory report was required to indicate the chemical structure of the products and how this is expected to affect the environment in terms of its effects on the water users and the aquatic life. The chemical will have to be related to other known hazards to come up with this information.

The environmental exposure assessment was to evaluate the fate, transport and biotic and abiotic fate parameters. Lastly, the ecological hazard and risk assessment was performed by the authority to assess the potential adverse effects of the chemicals to the ecosystem. General measurement of endpoints involved the use of mortality rates, growth and development, reproduction and other population demographics. The immediate, mid-term and long-term effects of PCBs was assessed to determine the risk.

Ecological Effect

The new chemical belongs to a class of compounds known as PCB compounds. Although nonelectrical and nonreactive, the chemicals are potentially toxic. They have a non-specific mode of action in the body. From the chemistry report, these chemicals have both chronic and acute effects. When accumulated in the body, the effects are known to increase. The chemicals are not expected to exit from the ecosystem rapidly due to their low solubility in water.

These products are deposited in the sludge at the base of the rivers and continuously contaminate the water. They are currently known to be carcinogenic, and have also been related to several other health risks. This means that chances of accumulation in the water, humans, animals and aquatic plants are high. The effect on algae and aquatic invertebrates was found to be minimal in low concentration of the compounds. However, the accumulated compound in the water still gives the concentration required to cause harm with prolonged exposure.

The health effects of PCBs have been identified as severe, extending from causing simple skin reaction with exposure to chronic conditions such as cancers. According to this case study, PCBs, in addition to being carcinogenic they are also are thought to trigger serious health problems, including low birth weight when pregnant mothers are exposed, thyroid and hyperthyroid defects, and mental illness, reproductive health issues, and immunological and autoimmune conditions.

Risk Management

From the risk assessment data, it is clear that there is enough information on many of the identified risks. PCBs being dangerous compounds with carcinogenic properties, and the chemistry report being so comprehensive to indicate the relationship between the compounds and other serious medical conditions, the only possible solution is having a project as this. Grudging of the river will involve the use of giant dredgers that will be fitted with large vacuum extractors that will suck out the sludge from the river base.

The use of vacuum will ensure that the removal of the sludge does not cause disturbance in the water that can cause escape of a dangerous material into the water. This project is expected to cost the government about $460 million to remove at least 2 million cubic meters of the contaminated sludge from the river. However, there still existed controversy during the extraction regarding the fate of the removed sediment.

The Residual Risk

Although dredging will effectively reduce the concentration of the PCBs in the river, the composition that is expected to remain is significantly high. This is in relation to the fact that most of the already buried sources of contamination will be exposed and since the products have been in this position for long, degradation could have made the products more water soluble. The residual risk, therefore, remains that the community using the water and its fish will experience a different level of exposure.

Further, the dredging exercise does not specify the fate of the dredged material from the river. The sediment, as noted, will be even more exposed to the people and the community. This is because exposing it to the environment increases the likelihood of exposure. If some of the sediment is left on the ground, the contamination levels are expected to increase significantly.


Horn, E.G., Hetling, L.J., Tofflemire, T.J., 1979. The problem of PCBs in the Hudson River system. Ann. N. Y. Acad. Sci. 320, 591–609.

McGraw-Hill Companies. Environmental Case Study: Dredging the Hudson River. The McGraw-Hill Companies, Inc.