Toxicology Update Tiffany Bredfeldt, Ph.D. Toxicology Division Texas Commission on Environmental Quality Advanced Air Permitting Seminar 2015

Updates New Odor White Paper Updated Odor Values Reminder to Use New ESL Forms Database in Progress ESL = effects screening level

Why Do We Regulate Odors? Odor - leading cause of citizen complaints Required by the Texas Clean Air Act What is the role of the odor-based ESL? Prevent odor nuisance conditions Not necessarily odor detection

New Odor White Paper Approach to odor ESL derivation has changed New approach uses a weight of evidence evaluation Visit the Toxicology website for more information The Toxicology web page can be found at http://www.tceq.texas.gov/toxicology.

Odor White Paper: Why Change? Odor data is highly variable The reason for the variance is unclear The purpose of an odor-based ESL is to prevent nuisance The goal is to produce a list of odor ESLs consistent in the manner in which they are derived

Odor: Previous Approaches Collect odor thresholds: Odor detection threshold - concentration at which a certain percent of a panel of humans detects odor Odor recognition threshold - concentration at which a chemical is recognized specifically The 50% odor detection threshold is typically used

Odor: Previous Approaches For chemicals with reported thresholds, the 50% odor detection threshold was used If more than one OD50 was available, a geometric average was taken If data was considered of lower quality, the lowest OD50 was taken For chemicals without odor detection thresholds, generic odor values were derived based on structure-activity relationships or chemical class OD50 = 50% odor detection threshold

Previous Approaches: Pitfalls Odor threshold data are highly variable Newer methodologies may be very sensitive and may result in bias If older values have not resulted in an odor complaint, should we change the value to newer data?

Odor: Updated Approaches Process is similar Steps: Identify odor character Is the chemical potentially malodorous? Search for available odor threshold data Agency records may guide the decisions regarding the odor ESL used Not all chemicals will have odor ESLs The focus is upon chemicals that could cause nuisance

Not all chemicals smell bad Isoamyl acetate Limonene Cis-rose oxide Beta-damascenone Beta-ionone Ocimenol Cinnamyl alcohol Ethyl-2-methoxybenzoate Methyl salicylate

Some chemicals smell bad Trimethylamine Ammonia Hydrogen Sulfide Methane 1,5-Pentanediamine (also known as cadaverine) 1,4-Butanediamine (also known as putrescine) When evaluating whether or not to derive and odor-based ESL, we consider whether the chemical of interest is described as smelling bad or offensive. 1,5-Pentanediamine 1,4-Butanediamine 2-Butene-1-thiol 3-Methyl-1-butanethiol

Odor: Updated Approaches If there is evidence that a chemical may cause odor nuisance but only at high concentrations, higher thresholds may be used Examples: Acetaldehyde Propionaldehyde Odor recognition threshold may be used

Example: Propionaldehyde Previous value (OD50): 22 µg/m3 Odor is described as fruity at lower concentrations Upon evaluation of available monitoring data, this value has been detected at sites where the odor was described as sweet by field investigators New value (OR50): 95 µg/m3 OD50 = 50% odor detection threshold µg/m3 = micrograms per cubic meter OR50 = 50% odor recognition threshold

Odor: Updated Approaches When selecting odor-based values: Consider odor character Determine odor if odor character is ubiquitous or dependent on concentration Identify available odor thresholds Research past values used (if any) and whether any odor complaints are associated with this chemical Select odor threshold

Odor: Other Changes No generic odor values will be used anymore (e.g., amines or carboxylic acids odor value) Instead, when odor values are not available, ESLs will be surrogated to chemicals with similar structure Values for chemicals where odor is described as mild or pleasant will not be derived In those cases, health values will be used All odor ESLs were reviewed at the same time Consistent application of new guidance

Odor Summary Some approaches to how we derive odor- based ESLs have changed We will still derive odor ESLs as needed for chemicals anticipated to be malodorous Detection or recognition thresholds may be used as the basis New odor values may be seen in the updated database And on our website The Toxicology website can be found at http://www.tceq.state.tx.us/toxicology.

Additional Updates ESL Documentation ESL Database Project TCEQ ESLs Internet TCEQ ESLs ESL = effects screening level For more information, please see https://www.tceq.texas.gov/toxicology/esl. Effects Screening Levels are screening levels used in TCEQ’s air permitting process to evaluate air dispersion modeling’s predicted impacts.  They are used to evaluate the potential for effects to occur as a result of exposure to concentrations of constituents in the air.  ESLs are based on data concerning health effects, the potential for odors to be a nuisance, and effects on vegetation. They are not ambient air standards. If predicted airborne levels of a constituent do not exceed the screening level, adverse health or welfare effects are not expected. If predicted ambient levels of constituents in air exceed the screening levels, it does not necessarily indicate a problem but rather triggers a review in more depth. Both short- and long-term ESLs are listed on the ESL List. “Short-term” generally indicates a one-hour averaging period. Exceptions are noted parenthetically after a constituent name. “Long-term” indicates an annual averaging period.

ESL Documentation New form to fill out for ESL requests The paperwork processed during ESL derivation has changed within the Toxicology Division That means that ESL derivations may take a bit longer due to the way records are generated and placed into a format that will be used for the database Expect a longer turnover time The new ESL request form is on the Toxicology Division Website. It is an Excel file and can be found at https://www.tceq.texas.gov/toxicology.

ESL Documentation Make sure that you fill out the ESL request form When consultants or companies ask for an ESL for a specific chemical: Check current ESL list Fill out ESL request form Get additional information (i.e., MSDS, physical chemical properties, etc.) MSDS = Material Safety Data Sheet Chemical Information

ESL Documentation Documentation may have slowed turn around time We are releasing a new ESL list this fall Please remember to check our website for ESLs New list will be publicized via the Toxicology Announcements (e-mail)

Database The ESL database is still in the process of being generated Some issues with getting it coded When complete, it should run through the public database TAMIS In PROGRESS! Keep up with the Toxicology Division Announcements online TAMIS = Texas Air Monitoring Information System (TAMIS Web) TAMIS can be found at http://www17.tceq.texas.gov/tamis/. To sign up to receive Toxicology Division announcements via e-mail, go to https://www.tceq.texas.gov/toxicology/announcements.

Thank you for your attention Tiffany Bredfeldt tiffany.bredfeldt@tceq.texas.gov 512-239-1799