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Page 8 <br />Radionuclides <br />California U.S. EPA <br />MCL MCL Effective <br />Date DLR PHG PHG <br />Date MCL MCL Effective <br />Date MCLG <br />Gross alpha particle <br />activity5 <br />156 <br />15 <br />2006-06-11 <br />1977 <br />3 none7 --15 1977-06-24 zero <br />Beta/photon emitters8 4 mrem/yr <br />50 <br />2006-06-11 <br />1977 <br />4 none7 --4 mrem/yr 1977-06-24 zero <br />Radium-226 ----1 0.05 2006 ------ <br />Radium-228 ----1 0.019 2006 ------ <br />Radium-226 + <br />Radium-228 <br />56 <br />57 <br />2006-06-11 <br />1977 <br />------5 1977-06-24 zero <br />Strontium-90 89 <br />810 <br />2006-06-11 <br />1977 <br />2 0.35 2006 4 mrem/yr10 <br />8 <br />2003-12-08 <br />1977-06-24 <br />-- <br />Tritium 20,0009 <br />20,00010 <br />2006-06-11 <br />1977 <br />1,000 400 2006 4 mrem/yr10 <br />20,000 <br />2003-12-08 <br />1977-06-24 <br />-- <br />Uranium 206 <br />207 <br />2006-06-11 <br />1989-01-01 <br />1 0.43 2001 30 µg/L11 2003-12-08 zero <br />5 Excludes alpha particle activity from radon and uranium. <br />6 Revised MCL applies to both community (CWS) and nontransient noncommunity water systems (NTNCWS); previous MCL <br />applied only to CWS. <br />7 OEHHA concluded in 2003 that it would not be practical to develop a PHG (for gross alpha particle activity, for gross beta <br />particle/photon emitters). <br />8 Beta/photon emitters MCLs are in units of millirems per year (mrem/yr) annual dose equivalent to the total body or any internal <br />organ. The DLR is in units of pCi/L of gross beta particle activity. <br />9 Revised MCL applies to all CWS and NTNCWS; previous MCL applied only to water systems with at least 30,000 service <br />connections that used surface water. <br />10 U.S. EPA does not have specific MCLs for strontium-90 or tritium; both are regulated under the beta/photon emitters MCL. <br />11 U.S. EPA MCL of 30 µg/L is equivalent to 20.1 pCi/L (unit conversion using natural uranium specific activity of 0.67 pCi/µg). <br />9.B. - Page 24 of 27 <br />213