Guidance for Air

The following guidance was developed by the Minnesota Department of Health (MDH) at the request of the Minnesota Pollution Control Agency (MPCA). Note: These values are for screening purposes of ethanol sector facilities only. For more information, contact the Health Risk Assessment Unit.

Ethanol Sector Specific Interim Exposure Values
July 26, 2005

At the request of the Minnesota Pollution Control Agency the Minnesota Department of Health (MDH) has developed the following set of Ethanol Sector Specific Interim Exposure Values (ESSIEVs) to serve as screening tools for environmental review of ethanol producing facilities. These numbers have a higher degree of uncertainty than either the Health Risk Values (HRVs) or the Health-Based Values (HBVs) that MDH has typically developed. MDH considers the ESSIEVs protective of the general population, but does regard them as sector specific for ethanol production facilities and cannot endorse the routine use of ESSIEVs for other types of facilities.

ESSIEVs have been developed for a group of short-chained organic acids, alcohols, aldehydes and esters that occur as by-products of the production of ethanol. Many of these chemicals are metabolic intermediates common to plants and animals, including humans, and most are considered to be mildly to moderately toxic. As a result of the lack of detailed toxicity information for these chemicals, MDH has departed from its normal procedures for developing health-based numbers and used occupational exposure limits (OELs) to develop ESSIEVs. OELs are often based on human studies conducted with healthy working individuals using intermittent exposures (typically an eight to ten hours per day, five days a week schedule) that allow time for elimination of chemicals from the body.

MDH has determined that the use of OELs in this circumstance is justified because the chemicals in question exert relatively low to moderate levels of toxicity that result because of their irritancy. Therefore, if exposures to these chemicals are limited to levels below which irritation occurs, the toxicity will be avoided. MDH has manipulated the selected OELs by adjusting for the timing of exposure because the exposure of the public to chemicals in ambient air will likely be continuous, and by dividing by an uncertainty factor to provide an additional level of protection for the general population. The conservative nature of this process is evidenced by the fact that in two cases (methanol and formaldehyde) where agencies such as MDH have been able to use available information to develop conventional health-based values, the resulting numbers were less stringent than those developed by manipulating OELs.

Equations:

Chronic ESSIEV = OEL/Time adjustment factor1/Uncertainty factor of 1002

Acute ESSIEV = OEL x Time adjustment3/Uncertainty factor of 1002

1 A factor of 4.2 to convert an 8 hour 5 day week exposure to a continuous one [1/ (5/7 x 8/24)].
2 The uncertainty factor is composed of a factor of 10 for intraspecies variability, and a combined factor of 10 for use of a mild LOAEL (3) and database deficiencies (3).
3 Factor of 2.8 to convert an 8-hour exposure to one-hour exposure (C1n x T1 = C2n x T2, where by default, n=2).

Table: Ethanol Sector Specific Interim Exposure Values*

Chemical4
CAS Number

OEL
ppm (mg/m3)

Chronic
ESSIEV

ug/m3

Acute ESSIEV ug/m3

Acetic Acid
64-19-7
10 (25)
60
700
Formic Acid
64-16-6
5 (9.4)
20
270
Lactic Acid5
50-21-5
-
70
850
Propionic Acid
79-09-4
10 (30)
70
850
Butanol
71-36-3
50 (152)
360
4,300
Ethanol6
64-17-5
1,000 (1,890)
15,000
180,000
Isoamyl
121-51-3
100 (360)
860
10,200
Propanol
71-23-8
200 (490)
1,200
14,000
Butyraldehyde
123-72-8
25 (72.5)
70
2,100
Furfural
98-01-0
2 (8)
20
230
Proprionaldehyde
128-38-6
20 (46)
110
1,300
Benzaldehyde
100-52-7
2 (8.6)
20
240
Ethyl Acetate
141-78-6
400 (1,400)
3,300
40,000

* Note: These values are for screening purposes of ethanol sector facilities only.

4 All ESSIEVs have an irritancy endpoint.
5 The value for lactic acid was developed using propionic acid as a surrogate.
6 Because there is an extensive database dealing with health effects of ethanol, the database deficiency factor of 3 was removed when calculating the ESSIEV.

Updated Thursday, November 14, 2013 at 07:50AM