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Information about PPH

2014 West Virginia Chemical Release

Toxicologic information on PPH and DiPPH is limited. Based on the Material Safety Data Sheets (MSDS) provided by the manufacturer, the reported toxicity of this material appears to be lower than the toxicity of MCHM (LD50 > 2000 mg/kg for the primary component of PPH vs. 825 mg/kg for MCHM). Given the small percentage of PPH in the tank, it is likely that any amount of PPH currently in the water system would be extremely low.

An initial review of the currently available toxicologic information does not suggest any new health concerns associated with the release of PPH. At this point, toxicologic information about PPH is limited; however, CDC/ATSDR will continue to work closely with the State of West Virginia and its Federal partner agencies to search for additional relevant information. Based on the currently available toxicologic information, scientists have recommended a screening level of 1.2 ppm (parts per million) for drinking water.

How was the 1.2 ppm short-term screening level for propylene glycol phenyl ether (PPH) calculated?

Scientists used the information available on PPH to calculate a short-term screening level recommendation. From the studies available, scientists used the lowest No Observed Adverse Effect Level (NOAEL) for PPH in the calculations to be as conservative as possible. A screening level was not calculated for dipropylene glycol phenyl ether (DiPPH) because a NOAEL is not available. However, the limited toxicological information available and the similar chemical structure of PPH and DiPPH suggest that the screening value calculated for PPH would also be protective for DiPPH.

The calculations for the short-term screening level used uncertainty factors to take into account the differences between animals and people and to consider possible effects on special populations. An additional factor was applied to account for the limited availability of data. Based on the application of these uncertainty factors and the available research studies, scientists recommend a screening level of 1.2 parts per million (1.2 ppm), or lower, of PPH in drinking water.

We believe that the short-term screening level is protective for both chemicals and we would not expect any adverse health effects at this level. Out of an abundance of caution, pregnant women may want to use an alternative source of drinking water until the system is documented to be at non detectable levels.

Our Federal partners have reviewed and concur with our approach and the short-term screening level recommendation. We will continue to seek and review additional information as it becomes available.

CDC/ATSDR used the following calculation to establish a short-term screening level of 1.2 parts per million (ppm) for the PPH spilled in the Elk River:

Equation: DW Advisory is less than or equal to the product of NOAEL times BW divided by the product of UF times Intake.

Where:

  • DW Advisory = Drinking Water Advisory
  • NOAEL = No Observed Adverse Effect Level in the experimental species
  • BW = Body weight of a pregnant mother (EPA Exposure Factor Handbook, 2011 Edition)
  • UF = Uncertainty factors that address differences between animals and humans (10X), address differences accounting for sensitive humans (10x), and account for weaknesses in the toxicological database (10X).
  • Intake = The estimated intake from drinking water of a pregnant mother in liters

Calculating using 75 kg BW and 2.5 L daily consumption rate:

NOAEL (mg/kg/d) BW (kg) UF (unitless) Intake (L/day) DW Advisory (mg/L or ppm)
40 75 1000 2.5 1.2 ppm
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