Further information the evaluation process and the complete set of 275 substances on the Priority List of Hazardous Substances for 1999 can be accessed at /99list.html

Each of the Top 20 substances listed below is identified with their 1999  Rank Number and includes a link to an ATSDR publication having further health and chemical information about that substance.  Those publications were prepared by the ATSDR Divison of Toxicology and include the ATSDR Toxicological Profiles, Public Health Statements, and ToxFAQs^TM sheets.  They provide answers to many health concerns that are voiced by community groups and give general information on various properties of the substance.

The complete lists of all available ATSDR  ToxFAQs^TM  Sheets and ATSDR Toxicological Profiles can be accessed at /toxfaq.html and /toxpro2.html , respectively.

Top 20 Substances

1. Arsenic
2. Lead
3. Mercury
4. Vinyl Chloride
5. Benzene 
6. Polychlorinated Biphenyls (PCBs)
7. Cadmium
8. Benzo(a)pyrene
9. Polycyclic Aromatic Hydrocarbons
10. Benzo(b)fluoranthene 
11. Chloroform
12. DDT, P'P'-
13. Aroclor 1260
14. Aroclor 1254
15. Trichloroethylene 
16. Chromium (+6)
17. Dibenz[a,h]anthracene
18. Dieldrin
19. Hexachlorobutadiene
20. DDE, P,P'