CINXE.COM

Just a moment...

<!DOCTYPE html><html lang="en-US"><head><title>Just a moment...</title><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><meta http-equiv="X-UA-Compatible" content="IE=Edge"><meta name="robots" content="noindex,nofollow"><meta name="viewport" content="width=device-width,initial-scale=1"><style>*{box-sizing:border-box;margin:0;padding:0}html{line-height:1.15;-webkit-text-size-adjust:100%;color:#313131;font-family:system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica Neue,Arial,Noto Sans,sans-serif,Apple Color Emoji,Segoe UI Emoji,Segoe UI Symbol,Noto Color Emoji}body{display:flex;flex-direction:column;height:100vh;min-height:100vh}.main-content{margin:8rem auto;max-width:60rem;padding-left:1.5rem}@media (width <= 720px){.main-content{margin-top:4rem}}.h2{font-size:1.5rem;font-weight:500;line-height:2.25rem}@media (width <= 720px){.h2{font-size:1.25rem;line-height:1.5rem}}#challenge-error-text{background-image:url(data:image/svg+xml;base64,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);background-repeat:no-repeat;background-size:contain;padding-left:34px}@media (prefers-color-scheme:dark){body{background-color:#222;color:#d9d9d9}}</style><meta http-equiv="refresh" content="390"></head><body class="no-js"><div class="main-wrapper" role="main"><div class="main-content"><noscript><div class="h2"><span id="challenge-error-text">Enable JavaScript and cookies to continue</span></div></noscript></div></div><script>(function(){window._cf_chl_opt={cvId: '3',cZone: "ehp.niehs.nih.gov",cType: 'managed',cRay: '918f9ceb98916bfd',cH: 'CIPQcugnZc7AOAbbd_fb.9Ko.Ms5FiXIsmlQyZtj8.c-1740737302-1.2.1.1-XlQWoKQrW6eQPjpL6Nz0FWl.JlvWiswkPTJsBWKeyoVI1k_P2L9l3BcTyzkdCj07',cUPMDTk: "\/doi\/10.1289\/ehp.120-a424?__cf_chl_tk=8m.xgNg6vpJZ2f6HVtaHhypUbw7UMHhOqaLHOm.xnvI-1740737302-1.0.1.1-m5clFppUvvL8eGFUlsGhflrHd1iE0cthY.dTvwVZSR0",cFPWv: 'b',cITimeS: '1740737302',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "",fa: "\/doi\/10.1289\/ehp.120-a424?__cf_chl_f_tk=8m.xgNg6vpJZ2f6HVtaHhypUbw7UMHhOqaLHOm.xnvI-1740737302-1.0.1.1-m5clFppUvvL8eGFUlsGhflrHd1iE0cthY.dTvwVZSR0",md: "Fhqw8oMbTiea7J_OPUAvK6L3_JYhSSoBiX42xtEEGek-1740737302-1.2.1.1-kgs7UCH3vUJOZUjqUmJMPMRi6k506cwTmK5OPqwoGVQok6fV1HGGat3MD3kUY_pi7LXXKiBk30plaieFXA.uiBCnR67Y3nan2yUaaNc.scpA5HuCWPSmjWXLLqw8lxxi_x4NGKcj2nGGpwToYMSThv7KLKh6M1B1bK8CL1_BO6CMdTMDdKr.l.kLP2wyrHtVjff.NPYiPHmsONxry2gb94bqVXQO_Ti_JWNFXgn36JHo36onGPx0YdA393A_wmXEMGg4t4BY.vxdStdJNnlp98A6NJbxolAoMOY_W69jfM9heTbN_Ql996.dDtvBNN_fxkLVEWjEv4YgZw1GCyIAoaTTSjwmvPo99JpJmdl3VHRRf.4x9eTBsNtrPh7JszQIr5hwPTrjCtaCOlrw.Nn9386hOXeQYrC56T1c8K8HMy32pz5VdZLp6wjZ_fST0AOGVM5sA37ITo4YTpCiNpJlPfnlC2DQ1fzpAH_tiz9WREYok5bz8TdtfmyntrriNcenzwpA2iNUAz7yZXW70jBNAeEFVURUL_HfH45hzmVjyMFbBY2RSpRJVyWBZM.EcZ8ZFMAY7MKb4gcrA8GtyuWs93ItyeYcA0wGMY5mLdtsFhe879NDMohxWJsxyJZygBt1GtV8fnHhqwOSY0BU0SKpmElBW9xfTatwaaaxiX6PQdGXfsEHkYW9P9AhOK.QLysGAkMfies4_Xbicovypxs0hjLg6BUljC5QbiklNimblzuLfUzsWt8UvFCQuNnJMmr6VOsa11b8VfYApGrqpHnaGgZiJjvf0GZmZQ4j2yyb3oXhkTrjxsddY8gLWTTJmS8buG0IKE94el8uy0zlDh3ZafibhLaY5.gOXgZigTzUEiYzII_Sh6MXxj2Tx7AkkCaUCAxUsrUiLh9UXrIkx45Uwuew_kOUyvJ7O8DMG_4bl82d4e74oqBbviSY7sMDgI1fDngJ5fGJ2n1gN_D1Kas7hdWBddcnA3aN0k3tcT4H4qHhICPI8yZ8S4ddGvUhNwK.4Ec3M5b4j5UhzY494ZBZnZarp9KvYzsE2X_P.mJvOENfFMPnPH06Vx4t0GvE.BSj9HoUS.AZLW7f4CmVO6QhVHGDaxoIJu5__R3wS3BR.Hcv42EzFpcIsYA8.N1YjdDU3QpIQCQnj6qMMOb1HYDWajnwv3VeXO6O5S9OwntL4cNzUGxVMyL8YxTpfiPbhWkh7WErF5pe03rA4sPs4Pzcl4Sm6fxXTeFhM7ITzAnvJcf8QDaHLjHdoRIf34XI5w6MybqE0FL.fCzImtLVuCOfX68L76VeBTNausKemSYc87XIcaI.DlTreqqUaHlr.lxK3a9c5xZBmnxLqsI32lyAjbcJ.F95MpIiwhm9bdR5Yf58ZOl8UPXIhTarKmae1c_pHPROag7nB.NTWwbghAx.xSH1av2T.x96zYqo.XPurs7lEaa.rW__kgOfXc45a7YnpSAjq2QzXy7u6raCLCqyXcMAml4TLDH3PhqgXjNP10wn_9D1iA0nnq931Pm8G1av8EREOnv8BL_gP8InwBg88.nh.eLhzMDCOJX75dTS29z9sioHMMrLDWamdVHJklGYo4GTgEBpDpbGZGo0YmYI_ZRJDhwtb9YHkZWqJ_e2.ZwtUBzeK6JdlQqu1KCMPfpgYWhlzbl5KlhQ9bf0ZqzRmgVOl8oXInvp70EO6t0dTO2ebs2l5sxLaup1qZv_aqLhqsOxz6BJLntK3vVVN6vXzOniDkPslMR49Czp4TKTr8GbUZwSNW8bESJpc1bUC07W4MByaUQC3H1q_ii4vxwIx7OEbK4_c5_AU2jub6YcI_3npKrlXxphbDj0aUBxycYnE9MZpnp0ShFCXTO.iXGBVh.02b4frcKOhTrMhdT3M9eIv2cFAGvgrXvRbJ2B1cWARrFEOfXk3R8V54OwdEVyxL4rvCWlHVJRKguOiEAdtpgFnGZ6Gg8B.YElxyJXBPKgPJot2xKDSIzgokZGxHRtASyGP7o.wxFB26s5sv8m3auwzAytTljgZBRO9aSXOzoFt763z2AwfNACO6vdHCY8ZiaWBgDJk2wV1F_k5WCSu9kYRsl9b30jj24RQZTy4VT2LOptwDPC4gS2tod_R7T91fZpDvbH_avyG7QZxTn6KfZa3iJOA9pSxttplUUOXxfs.0Fyj7PdRcG2TyMjsyfSX2e0FIc1X8T74aBDqB4gYhg7VPctFWoFnNOOqyHCB7dvu8XgKhDqsp.EmFBcUhn19_f2ZEuKi.Zx_LFESNa5iPrd35PzkBps3FIifPEv0Cd.rQ5qYyj9z7oxEXPNP6yt3uusXbJVdBC8RLmwafgZTTuOutpfGihX8COO_G_CX5rI0uvIKBcN_8xg5a3b3wNz7O.QAa2DPiMto4JtOPx.SjsJ_VEFIF.txjKatFGE0MyfX5K4OcV7v4ZNACegLd1H1sG7RAAVSNTcqSPbm0RE1WsHdHn4845Wy_aPrBfKSHRKei2xFULhalWKwxhfKWQVpfjeW0A8A5vlhN6basJz4To9BB76Vg6gSiWzLRhqSJ9JQzWpOKJymA7QDl_WUXz73Q",mdrd: "bJ1RcoePDvy.tLT_lDtD1jcRLit28xJM3ZvXAQd1wKk-1740737302-1.2.1.1-XLBhPOb1O7icmVSX.0lBWaDCWobGiqu52ZqCwhZzkIYVUV3t3lzAfafk0iD1lzw_KqxeWdOYoCFscJBYW9VOhref6ZEAcK_LTQE4EjcYiYJYgfKwu24c..D.AGMbdd4A31PBC0nvghuaZVih9_gmF.8nAivmCb7yighCpql2cV95K0utIkWh9UPmqSxWl4diArkmPm.qTlkLu9_ekvUhhxsoQG1nzDWJ0XVY3T95gey3gBo3Xu8cpKQpsFnYtPRYbx3lBJA2PTveaoQOOtfc8yqeezvtp7ylE5aVui37Iidjp0Q9cNfjBYi9pIWA6KC75.B98jeArjLSF9v.CZ_mSXI6NvtYKMnxLbdHsZKMT30Aq2zMOcAwA.4J_LR28VQ54MMs458Vr03ngC5Umtx9WLH4KH.AgGSmClBxqxDnvX0wUEhLSyi6NCbrV38.3IIiirVUETEaalMNhsX_Tv_GPdfkRV2.unEhi6HxHCIwWlWuG5NglHrR6JR0Ze7Tehj7G.OuyIGrrZ_XCI6osJqm_Xw0A6xpwWLsGSr7YSYad.VttQnAF.zuEuZRngyn4oSO2RhdDoG_lVNuevMQDsyC60PkTEzqGY2TW4b7QLTDVCMefABBEc54_3Da8XmcRhZeR6kMmva9laStL9LXg7b4ZISxE_RegHAfkLKvsjga7OXnwlvqEKkoZ_jJJjrP97lTecykp00WLlUx5ShGale_zW_PHNYR08f4zef8RqbCo8Rc7gGYKXjgMfIHuTDWFzFA_MrKmXGPy6sh2C4dzGtMLgQgY0dImRxlK.oQDcJK3g3R0Wh98miLv1dn0LCI8a9z6a0DtYd4hI0CUc7Qp5QqY57kuY0G9fCPFGq82xtHQbakc_fGPGCIzM_g3nDWLWGi8pYROL9OsFrrTaENIrUgf0Wo7r3Yu8Pdc8w95teMi2L6L9jQvcG08u54..5d1ISCFqIOpgd0z8oXOm8R.rJCc_QsI0l6xiBlcNk7fF22BsW7roFfCf0olZVhdMYRX4mOD86tnLfj0UILwbXsnkc3JM2wwBPkzSnxQjeEYhSK5vlBocqFa4x78f.Gonb2b5nOV9dHe4ZGmO.qN06JbmADuVFdRCEdycz8VKQVyZmvbImFGLolJobIleIEMYfak5ZYZkDzujgaOByEtt23h7uTMhF_BSEUi1Lvr4eZNsczdMvsjo_6xI8X4DhPG6Lx2Ly4ABmAin_0kSwDUww3d3oVrlWz_uYTQcRGnP_ek5sAc2rioJuWiFmzOuPv4edY3R2VIQQN9mtJamsNg9Jwku_R20uQNGEmqhoJXahE8HXjGK2HspUcgkFlJJXF_IEhZ.7uC1Z4PlUppaBH93uhpeIAA39W32SGzur5Cvqw1udQpidVrD5kwwgOQaqhrt5zV5sjAxz9eyEWPcN6R9bmnycy73lVL.vQmqf0BGnEISgIAfHvpHnNo8kWoLDrQsS.mBbyc7r3xft_KqfzBk0ZgbNZdJUdrv.TeYYl5XxewjoUZwZUcVI5mocfLXeLwQgTjR_14bFM.Uh2lqACYUQrj_lqRiJ8mW4lt.Kpq7QyvySwwMDAwYQZ.u9VN0O5rg.eHu9vGRDzt3T5HMjDLuslCX7Bujpy4k0H43HQbh7EuUHRHOJlKfEzZQ7mIXmZVveS60rdMLPByfKCN4DKFM5_VbB25dEu08OVdP4Hn_akFoT9Gu2LjpP.qGDTsFLq72RtL20bd3vS6AoTLBeYcdNzleS6qBGFhpjvxJiFknbQDYngGSkzGuehSoo2dc7L6ICYlt4KpIvNg3_k8YwTIFZJfU7WKX5p3Hh84_KE68SQHWMtB2KuuW.kmS1xPM.QKeUUDVAdB7EWAF0StxjGZnDBmbPaVX0JG5whCKLxZ4ue__PUBQAf6b23_yNr4lftfG5wfSsAWnQrlx2C80qEJaX6y68FbCqu1D4t2Cjws4PxCLSI1NemyuPiKD6hGT_e335VDPhg"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=918f9ceb98916bfd';window._cf_chl_opt.cOgUHash = location.hash === '' && location.href.indexOf('#') !== -1 ? '#' : location.hash;window._cf_chl_opt.cOgUQuery = location.search === '' && location.href.slice(0, location.href.length - window._cf_chl_opt.cOgUHash.length).indexOf('?') !== -1 ? '?' : location.search;if (window.history && window.history.replaceState) {var ogU = location.pathname + window._cf_chl_opt.cOgUQuery + window._cf_chl_opt.cOgUHash;history.replaceState(null, null, "\/doi\/10.1289\/ehp.120-a424?__cf_chl_rt_tk=8m.xgNg6vpJZ2f6HVtaHhypUbw7UMHhOqaLHOm.xnvI-1740737302-1.0.1.1-m5clFppUvvL8eGFUlsGhflrHd1iE0cthY.dTvwVZSR0" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>