I. Updates to Exposure Assessments

a. Dietary Exposure In evaluating dietary exposure, EPA consider ed exposure under the proposed exemption from the requirement of a tolerance. EPA conducted an updated dietary exposure assessment using food consumption information from the U.S. Department of Agriculture (USDA) National Health and Nutrition Examination Survey, What We Eat in America (NHANES/WWEIA). This dietary survey was conducted from 2003 to 2008. As to residue levels in food, no residue data
were submitted for C 9 rich aromatic hydrocarbons, C 10–11 rich aromatic hydrocarbons, and C 11–12 rich aromatic hydrocarbons. In the absence of specific residue data, EPA has developed an approach which uses surrogate information to derive upper bound exposure estimates for the subject inert ingredients. Upper bound exposure estim ates are based on the highest tolerance for a given commodity from a list of high-use insect icides, herbicides, and fungicides. A complete description of the general approach taken to assess inert ingredient risks in the absence of residue data can be found at http://www.regulations.gov in the document ‘‘Alkyl Amines Polyalkoxylates (Cluster 4): Acute and Chronic Aggregate (Food and Drinking Wa ter) Dietary Exposure and Risk Assessments for the Inerts,’’ in docket ID number EPA–HQ–OPP–2008–0738.
In the case of C 9 rich aromatic hydrocarbons, C 10–11 rich aromatic hydrocarbons, and C 11–12 rich aromatic hydrocarbons, EPA ma de specific adjustments to th e dietary exposure assessment to account for data submitted to the Agency demonstr ating evaporative loss, which is an important consideration for compounds such as C 9 rich aromatic hydrocarbons, C 10–11 rich aromatic hydrocarbons, and C 11–12 rich aromatic hydrocarbons. Based on the submitted data, the loss of C 9 rich aromatic hydrocarbons, C 10–11 rich aromatic hydrocarbons, and C 11–12 rich aromatic hydrocarbons due to evaporation, and therefore not available as potential re sidues in food commodities, was determined to be 98%.

b. Residential exposures. There are no residential exposures associated with the use of C 9 rich aromatic hydrocarbons, C 10–11 rich aromatic hydrocarbons, and C 11–12 rich aromatic hydrocarbons as inert ingredient in pesticid e products. However, C 9 rich aromatic hydrocarbons, C 10–11 rich aromatic hydrocarbons, and C 11–12 rich aromatic hydrocarbons may be used as additives for gasoline. Residential exposure is possible vi a the inhalation route and may occur during gasoline refuelingactivities for consumers. Drinking water exposures ma y also occur as the result of the presence of these substances in drinking water resulti ng from their use in gasoline additives.

i. Inhalation Exposure Assessment Inhalation exposures to C9 rich arom atic hydrocarbons, C10-11 rich aromatic hydrocarbons, and C11-12 rich aromatic hydrocarbons resulting from gasolin e refueling activities may occur. Such exposure would be considered of short-term durati on. While there are no reliable data related to inhalation exposures to C9 rich aromatic hydrocarbons, C10-11 rich aromatic hydrocarbons, and C11-12 rich aromatic hydroc arbons as a result of such activities, some data relative to inhalation exposures exist for other gasoline additives which can be used to conservatively estimate potential inhalation exposure to C9 ri ch aromatic hydrocarbons, C10-11 rich aromatic hydrocarbons, and C11-12 rich aromatic hydrocarbons. Available data on methyl-t-butyl ether (MTBE), a gasoline additive used at concentrations
far in excess of the concentration of C9 ri ch aromatic hydrocarbons, C10-11 rich aromatic hydrocarbons, and C11-12 rich aromatic hydrocarbons used in gasoline, suggest a maximum air
concentration of MTBE of 7.5 mg/m 3 (ECETOC, 1997). 1 Based on a conservative assumption that th e concentrations of C9 rich aromatic hydrocarbons, C10-11 rich aroma tic hydrocarbons, and C11-12 rich aromatic hydrocarbons would not exceed 5% in gasoline, it can be estimated that inhalation exposures resulting from gasoline refueling would not exceed 4.5 μg/kg/day.

ii. Drinking Water Exposures
While there are no reliable data related to concentration of C9 rich aromatic hydrocarbons, C10-11 rich aromatic hydrocarbons, and C11-12 rich aromatic hydrocarbons in drinking water as a result of their uses as gasoline additives, some da ta relative to concentrati ons of gasoline additives in ground and surface water can be used to conser vatively estimate concentrations of C9 rich

1 7.5 mg/m 3 (from ECETOC—maximum air concentration of MTBE @11%as additive in gasoline at service station) x 0.454 (adjustment fact or for a 5% level of additive) x 0.64 m 3 /hr (OPP residential SOP mean inhalation rate for a dults) x 0.167 hr (10 min exposure for gasoline refueling) / 80 kg (Residential SOP body weight adult) = 4.5 μg/kg/day.aromatic hydrocarbons, C10-11 rich aromatic hydrocarbons, and C11-12 rich aromatic hydrocarbons in drinking water.
An EPA Blue Ribbon Panel evaluated the uses of oxygenates in gasoline and in its report provided a summary of studies examining MTBE contamination of drinking water sources. The
cited data demonstrate that con centrations of MTBE in drinking water range from <5 to 20 ppb (EPA, 1999). Based on the fact that the occurr ence of C9 rich aromatic hydrocarbons, C10-11 rich aromatic hydrocarbons, and C11-12 rich arom atic hydrocarbons in gasoline additives is at
lower concentrations than MTBE is it reasonable to assume that drinking water concentrations of
these substances would not ex ceed the <5 to 20 ppb range. While gasoline containing C 9 rich aromatic hydrocarbons, C 10–11 rich aromatic hydrocarbons, and C 11–12 rich aromatic hydrocarbons may result in some potential exposure via drinki ng water, such drinking water exposures are already addressed by the conservative assumptions for estimated drinking water concentrations
utilized in the chronic di etary exposure assessment.

II. Updates to Aggregate Risk Findings

a. Acute risk The acute dietary exposure fr om food and water to C 9 rich aromatic hydrocarbons, C 10–11 rich aromatic hydrocarbons, and C 11–12 rich aromatic hydrocarbons will occupy 11% of the aPAD for children 1 to 2 years old, the population group receiving the grea test exposure. Therefore, C 9 rich aromatic hydrocarbons, C 10–11 rich aromatic hydrocarbons, and C 11–12 rich aromatic hydrocarbons are not expected to pose an acute risk.

b. Chronic risk EPA has concluded that chronic exposure to C 9 rich aromatic hydrocarbons, C 10–11 rich aromatic hydrocarbons, and C 11–12 rich aromatic hydrocarbons from food and water will utilize 2.1 % of the cPAD for children 1 to 2 years old, the population group receiving the greatest exposure. This number captures the likely exposure in groundwater from use of C 9 rich aromatic hydrocarbons, C 10–11 rich aromatic hydrocarbons, and C 11–12 rich aromatic hydrocarbons as gasoline additives.

c. Short-term riskShort term aggregate risk ta kes into account residential exposure plus average (or background) exposure to food and water. Ther e are no residential pesticidal uses for C 9 rich aromatic hydrocarbons, C 10–11 rich aromatic hydrocarbons, and C 11–12 rich aromatic hydrocarbons so the short-term risks would be equivalent to th e chronic risk discussed a bove and therefore not of concern. There is a potential for short-te rm inhalation exposure from use of C 9 rich aromatic hydrocarbons, C 10–11 rich aromatic hydrocarbons, and C 11–12 rich aromatic hydrocarbons as additives in gasoline. The MOE of >10,000 for shor t-term risk from inhalation exposures does not exceed the Agency’s level of concern (MOE<100). However, these inhalation exposures cannot be aggregated with oral (i.e., food and drinki ng water) exposures because, based on a routespecific inhalation toxicity study, the endpoints selected for oral and inhalation exposure are not based on a common specific target organ toxicity effects.

. d. Intermediate-term risk.

Intermediate-term risk is assessed based on intermediate-term resi dential exposure plus chronic dietary exposure. C 9 rich aromatic hydrocarbons, C 10–11 rich aromatic hydrocarbons, and
C 11–12 rich aromatic hydrocarbons are not contained in pesticide products registered for any specific use patterns (nor are there any non-pesticidal uses) that coul d result in in intermediate - term residential exposure. EPA considers the chronic risk assessm ent to cover intermediate-term
risk and concludes that there are no intermediate-term risk concerns.References: European Centre for Ecotoxicology and Toxi cology of Chemicals (ECETOX) (1997), TR 072 : Methyl tert-Butyl Ether (MTB E) Health Risk Characterisation, June 1997. Available from http://www.ecetoc.org/index.php?mact=MCSoap,cnt nt01,details,0&cntnt 01by_category=5&cntnt0 1template=display_list_reports&cntnt01order _by=Number%20Desc&cntnt01document_id=250&c
ntnt01returnid=89 accessed August 5, 2014

U.S. Environmental Protection Agency (EPA) (1997) . Achieving Clean Air and Clean Water: The Report of the Blue Ribbon Panel On Oxyge nates in Gasoline EPA Report EPA420-R-99-021 September 15, 1999. Available from http://www.epa.gov/OMS/cons umer/fuels/oxypanel/r99021.pdf accessed August 5, 2014

https://www.ehp.qld.gov.au/management/c oal-seam-gas/pdf/btex-report.pdf