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Substances Most Frequently Found in Completed Exposure Pathways (CEPs) at Hazardous Waste Sites

(the 1997 ATSDR CEP Site Count Report)

Exposure to hazardous substances is of significant concern to ATSDR. For the past number of years, ATSDR has been tabulating the substances to which people have been exposed at hazardous waste sites, and recently much interest has been focused on this tabulation. Therefore, ATSDR's Division of Toxicology will henceforth publish the following Completed Exposure Pathway report along with the CERCLA Priority List of Hazardous Substances. A completed exposure pathway (CEP) is an exposure pathway that links a contaminant source to a receptor population. The CEP ranking presented here is based on a site frequency count, and thus lists the number of sites at which a substance has been found in a CEP. ATSDR's HazDat database contains this information which is derived from ATSDR's Health Assessments and Consultations. Since this CEP report focuses on documented exposure, it provides an important prioritization based on substances to which people are exposed.

This CEP ranking is very similar to a sub-component in the CERCLA Priority List algorithm called "Exposure to Contaminant". This sub-component is part of the potential-for-human- exposure component of the listing algorithm, and is an incident count of substances in a completed exposure pathway. An incident count, rather than a site count, is more appropriate for the Priority List because it adds more discrimination to the less frequent substances on the List. Another difference between the two exposure counts is that since the Priority List is mandated by CERCLA, it only uses data from CERCLA sites on the National Priorities List (NPL), whereas this CEP ranking utilizes data from all sites in HazDat.

The substances on the CEP list are similar to the substances on the CERCLA Priority List of Hazardous Substances. However, there are some substances that are frequently found in CEPs, but have a very low toxicity (e.g., sodium). These low toxicity substances are not on the CERCLA Priority List because it incorporates three different components - toxicity, frequency of occurrence, and potential for human exposure - to determine its priority substances. Thus, due to their low toxicity, these substances are not on the CERCLA Priority List and consequently are not the subject of toxicological profiles.




Order
Name		 All
Sites		 NPL
Sites
CAS Number
1 TRICHLOROETHYLENE 227 213 000079-01-6
2 LEAD 206 181 007439-92-1
3 TETRACHLOROETHYLENE 171 157 000127-18-4
4 ARSENIC 138 121 007440-38-2
5 BENZENE 121 110 000071-43-2
6 CADMIUM 102 91 007440-43-9
7 CHROMIUM 99 91 007440-47-3
8 1,1,1-TRICHLOROETHANE 95 86 000071-55-6
9 POLYCHLORINATED BIPHENYLS 90 79 001336-36-3
10 1,1-DICHLOROETHENE 77 73 000075-35-4
11 CHLOROFORM 76 73 000067-66-3
11 ZINC 76 66 007440-66-6
13 MERCURY 74 61 007439-97-6
14 1,1-DICHLOROETHANE 71 69 000075-34-3
14 VINYL CHLORIDE 71 69 000075-01-4
16 MANGANESE 70 60 007439-96-5
17 1,2-DICHLOROETHANE 67 63 000107-06-2
18 METHYLENE CHLORIDE 65 62 000075-09-2
19 VOLATILE ORGANIC COMPOUNDS, UNSPECIFIED 61 54 HZ1900-01-T
20 TOLUENE 60 54 000108-88-3
20 COPPER 60 51 007440-50-8
22 NICKEL 53 49 007440-02-0
23 CARBON TETRACHLORIDE 49 42 000056-23-5
24 BARIUM 48 43 007440-39-3
25 POLYCYCLIC AROMATIC HYDROCARBONS 47 44 130498-29-2
26 1,2-DICHLOROETHENE, TRANS- 46 45 000156-60-5
26 DI(2-ETHYLHEXYL)PHTHALATE 46 45 000117-81-7
28 ANTIMONY 42 38 007440-36-0
29 BENZO(A)PYRENE 41 36 000050-32-8
30 BERYLLIUM 40 33 007440-41-7
30 NAPHTHALENE 40 32 000091-20-3
32 ETHYL BENZENE 38 33 000100-41-4
33 TOTAL XYLENES 37 32 001330-20-7
34 BENZO(A)ANTHRACENE 36 32 000056-55-3
34 VANADIUM 36 31 007440-62-2
34 IRON 36 29 007439-89-6
37 1,2-DICHLOROETHYLENE 35 34 000540-59-0
38 CHRYSENE 34 30 000218-01-9
39 CHLOROBENZENE 33 30 000108-90-7
40 ALUMINUM 32 26 007429-90-5
41 PHENANTHRENE 30 24 000085-01-8
42 SODIUM 29 27 007440-23-5
43 BENZO(K)FLUORANTHENE 28 24 000207-08-9
44 DDE, P,P'- 26 25 000072-55-9
44 DDT, P,P'- 26 25 000050-29-3
44 BENZO(B)FLUORANTHENE 26 22 000205-99-2
47 PENTACHLOROPHENOL 25 23 000087-86-5
47 1,2-DICHLOROETHENE, CIS- 25 22 000156-59-2
49 MAGNESIUM 24 19 007439-95-4
50 INDENO(1,2,3-CD)PYRENE 23 19 000193-39-5
51 DIBENZO(A,H)ANTHRACENE 22 17 000053-70-3
52 CHLORDANE 21 20 000057-74-9
52 DIELDRIN 21 20 000060-57-1
52 ACETONE 21 19 000067-64-1
52 NITRATE 21 18 014797-55-8
52 COBALT 21 17 007440-48-4
57 METALS, UNSPECIFIED 20 19 HZ0900-01-T
57 1,1,2,2-TETRACHLOROETHANE 20 18 000079-34-5
57 2-BUTANONE 20 17 000078-93-3
57 CALCIUM 20 17 007440-70-2
61 DDD, P,P'- 19 19 000072-54-8
61 PYRENE 19 17 000129-00-0
61 SELENIUM 19 15 007782-49-2
64 FLUORANTHENE 18 16 000206-44-0
64 2-METHYLNAPHTHALENE 18 15 000091-57-6
64 THALLIUM 18 14 007440-28-0
67 1,2-DICHLOROPROPANE 17 17 000078-87-5
67 1,1,2-TRICHLOROETHANE 17 16 000079-00-5
67 DIBENZOFURAN 17 12 000132-64-9
70 BROMODICHLOROMETHANE 16 16 000075-27-4
70 2,3,7,8-TETRACHLORODIBENZO-P-DIOXIN 16 15 001746-01-6
70 BENZO(GHI)PERYLENE 16 12 000191-24-2
73 AROCLOR 1254 15 15 011097-69-1
73 CYANIDE 15 14 000057-12-5
75 PHENOL 14 13 000108-95-2
75 POTASSIUM 14 13 007440-09-7
77 HEPTACHLOR EPOXIDE 13 13 001024-57-3
77 SILVER 13 12 007440-22-4
79 AROCLOR 1260 12 12 011096-82-5
79 PAHS (CARCINOGENIC) 12 11 HZ1500-02-T
79 TRICHLOROETHANE 12 11 025323-89-1
79 DI-N-OCTYL PHTHALATE 12 10 000117-84-0
79 ASBESTOS 12 9 001332-21-4
79 STYRENE 12 9 000100-42-5
85 FLUORENE 11 10 000086-73-7
85 HEAVY METALS, UNSPECIFIED 11 10 HZ0900-02-T
85 CHLOROMETHANE 11 8 000074-87-3
88 CARBON DISULFIDE 10 10 000075-15-0
88 CHLORODIBROMOMETHANE 10 10 000124-48-1
88 DICHLOROETHYLENE 10 10 025323-30-2
88 RADIUM 10 10 007440-14-4
88 HEXACHLOROBENZENE 10 9 000118-74-1
88 1,4-DICHLOROBENZENE 10 7 000106-46-7
88 ACENAPHTHYLENE 10 7 000208-96-8
95 BROMOFORM 9 9 000075-25-2
95 CHLORIDE 9 9 016887-00-6
95 CHLOROETHANE 9 9 000075-00-3
95 DI-N-BUTYL PHTHALATE 9 9 000084-74-2
95 METHYL ISOBUTYL KETONE 9 9 000108-10-1
95 RADON 9 9 010043-92-2
95 ACENAPHTHENE 9 8 000083-32-9
95 CHROMIUM, HEXAVALENT 9 8 018540-29-9
95 SULFATE 9 8 014808-79-8
95 ALDRIN 9 7 000309-00-2
95 BUTYL BENZYL PHTHALATE 9 7 000085-68-7
95 CRESOL, PARA- 9 7 000106-44-5
95 RADIUM-226 9 7 013982-63-3

(107 substances are shown because 13 were found at 9 sites and tie for 95th)

ALL Sites = all sites with ATSDR activities
NPL Sites = current and former sites on the National Priorities List
CAS Number = Chemical Abstracts Service number

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