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Step 1.5 Identifying Comparison Values

Advanced Exercise

In air and soil samples taken at the Oak Estates site, assessors found the chemicals listed in the following table. Maximum concentration levels are noted.

Identify the chemicals that need further evaluation. Click on “Chemicals and the evaluations needed” for feedback.

Ambient Air
Concentration (µg/m3)
Air Comparison Value (µg/m3)
Chemical Maximum Concentration Chronic EMEG CREG Intermediate
EMEG
Acute
EMEG
Acetone 13,700 30,000 na 30,000 60,000
Methylene Chloride 112 1,000 3 1,000 2,000
1,1,2- Trichloroethane 31.2 na 0.06 na na
Surface Soil Concentration (ppm) Soil Camparison Value (ppm)
Chemical Maximum Concentration Child EMEG Adult EMEG CREG
Aroclor 1254 14 1 10 na
Arsenic 11 20 200 0.5
Methylene Chloride 3.5 3,000 40,000 90

na = not available
ppm = parts per millions
µg/m3 = micrograms per cubic meter

Chemicals and the evaluations needed

Acetone

No further evaluation necessary

Because the maximum acetone level is below all of the comparison values in the table, no further evaluation is necessary.

Note: There is no CREG for acetone, but no further evaluation is needed because acetone has not been associated with cancer in humans.

Methylene Chloride

Further evaluation necessary

Because methylene chloride was found at levels above the comparison value.

1,1,2- Trichloroethane

Further evaluation necessary

Because the maximum concentration of 1,1,2-trichloroethane is above the comparison value.

Aroclor 1254

Further evaluation necessary

Because the maximum concentration of Aroclor 1254 is above the comparison value.

Arsenic

Further evaluation necessary

Because levels of arsenic in soil exceed the CREG.

Methylene Chloride

No further evaluation necessary

Because the maximum concentration value is below all of the comparison values presented in the table.

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