TOXICITY Test Results

As summarized in Table 3-1, the worst-case estimates of exposure to the trace metals in the mineral fiber insulation are 11- to 167,504-fold below their respective NSRL values. Thus, the risks of adverse effects attributable to the trace metals from use of the mineral fiber insulation are considered to be negligible. Table 3-1 Comparison of Heavy Metal Exposures from Use of Mineral Fiber insulation to the No Significant Risk Levels for the Metals 

Metal  NSRL (μg/day)  Exposure(μg/day)  NSRL/Exposure 

Arsenic  0.06(inhalation)  0.00000724  8,287 

Beryllium  0.1  0.00002896 3,453 

Chromium (VI) 0.001(inhalation)  0.0000884  11 

Cobalt  0.022  0.00001584  1,388 

Nickel *  0.4  0.000002388  167,504 

NSRL = no significant risk level.

* = as Nickel Subsulfide

In conclusion, potential risks associated with inhalation exposures to the trace levels of the heavy metals arsenic, beryllium, chromium, cobalt, and nickel, from the use of mineral fiber insulation in residential buildings, are considered to be insignificant. This conclusion is based on the estimated inhalation exposures to the metals being well below the corresponding NSRL values for these metals.

As noted, the NSRL is the ‘no significant risk level’ determined from the risk assessment conducted by the lead agency (which is OEHHA) and deemed to pose no significant cancer risk even with daily exposure over a 70-year lifetime. Concentrations of the metal in the fiber that would result in exposures in excess of the NSRL would be considered significant.