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Home My WebLink AboutSAC Presentation - Hansel - EPA GuidanceEPA’s 2019 Cyanotoxin Recommended Criteria Guidance Joel Hansel U.S. EPA Region 4 Overview of Presentation •Brief background on cyanotoxins •Background of CWA 304(a) guidance 2019 criteria •How was it developed •What can it be used for •Consideration of exposure routes •Practical considerations in the environment Background of cyanotoxins •Produced by cyanobacteria (blue-green algae) •Multiple genera produce toxins •Microcystis, Dolichospermum (Anabaena), Nostoc, Fischerella, Planktothrix, Gloeotrichia - microcystins •Raphidiopsis, Aphanizomenon, Umezakia, Anabaena, Lyngbya - cylindrospermopsin •Anabaena, Aphanizomenon, Cylindrospermopsis, Cylindrospermum, Lyngbya, Microcystis, Nostoc, Oscillatoria, Phormidium, Planktothrix, Raphidiopsis, Tychonema, Woronichinia – anatoxin-a •Presence of cells (count or visible matting) does not equate to toxin presence •These are living organisms Background of EPA’s criteria •https://www.epa.gov/sites/default/files/2019-05/documents/hh-rec-criteria-habs-document-2019.pdf •Criteria for two cyanotoxins •Microcystins – 8ug/L •Cylindrospermopsin – 15ug/L •Based on a recreator/swimmer scenario •Specifically used risk factors for a child (6-10 yrs old) •Most susceptible population •Toxicity factors derived from multiple studies •Also used in EPA’s Drinking Water Health Advisory •Targets non-cancer effects on liver (micro) and kidney (cylindro) Criteria Derivation •Formulated from a standard risk equation •Recreational value (ug/L) = RfD*(BW/IR) where •RfD is the reference dose (0.05ug/kg/day microcystin, 0.1ug/kg/day cylindrospermopsin) •BW is the mean body weight of a 6-10 year old (31.8kg) •From EPA’s Exposure Factors Handbook •IR is the daily recreational water incidental ingestion rate for a 6-10 year old (0.21 L/day) •From EPA’s Exposure Factors Handbook How can the criteria be used? •In current form, these represent EPA’s latest guidance to states and Tribes •Not directly enforceable •Become enforceable when adopted by a state or Tribe into water quality standards and approved by EPA •EPA published these values to be used for two purposes: •Issuance of swimming advisories or •For all purposes under the Clean Water Act •Dependent on how the state/Tribe adopts them Current Nationwide Adoption Status •For swimming advisories only •NM, SC, SD, Hoopa Valley Tribe, MTIF •No current adoptions for all purposes under the Act •Example language from SC: •R.61-68. G.10.j. Total microcystins-Not to exceed 8 µg/L. For freshwater primary contact recreational use notifications and advisories samples shall not exceed 8 µg/L. Other exposure routes •Considered both inhalation (while recreating) and dermal exposure in development of criteria •Neither was considered significant based on a comparative screening assessment •Ie., endpoint selected for criteria development was more stringent that endpoint using these exposure routes Practical environmental considerations •Blooms are transient (in some cases) •Presence of cells (counts or visible matting) does not predict toxin presence •Works both ways •High cell counts may have little toxin values •Low cell counts may have high toxin values •These criteria are only for two of the cyanotoxins and only for recreational exposure •May not encompass all toxins of interest •May not encompass all exposure of interest