Lead Acetate and Lead Phosphate
Reasonably Anticipated to be Human Carcinogens Ninth Report on Carcinogens 2000
CAS Nos.301-04-2 and 7446-27-7
First Listed in the Second Annual Report on Carcinogens
U.S. Department of Health and Human Services
Public Health Service
National Toxicology Program
Pursuant to Section 301(b) (4) of the Public Health Service Act as Amended by Section 262, PL 95-622

Lead Acetate

CARCINOGENICITY
Lead acetate and lead phosphate are reasonably anticipated to be human carcinogens based on sufficient evidence of carcinogenicity in experimental animals (IARC V.1,1972; IARC,V.23,1980;IARC S.4,1982;IARC S.7,1987).When administered in the diet, lead acetate induced renal adenomas and carcinomas and cerebral gliomas in rats of both sexes. Subcutaneous injections of lead phosphate induced renal cortical tumors, including adenomas, papillomas, cystadenomas, and carcinomas in rats.
There is inadequate evidence for the carcinogenicity of lead acetate and lead phosphate in humans (IARC S.7,1987).

PROPERTIES
Lead acetate and its trihydrate (6080-56-4)occur in the form of white or colorless crystals or flakes; the commercial grades are frequently brown or gray lumps. Lead acetate has a sweetish taste and a slight acetic odor. In the United States, lead acetate is usually marketed as lead acetate trihydrate, and is available in reagent, purified, and technical grades. Typically, trace impurities are iron and chlorides (Cl - ).Lead acetate and its trihydrate are soluble in water, slightly soluble in alcohol, and very soluble in glycerol. Lead phosphate occurs either in the form of hexagonal crystals or as a white powder that is insoluble in water and alcohol. It is soluble in acids and alkali. When heated to decomposition, lead acetate, lead acetate trihydrate, and lead phosphate emit toxic fumes of lead oxide.

USE
Lead acetate is often used for the preparation of other lead salts by the wet method (Kirk-Othmer V.14,1981).The commercial form of lead acetate, lead acetate trihydrate, is used as a mordant in cotton dyes, as a lead coating for metals, as a drier in paints, varnishes, and pigment inks, and as a colorant in hair dyes (IARC V.23,1980;Sax,1987;Sittig,1985).It is also used in antifouling paints, waterproofing, insecticides, and the gold cyanidation process (Sax,1987). Lead acetate has been used in explosives and in dilute solutions as poultices and washes for treatment of poison ivy. Formerly, it was used as a pharmaceutical in astringents (IARC V.23, 1980).Lead phosphate is used as a stabilizer in styrene and casein plastics and in small amounts in special glasses (IARC V.23,1987;Sax,1987).

PRODUCTION
Current domestic production volumes for lead acetate and lead phosphate are not available. There is no evidence that lead phosphate is produced in commercial quantities in the United States. In 1986,there were seven producers and five suppliers of lead acetate, and one supplier of lead phosphate (Chem Sources,1986).U.S.imports of lead acetate were 115,411 lb in 1985 and 111,201 lb in 1984 (USDOC Imports,1985;USDOC Imports,1986).According to EPA, seven producers in 3 regions reported that domestic production of lead acetate was about 407,000 lb in 1980.In 1978,250 lb of lead acetate were imported (IARC V.23,1980).The 1979 TSCA Inventory identified six companies producing 661,000 lb of lead acetate in 1977, and 1 importer with no volume reported, with some site limitations. The CBI Aggregate was between 1 million and 100 million lb. The TSCA Inventory identified one importer of lead phosphate in 1977,but no volume was reported (TSCA,1979).Lead acetate was first produced commercially in the U.S. in 1944 (IARC V.23,1980).

EXPOSURE
The primary routes of potential human exposure to lead acetate and lead phosphate are ingestion, inhalation, and dermal contact. Lead acetate is absorbed about 1.5 times as fast as other lead compounds. In 1978,sales of hair dyes containing lead acetate exceeded 1 million bottles (Sittig,1985).The National Occupational Hazard Survey, conducted by NIOSH from 1972 to 1974,estimated that 132,000 and 18,000 workers were possibly exposed to lead acetate and lead phosphate, respectively, in the workplace (NIOSH,1976).However,OSHA has estimated that 223,000 workers may be exposed to lead acetate,28,000 to lead phosphate dibasic, and 27,000 to lead phosphate tribasic. The differences are the result of different methods used to estimate exposure (Sittig,1985).It has been estimated that airborne emissions of lead in the United States are 46.9 million lb per year (Chem.Engr.News,1988a).The ACGIH has established a threshold limit value of 0.15 mg/m 3 ,as lead for inorganic compounds (dust and fumes), as an 8-hr time-weighted average (TWA )in air (ACGIH,1986).Additional exposure information may be found in the ATSDR Toxicological Profile for Lead (ATSDR, 1993h).

REGULATIONS
CPSC initially banned the use of certain lead-containing paints and similar surface- coating materials in consumer products under the Federal Hazardous Substances Act (FHSA). The ban on lead or lead compounds applied when the lead content exceeded 0.5%of the weight of the product, but excluded artists' paints and related materials. The Consumer Product Safety Act (CPSA) amended the limit of lead content in paints from 0.5%to 0.06%of the weight of the product. CPSC evaluated consumer exposure to lead inks in printed consumer products and found no lead in printed matter intended for children; lead was found in some inks used in printed products, but the levels in the final products did not warrant further action. CPSC found little lead in other printed consumer products. EPA regulates lead and certain lead compounds under the Clean Water Act (CWA), Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), Resource Conservation and Recovery Act (RCRA), Superfund Amendments and Reauthorization Act (SARA), and Safe Drinking Water Act (SDWA). The dissociated lead ion addressed in these regulations would provide a degree of control over many lead compounds, including lead acetate and lead phosphate. EPA has established a maximum concentration for lead of 0.05 ?g/L in wastes for the protection of health under RCRA,and has published a water quality criteria document under CWA for the protection of human health. Under SDWA, EPA published a primary drinking water standard for lead of 0.05 mg/L, which was not based on carcinogenicity. Reportable quantities (RQs) of 5,000 lb (subject to carcinogenicity assessment) has been established for lead acetate and 1 lb (statutory) for lead phosphate under CERCLA. FDA regulates the use of lead acetate in hair dyes under the Food, Drug, and Cosmetic Act (FD&CA). OSHA established a permissible exposure limit (PEL) of 50 ?g/m 3 as an 8-hr TWA and 50 ?g/100 g as the maximum permissible lead level in blood; the standard requires personal protective equipment, engineering and work practice controls, and medical surveillance with provisions for medical removal. OSHA regulates lead on the basis of acute and chronic toxicity for several organ systems, but not on the basis of carcinogenicity. OSHA regulates lead acetate and lead phosphate under the Hazard Communication Standard and as chemical hazards in laboratories. Regulations are summarized in Volume II, Table B-77.