el particulates adsorbed to another variety of particulate can be inhaled as oneparticle.
- Nickel oxide is insoluble in water hence, there exists the likely-hood of particlesbecoming airborne again and again.
- When inhaled, nickel oxide is retained longer in the lung than any other form ofnickel.
- Nickel can cross the placental barrier.
- Nickel is a mutagen (human)
ATSDR Response: ATSDR has reviewed all of the data collected by or through theKentucky Federal Facility Oversight Unit that they have provided to ATSDR. Although thedata sets do contain some measurements of nickel (or nickel compounds) in various media,we have not reviewed any specific nickel cyanide or nickel carbonyl measurements in theavailable data. Several different PGDP process operations may result in nickel emissions. Asindicated in the Health Consultation, past smelting operations and fossil fuel combustionrelease(d) nickel and nickel oxides. Limited quantities of nickel carbonyl or nickel cyanideas liquid effluents may be released from metal cleaning/degreasing operations in C-400building. However, these compounds are not stable in the environment (nickel carbonyl is aliquid at ambient temperatures) and will quickly be transformed to more stable compounds(nickel hydrates in water or nickel ferrite in soil) .
In determining the contaminants of concern for the Public Health Assessment, ATSDR didnot attempt to correlate specific sources of nickel for each environmental media. The PHAevaluation was based on the measured concentrations of the contaminants in various media,such as soil, water, and sediment. The rationale for conducting this health consultation is thatwe did not include metal particulates released from smelting operations in assessing airbornecontaminant distributions. Nickel, as dissolved or total nickel, is monitored in surface water,ground water, and soil. This Health Consultation used modeled airborne nickelconcentrations to estimate off-site distributions, because nickel was not monitored at off-site locations.
ATSDR Response: ATSDR has reviewed a number of documents relating to various aspectsof the aluminum and nickel smelting processes including the referenced DOE report on the"Metals Recovery Program" . While that document does discuss the types of documentsthat were reviewed, neither that document or the Phase II Report  contain specificreferences or bibliographies. Consequently, ATSDR cannot determine if we have reviewedthose same documents. However, ATSDR did review, and the Health Consultation doesreference, the report produced by that investigative team (as well as the report of anotherteam investigating related issues) [1,2]. ATSDR has not reviewed the "1972 study ofradionuclides in scrap." Although, it is mentioned, as stated by the commentor, in the PhaseII Report, it is not specifically referenced so ATSDR has no way of finding or tracking thatdocument.
As stated in the Health Consultation, smelting activities in C-746A did apparentlycommence in the 1950's. However, the summary statement describing the years of smeltingoperation are the only reference to smelting in the 1950's (other documents suggest thatearlier smelting activities mainly involved aluminum). Based on available reports, the yearsof significant nickel smelting were restricted to 1977 to 1986 (inclusive). While limitedquantities of nickel may have been smelted during other years, the exposure assessment inthis consultation focuses on those years of maximum nickel smelting (1977-86) and airborneemissions. As the airborne nickel concentrations estimated using conservative (healthprotective) assumptions during years of peak smelter operation are below levels of healthconcern, emissions during any earlier years of lower emission concentrations are also below levels of public health concern.
ATSDR Response: In determining the contaminants of concern for the Public CommentRelease of the Public Health Assessment, ATSDR did not evaluate specific sources of nickelor lead. That evaluation was based on the measured concentration of the contaminants invarious media,