At a glance
- ATSDR develops a list of substances commonly found at facilities on the National Priorities List (NPL).
- These substances are determined to pose the most significant potential threat to human health.
- The priority list ranks substances and provide guidance in selecting which substances will be the subject of toxicological profiles.
Background
The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) section 104 (i), as amended by the Superfund Amendments and Reauthorization Act (SARA), requires ATSDR and the EPA to prepare a list, in order of priority, of substances that are most commonly found at facilities on the NPL and which are determined to pose the most significant potential threat to human health due to their known or suspected toxicity and potential for human exposure at these NPL sites. CERCLA also requires this list to be revised periodically to reflect additional information on hazardous substances. In CERCLA, it is called the priority list of hazardous substances that will be candidates for toxicological profiles.
This substance priority list (SPL) is generally revised and published every two years, with an informal review and revision each year. Each substance on the list is a candidate to become the subject of a toxicological profile prepared by ATSDR. The listing algorithm prioritizes substances based on frequency of occurrence at NPL sites, toxicity, and potential for human exposure to the substances found at NPL sites.
Some substances with low toxicity but high NPL occurrence and exposure may be on the priority list. The priority list's objective: rank substances across NPL hazardous waste sites to guide selecting substances ATSDR will prepare for toxicological profiles.
Contact us
Agency for Toxic Substances and Disease Registry
Phone: 1-800-CDC-INFO
Email: Contact CDC-INFO
Substance Priority List
The ATSDR 2025 Substance Priority List
| 2025 Rank | Substance Name | Total Points | CAS RN |
|---|---|---|---|
|
1 |
LEAD |
1796 |
7439-92-1 |
|
2 |
ARSENIC |
1642 |
7440-38-2 |
|
3 |
CADMIUM |
1561 |
7440-43-9 |
|
4 |
VINYL CHLORIDE |
1511 |
75-01-4 |
|
5 |
TRICHLOROETHYLENE |
1510 |
79-01-6 |
|
6 |
NICKEL |
1495 |
7440-02-0 |
|
7 |
BENZO(A)PYRENE |
1492 |
50-32-8 |
|
8 |
BENZENE |
1489 |
71-43-2 |
|
9 |
BERYLLIUM |
1474 |
7440-41-7 |
|
10 |
MANGANESE |
1458 |
7439-96-5 |
|
11 |
2,3,7,8-TETRACHLORODIBENZO-P-DIOXIN |
1453 |
1746-01-6 |
|
12 |
TETRACHLOROETHYLENE |
1436 |
127-18-4 |
|
13 |
CHLOROFORM |
1431 |
67-66-3 |
|
14 |
DIELDRIN |
1422 |
60-57-1 |
|
15 |
1,2-DICHLOROETHANE |
1418 |
107-06-2 |
|
16 |
POLYCYCLIC AROMATIC HYDROCARBONS |
1415 |
130498-29-2 |
|
17 |
NAPHTHALENE |
1412 |
91-20-3 |
|
18 |
PHENANTHRENE |
1412 |
85-01-8 |
|
19 |
DIBENZO(A,H)ANTHRACENE |
1407 |
53-70-3 |
|
20 |
BENZO(A)ANTHRACENE |
1407 |
56-55-3 |
|
21 |
POLYCHLORINATED BIPHENYLS |
1402 |
1336-36-3 |
|
22 |
BENZO(B)FLUORANTHENE |
1399 |
205-99-2 |
|
23 |
MERCURY |
1399 |
7439-97-6 |
|
24 |
DI(2-ETHYLHEXYL)PHTHALATE |
1390 |
117-81-7 |
|
25 |
ANTIMONY |
1374 |
7440-36-0 |
|
26 |
INDENO(1,2,3-CD)PYRENE |
1373 |
193-39-5 |
|
27 |
RADIUM-226 |
1370 |
13982-63-3 |
|
28 |
METHYLENE CHLORIDE |
1357 |
75-09-2 |
|
29 |
THALLIUM |
1356 |
7440-28-0 |
|
30 |
CHROMIUM, HEXAVALENT |
1355 |
18540-29-9 |
|
31 |
1,1-DICHLOROETHANE |
1353 |
75-34-3 |
|
32 |
VANADIUM |
1351 |
7440-62-2 |
|
33 |
DDT, P,P'- |
1349 |
50-29-3 |
|
34 |
AROCLOR 1260 |
1349 |
11096-82-5 |
|
35 |
1,1-DICHLOROETHENE |
1348 |
75-35-4 |
|
36 |
ALDRIN |
1342 |
309-00-2 |
|
37 |
CHROMIUM |
1341 |
7440-47-3 |
|
38 |
CARBON TETRACHLORIDE |
1338 |
56-23-5 |
|
39 |
HEPTACHLOR EPOXIDE |
1333 |
1024-57-3 |
|
40 |
BENZO(GHI)PERYLENE |
1333 |
191-24-2 |
|
41 |
PENTACHLOROPHENOL |
1333 |
87-86-5 |
|
42 |
BENZO(K)FLUORANTHENE |
1312 |
207-08-9 |
|
43 |
DDE, P,P'- |
1310 |
72-55-9 |
|
44 |
COPPER |
1307 |
7440-50-8 |
|
45 |
TOLUENE |
1301 |
108-88-3 |
|
46 |
1,2-DICHLOROETHENE, CIS- |
1300 |
156-59-2 |
|
47 |
HEPTACHLOR |
1297 |
76-44-8 |
|
48 |
1,1,2-TRICHLOROETHANE |
1296 |
79-00-5 |
|
49 |
COBALT |
1294 |
7440-48-4 |
|
50 |
XYLENES, TOTAL |
1292 |
1330-20-7 |
|
51 |
DDD, P,P'- |
1290 |
72-54-8 |
|
52 |
CHRYSENE |
1286 |
218-01-9 |
|
53 |
ACENAPHTHYLENE |
1286 |
208-96-8 |
|
54 |
AROCLOR 1254 |
1282 |
11097-69-1 |
|
55 |
THORIUM |
1277 |
7440-29-1 |
|
56 |
ETHYLBENZENE |
1273 |
100-41-4 |
|
57 |
1,1,2,2-TETRACHLOROETHANE |
1270 |
79-34-5 |
|
58 |
HEXACHLOROCYCLOHEXANE, ALPHA- |
1270 |
319-84-6 |
|
59 |
AROCLOR 1248 |
1268 |
12672-29-6 |
|
60 |
ZINC |
1263 |
7440-66-6 |
|
61 |
CHLORDANE |
1252 |
57-74-9 |
|
62 |
2-METHYLNAPHTHALENE |
1248 |
91-57-6 |
|
63 |
1,2-DICHLOROETHENE, TRANS- |
1246 |
156-60-5 |
|
64 |
ASBESTOS |
1246 |
1332-21-4 |
|
65 |
RADIUM |
1240 |
7440-14-4 |
|
66 |
HEXACHLOROCYCLOHEXANE, GAMMA- |
1238 |
58-89-9 |
|
67 |
HEXACHLOROCYCLOHEXANE, BETA- |
1236 |
319-85-7 |
|
68 |
CYANIDE |
1236 |
57-12-5 |
|
69 |
BARIUM |
1232 |
7440-39-3 |
|
70 |
1,2-DICHLOROETHYLENE |
1230 |
540-59-0 |
|
71 |
CARBAZOLE |
1230 |
86-74-8 |
|
72 |
THORIUM-230 |
1222 |
14269-63-7 |
|
73 |
SELENIUM |
1220 |
7782-49-2 |
|
74 |
RADIUM-228 |
1220 |
15262-20-1 |
|
75 |
SILVER |
1214 |
7440-22-4 |
|
76 |
CESIUM-137 |
1209 |
10045-97-3 |
|
77 |
1,1,1-TRICHLOROETHANE |
1209 |
71-55-6 |
|
78 |
RADON |
1204 |
10043-92-2 |
|
79 |
CHLOROBENZENE |
1203 |
108-90-7 |
|
80 |
URANIUM-234 |
1202 |
13966-29-5 |
|
81 |
AROCLOR 1242 |
1200 |
53469-21-9 |
|
82 |
HEXACHLOROBENZENE |
1198 |
118-74-1 |
|
83 |
IRON |
1197 |
7439-89-6 |
|
84 |
1,4-DIOXANE |
1190 |
123-91-1 |
|
85 |
TRITIUM |
1180 |
10028-17-8 |
|
86 |
PYRENE |
1178 |
129-00-0 |
|
87 |
BROMODICHLOROMETHANE |
1174 |
75-27-4 |
|
88 |
FLUORANTHENE |
1169 |
206-44-0 |
|
89 |
URANIUM-235 |
1165 |
15117-96-1 |
|
90 |
1,4-DICHLOROBENZENE |
1161 |
106-46-7 |
|
91 |
DIBENZOFURAN |
1161 |
132-64-9 |
|
92 |
HEXACHLOROCYCLOHEXANE, DELTA- |
1159 |
319-86-8 |
|
93 |
ACETONE |
1154 |
67-64-1 |
|
94 |
BIS(2-CHLOROETHYL) ETHER |
1154 |
111-44-4 |
|
95 |
ALUMINUM |
1153 |
7429-90-5 |
|
96 |
2,3,7,8-TETRACHLORODIBENZOFURAN |
1152 |
51207-31-9 |
|
97 |
STRONTIUM-90 |
1152 |
10098-97-2 |
|
98 |
TRICHLOROETHANE |
1149 |
25323-89-1 |
|
99 |
1,2-DICHLOROPROPANE |
1140 |
78-87-5 |
|
100 |
THORIUM-228 |
1139 |
14274-82-9 |
|
101 |
COBALT-60 |
1136 |
10198-40-0 |
|
102 |
DIBROMOCHLOROMETHANE |
1128 |
124-48-1 |
|
103 |
FLUORENE |
1126 |
86-73-7 |
|
104 |
PHENOL |
1122 |
108-95-2 |
|
105 |
CRESOL, PARA- |
1115 |
106-44-5 |
|
106 |
PLUTONIUM-239 |
1113 |
15117-48-3 |
|
107 |
1,2-DIBROMOETHANE |
1112 |
106-93-4 |
|
108 |
2-BUTANONE |
1111 |
78-93-3 |
|
109 |
2,4-DINITROTOLUENE |
1110 |
121-14-2 |
|
110 |
PLUTONIUM-238 |
1107 |
13981-16-3 |
|
111 |
CIS-CHLORDANE |
1098 |
5103-71-9 |
|
112 |
ACENAPHTHENE |
1097 |
83-32-9 |
|
113 |
PENTACHLORODIBENZO-P-DIOXIN |
1096 |
36088-22-9 |
|
114 |
LEAD-210 |
1094 |
14255-04-0 |
|
115 |
TETRACHLORODIBENZO-P-DIOXIN |
1092 |
41903-57-5 |
|
116 |
RADON-222 |
1092 |
14859-67-7 |
|
117 |
N-NITROSODI-N-PROPYLAMINE |
1092 |
621-64-7 |
|
118 |
DI-N-BUTYL PHTHALATE |
1090 |
84-74-2 |
|
119 |
1,2,3,7,8-PENTACHLORODIBENZO-P-DIOXIN |
1087 |
40321-76-4 |
|
120 |
ENDRIN |
1081 |
72-20-8 |
|
121 |
CHLOROMETHANE |
1078 |
74-87-3 |
|
122 |
1,2,4-TRICHLOROBENZENE |
1077 |
120-82-1 |
|
123 |
N-NITROSODIPHENYLAMINE |
1076 |
86-30-6 |
|
124 |
1,2,3-TRICHLOROPROPANE |
1076 |
96-18-4 |
|
125 |
CARBON DISULFIDE |
1074 |
75-15-0 |
|
126 |
OCTACHLORODIBENZO-P-DIOXIN |
1074 |
3268-87-9 |
|
127 |
1,2-DICHLOROBENZENE |
1074 |
95-50-1 |
|
128 |
NITROBENZENE |
1074 |
98-95-3 |
|
129 |
ANTHRACENE |
1071 |
120-12-7 |
|
130 |
TECHNETIUM |
1068 |
7440-26-8 |
|
131 |
2,6-DINITROTOLUENE |
1066 |
606-20-2 |
|
132 |
HEXACHLOROBUTADIENE |
1061 |
87-68-3 |
|
133 |
TOXAPHENE |
1060 |
8001-35-2 |
|
134 |
1,2,3,4,6,7,8-HEPTACHLORODIBENZO-P-DIOXIN |
1060 |
35822-46-9 |
|
135 |
2,4-DIMETHYLPHENOL |
1058 |
105-67-9 |
|
136 |
URANIUM |
1047 |
7440-61-1 |
|
137 |
HEXACHLORODIBENZO-P-DIOXIN |
1043 |
34465-46-8 |
|
138 |
1,2,3,4,7,8-HEXACHLORODIBENZOFURAN |
1043 |
70648-26-9 |
|
139 |
PENTACHLORODIBENZOFURAN |
1043 |
30402-15-4 |
|
140 |
HEPTACHLORODIBENZO-P-DIOXIN |
1037 |
37871-00-4 |
|
141 |
STYRENE |
1033 |
100-42-5 |
|
142 |
TETRACHLORODIBENZOFURAN |
1031 |
30402-14-3 |
|
143 |
RDX (CYCLONITE) |
1030 |
121-82-4 |
|
144 |
N-NITROSODIMETHYLAMINE |
1028 |
62-75-9 |
|
145 |
BENZIDINE |
1026 |
92-87-5 |
|
146 |
NEPTUNIUM |
1021 |
7439-99-8 |
|
147 |
METHYL ISOBUTYL KETONE |
1020 |
108-10-1 |
|
148 |
CARBON-14 |
1017 |
14762-75-5 |
|
149 |
ISOPHORONE |
1016 |
78-59-1 |
|
150 |
PLUTONIUM-240 |
1009 |
14119-33-6 |
|
151 |
BUTYL BENZYL PHTHALATE |
1007 |
85-68-7 |
|
152 |
CRESOL, ORTHO- |
1007 |
95-48-7 |
|
153 |
DI-N-OCTYL PHTHALATE |
1007 |
117-84-0 |
|
154 |
2,4,6-TRINITROTOLUENE |
1005 |
118-96-7 |
|
155 |
BROMOFORM |
1005 |
75-25-2 |
|
156 |
PERFLUOROOCTANOIC ACID |
1000 |
335-67-1 |
|
157 |
2-HEXANONE |
997 |
591-78-6 |
|
158 |
MOLYBDENUM |
987 |
7439-98-7 |
|
159 |
1,2,3,6,7,8-HEXACHLORODIBENZO-P-DIOXIN |
986 |
57653-85-7 |
|
160 |
1,3-DICHLOROBENZENE |
985 |
541-73-1 |
|
161 |
1,2,3,4,6,7,8,9-OCTACHLORODIBENZOFURAN |
983 |
39001-02-0 |
|
162 |
2,3,4,7,8-PENTACHLORODIBENZOFURAN |
978 |
57117-31-4 |
|
163 |
ENDRIN KETONE |
977 |
53494-70-5 |
|
164 |
3,3'-DICHLOROBENZIDINE |
976 |
91-94-1 |
|
165 |
ENDRIN ALDEHYDE |
973 |
7421-93-4 |
|
166 |
PERFLUOROOCTANE SULFONIC ACID |
972 |
1763-23-1 |
|
167 |
CHLOROETHANE |
971 |
75-00-3 |
|
168 |
POTASSIUM-40 |
964 |
13966-00-2 |
|
169 |
AROCLOR 1016 |
963 |
12674-11-2 |
|
170 |
1,2-DIBROMO-3-CHLOROPROPANE |
960 |
96-12-8 |
|
171 |
RADON-220 |
953 |
22481-48-7 |
|
172 |
DIETHYL PHTHALATE |
952 |
84-66-2 |
|
173 |
1,3-DICHLOROPROPENE, TRANS- |
951 |
10061-02-6 |
|
174 |
2,4-DICHLOROPHENOL |
950 |
120-83-2 |
|
175 |
ACTINIUM-227 |
949 |
14952-40-0 |
|
176 |
EUROPIUM-152 |
948 |
14683-23-9 |
|
177 |
2,4,6-TRICHLOROPHENOL |
946 |
88-06-2 |
|
178 |
TRICHLOROFLUOROMETHANE |
939 |
75-69-4 |
|
179 |
1,2,3,4,7,8-HEXACHLORODIBENZO-P-DIOXIN |
939 |
39227-28-6 |
|
180 |
LEAD-212 |
939 |
15092-94-1 |
|
181 |
METHOXYCHLOR |
931 |
72-43-5 |
|
182 |
4-NITROPHENOL |
929 |
100-02-7 |
|
183 |
BENZOIC ACID |
925 |
65-85-0 |
|
184 |
HEXACHLOROETHANE |
925 |
67-72-1 |
|
185 |
O-XYLENE |
920 |
95-47-6 |
|
186 |
NITRATE |
918 |
14797-55-8 |
|
187 |
FLUORIDE ION |
915 |
16984-48-8 |
|
188 |
BISMUTH-214 |
912 |
14733-03-0 |
|
188 |
LEAD-214 |
912 |
15067-28-4 |
|
190 |
2,4-DINITROPHENOL |
912 |
51-28-5 |
|
191 |
AMERICIUM |
910 |
7440-35-9 |
|
192 |
HEXACHLORODIBENZOFURAN |
907 |
55684-94-1 |
|
193 |
EUROPIUM-155 |
906 |
14391-16-3 |
|
194 |
PLUTONIUM |
906 |
7440-07-5 |
|
195 |
1-METHYLNAPHTHALENE |
904 |
90-12-0 |
|
196 |
THORIUM-234 |
903 |
15065-10-8 |
|
197 |
ENDOSULFAN |
903 |
115-29-7 |
|
198 |
PERCHLORATE |
901 |
14797-73-0 |
|
199 |
ENDOSULFAN SULFATE |
901 |
1031-07-8 |
|
200 |
AMMONIA |
901 |
7664-41-7 |
|
201 |
AMERICIUM-241 |
900 |
86954-36-1 |
|
202 |
1,3-DICHLOROPROPENE, CIS- |
899 |
10061-01-5 |
|
203 |
BIPHENYL |
899 |
92-52-4 |
|
204 |
METHANE |
898 |
74-82-8 |
|
205 |
1,1,1,2-TETRACHLOROETHANE |
898 |
630-20-6 |
|
206 |
PERFLUOROHEXANESULFONIC ACID |
897 |
355-46-4 |
|
207 |
ANILINE |
895 |
62-53-3 |
|
208 |
DICHLOROETHYLENE |
893 |
25323-30-2 |
|
209 |
URANIUM-233 |
893 |
13968-55-3 |
|
210 |
AROCLOR 1232 |
892 |
11141-16-5 |
|
211 |
ENDOSULFAN, BETA |
890 |
33213-65-9 |
|
212 |
2-CHLOROPHENOL |
889 |
95-57-8 |
|
213 |
RADIUM-224 |
883 |
13233-32-4 |
|
214 |
PERFLUOROHEPTANOIC ACID |
881 |
375-85-9 |
|
215 |
DICHLORODIFLUOROMETHANE |
879 |
75-71-8 |
|
216 |
ENDOSULFAN, ALPHA |
877 |
959-98-8 |
|
217 |
2,3,4,6,7,8-HEXACHLORODIBENZOFURAN |
876 |
60851-34-5 |
|
218 |
HEPTACHLORODIBENZOFURAN |
875 |
38998-75-3 |
|
219 |
1,2,3,4,6,7,8-HEPTACHLORODIBENZOFURAN |
868 |
67562-39-4 |
|
220 |
METHYLMERCURY |
867 |
22967-92-6 |
|
221 |
IODINE-129 |
865 |
15046-84-1 |
|
222 |
ACROLEIN |
864 |
107-02-8 |
|
223 |
METHYL-T-BUTYL ETHER |
863 |
1634-04-4 |
|
224 |
1,2,3,7,8,9-HEXACHLORODIBENZO-P-DIOXIN |
862 |
19408-74-3 |
|
225 |
ACRYLONITRILE |
862 |
107-13-1 |
|
226 |
PLUTONIUM-242 |
861 |
13982-10-0 |
|
227 |
DIMETHYL PHTHALATE |
861 |
131-11-3 |
|
228 |
BORON |
857 |
7440-42-8 |
|
229 |
1,3-DINITROBENZENE |
855 |
99-65-0 |
|
230 |
BROMOMETHANE |
853 |
74-83-9 |
|
231 |
1,3-DICHLOROPROPENE |
852 |
542-75-6 |
|
232 |
AROCLOR 1221 |
851 |
11104-28-2 |
|
233 |
HEXACHLOROCYCLOPENTADIENE |
851 |
77-47-4 |
|
234 |
CUMENE |
850 |
98-82-8 |
|
235 |
POLONIUM-210 |
849 |
13981-52-7 |
|
236 |
4-CHLOROANILINE |
847 |
106-47-8 |
|
237 |
1,3-BUTADIENE |
846 |
106-99-0 |
|
238 |
EUROPIUM-154 |
844 |
15585-10-1 |
|
239 |
THORIUM-227 |
844 |
15623-47-9 |
|
240 |
ACTINIUM-228 |
842 |
14331-83-0 |
|
241 |
BENZO(A)FLUORANTHENE |
841 |
203-33-8 |
|
242 |
TRANS-CHLORDANE |
840 |
5103-74-2 |
|
243 |
2,4-D ACID |
832 |
94-75-7 |
|
244 |
PROTACTINIUM-231 |
827 |
14331-85-2 |
|
245 |
PHOSPHORUS, WHITE |
827 |
7723-14-0 |
|
246 |
2-NITROPHENOL |
825 |
88-75-5 |
|
247 |
DICHLOROBENZENE |
824 |
25321-22-6 |
|
248 |
TETRAHYDROFURAN |
822 |
109-99-9 |
|
249 |
PROMETHIUM-147 |
821 |
14380-75-7 |
|
250 |
2-AMINO-4,6-DINITROTOLUENE |
820 |
35572-78-2 |
|
251 |
DIMETHYLMERCURY |
818 |
593-74-8 |
|
252 |
PERFLUOROPENTANOIC ACID |
810 |
2706-90-3 |
|
253 |
DIBENZODIOXIN |
810 |
262-12-4 |
|
254 |
DICHLOROETHANE |
807 |
1300-21-6 |
|
255 |
1,23-TRICHLOROBENZENE |
807 |
87-61-6 |
|
256 |
1,1,2-TRICHLORO-1,2,2-TRIFLUOROETHANE |
806 |
76-13-1 |
|
257 |
1,2-DIPHENYLHYDRAZINE |
804 |
122-66-7 |
|
258 |
TIN |
803 |
7440-31-5 |
|
259 |
COAL TAR CREOSOTE |
803 |
8001-58-9 |
|
260 |
1,3,5-TRINITROBENZENE |
796 |
99-35-4 |
|
261 |
CRESOLS |
795 |
1319-77-3 |
|
262 |
NICKEL-63 |
794 |
13981-37-8 |
|
263 |
BENZO(E)PYRENE |
792 |
192-97-2 |
|
264 |
TECHNETIUM-99 |
787 |
14133-76-7 |
|
265 |
SULFURIC ACID |
787 |
7664-93-9 |
|
266 |
TETRACHLOROETHANE |
786 |
25322-20-7 |
|
267 |
BENZYL ALCOHOL |
785 |
100-51-6 |
|
268 |
BISMUTH-212 |
783 |
14913-49-6 |
|
268 |
THALLIUM-208 |
783 |
14913-50-9 |
|
270 |
RUTHENIUM-106 |
782 |
13967-48-1 |
|
271 |
HEXACHLOROCYCLOHEXANE, TECHNICAL GRADE |
778 |
608-73-1 |
|
272 |
STRONTIUM |
775 |
7440-24-6 |
|
273 |
M-XYLENE |
770 |
108-38-3 |
|
274 |
4-AMINO-2,6-DINITROTOLUENE |
770 |
19406-51-0 |
|
275 |
2,4,5-TRICHLOROPHENOL |
767 |
95-95-4 |
Resources
These resources provide supporting information regarding the development of the Substance Priority List, as well as expanded information on current and past lists.
Support Document to the 2025 Substance Priority List
Describes the methodology used to generate the Substance Priority List.
ATSDR 2025 Full SPL Spreadsheet
A file containing a Microsoft Excel spreadsheet of the 2025 SPL.
ATSDR Past SPLs (2022 and earlier)
A zip file containing a Microsoft Excel spreadsheet of past SPL and CEP Reports.
The spreadsheet's Cover Notes PDF in the zip file contains more information.