ATTACHMENT NO. 1 2019 PHG Triennial Report: Calendar Years 2019-2020-2021
OFFICE OF ENVIRONMENTAL HEALTH HAZARD ASSESSMENT
Public Health Goals Health Risk Information for Public Health Goal Exceedance Reports February 2022 Pesticide and Environmental Toxicology Branch Office of Environmental Health Hazard Assessment California Environmental Protection Agency Office of Environmental Health Hazard Assessment Water Toxicology Section February 2022 1 ATTACHMENT NO. 2 2022 Health Risk Information for Public Health Goal Exceedance Reports
Health Risk Information for Public Health Goal Exceedance Reports Prepared by Office of Environmental Health Hazard Assessment California Environmental Protection Agency February 2022 NEW for the 2022 Report: New in this document are an updated Public Health Goal (PHG) for 1,2-dibromo-3-chloropropane (DBCP) and newly established PHGs for the trihalomethanes bromodichloromethane, bromoform, chloroform, and dibromochloromethane. Background: Under the Calderon-Sher Safe Drinking Water Act of 1996 (the Act), public water systems with more than 10,000 service connections are required to prepare a report every three years for contaminants that exceed their respective PHGs.1 This document contains health risk information on regulated drinking water contaminants to assist public water systems in preparing these reports. A PHG is the concentration of a contaminant in drinking water that poses no significant health risk if consumed for a lifetime. PHGs are developed and published by the Office of Environmental Health Hazard Assessment (OEHHA) using current risk assessment principles, practices and methods.2 The water system’s report is required to identify the health risk category (e.g., carcinogenicity or neurotoxicity) associated with exposure to each regulated contaminant in drinking water and to include a brief, plainly worded description of these risks. The report is also required to disclose the numerical public health risk, if available, associated with the California Maximum Contaminant Level (MCL) and with the PHG for each contaminant. This health risk information document is prepared by OEHHA every three years to assist the water systems in providing the required information in their reports. 1 Health and Safety Code Section 116470(b) 2 Health and Safety Code Section 116365 Office of Environmental Health Hazard Assessment Water Toxicology Section February 2022 2 ATTACHMENT NO. 2 2022 Health Risk Information for Public Health Goal Exceedance Reports
Numerical health risks: Table 1 presents health risk categories and cancer risk values for chemical contaminants in drinking water that have PHGs. The Act requires that OEHHA publish PHGs based on health risk assessments using the most current scientific methods. As defined in statute, PHGs for non-carcinogenic chemicals in drinking water are set at a concentration “at which no known or anticipated adverse health effects will occur, with an adequate margin of safety.” For carcinogens, PHGs are set at a concentration that “does not pose any significant risk to health.” PHGs provide one basis for revising MCLs, along with cost and technological feasibility. OEHHA has been publishing PHGs since 1997 and the entire list published to date is shown in Table 1. Table 2 presents health risk information for contaminants that do not have PHGs but have state or federal regulatory standards. The Act requires that, for chemical contaminants with California MCLs that do not yet have PHGs, water utilities use the federal Maximum Contaminant Level Goal (MCLG) for the purpose of complying with the requirement of public notification. MCLGs, like PHGs, are strictly health based and include a margin of safety. One difference, however, is that the MCLGs for carcinogens are set at zero because the US Environmental Protection Agency (US EPA) assumes there is no absolutely safe level of exposure to such chemicals. PHGs, on the other hand, are set at a level considered to pose no significant risk of cancer; this is usually no more than a one-in-one-million excess cancer risk (1´10-6) level for a lifetime of exposure. In Table 2, the cancer risks shown are based on the US EPA’s evaluations. For more information on health risks: The adverse health effects for each chemical with a PHG are summarized in a PHG technical support document. These documents are available on the OEHHA website (https://oehha.ca.gov/water/public-health-goals- phgs).
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs) Office of Environmental Health Hazard Assessment Water Toxicology Section February 2022 3
Chemical Health Risk Category1 California PHG (mg/L)2 Cancer Risk3 at the PHG California MCL4 (mg/L) Cancer Risk at the California MCL Alachlor carcinogenicity (causes cancer) 0.004 NA5,6 0.002 NA Aluminum neurotoxicity and immunotoxicity (harms the nervous and immune systems)
0.6 NA 1 NA
Antimony hepatotoxicity (harms the liver) 0.001 NA 0.006 NA Arsenic carcinogenicity (causes cancer) 0.000004 (4×10-6) 1´10-6 (one per million) 0.01 2.5´10-3 (2.5 per thousand) Asbestos carcinogenicity (causes cancer) 7 MFL7 (fibers >10 microns in length) 1´10-6 7 MFL (fibers >10 microns in length) 1´10-6 (one per million) Atrazine carcinogenicity (causes cancer) 0.00015 1´10-6 0.001 7´10-6 (seven per million) 1 Based on the OEHHA PHG technical support document unless otherwise specified. The categories are the hazard traits defined by OEHHA for California’s Toxics Information Clearinghouse (online at: https://oehha.ca.gov/media/downloads/risk-assessment//gcregtext011912.pdf). 2 mg/L = milligrams per liter of water or parts per million (ppm) 3 Cancer Risk = Upper bound estimate of excess cancer risk from lifetime exposure. Actual cancer risk may be lower or zero. 1´10-6 means one excess cancer case per million people exposed. 4 MCL = maximum contaminant level. 5 NA = not applicable. Cancer risk cannot be calculated. 6 The PHG for alachlor is based on a threshold model of carcinogenesis and is set at a level that is believed to be without any significant cancer risk to individuals exposed to the chemical over a lifetime. 7 MFL = million fibers per liter of water.
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs) Office of Environmental Health Hazard Assessment Water Toxicology Section February 2022 4
Chemical Health Risk Category1 California PHG (mg/L)2 Cancer Risk3 at the PHG California MCL4 (mg/L) Cancer Risk at the California MCL Barium cardiovascular toxicity (causes high blood pressure) 2 NA 1 NA Bentazon hepatotoxicity and digestive system toxicity (harms the liver, intestine, and causes body weight effects8)
0.2 NA 0.018 NA
Benzene carcinogenicity (causes leukemia) 0.00015 1´10-6 0.001 7´10-6 (seven per million) Benzo[a]pyrene carcinogenicity (causes cancer) 0.000007 (7´10-6) 1´10-6 0.0002 3´10-5 (three per hundred thousand) Beryllium digestive system toxicity (harms the stomach or intestine) 0.001 NA 0.004 NA Bromate carcinogenicity (causes cancer) 0.0001 1´10-6 0.01 1´10-4 (one per ten thousand) Cadmium nephrotoxicity (harms the kidney) 0.00004 NA 0.005 NA Carbofuran reproductive toxicity (harms the testis) 0.0007 NA 0.018 NA 8 Body weight effects are an indicator of general toxicity in animal studies.
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs) Office of Environmental Health Hazard Assessment Water Toxicology Section February 2022 5
Chemical Health Risk Category1 California PHG (mg/L)2 Cancer Risk3 at the PHG California MCL4 (mg/L) Cancer Risk at the California MCL Carbon tetrachloride carcinogenicity (causes cancer) 0.0001 1´10-6 0.0005 5´10-6 (five per million) Chlordane carcinogenicity (causes cancer) 0.00003 1´10-6 0.0001 3´10-6 (three per million) Chlorite hematotoxicity (causes anemia) neurotoxicity (causes neurobehavioral effects)
0.05 NA 1 NA
Chromium, hexavalent carcinogenicity (causes cancer) 0.00002 1´10-6 none NA Copper digestive system toxicity (causes nausea, vomiting, diarrhea) 0.3 NA 1.3 (AL9) NA Cyanide neurotoxicity (damages nerves) endocrine toxicity (affects the thyroid)
0.15 NA 0.15 NA
Dalapon nephrotoxicity (harms the kidney) 0.79 NA 0.2 NA Di(2-ethylhexyl) adipate (DEHA) developmental toxicity (disrupts development) 0.2 NA 0.4 NA 9 AL = action level. The action levels for copper and lead refer to a concentration measured at the tap. Much of the copper and lead in drinking water is derived from household plumbing (The Lead and Copper Rule, Title 22, California Code of Regulations [CCR] section 64672.3).
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs) Office of Environmental Health Hazard Assessment Water Toxicology Section February 2022 6
Chemical Health Risk Category1 California PHG (mg/L)2 Cancer Risk3 at the PHG California MCL4 (mg/L) Cancer Risk at the California MCL Di(2-ethylhexyl) phthalate (DEHP) carcinogenicity (causes cancer) 0.012 1´10-6 0.004 3´10-7 (three per ten million) 1,2-Dibromo-3- chloropropane (DBCP) carcinogenicity (causes cancer) 0.000003 (3x10-6) 1´10-6 0.0002 7´10-5 (seven per hundred thousand) 1,2-Dichloro- benzene (o-DCB) hepatotoxicity (harms the liver) 0.6 NA 0.6 NA 1,4-Dichloro- benzene (p-DCB) carcinogenicity (causes cancer) 0.006 1´10-6 0.005 8´10-7 (eight per ten million) 1,1-Dichloro- ethane (1,1-DCA) carcinogenicity (causes cancer) 0.003 1´10-6 0.005 2´10-6 (two per million) 1,2-Dichloro- ethane (1,2-DCA) carcinogenicity (causes cancer) 0.0004 1´10-6 0.0005 1´10-6 (one per million) 1,1-Dichloro- ethylene (1,1-DCE) hepatotoxicity (harms the liver) 0.01 NA 0.006 NA 1,2-Dichloro- ethylene, cis nephrotoxicity (harms the kidney) 0.013 NA 0.006 NA 1,2-Dichloro- ethylene, trans immunotoxicity (harms the immune system) 0.05 NA 0.01 NA Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs) Office of Environmental Health Hazard Assessment Water Toxicology Section February 2022 7
Chemical Health Risk Category1 California PHG (mg/L)2 Cancer Risk3 at the PHG California MCL4 (mg/L) Cancer Risk at the California MCL Dichloromethane (methylene chloride) carcinogenicity (causes cancer) 0.004 1´10-6 0.005 1´10-6 (one per million) 2,4-Dichloro- phenoxyacetic acid (2,4-D) hepatotoxicity and nephrotoxicity (harms the liver and kidney)
0.02 NA 0.07 NA
1,2-Dichloro- propane (propylene dichloride)
carcinogenicity (causes cancer) 0.0005 1´10-6 0.005 1´10-5 (one per hundred thousand) 1,3-Dichloro- propene (Telone IIâ) carcinogenicity (causes cancer) 0.0002 1´10-6 0.0005 2´10-6 (two per million) Dinoseb reproductive toxicity (harms the uterus and testis) 0.014 NA 0.007 NA Diquat ocular toxicity (harms the eye) developmental toxicity (causes malformation)
0.006 NA 0.02 NA
Endothall digestive system toxicity (harms the stomach or intestine) 0.094 NA 0.1 NA Endrin neurotoxicity (causes convulsions) hepatotoxicity (harms the liver)
0.0003 NA 0.002 NA
Ethylbenzene (phenylethane) hepatotoxicity (harms the liver) 0.3 NA 0.3 NA Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs) Office of Environmental Health Hazard Assessment Water Toxicology Section February 2022 8
Chemical Health Risk Category1 California PHG (mg/L)2 Cancer Risk3 at the PHG California MCL4 (mg/L) Cancer Risk at the California MCL Ethylene dibromide (1,2- Dibromoethane) carcinogenicity (causes cancer) 0.00001 1´10-6 0.00005 5´10-6 (five per million) Fluoride musculoskeletal toxicity (causes tooth mottling) 1 NA 2 NA Glyphosate nephrotoxicity (harms the kidney) 0.9 NA 0.7 NA Heptachlor carcinogenicity (causes cancer) 0.000008 (8×10-6) 1´10-6 0.00001 1´10-6 (one per million) Heptachlor epoxide carcinogenicity (causes cancer) 0.000006 (6×10-6) 1´10-6 0.00001 2´10-6 (two per million) Hexachloroben- zene carcinogenicity (causes cancer) 0.00003 1´10-6 0.001 3´10-5 (three per hundred thousand) Hexachloro- cyclopentadiene (HCCPD) digestive system toxicity (causes stomach lesions) 0.002 NA 0.05 NA Lead developmental neurotoxicity (causes neurobehavioral effects in children) cardiovascular toxicity (causes high blood pressure) carcinogenicity (causes cancer)
0.0002 <1´10-6 (PHG is not based on this effect)
0.015 (AL9) 2´10-6 (two per million)
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs) Office of Environmental Health Hazard Assessment Water Toxicology Section February 2022 9
Chemical Health Risk Category1 California PHG (mg/L)2 Cancer Risk3 at the PHG California MCL4 (mg/L) Cancer Risk at the California MCL Lindane (g-BHC) carcinogenicity (causes cancer) 0.000032 1´10-6 0.0002 6´10-6 (six per million) Mercury (inorganic) nephrotoxicity (harms the kidney) 0.0012 NA 0.002 NA Methoxychlor endocrine toxicity (causes hormone effects) 0.00009 NA 0.03 NA Methyl tertiary- butyl ether (MTBE) carcinogenicity (causes cancer) 0.013 1´10-6 0.013 1´10-6 (one per million) Molinate carcinogenicity (causes cancer) 0.001 1´10-6 0.02 2´10-5 (two per hundred thousand) Monochloro- benzene (chlorobenzene) nephrotoxicity (harms the kidney) 0.07 NA 0.07 NA Nickel developmental toxicity (causes increased neonatal deaths) 0.012 NA 0.1 NA Nitrate hematotoxicity (causes methemoglobinemia) 45 as nitrate NA 10 as nitrogen (=45 as nitrate) NA
Nitrite hematotoxicity (causes methemoglobinemia) 3 as nitrite NA 1 as nitrogen (=3 as nitrite) NA
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs) Office of Environmental Health Hazard Assessment Water Toxicology Section February 2022 10
Chemical Health Risk Category1 California PHG (mg/L)2 Cancer Risk3 at the PHG California MCL4 (mg/L) Cancer Risk at the California MCL Nitrate and Nitrite hematotoxicity (causes methemoglobinemia) 10 as nitrogen10 NA 10 as nitrogen NA N-nitroso- dimethyl-amine (NDMA) carcinogenicity (causes cancer) 0.000003 (3´10-6) 1×10-6 none NA Oxamyl general toxicity (causes body weight effects) 0.026 NA 0.05 NA Pentachloro- phenol (PCP) carcinogenicity (causes cancer) 0.0003 1´10-6 0.001 3´10-6 (three per million) Perchlorate endocrine toxicity (affects the thyroid) developmental toxicity (causes neurodevelop- mental deficits)
0.001 NA 0.006 NA
Picloram hepatotoxicity (harms the liver) 0.166 NA 0.5 NA Polychlorinated biphenyls (PCBs) carcinogenicity (causes cancer) 0.00009 1´10-6 0.0005 6´10-6 (six per million) Radium-226 carcinogenicity (causes cancer) 0.05 pCi/L 1´10-6 5 pCi/L (combined Ra226+228) 1´10-4 (one per ten thousand) 10 The joint nitrate/nitrite PHG of 10 mg/L (10 ppm, expressed as nitrogen) does not replace the individual values, and the maximum contribution from nitrite should not exceed 1 mg/L nitrite-nitrogen.
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs) Office of Environmental Health Hazard Assessment Water Toxicology Section February 2022 11
Chemical Health Risk Category1 California PHG (mg/L)2 Cancer Risk3 at the PHG California MCL4 (mg/L) Cancer Risk at the California MCL Radium-228 carcinogenicity (causes cancer) 0.019 pCi/L 1´10-6 5 pCi/L (combined Ra226+228) 3´10-4 (three per ten thousand) Selenium integumentary toxicity (causes hair loss and nail damage) 0.03 NA 0.05 NA Silvex (2,4,5-TP) hepatotoxicity (harms the liver) 0.003 NA 0.05 NA Simazine general toxicity (causes body weight effects) 0.004 NA 0.004 NA Strontium-90 carcinogenicity (causes cancer) 0.35 pCi/L 1×10-6 8 pCi/L 2´10-5 (two per hundred thousand) Styrene (vinylbenzene) carcinogenicity (causes cancer) 0.0005 1×10-6 0.1 2´10-4 (two per ten thousand) 1,1,2,2- Tetrachloro- ethane carcinogenicity (causes cancer) 0.0001 1´10-6 0.001 1´10-5 (one per hundred thousand) 2,3,7,8-Tetra- chlorodibenzo-p- dioxin (TCDD, or dioxin) carcinogenicity (causes cancer) 5´10-11 1´10-6 3´10-8 6´10-4 (six per ten thousand) Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs) Office of Environmental Health Hazard Assessment Water Toxicology Section February 2022 12
Chemical Health Risk Category1 California PHG (mg/L)2 Cancer Risk3 at the PHG California MCL4 (mg/L) Cancer Risk at the California MCL Tetrachloro- ethylene (perchloro- ethylene, or PCE) carcinogenicity (causes cancer) 0.00006 1´10-6 0.005 8´10-5 (eight per hundred thousand) Thallium integumentary toxicity (causes hair loss) 0.0001 NA 0.002 NA Thiobencarb general toxicity (causes body weight effects) hematotoxicity (affects red blood cells)
0.042 NA 0.07 NA
Toluene (methylbenzene) hepatotoxicity (harms the liver) endocrine toxicity (harms the thymus)
0.15 NA 0.15 NA
Toxaphene carcinogenicity (causes cancer) 0.00003 1´10-6 0.003 1´10-4 (one per ten thousand) 1,2,4-Trichloro- benzene endocrine toxicity (harms adrenal glands) 0.005 NA 0.005 NA 1,1,1-Trichloro- ethane neurotoxicity (harms the nervous system), reproductive toxicity (causes fewer offspring) hepatotoxicity (harms the liver) hematotoxicity (causes blood effects) 1 NA 0.2 NA
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs) Office of Environmental Health Hazard Assessment Water Toxicology Section February 2022 13
Chemical Health Risk Category1 California PHG (mg/L)2 Cancer Risk3 at the PHG California MCL4 (mg/L) Cancer Risk at the California MCL 1,1,2-Trichloro- ethane carcinogenicity (causes cancer) 0.0003 1x10-6 0.005 2´10-5 (two per hundred thousand) Trichloro- ethylene (TCE) carcinogenicity (causes cancer) 0.0017 1´10-6 0.005 3´10-6 (three per million) Trichlorofluoro- methane (Freon 11) accelerated mortality (increase in early death) 1.3 NA 0.15 NA 1,2,3-Trichloro- propane (1,2,3-TCP) carcinogenicity (causes cancer) 0.0000007 (7×10-7) 1x10-6 0.000005 (5×10-6) 7´10-6 (seven per million) 1,1,2-Trichloro- 1,2,2-trifluoro- ethane (Freon 113) hepatotoxicity (harms the liver) 4 NA 1.2 NA
Trihalomethanes: Bromodichloro- methane carcinogenicity (causes cancer) 0.00006 1x10-6 0.080* 1.3´10-3 (1.3 per thousand)11 Trihalomethanes: Bromoform carcinogenicity (causes cancer) 0.0005 1x10-6 0.080* 2´10-4 (two per ten thousand)12 * For total trihalomethanes (the sum of bromodichloromethane, bromoform, chloroform, and dibromochloromethane). There are no MCLs for individual trihalomethanes. 11 Based on 0.080 mg/L bromodichloromethane; the risk will vary with different combinations and ratios of the other trihalomethanes in a particular sample. 12 Based on 0.080 mg/L bromoform; the risk will vary with different combinations and ratios of the other trihalomethanes in a particular sample.
Table 1: Health Risk Categories and Cancer Risk Values for Chemicals with California Public Health Goals (PHGs) Office of Environmental Health Hazard Assessment Water Toxicology Section February 2022 14
Chemical Health Risk Category1 California PHG (mg/L)2 Cancer Risk3 at the PHG California MCL4 (mg/L) Cancer Risk at the California MCL Trihalomethanes: Chloroform carcinogenicity (causes cancer) 0.0004 1x10-6 0.080* 2´10-4 (two per ten thousand)13 Trihalomethanes: Dibromochloro- methane carcinogenicity (causes cancer) 0.0001 1x10-6 0.080* 8´10-4 (eight per ten thousand)14 Tritium carcinogenicity (causes cancer) 400 pCi/L 1x10-6 20,000 pCi/L 5´10-5 (five per hundred thousand) Uranium carcinogenicity (causes cancer) 0.43 pCi/L 1´10-6 20 pCi/L 5´10-5 (five per hundred thousand) Vinyl chloride carcinogenicity (causes cancer) 0.00005 1´10-6 0.0005 1´10-5 (one per hundred thousand) Xylene neurotoxicity (affects the senses, mood, and motor control)
1.8 (single isomer or sum of isomers)
NA 1.75 (single isomer or sum of isomers)
NA
* For total trihalomethanes (the sum of bromodichloromethane, bromoform, chloroform, and dibromochloromethane). There are no MCLs for individual trihalomethanes. 13 Based on 0.080 mg/L chloroform; the risk will vary with different combinations and ratios of the other trihalomethanes in a particular sample. 14 Based on 0.080 mg/L dibromochloromethane; the risk will vary with different combinations and ratios of the other trihalomethanes in a particular sample.
Table 2: Health Risk Categories and Cancer Risk Values for Chemicals without California Public Health Goals Office of Environmental Health Hazard Assessment Water Toxicology Section February 2022 15
Chemical Health Risk Category1 US EPA MCLG2 (mg/L) Cancer Risk3 at the MCLG California MCL4 (mg/L) Cancer Risk at the California MCL Disinfection byproducts (DBPs) Chloramines acute toxicity (causes irritation) digestive system toxicity (harms the stomach) hematotoxicity (causes anemia) 45,6 NA7 none NA
Chlorine acute toxicity (causes irritation) digestive system toxicity (harms the stomach) 45,6 NA none NA Chlorine dioxide hematotoxicity (causes anemia) neurotoxicity (harms the nervous system)
0.85,6 NA none NA
Disinfection byproducts: haloacetic acids (HAA5) Monochloroacetic acid (MCA) general toxicity (causes body and organ weight changes8) 0.07 NA none NA 1 Health risk category based on the US EPA MCLG document or California MCL document unless otherwise specified. 2 MCLG = maximum contaminant level goal established by US EPA. 3 Cancer Risk = Upper estimate of excess cancer risk from lifetime exposure. Actual cancer risk may be lower or zero. 1´10-6 means one excess cancer case per million people exposed. 4 California MCL = maximum contaminant level established by California. 5 Maximum Residual Disinfectant Level Goal, or MRDLG. 6 The federal Maximum Residual Disinfectant Level (MRDL), or highest level of disinfectant allowed in drinking water, is the same value for this chemical. 7 NA = not available. 8 Body weight effects are an indicator of general toxicity in animal studies.
Table 2: Health Risk Categories and Cancer Risk Values for Chemicals without California Public Health Goals Office of Environmental Health Hazard Assessment Water Toxicology Section February 2022 16
Chemical Health Risk Category1 US EPA MCLG2 (mg/L) Cancer Risk3 at the MCLG California MCL4 (mg/L) Cancer Risk at the California MCL Dichloroacetic acid (DCA) Carcinogenicity (causes cancer) 0 0 none NA Trichloroacetic acid (TCA) hepatotoxicity (harms the liver) 0.02 NA none NA Monobromoacetic acid (MBA) NA none NA none NA Dibromoacetic acid (DBA) NA none NA none NA Total haloacetic acids (sum of MCA, DCA, TCA, MBA, and DBA) general toxicity, hepatotoxicity and carcinogenicity (causes body and organ weight changes, harms the liver and causes cancer) none NA 0.06 NA
Radionuclides Gross alpha particles9 carcinogenicity (causes cancer) 0 (210Po included) 0 15 pCi/L10 (includes radium but not radon and uranium) up to 1x10-3 (for 210Po, the most potent alpha emitter) 9 MCLs for gross alpha and beta particles are screening standards for a group of radionuclides. Corresponding PHGs were not developed for gross alpha and beta particles. See the OEHHA memoranda discussing the cancer risks at these MCLs at http://www.oehha.ca.gov/water/reports/grossab.html. 10 pCi/L = picocuries per liter of water.
ATTACHMENT NO. 2 2022 Health Risk Information for Public Health Goal Exceedance Reports Office of Environmental Health Hazard Assessment Water Toxicology Section February 2022 17
Chemical Health Risk Category1 US EPA MCLG2 (mg/L) Cancer Risk3 at the MCLG California MCL4 (mg/L) Cancer Risk at the California MCL Beta particles and photon emitters9 carcinogenicity (causes cancer) 0 (210Pb included) 0 50 pCi/L (judged equiv. to 4 mrem/yr) up to 2x10-3 (for 210Pb, the most potent beta- emitter)