Common Contaminants in Urban Watersheds - Urban Watersheds: Geology, Contamination, and Sustainable Development - page 246

TABLE 7.13
Data for Select Heavy Metals

Heavy Metal CAS Registry Number Carcinogenicity Rating

Arsenic 7440-38-2 Group: A1

Barium 7440-39-3 Group: A4

Cadmium 7440-43-9 Group: A2

Chromium III 16065-83-1 Group: A4

Chromium VI a 18540-29-9 Group: A1

Copper 7440-50-8 Not Available

Lead 7439-92-1 Group: A2

Mercury 7439-97-6 Group: A4

Nickel 7440-02-0 Not available

Selenium 7782-49-2 Group: A4

Silver 7440-22-4 Group: A4

Zinc 7440-66-6 Inadequate information

Source: United States Environmental Protection Agency, Integrated
Risk Information System (IRIS), http://www.epa.gov/
ncea/iris/intro.htm (accessed October 21, 2009), 2009b.
a Classified as Group: A1 inhalation route of exposure and Group:
A4 by ingestion route of exposure.

As shown in Table 7.13, the toxicity and carcinogenicity of heavy metals varies widely.
Additional but brief explanations of their general toxicities are given in the following:

• Arsenic is considered a human carcinogen (USEPA 2009b).
• Barium exposure can cause gastrointestinal disturbances and muscular weakness
if it is ingested in a soluble form (ATSDR 2007e).
• Cadmium is considered a suspected or probable human carcinogen (USEPA 2009b;
ATSDR 2008b).
• Chromium VI is considered a human carcinogen (ASTDR 2008a; USEPA 2009b).
Chromium III is an essential nutrient that helps the body use sugar, protein, and
fat.
• Copper is essential for good health in small amounts. High levels, however, can be
harmful and cause nausea, vomiting, and diarrhea. Very high amounts can dam-
age the liver and kidneys (ATSDR 2004a).
• Lead is considered a suspected or probable human carcinogen (USEPA 2009b).
Lead can damage the nervous system and the brain (ATSDR 2007d).
• Mercury exposure may affect the brain and central nervous system (ATSDR 1999a).
• Nickel exposure most often results in an allergic reaction. Nickel may also affect
the lungs (ATSDR 2005c).
• Selenium has beneficial and harmful effects. Low doses of selenium are neces-
sary to maintain good health. High doses can cause harmful health effects such
as, nausea, vomiting, and diarrhea. Prolonged exposure to selenium can cause a
disease called selenosis (ATSDR 2003b).
• Silver exposure may result in a condition called arygia if exposure is prolonged.
Arygia is a condition that causes a blue-gray discoloration of the skin and other
body tissue (ATSDR 1999b).