Nature itself presents hazards to human health, including disease, natural poisons, and radiation. Regulators use a process called environmental risk assessment to decide whether they need to take risk management steps in relation to a risk. In this activity, you will carry out three steps of an environmental risk assessment called release analysis, exposure analysis, and health effects analysis. This activity will require outside research in addition to the textbook and will set the stage for a larger assignment in Week 4.
Instructions
Write a 1–2 page paper using the following instructions.
Select an environmental risk that occurs in nature, and research information about its release, exposure scenarios, and health effects. The specific data in each area of the analysis will depend on the environmental risk you choose. Write at least one paragraph for each analysis:
Release Analysis: Identify the contaminant, and how it is released, measured, or detected. Include units of measurement, setting for the release, and scientific fields related to the contamination or measurement.
Exposure Analysis: Analyze the risk of exposure such as settings in which people encounter the risk or plausible scenarios in which exposure occurs.
Health Effects Analysis: Estimate the risks to human health, including short and long-term effects, demographic groups at risk, and health effects on individuals and populations.
Use 1–2 sources to support your writing. Choose sources that are credible, relevant, and appropriate. Cite each source listed on your source page at least one time within your assignment. For help with research, writing, and citation, access the library or review library guides.
Sample Answer
Environmental Risk Assessment: Naturally Occurring Radon Gas
The following is an environmental risk assessment for Radon-222 ($\text{Rn}^{222}$), a naturally occurring radioactive gas.
Release Analysis
The contaminant is Radon-222 (1$\text{Rn}^{222}$), a colorless, odorless, chemically inert radioactive gas.2 Radon is the primary decay product of radium-226 (3$\text{Ra}^{226}$), which is found naturally in uranium-bearing rocks and soil (such as granite, shale, and phosphates) and, to a lesser extent, in groundwater.4 The release mechanism is the natural radioactive decay chain of uranium.5 As radium decays in the soil, radon is produced and is released into the atmosphere through porous rock fissures and soil.6 The primary setting for human exposure, however, is the indoor environment, where radon is continuously released from the ground and concentrates in enclosed spaces.7 Radon is typically measured using specialized detectors (like alpha track detectors or electret ion chambers) and is reported in units of picoCuries per liter (8$\text{pCi}/\text{L}$) or Becquerels per cubic meter (9$\text{Bq}/\text{m}^3$).10 The scientific fields central to this contamination are radiochemistry, geology, and atmospheric science (Agency for Toxic Substances and Disease Registry [ATSDR], 2020).
Exposure Analysis
The risk of exposure to radon is ubiquitous, as it is naturally present in all outdoor air and soil; however, the level of concern centers on indoor exposure.11 Plausible exposure scenarios occur when radon gas seeps into homes, schools, and workplaces through cracks in solid floors, construction joints, utility penetrations, and sumps.12 Because radon is heavier than air, it tends to accumulate in basements, crawlspaces, and ground-level rooms.13 Individuals encounter the risk by inhalation of the gas and its short-lived solid decay products (polonium, bismuth, and lead), which attach to dust particles.14 A high-risk scenario is chronic, long-term exposure for a resident living in a single-family home in an area with high uranium content in the underlying geology (e.g., the Appalachian or Rocky Mountain regions of the U.S.). The risk is proportional to the concentration of radon and the amount of time spent in the contaminated indoor setting (U.S. Environmental Protection Agency [EPA], 2023).
Health Effects Analysis
The primary health risk from chronic radon exposure is lung cancer.15 Radon itself is inert, but its solid decay products (or "daughters") are radioactive and can become lodged in the lining of the lungs when inhaled.16 These decay products emit alpha particles, which cause genetic damage to the lung tissue, leading to cancerous cell formation.17 This is a long-term effect, typically manifesting 5 to 25 years after significant exposure.18 Short-term effects are generally not observed. Radon is the second leading cause of lung cancer overall (after smoking) and the leading cause among non-smokers.19 Demographic groups at greatest risk include miners (due to high exposure in enclosed mines) and smokers, as the combined risk of radon and tobacco smoke exposure is significantly greater than the sum of the individual risks. On an individual level, chronic high exposure dramatically increases the lifetime risk of a fatal malignancy. On a population level, the EPA estimates that radon causes about 20$\text{21,000}$ lung cancer deaths each year in the United States alone (U.S. EPA, 2023; ATSDR, 2020).21