SDMS DocID 530157

1> ."•

' STATE .OF MAINE

eparfment of Environmental Protection MAIN OFFfCd- ftAV DUILDiNG. HOSPITAL M f t t t T . AUGUS1A

MAIL ADDRESS: &)«•• Mou l t S l i t ion 17. AygwtU. 0-4133

H€H«y C WABBfM CrWXKNOR COMMlSSlONEA VMEMORANDUM

A p r i l 13, 1982 Sepcrfund Records Center. SITE: tM\0^ CiViY\Vf.»V BREAK:

TO: David Dutnas

FROM: .Norman Anderson

SUBJECT: Toxicity Assessment of Union Chemical's Air Emissions

I . Introduction ..

Becissse of the considerable amount of concern that has been generated by ^ some of Hope's citizens regarding the operations at Union Chemical, I thought i t might be advisable to research the health effects associated with the air emissions from this company. Though I have made an effort to contact all major authoritative sources on the subject (Environmental Protection Agency, World . Health Organization, National Institute for Occupational Safety and Health), the survey I have made is by no means exhaustive. Such an undertaking would be very time-consuming and would probably s t i l l not serve to anser the question at -.hand.'

This question, in my opinion, is one of interpreting ignorance, not knowledge. I t is an ignorance which affects our ability to precisely determine a no adverse effect level, a task which is far more difficult than determining the levels at which the effects can occur. For example, though one may safely state that exposure to methylene chloride at concentrations above 1,000 parts per million can cause fatigue and chest pains, this does not mean that exposures to concentrations below that value wi l l not result in fatigue or c/.evt pains. Each person, being a unique physiological entity, may consequently respond differently to tin's level of pollutant insult. Some may not respond at a l l . Some may respond more severely than others. Ideally, public health studies would focus on the mout severe responders and, through a series of does-response measurements, determine the pollutant level at which these effects would begin to occur. Only in very rare circumstanes, however, can personal exposures, be monitored (e.g. lead) and precise correlations drawn between pollutant dose and health effect. Yet, even with a pollutant as widely and intensively studied as lead, the determination of a no effect level may s t i l l be theoretically questionable.

• ' •• '•" REGIONAL OFFICES :. j . : .-. . : v.i.-^v .• • «Portl»rtd« •..<>*.--,.•:•••• ..• .Bangor* ,•• '* •-•'.'! — — . Pretque M o •

With regard to the pollutants of concern at Union Chemical, neither the sensitive populations (i.e. the most severe responders) nor the threshold pollutant levels below which these populations are unaffected has been determined. Sufficient criteria are absent, therefore, on which to base ambient air quality standards. In the absence of an ambient air quality standard, the approach commonly taken to control a toxic air pollutant is to apply an uncertainty factor to an occupational standard with the intention of minimizing the potential health risks on members of the population. The larger the uncertainty factor, the greater the likelihood that the health of the; sensitive populations will be protected. However, as the uncertainty factor increases, the health risk attributable to that pollutant relative to background levels decreases, as does the corresponding health benefit realized from controlling the pollutant emissions to the levels so dictated.

I I . Emission Sources . • • '.-->• The main function of Union Chemical is to collect waste solvents from

various industrial operations throughout the state and purify the contaminated "solvents for reuse'4); burned as fuel or incinerated; Specifically, the rion-chlorinated solvents are burned in a 60 horsepower boiler and produce enough steam to heat the plant. The chlorinated solvents are incinerated in a Class VII incinerator (4).

Volatile organic compound emissions could thus result from four major steps in this process: the loading and storage of the spent solvent in the storage tank, the emissions from the boiler, the emissions from the incinerator, and the emissions from the distillation process. Although chemical speciation is apparently done on all receivables, only the emissions from the distillation process are quantified on a compound-specific basis. Emissions from the boiler and incinerator are determined for total hydrocarbons only. As far as I can t e l l , no testing of the storage tank emissions has been undertaken.

I t is not feasible to predict what the organic emissions from the boiler and incinerator might be as the combustion process itself probably alters the chemical composition of the feedstock. Relative to the s t i l l , however, the combustion emissions do not represent a significant air emissions source; the emission rate from the distillation process is 0.47 lbs/hr., while both the boiler and incinerator average between 0.004 and 0.03 lbs./hr The storage tanks could be a significant source of emissions (relative to the, other emission sources, that is) during the time in which they are f i l l e d with spent solvents. During the remainder of the time, however, the tank emissions are prohfably neggligible. Thus, the only significant source of continuous organic air emissions is the s t i l l room.

In addition, to volatile organic compound emissions, trace metals may also be emitted as a result of combustion or incineration processes. According to the i n i t i a l sampling undertaken by John Fancy, Inc., no detectable ambient air quality impact exists for the toxic metals (lead, chromium) present in this plant's feedstock ( 4 ) .

IH. S t i l l Room Emissions

The chemical-specific emission rates from the s t i l l room are listed below:

Compound Emission Rate

Xylene 1 ug/ft3

Toluene 0.9 uq/ft3

1,1,1 Trichloroethane 75 ug/ft3

Methyl Ethyl Ketone 182 ug/ft3

Methylene Chloride 425 ug/ft3

Isopropanol 7 ug/ft 3

No modelling or ambient air sampling has been done to determine the ambient air quality impact of these emissions. However, the emission rates are low enough so that they can be evaluated directly. If the concentrations of the emissions at the source are not- of suff icient magnitude to constitute a v

significant public health risk, i t is reasonable to conclude that the resulting public health risk will also be insignificant. The emission rates are thus compared to the 8-hour time weighted average (TWA) and the 15-minute short term exposure limit (STEL) of occupational environments (1).

Compound Emission Concentration (mg/m3)

TWA (mg/m3

STEL (oig/m3)

Xylene ;Toluene

0.04 .03

435 375

655 560

1,1,1 TrichloroethaneMethyl Ethyl KetoneMethylene ChorideIsopropanol

2.6 6.4

15.-0 0.25

1,900 590 360 980

2,380 885

1,700 1,225

jA few considerations should be borne in mind with regard to the evaluation of the occupational standards. The general overt symptoms of exposure to these compounds are headaches, eye irritation, fatigue, and central nervous system depression (6,8). Toxicological studies on animals also Indicate that liver and kidney damage can result from exposure to high concentrations of these substances (9). Occupational standards have been established to protect most of the working population from these adverse effects" (1). Those not protected are generally the most sensitive populations.

Another area which may not be adequately considered in the occupational standards is the potential of certain compounds to cause chronic effects such as cancer when present in the air at low concentrations.. Some chlorinated solvents and pesticides have been identified as possible carcinogenic agents since they have been shown to cause liver and kidney tumors when administered orally to test animals (a). Among these compounds are carbon tetrachloride, chloroform, and ethylene dichloride (9). There is no evidence to date which indicate that either methylene chloride or 1,1,1 - trichloroethane is carcinogenic (6,9). Isopropanol, toluene, and methyl ethyl ketone are also negative for carcinogenicity. Xylene may be.carcinogenic, but the data base for this compound is too limited to make any definitive statements. I t may also be worth mentioning that no teratogenic effects have been associated with exposures to these pollutants.

Other chronic effects associated with long term, low-level pollutant exposure are primarily dependent on the cumulative body burden. Again, to use the example of lead, exposures to this metal at concentrations which do not cause any acute symptoms can lead to chronic lead poisoning as a result of protracted exposures:: A key factor in the risk estimation of-chronic-health—*-^ effects is therefore the efficiency by which a pollutant is metabolized and excreted. Experimental evidence indicates that both 1,1,1 trichloroethane (9) and methylene chloride (6,9) are metabolized and excreted very rapidly (e.g. within a few hours of administration), thus greatly minimizing the likelihood that these substances could cause chronic effects. Though I could find no specific pharmacokinetic data for the other compounds of interest, they f a l l into classes of chemicals which are also quickly eliminated (8).

With these condiderations in mind, we should consider uncertainty factors which compensate for the following gaps in our knowledge: (a) the immediate effects of pollutant exposure on sensitive populations, (b) the carcinogenic effects of pollutant exposures, and (c) the chronic, non-carcinogenic effects of pollutant exposures. Factors generally employed range from 10 to 1,000. Because adequate dose-response data are usually lacking for chronic carcinogenic and non-carcinogenic effects, compounds which may exhibit such potential are controlled by the application of the higher uncertainty factors. Compounds not associated with these effects are controlled to a lesser degree. In accordance with such a scenario, the compounds emitted in Union Chamical's s t i l l exhaust should probably warrant the lower uncertainty factors since they have not been implicated as agefcts responsible for chronic diseases. . '*

* Comparing the concentrations of the emissions at the source to the time-weighted average for occupational environments, differences in concentrations range from three to four orders of magnitude for all compounds except methyl ethyl ketone and methylene chloride. If we note that an _ uncertainty factor of 1,000 is.among the most conservative factors used in the extrapolation of industrial to ambient standards, we can confidently assume that an individual breathing the exhaust gases from the s t i l l room would not suffer any significant health risk due to inhalation of xylene, toluene, 1.1." - trichloroethane, or isopropanol.

With regard to the two remaining compounds, methylene chloride and methyl ethyl ketone, we calculate emission concentration to TWA concentration ratios of 0.04 and 0.01, respectively. Although methyl ethyl ketone has not been studied as extensively as methylene chloride, EPA has scored this compound with toxicity.Jting equivalent to isopropyl alcohol (rubbing alcohol) (Z), so a

a

factor of 100 is probably sufficient to minimize the risks associated with this pollutant. j - •

Because methylene chloride is metabolized in the body to carbon monoxide, exposure to this pollutant can result in the same symptoms as exposure to carbon monoxide. : Basically, what happens during carbon monoxide poisoning is that the carbon monoxide molecule competes with oxygen for binding sites on the hemoglobins anolecule in the red blood cell. When carbon monoxide binds with hemoglobin, I t forms a molecule known as carboxyhemoglobin. As levels of carboxyhemoglofeiin in the blood increase, oxygen uptake by the tissues decreases, and adverse cardiovascular and central nervous system effects start • to develop. In toxical©aScal terms, this effect is extremely important because^ i t relates a measure off toxicity (carboxyhemoglobin levels) with an air y \ concentration Of a pollaftarit. The National Institute for Occupational Safety v. \ and Health (NIOSH) has examined this correlation to determine the concentration1

limit of methylene chloride that would prevent the formation of toxic concentrations of cartMsxyhenwglobih in industrial employees. The recommended standard which they derfivved is 75 ug/m3(6). Because we know more about the toxic mechanisms of mettoylene chloride, we can apply a smaller uncertainty factor to protect the j ^ u l a t i o n ̂ t-large.,.-,,A result in an acceptable ambient level of 7.5 ug/mJ. The s t i l l room concentration of 15 ug/ci3 may not be low enough, consequently, to protect tne most sensitive members <of the population (e.g. people with cardiovascular. disease, cigarette smokers) from the adverse effects of this pollutant. The toxic role methylene dSateride -plays at this concentration, however, is more likely be exacerbative than causative.

With the possible exception of methylene chloride, i t is unlikely that the emissions from the s t i l l room at the point of exhaust constitute any ascertainable health risk. Assuming substantial dilution of these chemicals in the atmosphere, I find mo evidence to indicate that public health is being adversely affected by tfee air. emissions at this source;

IV. Recommendations

The validity of the health assessment I have undertaken is, of course, dependent on the accuracy of the analytical results. Assuming that the analytical procedures were done properly, I see no medical reason to indicate that the air emissions from Union Chemical are having an adverse public health impact. The approach I have taken has been a very conservative one. Though a health risk may theoretically exist due to uncertainty, I would,think i t quite insignificant relative to background risks (7). In fact, I see l i t t l e , " any, health benefit, to be gained, by reducing emissions from this plant below their present rates. Of comrse, additional control may wish to be implemented for reasons other than those pertaining to health. :

f do believe, however, that an extensive monitoring program should . continue to be implemented at this source. This should include analyses of spent solvents entering the source, the determination of compound-specific emission rates from the s t i l l room exhaust, and the measurement of particulate and gaseous hydr.ocart>w.'.;i.ev.els- 'tn. the-''Stack's .and. ambient- -air;- (Because of the small quantitites of hydrocarbons emitted through the stacks as well as the small quantities 1 expect are present in the ambient air; a chemical speciation may not be practicable when considering the limitations of the monitoring . equipment.) In addition, emissions from the storage tanks should be monitored, preferably when spend solvents are being received.

Because the chemicals surveyed in this analysis have the potential to cause systemic abnormalities (e.g. central nervous system depression) any tMicolJqica evaluation should consider the total body.burden (e.g. the aosbr?ffi" a Inhalation, ingestion, and the skin) of these chemica * on man It is'therefore important that the monitoring network not be restricted to air. but include water sampling as well. Precise delineation of humanuptake^f^ sJchTo TutaJts from different environmental media is especlal y.•WUnt^when evaluating the pollutant levels in different environmental media, the affected tissues and the differential rates by which these target tissue absorb compounds from different exposure routes (5). Considering the.P^sent^-W a t i n q conditions at Union Chemical, an extensive toxicological studjr of this sort " c l e a r l y not warranted. From an environmental heath standpoint hSweve?" the monitoring information would provide a highly desirable basis for a study should a problem occur at this plant.

I would like to point out that I believe that most of these . . recorrniendaSns are already being implemented. Any further recordations whiTl have made are more for the sake of scientific completeness than for Sake of abating I known public health problem. Yet, the importance^ ;9ood "onnSring dita cannot be overemphasized. I t Hnks^the P ™ " " * , * ^ . S u c n

industry with an intelligent estimation of the.P?"1'^* t " l t h effect*. - Sucn integration is desirable everywhere, but especially in the handJing of pTtenUally toxic substances. For the initiative and effort which Dr. Espositio has taken in this area, he is to be commended.

REFERENCES

1. American Conference of Rnvernmental Industrial Hygienists. Threshold Limit Values for Chemical Substances arid Physica1 Agents in the Work room Environment with Intended Changes for 1980, ACGIH, Cincinnati, Ohio, 1980.

2 Fuller, B., etal. Preliminary Scoring qf Selected Organic Air Pollutants^ U. S. Environmental Protection Agency, Research Triangle Park, North Carolina, October, 1976. (EPA - 450/3-77-008a)

3 Maine Department of Environmental Protection, Air Emissions Inventory for Point and Area Screes in the Metropolitan Portland and Central Maine Air Quality Control Reqions.Bureau of Air Quality Control, 19817

4. Maine Department of Environmental Protection, Union Chemical Air Emission rv vr"License-' file.'""" ""'"*" '" " ~ • *"*'" '•-"* — -------- ­

5. Roberts, B. L., and Oorough, H. W., "Disposition of Carbaryl -14C Residues following Inhalation and Oral Exposure," presented at the 21st Annual Conference of the Society of Toxicology, Boston, Masss., January, 1982.

6. United States Department of Health Education, and Welfare, NIOSH Criteria^ for a Recommended Standard: Occupational Exposure to Methylene Chloride, U. S. Government Printing Office, Washington, 0. C, March, 1976.

7 United States Environmental Protection Agency, Compilation of Air Pollution Emission Factors (AP - 42), Washington. 0. C, February, 1980.

8. Van Duuren, B. L-, e t a l . , Vapor - Phase Organic Pollutants. National Academy of Sciences, Washington, 0. C, 1976.

9. World Health Organization, IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans, Vol. 20: Some Halogenated Hydrocarbons, International Agency for Research on Cancer, Lyon, France, October, 1979.

cc: Greg Bogdin, Bureau of Health Jack Krueger, Bureau of Oil and Hazardous Materials ­George Nilson, Maine Lung Association Earl Mineau, Office of the Oistrict Attorney, Rockland