1988 "Only Asarco’s El Paso smelter currently treats concentrates that are considered to have high levels of volatile impurities"

"....[1988 - four years before the ConTop installation...] contamination of the soil surrounding a smelter also is of concern. Fortunately, toxic metals are present only in very small concentrations in most domestic copper ores.  Only Asarco's El Paso smelter currently treats concentrates that are considered to have high levels of volatile impurities. The Anaconda-Butte and Asarco-Tacoma smelters used to treat such concentrates, but they closed in 1980 and 1985, respectively..."

U.S. Congress, Office of Technology Assessment, Copper: Technology and Competitiveness,
OTA-E-367 (Washington, DC: U.S. Government Printing Office, September 1988).

1998: Yet another study that showed it is not just Lead-pottery and Lead-candy-wrappers

"...for three smelter studies: El Paso, Texas Lead Study [19], Helena Valley Lead Study [20],
and Silver Valley-Revisited Lead Study [17]. In the Midvale Community Lead Study [22] ....
The isopleths [i.e. graphs], which show increasing soil-lead concentrations in the vicinity of the smelters,
“support the conclusion that the smelters are the primary sources of lead contamination in the
area.” In addition, the Heavy Metal Exposure Study [60] found that “there was a general trend
toward increasing levels of environmental metal burdens with proximity to the smelter.” The
evidence for the emitter being the contributing source of the lead, therefore, stems from
increasing soil-lead concentrations with decreasing distance from the emitter."

February 1998
EPA 747-R-98-001a
FINAL REPORT
SOURCES OF LEAD IN SOIL:
A LITERATURE REVIEW
Prepared by
Battelle Memorial Institute
Technical Programs Branch
Chemical Management Division
Office of Pollution Prevention and Toxics
Office of Prevention, Pesticides, and Toxic Substances
U.S. Environmental Protection Agency
Washington, DC 20460