Occupational Health and Safety: Calculating Permissible Exposure Level

A manufacturing plant is "handling the removal of toxic material" by discharging it into an adjacent creek. The toxic material is dimethyl sulfate which is a suspected carcinogen and known to cause lung damage if ingested. Suppose 3.2 mg of dimethyl sulfate is carried in every 1.0 liter of effluent discharged. The effluent goes into the stream at the rate of 45 liters/minute.

If the creek is flowing at a rate of 2.8 ft3/s, is the company well below the OSHA P.E.L. (permissible exposure level) in the stream for dimethyl sulfate of 5.8 mg/m3?


The Company is discharging:

2.4 mg of toxic substance is discharged into the creek per second.

The creek moves a volume of 0.079296 cubic meters per second:

The concentration of dimethyl sulfate moving through the creek is

Thus the company is way above the permissible exposure level of 5 mg/m3.

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Written by Louise Routledge, September 1, 1998