Smelting Plant Cadmium/Arsenic Exposure Cohort Analysis

Objective/Intended Use

This is a data collection and analysis effort undertaken jointly by NIOSH and EPA to support specific guidelines, i.e., those for carcinogenicity of inhaled cadmium to humans, which includes EPA's IRIS as well as NIOSH's REL values. This has been a funds-out IAG with NIOSH with the analyses and data being totally in the control of NIOSH. EPA's funding and scientific input has ended such that this activity may be considered complete. Product completion depends upon NIOSH.

Abstract

EPA's proposed IRIS cancer assessment (as well as OSHA, NIOSH and the European Union assessments) classify cadmium as a probable human carcinogen by inhalation exposure, based principally on data from the Globe Manufacturing facility located in the Western U.S. A major confounding factor at this facility and a major source of scientific controversy, with regulatory implications, is the fact that portions of this same facility were used in the past as an arsenic smelter. A decades-long argument has persisted about whether worker exposures can be segregated between arsenic only and cadmium only. Recent work has been done on analysis of worker paysheets that allow a better insight into actual cadmium exposure but not arsenic exposure. Information on known area exposures to arsenic have yet to be integrated into the effort to segregate and quantify worker exposures. This project, which was performed predominately by NIOSH, collated and analyzed more data on worker arsenic exposure at this facility. Analysis of the arsenic exposure data will enhance ability to interpret the Globe facility epidemiology data by reducing uncertainties regarding relative contributions of arsenic versus cadmium to observed increments in lung cancer risks. Reducing uncertainties regarding arsenic and cadmium lung cancer likelihood will improve the applicability of the IRIS cadmium cancer assessment (and possibly the arsenic assessment) to both air toxics and hazardous waste risk assessments for this persistent bioaccumulative toxin.

Project Status

This effort has been codified into an Interagency Agreement that was cleared by Agency grants division in May of 2002. Work as per the project description has proceeded in NIOSH. A site visit was made to NIOSH in October of 2002 to inspect and review documents prepared by NIOSH concerning the historical exposures of the Globe facility and the role of the principal confounder at this site, arsenic. Initial results suggest that arsenic levels at several worker locations at the exposure worksite were at or above the arsenic TLV well into the 1970s vice ending in 1926 as previously claimed. Contracts for Worksheet coding were let, and data entry has been completed. The NIOSH co-investigator has made the decision that the design of the exposure analysis should be changed from the original "nested cohort case-control" design to a full cohort analysis. This altered design obligates more funding which has been provided by EPA. NIOSH analysis of exposure matrices of cohort mortality update is underway as of December 2003. Interim reports have not been requested. A final report is projected to be available in September 2004.

Project Start Date

05/15/2002

Project Completion Date (Actual/Projected)

06/15/2006