Hanford Tank Farm Health Process Plan (HPP)
HPP provides the Tank Operations Contractor (TOC), Washington River Protection Solutions (WRPS), and the U.S. Department of Energy (DOE) a plan for a transparent, peer-reviewed process of assessing potential health risks associated with worker exposures to chemical emissions from the Hanford Tank Farms (HTF). WRPS has established a formal review process and chartered an Internal Review Panel and External Review Panel for evaluation of HPP recommendations.
The HPP approach builds from the strategy and processes based in the current industrial-hygiene technical basis. It defines the strategy and plan for regularly, and rigorously, reviewing and updating the Chemicals of Potential Concern (COPC) in the Hanford tanks.
The HPP is used to review the corresponding Occupational Exposure Limits (OEL), and it is the strategy used when proposing exposure action levels for those COPCs or mixtures of COPCs where no acceptable limits exist. The HPP approach extends the assessments to include chronic exposure limits, acute transient exposure concentrations, and COPC mixtures.
The chartered review panels evaluate HPP recommendations, including the economic and feasibility impacts of implementation, and provides recommendations to the DOE - Office of River Protection (ORP) regarding the implementation of proposed changes. The formal, chartered review process using of the Internal and External review panels is the process WRPS uses to evaluate the following reports from Pacific Northwest National Laboratory (PNNL), listed below.
HPP Established
In September 2016, PNNL evaluated a recommendation made by the Tank Vapor Assessment Team (TVAT) that WRPS establish a team to evaluate Hanford tank farm vapors OELs, develop strategies for evaluating COPCs with no current industrial hygiene (IH) or toxicological data, and communicate those findings to the workforce.
To that end, PNNL recommended that WRPS and the DOE form a HPP assessment team of subject matter experts from WRPS, DOE, and academic, medical and private institutions. The HPP team would serve as a central resource for the WRPS and be responsible for the integration of all information about tank farm emissions, exposure guidelines, and critical data or research needs to enable risk management decisions and stakeholder communication.
PNNL also recommended that a second committee be formed to provide oversight and review of proposed processes and recommendations put forth by the assessment team. This an External Advisory Committee (EAC), also be made up of nationally recognized experts in chemistry, toxicology, industrial hygiene, risk assessment and communication, and other stakeholders, would serve appointments lasting a minimum of three years.
These two teams would begin the process of developing a thorough and robust exposure assessment plan for the HTF. This process would include the development of a database containing all relevant existing and new research documentation, modeling and simulation data, sampling data, and exposure limit guidelines. Once the proposed plan was reviewed, evaluated and refined, the team would be responsible for developing a detailed and transparent implementation plan to leverage the data being used to drive the process and justify the science behind it. For the full text, please visit this
link.
PNNL-25791 Hanford Tank Farm Occupational Exposure & Risk Assessment Plan: Health Process project, and
PNNL-25791, Rev 1 (click here).
This report documents the re-evaluation of new regulatory information since 2016 that could impact existing HTFOELs for the 61 COPCs. The report summarizes the technical basis and the process used to derive updated chronic OELs. New regulatory information was identified for two of the 61 COPCs, formaldehyde and 2, 4-dimethylpyridine. This new information was used to update OELs for these two COPCs. The OELs for the remaining COPCs did not change from the 2016 assessment. (
Full report here).
This PNNL report details several efforts related to approaches for establishing alternatives to traditional acute OEL for chemicals without existing values and for evaluating exposures to mixtures of COPC. Two approaches for assessing hazards associated with exposures to mixtures of COPCs are presented. Both methods can be used to evaluate the potential for additive effects of mixtures of COPC on Hanford Tank Farm workers. These tools enable rapid and efficient evaluation of mixtures using a combination of measured exposures, Health Code Numbers (HCN), and HTFOELs, thus complementing conventional approaches used for evaluating the hazards of individual compounds. (
Full Report Here).
HTFOELs are currently used to protect workers from potential effects of long-term tank vapor exposures. This includes exposures to 61 COPCs. These COPCs, like many chemicals, may produce effects from single or short-term (acute) exposures that are different from long-term effects. PNNL released a report in July 2018 that proposed acute exposure limits for 12 of the 61 current COPCs. These exposure limits are called Transient Effect Concentrations (TECs). They are designed to reduce risk of short-term discomfort, irritation, or other temporary effects that may be experienced by a worker. The TECs in the PNNL report are based on exposure limits already established by regulatory and scientific authorities. Airborne levels of COPCs that may cause short-term health effects are usually much higher than the concentrations that cause long-term effects. The TECs proposed by PNNL may be used along with the long-term HTFOELs to protect workers from a broader range of potential effects than if HTFOELs are used alone.
Air sampling at the HTF contributes to a large body of information about the identities and levels of tank vapor chemicals, and is routinely performed to measure the airborne levels of these chemicals in the workplace. PNNL reviewed the air sampling methods currently in use at the HTF. This report discusses analytical advances that could enhance the characterization of tank vapors. The PNNL report discusses new laboratory instruments capable of detecting chemical vapors at very low concentrations, and recommends ways to improve the accuracy and reliability of current sampling methods. (
Full Report Here).
PNNL released a Hanford Tank Vapor Chemicals of Potential Concern (COPC) update following a review of an updated set of tank vapor concentrations and improved estimates for HTFOELs. Air sampling results for tank headspace vapors and airborne emissions, including a range of operating conditions (i.e., quiescent, sluicing, tank transfers, etc.) were used to assess whether the updated HTFOELs or vapor concentration measurements changed the COPC status of any chemicals. Two new COPC-related recommendations were made following this assessment, including identification of nitrosodipropylamine as a COPC candidate, and retaining alkyl-substituted furans as a COPC. For the full text,
please visit this link.
PNNL reviewed the HTFOELs for chronic exposures to nitrile-class COPCs and 2,4-dimethylpyridine. PNNL concluded that no changes to these chronic HTFOELs are needed. The review of the compounds was initiated after differences between the chronic HTFOELs and short-term exposure guideline values developed by the United States Environmental Protection Agency (EPA) was identified. This report presents a comprehensive evaluation of the technical basis for the short-term EPA exposure guidelines and the chronic HTFOELs for nitrile-class COPCs and 2,4-dimethylpyridine. For the full text, please follow
this link.
Proposed Risk-Based Approach for Nitrosamine COPC documents the re-evaluation of HTFOELs for five N-nitrosamines identified as COPCs, and two other N-nitrosamines being considered as COPCs. PNNL proposed a risk-based approach to establish risk-specific doses for occupational exposures to N-nitrosamine COPCs. This approach establishes a range of N-nitrosamine inhalation exposures associated with risk levels that can be used as a tool for protecting HTF workers. (
Full Report Link).
PNNL reviewed the regulatory guidelines available for COPCs related to HTF operations. Regulatory guidelines for 34 of the 61 current COPCs were identified in databases developed by private or government agencies, including the American Conference of Governmental Industrial Hygienists (ACGIH) and the Occupational Safety and Health Administration (OSHA). Updated information for four COPCs (3-methyl-3-buten-2-one, 6-methyl-2-heptanone, dibutyl butylphosphonate, and tributylphosphate) was applied to propose updates for their respective HTFOELs. No changes for the remaining 30 COPCs with regulatory information were identified. Dimethyl mercury and 2-propenal are new additions to the COPC list. Both compounds had available regulatory guidelines. The remaining COPCs were also reviewed. For additional information, please visit
this link.
In 2019, PNNL re-evaluated the current HTFOELs for furan and 13 associated substituted furans identified as COPCs. The proposed OEL for Furans documents the toxicology data evaluated, the process used to develop the proposed OEL, and recommendations.
(Full Report Link)
