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.

Table 1
Chemical	Maximum Concentration	Chronic EMEG	CREG	Intermediate EMEG	Acute EMEG
	Ambient Air Concentration (µg/m³)	Air Comparison Value (µg/m³)
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

Table 2
Chemical	Maximum Concentration	Child EMEG	Adult EMEG	CREG
	Surface Soil Concentration (ppm)	Soil Camparison Value (ppm)
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

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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