Exposure Assessment Case Study: 50 Points Directions After R

Exposure Assessment Case Study50 Pointsdirectionsafter Reading The

After reading the Centers for Disease Control and Prevention case study, answer the following questions.

Case Study: “Cross-sectional Exposure Assessment of Environmental Contaminants in Churchill County, Nevada” by the Centers for Disease Control and Prevention.

Identify the agent:

_____________________________________________________

What type of agent is described?

biological chemical

Source:

anthropogenic non-anthropogenic

Area:

point stationary mobile indoor outdoor

Transport/carrier medium:

air water soil dust food product item

Exposure pathways:

  • eating contaminated food
  • breathing contaminated air
  • touching a contaminated surface
  • drinking contaminated water

Exposure concentration:

  • mg/kg (food)
  • mg/litre (water)
  • ug/m3 (air)
  • ug/cm3 (contaminated surfaces)
  • % by weight
  • fibres/m3 (air)

Exposure route:

inhalation dermal contact ingestion multiple routes

Exposure frequency:

continuous intermittent cyclic random rare

Exposure duration:

seconds minutes hours days weeks months years lifetime

Exposure setting:

occupational non-occupational residential non-residential indoors outdoors

Exposed population:

general population population subgroups individuals

Geographic scope:

site specific local regional national international global

Paper For Above instruction

The Centers for Disease Control and Prevention (CDC) conducted an exposure assessment study in Churchill County, Nevada, to evaluate the presence and potential health impacts of environmental contaminants in the region. This comprehensive assessment incorporated numerous facets of environmental health science to identify the contaminant agents, their sources, pathways of exposure, and the populations at risk. Such an investigation is crucial for informing public health policies and intervention strategies aimed at reducing exposure and preventing disease.

Identification of the Agent

The primary focus of the CDC case study was on the exposure to environmental contaminants, specifically metals like arsenic and other inorganic substances. These agents are known for their toxicity and propensity to accumulate in environmental media, potentially leading to adverse health outcomes. In Churchill County, arsenic contamination was identified in groundwater sources, which posed a significant health risk to local populations relying on well water for drinking and irrigation purposes.

Type of Agent

The agents of concern in the study are chemical contaminants, notably inorganic chemicals like arsenic and possibly others such as manganese and uranium. These are chemical agents rather than biological pathogens, emphasizing chemical toxicity's role in environmental health risk assessments.

Source and Area of Contamination

The contamination sources in Churchill County were largely anthropogenic, including agricultural practices, mining activities, and naturally occurring geological deposits that become mobilized through human activities. The contamination was primarily area-specific, with the source localized around groundwater extraction sites, although the pollutants can disseminate through water and soil media, affecting broader regions dependent on the contaminated aquifers.

Transport and Carrier Medium

The main transport medium for the contaminants was water, notably groundwater that served as the drinking water source. Arsenic and other inorganic contaminants dissolved into the water, facilitating movement through the aquifer system. Dust in the environment can also carry particles containing contaminants, especially during wind events, potentially inhaled or deposited on surfaces.

Exposure Pathways

Human exposure occurred mainly through ingestion of contaminated water, which was the primary pathway due to reliance on groundwater supplies. Other pathways included contact with contaminated soil or dust particles and contact with contaminated surfaces. Although dermal absorption is limited for inorganic chemicals like arsenic, ingestion remains the dominant route.

Exposure Concentrations

The exposure levels were measured in various units appropriate to the media: milligrams per kilogram for food, milligrams per liter for water, and micrograms per cubic meter for air. The study indicated arsenic levels in groundwater exceeding federal safety standards, emphasizing the significance of dose in risk assessment.

Exposure Route

Ingestion was the primary exposure route in the study, especially through drinking contaminated groundwater. Inhalation of dust particles containing arsenic could also contribute to exposure, particularly during dry, windy conditions. Dermal contact over extended periods was considered less significant but still relevant, especially for agricultural workers or residents routinely contacting contaminated soil.

Exposure Frequency and Duration

The exposure was characterized as intermittent to continuous, depending on individual water consumption patterns and other behaviors. Residents consuming groundwater routinely experienced more continuous exposure, potentially spanning years or even decades. The duration of exposure was often lifelong for local populations dependent on contaminated water sources.

Exposure Setting and Population

The exposure occurred primarily in residential settings, where private wells supplied water for household use. The population included the general residents of Churchill County, with particular concern for vulnerable subgroups such as children, pregnant women, and the elderly, who are more susceptible to toxic effects.

Geographic Scope

While primarily a site-specific study, the implications of these findings extended regionally within Nevada and potentially nationally, given the use of groundwater for drinking in various arid regions across the United States.

Conclusion

This case study underscores the importance of comprehensive exposure assessments in identifying environmental health risks. Understanding the agent, source, pathways, and populations allows public health officials to develop targeted interventions, such as water treatment or alternative water supplies, to mitigate the health impacts of contaminants like arsenic. Continuous monitoring and policy implementation are vital for protecting public health in areas with environmental contamination issues.

References

  • Agency for Toxic Substances and Disease Registry (ATSDR). (2019). Arsenic Toxicity. Atlanta, GA.
  • Centers for Disease Control and Prevention (CDC). (2014). Cross-sectional Exposure Assessment of Environmental Contaminants in Churchill County, Nevada.
  • World Health Organization (WHO). (2017). Guidelines for Drinking-water Quality.
  • California Department of Public Health. (2018). Arsenic in Drinking Water.
  • US Geological Survey (USGS). (2020). Groundwater Contamination and Quality Data.
  • National Research Council (NRC). (2001). Arsenic in Drinking Water: 2001 Update.
  • Environmental Protection Agency (EPA). (2016). Integrated Risk Information System (IRIS) - Arsenic.
  • McClintock, T. R., & Balistreri, M. (2014). Water Quality and Public Health Implications. Journal of Environmental Health.
  • García, D. R., et al. (2019). Regional Distribution of Groundwater Contaminants. Environmental Science & Technology.
  • Ramirez, M. O., & Woodruff, T. J. (2021). Environmental Exposures and Vulnerable Populations. Environmental Epidemiology.

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