PHE 540 Module 3 Milestone One Example

Planning Before Measuring: Scope and Sources for an Ethylene Oxide Risk Assessment in a Tennessee Valley City

[Student Name]

Southern New Hampshire University

PHE 540: Principles of Environmental Health

Final Project Milestone One

[Instructor Name]

[Date]

The organization, setting and figures below are a composite written as a model document. No real employer, client, colleague or patient is described.

Planning Before Measuring: Scope and Sources for an Ethylene Oxide Risk Assessment in a Tennessee Valley City

Part A: Planning

Risk assessment in the United States follows the framework the National Research Council (1983) set out: identifying the hazard, describing how response changes with dose, estimating exposure and then characterizing risk, kept separate from the risk management decisions that follow. Planning comes first, because the questions asked shape which data are gathered and how results will be used.

Purpose

The assessment will estimate the added lifetime cancer risk to people living, studying and working near the sterilization plant from breathing ethylene oxide released by it, and will identify the groups at greatest risk. Results will inform the regional health department, the state air agency and the city council as they consider monitoring, emission controls and communication with residents. The final report will be written for residents as well as agencies.

Scope

The assessment covers one chemical, ethylene oxide; one source, the plant; one route, inhalation; and residential, school and nearby community exposures within two kilometers. It excludes plant workers, who are covered by workplace standards, and other sources, which are treated as background. The main health endpoints are lymphoid cancers and breast cancer, where human evidence is strongest. Noncancer effects at community levels are expected to be minor and will be noted but not quantified. Short-term peaks will be reported but not used to estimate lifetime risk.

Conceptual Site Model

The site model links source to receptor. Stack and fugitive releases enter outdoor air, disperse with wind and are often trapped near the ground on calm nights; outdoor air enters homes and classrooms; residents, students and staff inhale it. The model will guide where air samples are placed and which groups are assessed separately.

Assessment Questions

Four questions organize the work. What is the evidence that ethylene oxide causes cancer in people? What dose-response value should be used? What are the long-term average concentrations at the apartments, the school and nearby homes, and how much comes from the plant? And what added lifetime cancer risk do these imply for each group, with what uncertainty?

Data Sources

Hazard and dose-response information will come from the EPA's evaluation and the peer-reviewed literature. Exposure data will come from 24-hour air samples at six locations over three seasons, the plant's reported emissions and dispersion modeling with local weather data. Population data will come from the census and school enrollment records.

Stakeholders and Timeline

Stakeholders include residents of the apartments and nearby homes, the school district and parents, the plant's operator, the state air agency, the regional health department and the city council. A residents' advisory group of six will review the plan and draft results. Planning and literature review take months one and two, sampling months three through eleven, analysis month twelve and the report month thirteen.

Key Uncertainties Anticipated

Three uncertainties are expected from the start. First, the dose-response value comes from workers exposed at concentrations far higher than any resident breathes, so applying it to community levels requires extrapolation. Second, a year of sampling may not capture the plant's long-term average emissions, especially if operations change. Third, separating the plant's contribution from background may be difficult when concentrations are low, because background itself carries measurable risk. Each will be described in the risk characterization rather than hidden, with a range of estimates where possible.

Quality Assurance

Air samples will be collected and analyzed by a certified laboratory using a standard method, with field blanks and duplicate samples at one site each round. Modeling inputs and assumptions will be documented so others can reproduce the results. Draft findings will be reviewed by an outside toxicologist before release.

Part B: Annotated Bibliography

The five sources below form the core of the hazard and exposure evidence.

Steenland et al. (1991)

This mortality study followed more than 18,000 workers at sterilization and production facilities. It found suggestive excesses of lymphatic and blood cancers among workers with the longest exposure, though overall mortality was not raised. It is one of the founding cohort studies and established the outcomes later work examined. Its limitation is that exposure was estimated rather than measured for each worker. Use: hazard identification. Later follow-ups of the same cohort refined these findings and were used in the EPA's dose-response analysis, so this paper is the starting point for tracing that evidence.

Steenland et al. (2003)

This study of 7,576 women who worked in commercial sterilization facilities found breast cancer incidence rising with cumulative exposure, with a positive exposure-response trend, after accounting for under-ascertainment. Its strength is a gradient with dose; its limits include incomplete interviews. Use: supports breast cancer as an endpoint. Breast cancer matters here because many adults living near the plant are women, including most of the school's staff.

The EPA Evaluation of 2016

The agency's Integrated Risk Information System evaluation (U.S. Environmental Protection Agency, 2016) concluded that ethylene oxide is carcinogenic to humans by inhalation and derived an inhalation unit risk from the worker cohort, applying adjustments for early-life exposure because of its mutagenic action. Its strength is a full, peer-reviewed analysis; its main uncertainty is extrapolating from high occupational exposures to low community levels. Use: the dose-response value.

Jinot et al. (2018)

Written by EPA scientists, this review summarizes the 2016 evaluation's key findings, especially the weight of evidence for lymphoid and breast cancers and the central role of mutagenicity. It is useful as a concise, peer-reviewed account of reasoning that is spread over hundreds of pages in the full report. Use: explaining the hazard to readers.

Olaguer et al. (2020)

This study measured ethylene oxide around a Michigan sterilizer, combined measurements with modeling to estimate emissions and found nearby concentrations implying added cancer risks far above usual targets, along with a measurable urban background unrelated to the plant. Its design is close to the one planned here. Its limits are a single facility and short sampling periods. Use: design of the exposure assessment and comparison of results. It also shows how emissions can be estimated from measurements when facility reports are uncertain, a method the assessment may borrow if reported releases seem low.

References

Jinot, J., Fritz, J. M., Vulimiri, S. V., & Keshava, N. (2018). Carcinogenicity of ethylene oxide: Key findings and scientific issues. Toxicology Mechanisms and Methods, 28(5), 386-396. https://doi.org/10.1080/15376516.2017.1414343

National Research Council. (1983). Risk assessment in the federal government: Managing the process. National Academy Press. https://doi.org/10.17226/366

Olaguer, E. P., Robinson, A., Kilmer, S., Haywood, J., & Lehner, D. (2020). Ethylene oxide exposure attribution and emissions quantification based on ambient air measurements near a sterilization facility. International Journal of Environmental Research and Public Health, 17(1), Article 42. https://doi.org/10.3390/ijerph17010042

Steenland, K., Stayner, L., Greife, A., Halperin, W., Hayes, R., Hornung, R., & Nowlin, S. (1991). Mortality among workers exposed to ethylene oxide. New England Journal of Medicine, 324(20), 1402-1407. https://doi.org/10.1056/NEJM199105163242004

Steenland, K., Whelan, E., Deddens, J., Stayner, L., & Ward, E. (2003). Ethylene oxide and breast cancer incidence in a cohort study of 7576 women (United States). Cancer Causes & Control, 14(6), 531-539. https://doi.org/10.1023/A:1024891529592

U.S. Environmental Protection Agency. (2016). Evaluation of the inhalation carcinogenicity of ethylene oxide (CASRN 75-21-8) in support of summary information on the Integrated Risk Information System (IRIS) (EPA/635/R-16/350Fa). U.S. Environmental Protection Agency.