svEPA
           United States
           Environmental Protection
           Agency
            Office of Water
            Planning and Standards (WH-553)
            Washington DC 20460
January 1979
EPA-440/4- 79-016
           Water
Identification and
Evaluation of Waterborne
Routes of Exposure from
Other Than  Food and
Drinking Water

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                           DISCLAIMER

This report has been reviewed by the Office of Water
Planning and Standards, EPA, and approved for publication.
Approval does not signify that the contents necessarily
reflect the views and policies of the Environmental Protec-
tion Agency, nor does mention of trade names or commercial
products constitute endorsement or recommendation for use.

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                                            EPA-440/4-79-016
                                            January. 1979
IDENTIFICATION AND EVALUATION OF WATERBORNE ROUTES OF
   EXPOSURE FROM OTHER THAN FOOD AND DRINKING WATER
               Contract No.  68-01-3857
                        Task 4
          Project  Officer:   Martin P.  Halper
          Task  Manager:   Michael  A.  Callahan
         Monitoring and  Data Support Division
        Office  of  Water  Planning  and Standards
               Washington,  D.C.   20460
        OFFICE  OF  WATER  PLANNING  AND  STANDARDS
        OFFICE OF WATER AND  WASTE  MANAGEMENT
        U.S. ENVIRONMENTAL PROTECTION AGENCY
               WASHINGTON, D.C.   20460

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                                 ABSTRACT
The purposes for this task were (1) to identify major human exposure
routes (other than food and drinking water) for waterborne pollutants; (2)
to develop a methodological framework for establishing the significance of
these routes for quantifying the risks to humans associated with these
routes; and (3) to incorporate this framework into a risk assessment
methodology and test its usefulness for risk assessments of chlordane and
heptachlor.

Inhalation of vapors from polluted water and absorption of pollutants
through the skin during direct contact with water were chosen as the most
significant alternative exposure routes for consideration in this report.
The process of estimating water exposure consists of (1) identification of
human activities that can result in exposure; (2) identification of
subpopulations involved in these activities; (3) assessment of activity
duration or degree of daily exposure to the different sources of water;
and (4) summation of average daily exposures for different subpopulations.
Seventeen exposure activities  (bathing, dishwashing, etc.) in personal,
recreational, and household categories were identified.  Estimates for
these activities were made of  average daily exposure by inhalation or skin
absorption routes, exposure extent, and total national yearly exposure,
with subpopulations  identified by  age, sex, and geographic location in
several cases.

Calculations for chlordane and heptachlor showed inhalation of vapors from
polluted water to be negligible compared to other intakes, but for
chlordane, skin absorption from water contact may be a significant
exposure route.
                                     ii

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                                 FOREWORD

This report is part of a series of reports  being  prepared  under  the
Monitoring and Data Support Division's risk  assessment  program.   This
program is directed towards investigating the  risks  due to  presence  of  129
Priority Pollutants in our nation's waters.

Some of the reports prepared under this program will address  specific
pollutants.  Others, such as this one, are  generic  in nature  and  are meant
to be tools to use when performing risk assessments  on  a wide variety of
pollutants.

The information in this report can be used to  assess the significance of
two general exposure routes to humans from waterborne pollutants:
inhalation of vapors from polluted water and dermal  absorption from
contact with polluted water.  The properties of the  specific  pollutant
being assessed are used along with the general information  contained in
this report to determine the significance of either  of these  two  exposure
routes.

The information in this report was used in two test  cases:  chlordane and
heptachlor.  For both chemicals, inhalation of vapors from  polluted water
was shown to be an insignificant exposure route when compared to  other
sources of exposure.  For heptachlor, dermal absorption was also  shown to
be a relatively minor exposure route.  But in the case of chlordane, the
exposure levels from dermal  absorption for certain scenarios  could not be
termed insignificant, as they could possibly be of the same order of
magnitude as other exposures.   Use of the information in this report in
this way has therefore highlighted a potentially  important exposure route
for some subpopulations, and any risk assessment  for chlordane from
waterborne sources must address this exposure route.

A companion report is now being prepared which investigates the
significance of waterborne pollution in contaminating food and drinking
water.  The report will look at various ways in which waterborne
pollutants may end up in food or drinking water,  and estimate the
importance of the various routes.   These two reports are being
incorporated into the overall  risk assessment methodology used in
Monitoring and Data Support  Division's risk assessment program.
                                            Michael A. Callahan
                                            Task Manager

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                              TABLE OF CONTENTS
I.   SUMMARY                                                        1

II. INTRODUCTION                                                   4

III.GENERAL METHODOLOGY                                            6

    A.  WATER EXPOSURE                                             6
    B.  AVERAGE DAILY INTAKE                                       8
    C.  RISK ESTIMATION                                           10

IV. EXPOSURE TO PRIORITY POLLUTANTS                               13

    A.  FRAMEWORK FOR ANALYSIS                                    13
    B.  EXPOSURE ROUTES                                           13
    C.  EXPOSURE ACTIVITIES                                       14
    D.  SOURCES OF WATER                                          17
    E.  SITUATIONAL CATEGORIES                                    17
    F.  EXTENT'OF EXPOSURE                                        18
    G.  FREQUENCY/DURATION                                        18
    H.  SUBPOPULATION CATEGORIES                                  19
    I.  RESULTS OF EXPOSURE ESTIMATES                             19

V.  EFFECTIVE  DOSE RATE                                           27

    A.  INTRODUCTION                                              27
    B.  VAPOR  INHALATION                                          27
    C.  SKIN ABSORPTION                                           35

VI. APPLICATION OF METHODOLOGY TO CHLORDANE AND
    HEPTACHLOR RISK ASSESSMENTS                                   39

References                                                        43

APPENDICES

    A.  MATHEMATICAL APPENDIX                                    A-l
    B.  RECREATIONAL SUBPOPULATION  EXPOSURES                      B-l
                                   IV

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                            I.  SUMMARY

     Previous assessments of risks to man from waterborne priority pollu-
tants, conducted for the Monitoring and Data Support Division of the
Environmental Protection Agency, have focused on food and water ingestion
as the primary routes of exposure.  The purposes of this task were to:
     »  Identify other major human exposure routes for waterborne
        priority pollutants.
     e  Develop a methodological framework for establishing the
        significance of these routes and for quantifying the risk
        to humans associated with these routes.
     o  Incorporate this framework into a risk assessment methodology
        and test its usefulness by application to chlordane and
        heptachlor/heptachlor epoxide risk assessments.
     Inhalation of vapors from water containing priority pollutants and
absorption of priority pollutants through the skin during direct contact
with water were chosen as the most significant alternative exposure routes
for consideration in this analysis.  The methodological framework
developed for assessing human risks by these routes incorporated three
areas:  estimation of water exposure by subpopulation and water source:
estimation of an "average daily intake" for persons subjected to inhala-
tion or skin absorption exposure, and consideration of potential toxicity
via these routes.
     The process of estimating water exposure consists of identifying
human activities that can result in exposure and subpopulations involved
in these activities, assessing activity duration and/or degree of daily
exposure to different sources of water and summation of average daily
exposures for different subpopulations.  Seventeen exposure activities
(e.g., bathing, washing, fishing, swimming, dishwashing, etc.) in personal,
recreational and household categories were identified and estimates of
average daily exposure by inhalation or skin absorption routes, exposure
extent, and total national yearly exposure were made with subpopulations

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identified by age, sex and geographic location in several cases.  Repre-
sentative exposure results are given below:
Activity
Breathing humdified
air in home
Household cleaning
Bathing/Showering
Water Therapy
Boating

Swimming
Total Popula-
tion Exposed
78 x 1(T
71 x 10
215 x 1(T
68 x
181 x 10'
Total
Annual
Exposure
(person-hrs/yr)

59 x 109
26 x 109

9.9 x 109
6.2 x 106
1.6 x 109

3.2 x 109
Extent*
  0.1

  1.0
  0.6
  0.4

  1.0
Routes
inhalation
absorption &
inhalation
absorption &
inhalation
absorption &
inhalation
absorption &
inhalation
absorption &
inhalation
      Several methods  for estimating the "average daily intake"  of  priority
 pollutants via inhalation and skin absorption were examined.  The  concept
 of  "effective dose rate," i.e.,  the rate of transfer of pollutant  to  the
 body for different types of exposure,  was used in developing  daily intakes
 for inhalation and skin absorption.  For vapor Inhalation,  the  critical
 parameters in estimating the effective dose rate are the rate of ventila-
 tion, the concentration of pollutant in the water, the vapor  pressure of
 the pollutant and the chemical activity of the pollutant in water.**
 Example calculations  show that daily inhalation intake might  range from
                 -9
 as  low as 1 x 10   mg/day of chlordane at an ambient water  concentration
 of  1 ppb to 28 mg/day chloroform at an ambient water concentration of
 1 ppm.  In general, we concluded that because of the relatively low vapor
 pressure of priority  pollutants and the low concentrations  found in
 ambient water, inhalation of vapor will probably not be a significant
^Estimated fraction of body surface area exposed.
  To be conservative, we assumed that any pollutant inhaled remained in the .
  body.  Further, we did not consider metabolism or excretion of the priority
  pollutant, but focused only on the total amount inhaled or absorbed.

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exposure route, compared to food and water ingestion, unless a  fog or
mist of water is inhaled.  In the latter case, the moisture content  of
the fog and the actual exposure duration are critical elements  in the
analysis.
     Examination of the skin absorption exposure route indicated that
the critical factors in establishing the effective dose rate are the
extent of surface exposed, the concentration of pollutant in the water,
and the diffusion rate through the stratum corneum layer of the skin,
which is in turn dependent upon the permeability coefficient of the pollu-
tant and/or the partition coefficient of the pollutant between  the skin
and water.  Although no physical/chemical data were readily available in
the literature on skin absorption of specific priority pollutants, general
methods for estimating the effective dose rate for skin absorption were
developed.  Our calculations suggested that the effective dose rate of
priority pollutants might range from about 10   to 0.1 mg/day for total
body exposure to priority pollutants at ambient water concentrations of
1 ppb to 1 ppm, respectively.  Therefore, depending upon the actual
frequency and extent of water exposure, and pollutant concentrations,
the average daily intake of priority pollutants from skin absorption
might be the same order of magnitude as the daily intake from food or
water ingestion.  Future risk assessments should consider the skin absorp-
tion route, especially for subpopulations with high water exposure
potential.
     The methods developed for estimating effective dose  rate  and  daily
intake by inhalation and skin absorption were used  to  determine  the  daily
intakes of chlordane, heptachlor and heptachlor epoxide.   The  results showed
that inhalation of vapor from water  containing these pollutants  at ambient
levels would result in average daily intakes  that are  negligible compared
to intake via food and drinking water ingestion.  Similarly, average  daily
intake by skin absorption of heptachlor and heptachlor epoxide was estimated
to be about 1% to 5% of the intake via food and drinking  water ingestion
for 24-hour total body exposure to water at ambient concentration  levels.
Calculations for chlordane, however, indicated that skin  absorption  could
possibly result in average daily exposure of  comparable magnitude  to  food
and water ingestion.  Thus this mechanism needs to  be  considered in  the
chlordane risk assessments.
                                    3

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                           II.   INTRODUCTION
     The Monitoring and Data Support Division, Environmental Protection
Agency, is conducting a systematic investigation of the sources and distri-
bution of 129 priority pollutants in the nation's environment in order to
determine the exposure and risks to man, fish and other biota.  The results
of this effort will be the development of recommendations for regulatory
action.
     One part of this program is the preparation of risk assessments for
specific chemicals, which identify the populations chronically exposed and
give estimates of the health risks to man, fish and wildlife.  In the
conduct of these risk assessments, it is important to identify and quantify
the major water-based routes of human exposure to the priority pollutants.
Most previous work has focused on food and drinking water ingestion as the
primary routes of human exposure, since they affect the broadest segment
of the population.  However, there are a number of other potential water-
related routes of exposure that might be significant for specific pollu-
tants or human subpopulations.  For example, inhalation exposure might
occur through humidified air in the home; skin absorption might occur
through bathing, swimming or occupational exposure.
     The objectives of this task are to:

     •  Identify major human exposure routes for waterborne pollutants
        other than direct ingestion of food and drinking water and the
        populations exposed through some of these routes.
     •  Develop a methodological framework for establishing the signifi-
        cance of these routes and for quantifying the risk to humans
        associated with these routes.
     •  Incorporate this framework into the risk assessment methodology
        previously developed and test its usefulness by applying it to
        chlordane and heptachlor/heptachlor epoxide risk assessments.

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     In order to complete this task within the authorized level of effort,
we have adopted an approach which is based upon the following assumptions
and conditions:
     •  Two principal exposure routes are considered—inhalation of vapor
        or mist from a water source which contains a priority pollutant
        and skin absorption of a priority pollutant due to immersion of
        portions of the body in water containing the pollutant.
     •  Activities which can result in exposure by these two routes are
        identified, but the numbers of persons engaged in these activities,
        and the duration and/or frequency of exposure are quantified only
        for some examples for which data were readily available.
     •  Details of the mechanisms of skin absorption and vapor inhalation,
        and the toxic effects of chemicals via these routes are not ex-
        amined.  Methods are described only to estimate  the quantities
        absorbed or inhaled.  It is assumed that these quantities can be
        directly compared to those ingested in food and water, and that
        the physiological response to absorption and inhalation of
        priority pollutants is known or can be evaluated.
     •  The main focus of this task is methodological, with the aim of
        establishing an approach to calculation of risk for subpopulations
        exposed to priority pollutants by routes other than food and
        drinking water.
     Section III briefly describes the methodology that can be used to
estimate human risk from inhalation and skin absorption routes.  A more
mathematical treatment of the approach is given in Appendix A.  Section
IV discusses the number of persons exposed and the frequency and duration
of exposure to water in selected exposure activities.   Section V presents
methods for estimating the rates at which priority pollutants are inhaled or
are absorbed through the skin.  Section VI contains some sample calcula-
tions using chlordane, heptachlor and heptachlor epoxide to compare the
daily intake of these pollutants by inhalation of vapor and by absorption
through the skin to the daily intake from food and drinking water inges-
tion.

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                        III.  GENERAL METHODOLOGY

     A primary objective of this task was to develop a methodological
framework for quantifying both exposure and risk to humans from waterborne
pollutants, for exposure routes other than ingestion.  This framework was
to be incorporated into  an overall risk assessment methodology, which
originally focused upon the ingestion route.  Our approach consisted of
expanding and generalizing the risk assessment methodology to account
for the more complex .exposure mechanisms associated with non-ingestion
routes, and to permit identification of subpopulations with significant
exposure levels.  The effort was divided into three methodological areas:
     1.   Develop methods to allow estimation of total human water expos-
          ure by subpopulation and water type.
     2.   Develop methods to allow estimation of average human daily
          pollutant intake by subpopulation.
     3.   Indicate the use of these methods in estimation of risk to
          humans.
 These areas are addressed separately below and are displayed in diagrammatic
 form in Figure 1.  Note that the double-bordered boxes refer to calcula-
 tions involving a specific pollutant.  The other boxes, which describe
 the estimation of total water exposure, need to be performed only once
 for all pollutants.
A.   WATER EXPOSURE
     For  each exposure  route  that  is  identified, the  average daily human
exposure  to water can be estimated in the  following ways:
     - Identify the activities which could  result in exposure along that
        route.

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                    FIGURE  1:   Exposure and Intake Estimates
              Identify  Exposure
              Routes  (e.g.,
              Inhalation)
                         Estimate Pollutant
                         Concentration by
                         Water Source

              Identify  Relevant
              Activities  for
              Each  Route  (e.g.,
              Swimming)
                Determine Relevant
                Physical or Chem-
                ical Properties
                (e.g., Vapor
                Pressure)
 Identify Water
Source  (e.g., Lake)
Identify Subpopu-
1 ation Groups
(e.g., Housewives^
                                  1
Estimate Effective
Dose Rate for
Each Route
                              Estimate Activity
                              Rates for Each
                              Group (Degree of
                              Exposure)
                              I
                                 I
                          Compute Average
                          Daily Intake for
                          Each  Group by
                          Activity and Water
                          Source
                Compute Average
                Daily Exposure
                for Each Group by
                Water Source
                                 I
                       Compute  Average
                       Daily  Intake  of
                       Pollutant  for
                       Each Group
  Compute National
  Average Daily '
  Water Exposure
                       T
             Use in Risk Calculations

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        Identify  the  subpopulation categories  which might  be involved
        in these  activities.
        Identify  the  sources of water relevant to exposure through these
        activities.
     -   Using average daily activity rates,  estimate the degree of daily
        exposure  for  each of these activities.
        Sum overall activities to obtain the average daily water exposure
        for each  subpopulation group, by water source.
        Compute the national average daily water exposure using the
        relative  sizes of different subpopulations.
     The degree of exposure will be defined in different ways for differ-
ent exposure routes.   In the case of inhalation, the degree of exposure
is simply the total volume of air inhaled per day.  (It is assumed that
the air may contain traces of pollutants which were originally waterborne,
and subsequently vaporized).  In the case of skin absorption, the degree
of exposure  is the product of a number of factors,  primarily the extent
of exposed skin  area  and  the duration of exposure.  Of  course,  for inges-
tion,  the degree of  exposure is simply the amount  of solid  or  liquid in-
gested per day.  Thus the degree  of exposure  is a  measure of daily exposure
per  capita for each  different exposure route.  These concepts  are elabor-
ated in Section  IV below,  as well as in  the Mathematical  Appendix.
B.   AVERAGE DAILY INTAKE
     For  a specific pollutant, the  average daily intake may be estimated
from a knowledge of  the pollutant concentration in water and the total
daily  exposure to water derived above.  In the case of water ingestion,
the  average  daily intake  is simply  the product of daily water intake and
concentration.   However, with other exposure  routes it is necessary to
compute an effective  dose  rate, which relates pollutant concentration in
water  to  the actual  amount of pollutant entering the human body.  The
effective dose rate will  be defined as the quantity of pollutant taken in
 (via absorption, inhalation, ingestion, etc.) per unit of exposure.  Thus,
 if exposure  is measured  in area-hours per day  (e.g., skin contact), then

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the effective dose rate would be measured in ug per area-hour.  Table 1
displays all the units of measurement necessary to apply this methodology
to three principal exposure routes.  Note that the effective dose rate
for ingestion is equivalent to pollutant concentration.
     For the non-ingestion routes, the effective dose rate must be computed
from the pollutant concentration, certain physical and chemical properties
of the substance in question, and pertinent human physiological parameters.
For vapor inhalation, the relevant properties are the vapor pressure of the
substance and the activity coefficients of the solution,  etc. , which deter-
mine the amount of pollutant in the vapor above a solution.  For skin
absorption, the relevant properties are the diffusion and/or the perme-
ability coefficients, partition coefficients for tissues  vs solution, and
skin thickness.  The basis for calculating effective dose rate for both
of these routes is explained more fully in Section V.   Again,  the necessary
computational steps are diagrammed in Figure 1:
     -  Determine the values of the relevant physical, or chemical proper-
        ties of the pollutant, and the relevant human physiological
        properties for each exposure route being considered.
     -  Estimate the effective dose rate as a function of these properties
        and of the concentrations of the pollutant in various  sources of
        water.
     -  Multiply the effective dose rate by the degree of exposure for
        each activity to obtain the average daily intake  via  that activity,
        for various population groups.
     -  By summing over all activities  and water sources, determine the
        average daily intake of pollutant for each group,  via  the differ-
        ent routes.
     If so desired, the summation can be adjusted to yield total intake
through a given water source,  or via  a particular activity.  These computa-
tions would be analogous to those shown for total water exposure in the
Mathematical Appendix.

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C.   RISK ESTIMATION
     Once the average daily intake has been determined, risk can be
estimated by two possible approaches:
     Method A:  Assuming the toxicity is independent of the exposure
                route (i.e., once the pollutant enters the human, the
                toxicity is a function only of the amount of intake, not
                the site of intake), risk can be computed from the
                average daily intake from any route, e.g., from inhala-
                tion or skin absorption.
     Method B:  If the toxic effects are dependent on a specific route
                (e.g., skin absorption), then risk should be computed
                from the degree of exposure, the pollutant concentration
                and the toxicity resulting from that specific exposure
                route.
     One  form  in which toxicity data are expressed, after appropriate
normalization  and extrapolation, is "excess risk per unit of exposure."
For chronic effects such as carcinogenicity, some investigators assume a
linear relationship between exposure and risk, and for other types of
toxicological  responses non-linear  dose-response models are often found.
If one considers toxicity based on  inhalation exposure, the risk from a
carcinogenic substance could be expressed as the probability of a tumor
being  induced  in an organism chronically exposed to a given airborne
concentration  of that substance.  For a linear model, the excess risk per
unit of exposure is simply  the slope of the dose-response curve, and can
be interpreted as  the increase in probability of tumor per unit of  In-
creased concentration.  There may be a background incidence of tumors,
so that a positive probability of tumors exists even at zero exposure.
     The units of  measurement  for risk estimation, as well as the formulae
 to be  used,  are given in Table 1.   The two approaches can be summarized
as follows:
                                     10

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                                  Table 1
                             Units of Measurement

Extent or Quantity
Frequency
Degree of Exposure
Concentration
Effective Dose Rate
Average Daily Intake
Toxicity Based
on Intake (Method A)
Toxicity Based on
Concentration
(Method B)
INGESTION
Liters
per Day
Liters per Day
ug./l.
ug./l.
ug./bay
ABSORPTION
p
Area (e.g. m )
Hours/Day
Area-Hours/Day
ug./l
ug./Area-Hrv
ug./Day
INHALATION*
m. /Hour
Hours/Day
m.3/Day
ug./m.3
ug./m.3
ug./Day
% Increased Probability of Effect per ug./Day
% Increase
per ug./l.
% Increase
per ug./l.
% Increase
per ug./m.3
Degree of Exposure  »  Extent (or Quantity) x Frequency

Average Per Capita Daily Intake - Degree of Exposure x Effective Dose-Rate

Risk per Capita - Average per Capita Daily Intake x Toxicity Based on
                  Intake

or

Risk per Capita - Concentration x Toxicity Based on Concentration
                  (for specific route)

Total Risk - Number Exposed x Risk per Capita
n
 Note:   In this r.eport we have used the term inhalation to represent
 the route of exposure, and ventilation to represent the actual
 quantity breathed per time.
                                  11

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    Method A:   Toxicity. is  expressed as excess risk per unit of
                daily pollutant intake.   Risk per capita is obtained
                by multiplying the average daily intake by the
                toxicity of  the substance.
    Method  B:   Toxicity is  expressed as excess risk per unit of
                pollutant concentration, for a specific exposure
                route.  In extrapolating from experiments with
                laboratory animals, adjustments must be made to
                compensate not only for species differences in toxic
                effects  but  also for the degree of exposure.   Then
                the risk per capita is obtained from the product of
                concentration and adjusted toxicity.
     In most cases, available data will be suitable only for Method A.
However, the advantage of Method B is that there is no need to calculate
an effective dose rate, which is based on idealized physical and chemical
         pi-
laws or assumptions.
     Finally, the risk per capita can be multiplied by the number exposed
in a subpopulation to obtain the total risk for that subpopulation.  The
Mathematical Appendix shows various ways  to calculate risk, focusing on
either a specific water source or a specific activity.
                                      12

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            IV.  EXPOSURE TO PRIORITY POLLUTANTS

A.   FRAMEWORK FOR ANALYSIS
     In order to develop reasonable estimates of exposure of certain sub-
populations to priority pollutants, a general framework describing the
nature of the exposure must first be specified.  The framework presented
here consists of a number of factors which characterize the exposure of
an individual or groups of individuals to priority pollutants.  Quanti-
fication of these characteristics then permits estimates of populations
exposed to priority pollutants.  The factors include:
     Exposure Route—The anatomical sites through which the pollutant
     contacts or enters humans.
     Exposure Activities—The human functions which lead to exposure to
     water by some exposure route.
     Sources of Water—The nature of the water source,  containing the
     priority pollutant, to which persons are exposed.
     Situational Categories—The environmental, geographic or locational
     factors which influence exposure.
     Extent of Exposure—The fraction of the body exposed to water con-
     taining the priority pollutant.
     Frequency/Duration—The number of hours (per day,  year, etc.)
     during which exposure occurs.
     Subpopulation Categories—Demographic factors which influence ex-
     posure (male, female, adult, children,  etc.)
     In this section we will first discuss these factors individually
and then develop representative estimates of the numbers and durations
of persons exposed by different routes through different exposure
activities.
B.   EXPOSURE ROUTES
     The exposure route was defined as the means by which a waterborne
pollutant enters the human body.  For this task, dermal absorption and
inhalation were considered to be the most significant routes encountered
in normal, every-day activity.  Other exposure routes,  such as sub-cutaneous
                                  13

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injection, and exposure of a specific organ (eyes), or finer detail in
identified routes, such as greater absorption potential in certain areas
of the body (forehead, scrotum) or dermal absorption of vapors were not
examined because of limited data.
     Several assumptions were made when considering the dermal absorp-
tion route.  As mentioned above, the potential for absorption was con-
sidered to be equal for all parts of the body.  The absorption rate was
considered to be constant under all conditions such as varying water
temperatures, flow rates, or intensities of activity.  In addition, the
volume of water to which a person was exposed was not considered Impor-
tant.  For example, being totally submerged in a pool of water was con-
sidered equivalent to being thoroughly sprayed by water.  Spray coats the
body with a film of water which is available for absorption.  Similarly,
wet clothing holds a small reservoir of water against the body which can
be absorbed over time.
     In considering inhalation, some simplifying assumptions can also be
made which result in conservative (high) values of exposure.  We assumed
that any  pollutant vapor inhaled is removed (absorbed) by the lungs,
whether it was  in the form of vapor or*droplets of varying sizes.  Ventila-
tion rate varies with activity, but for our estimates, we considered a
normal ventilation rate  for persons engaged in moderate activity.
C.   EXPOSURE ACTIVITIES
     Exposure activities were generally defined as human functions or
processes which may lead to exposure to waterborne pollutants through
inhalation and/or dermal absorption.  A large number of water-related
activities were identified and grouped into five categories:  personal,
recreational,' household, occupational and  incidental exposure.  Table 2
lists  those activities  that were selected  for developing exposure
estimates.
                                   14

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                               Table 2
            Activities for Which Exposure Estimates were Developed

        Personal                 Recreational       Household
        Bathing/Showering        Boating            Breathing artificially
        Dental Care              Fishing               humidified air
        Hand and Face Washing    Swimming           Automobile washing
        Shaving                  Water skiing       Hand clothes-washing
        Toothbrushing                               Hand dishwashing
        Water Therapy                               Household cleaning
                                                    Ironing
                                                    Lawn watering
     A large number of other water-related activities were initially
identified but excluded from the analysis because of lack of data and/or
a presumably low risk.  Some of the activities worth noting are:  personal
activities such as wearing cosmetics and contact lenses, douching; snow
sports, puddle playing, ice skating, water-related entertainment (e.g.,
amusement park rides); and incidental breathing and contact with natur-
ally humidified air (e.g., fog, living near lakes), rain and snow.
Some of the exposure activities we examined may have equally
low risk; nevertheless, to provide a data base representative of a wide
range of exposures, consideration of low risk activities is warranted
when data are readily available.
     Another important exposure activity category is occupational expos-
ure.  Table 3 lists occupational categories that could result in signi-
ficant water exposure.  In this task, however, determination of occupa-
tional exposure was not possible.  No information was readily available
on the frequency of exposure to water in different occupations.   Avail-
able information on water intake and discharge rates for industry sectors
was not believed to be representative of the amount of water potentially
available for exposure because a significant percentage of it is enclosed
and never comes in contact with employees.   Within an occupation, employees
have different exposure frequencies and extents.  For example,  two people
working in a carwash, a washer and a cashier, would have significantly
different exposures-.  Information on the number of people employed in
                                  15

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                                Table 3

         Occupational Categories with  Potential  for Water Exposure
Coast Guard, Navy, Merchant Marine                Snowmakers
Skin divers (police)
Fisherman                                         Aquarium employees
Underwater photographers                          Zoo keepers
Professional swimmers, instructors, lifeguards    Fish farmers
Rowers, professional water sportsmen
Water transportation workers                      Gardeners
                                                  Greenhouse workers
Skating instructors                               Landscape workers
Ski instructors
Amusement park workers                            Farm laborers
Firemen

Food service people, bartenders
Dishwashers

Cleaning people
Laundry workers
Window washers
Plumbers
Barbers, hairdressers, manicurists
Carwashers
Heating/ventilation/air-conditioning workers

Textile workers
Meat packers
Food processers

Physicians, nurses,  therapists,  dentists
Researchers  (laboratory)
Researchers  (field)

Sewage  treatment plant workers
Dredge  workers
Tunnel  makers
Miners,  oil drillers
Hydro-electric utility workers
Sawmill workers
Well  diggers
Quarriers
 (Utility workers in holes)
                                    16

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various  occupational  categories  does  not  clearly differentiate between
people with different types  of jobs within the  category.   A great amount
of  time  and effort would have to be devoted in  contacting different
industries and commercial establishments  and interviewing representative
water-exposed employees to make  useful estimates of  occupational  exposure.
Nonetheless, the methods given in Appendix A do  permit computation of
occupational exposure, provided  that  the  data become available.
     For all activities, the associated exposure route was either  inhala-
tion alone or dermal  absorption plus  inhalation.  Under all conditions
when dermal contact with a body of water was made, the water was assumed
to have vaporized into the air around it.  An individual with his  hands
submerged in water would therefore also inhale water vapor at the  same
time. Inhalation of water vapor alone, without dermal contact, was possi-
ble, however, as in the breathing of artificially humidified air.   For the
purpose  of this task, when a dermal absorption exposure was calculated, the
concurrent inhalation exposure was not considered.
D.   SOURCES OF WATER
     Depending upon the activity being considered and the environmental
characteristics, people may be exposed to  different  types of water.  These
may be classified as  follows:
         (i) ocean                       (v)  lake
       (ii) water supply               (vi)  rivers and streams
      (iii) process water             (vii)  other (pools,  drainage, etc.)
       (iv) precipitation
Exposure computations ideally should distinguish between exposure  to
various  water sources,  since ultimately a different level of pollutant
concentration may be  ascribed to each water source.   Of course, some
activity classifications will correspond  to  only one water source  (e.g.,
household dishwashing—water supply).  In other cases, such as recreational
activities, different water sources must be identified.  Because the pollu-
tant concentration is the most 'important variable, we did not attempt to
distinguish between different sources of water  in our example calculations.
E.   SITUATIONAL CATEGORIES
     Geographic and environmental conditions will imply fluctuations in
both the number of 'people involved in certain occupations and the sources
                                  17

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of water encountered.  Hence, the possible situations should be sub-
divided into a matrix of environmental and habitational categories.  The
environmental categories describe the prevalent geographic and climatic
conditions, whereas the habitational categories characterize the density
and nature of human settlement.
          Environmental                     Habitational
          coastal                           urban
          near lakes                        suburban/town village
          rivers                            rural
          arid regions                      wilderness
To simplify our work, we did not consider  these situational categories
in our  examples.
F.    EXTENT OF EXPOSURE
      The  extent value is an estimate of  the portion  of  the body exposed
through skin  absorption.  (For  inhalation we assumed  that the same
area  of body  is exposed  to water particles or vapor  during each breath, and
no extent estimate was necessary.)
      Extent values,  ranging from 0.1 to  1.0,  are based  on the percent of
the  total body surface area exposed.     Hands (including lower arms) or
face  (and neck) each have  values of 0.1, for  example, while the entire
body  has  a value  of  1.0.   Each activity  with  a dermal exposure was assign-
ed an average extent value estimated to  be representative of the degree
of contact with water.
G.    FREQUENCY/DURATION
      Frequency was defined as  the  number of hours  per year an  individual
 is exposed to water through an activity.  Frequency  was developed  in two
 forms from literature  data or  through  estimates by knowledgeable staff.
 In some cases,  the population  exposed  and the actual number of events per
 person annually was available  (as  for  swimming).   The product of these two
 was  multiplied by an estimated number of hours  per  event  to provide hours
 per  annum.  In other cases (for example, water therapy), only  the  number
 of person-hours per year was available with no information on  the  actual
 number of people exposed or  the average number of experiences per
                                    18

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individual.  The number of person-hours was useful in determining the
exposure of the total population via the activity but would not enable
subpopulation breakdown.
H.  SUBPOPULATION CATEGORIES
     Subpopulations exposed to waterborne pollutants within each activity
were identified when possible.  Identification was most successful in
activities, such as recreational, for which a large body of statistical
information was available.  In these cases, subpopulations by age group,
sex, and, occasionally, region could be identified and their associated
exposures determined.  In most cases, however, the information available
was an estimation of the total population at risk.  Further estimation
of subpopulation exposure,using census data or other sources, could be
performed but the usefulness is questionable in this methodology task.
     To maintain consistency throughout the report, the 1976 U.S.  popula-
tion census figure of 215,118,000 was chosen and used whenever possible.  In
cases where the percent of population involved in the activity during another
year (such as 1975) was available, it was updated for the 1976 population
assuming that the percentage had not changed over time.  In some cases,
however, only absolute numbers of participants during a previous year were
available.  It was assumed, then, that the numbers roughly represented
1976 participation as well.
I.   RESULTS OF EXPOSURE ESTIMATES
     Using the framework described above, and the mathematical formula-
tion of exposure given in Appendix A, we estimated exposure values for
the total U.S. population and subpopulations using readily available
data.  The results and discussion which follow are representative  and
are not intended to be complete or exhaustive.  They are presented here
to give some useful information and to show how one can estimate various
exposure factors if data are available.
     Table 4 summarizes data on exposure activity, populations exposed,
extent, water sources and exposure route for household, personal and recrea-
tional categories.  A more detailed discussion of the exposure estimates
is provided below.

                                   19

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                                                   Table 4
N>
O
Summary of Exposure Information
Exposure
Activity
HOUSEHOLD
Artificially humidified air
humdifier
dishwasher
Hand clothes washing
Hand dishwashing
Household cleaning
Ironing
Outdoor household water use
PERSONAL
Bathing/Showering
Dental Care
Hand and face washing
Shaving
Population
Exposed
(million)
76.5
90
65
71
71
74
63

215
215
215
80
Total
Exposure
(10 person-hrs/yr)
59,000
16,000
840
25,900
7,400
7,700
3,300

9,900
57
3,900
960
Extent

NA2
NA
0.1
0.1
0.1
NA2
0.1

1.0
0.1
0.2
0.1
Water Source

water supply
water supply
water supply
water supply
water supply
water supply
water supply

water supply
water supply
water supply
water supply
Routes

vapor inhalation
vapor inhalation
absorption, vapor
inhalation
absorption, vapor
inhalation
absorption, vapor
inhalation
vapor and droplet
inhalation
absorption, vapor
and droplet inhalation

absorption, vapor
and droplet inhalation
absorption, vapor
and droplet inhalation
dermal absorption
absorption
   All sources cited in text.
   Not applicable.

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                                            Table 4, (Continued)
Exposure
Activity
    Toothbrushing
    Water therapy

 RECREATIONAL
    Boating

    Fishing

2   Swimming

    Water skiing
  Population
  Exposed
  (million)
     177
      19
person-events
annually

      68
                                      54
                                     181
                                      20
    Total
    Fvpn.ciirp
(10  person-hrs/yr)
      2,200
Extent  Water Source
 0.1    water supply
 0.6    water supply
                                                                                              Routes
                                                                                              absorption
                                                                                              absorption and
                                                                                                inhalation
1,600


6,600


3,300

0.4 ocean, lake,
river and
stream
0.2 lake, river
and stream,
ocean, pond
1.0 outdoor pool,
ocean, lake,
absorption, vapor
and droplet inhalation

absorption, vapor
and droplet inhalation

absorption, vapor
and inhalation
rivers and stream
260


1.0 ocean, lake,
river and
stream
absorption, vapor and
droplet inhalation


-------
     1.  Household
     Six household activities involving exposure to water were examined.
The activities were Ironing, hand dishwashing, household cleaning, hand
clothes washing, outdoor household activities and breathing artificially
humidified air.  For ironing, cleaning, dishwashing and outdoor activities,
it was assumed that one person per household was involved in each
activity.  The number of households in the United States was obtained
                           (23)
from the Bureau of Census.  '    The number of households owning irons
                                              (4)
was found in Merchandising annual statistics.     In the case of hand
clothes washing, the population exposed was assumed to be all females
aged 18  to 64  years old, probably a conservative over-estimation of  the
lingerie hand  washing  inclinations of women.  The extent of  exposure
was estimated  to be 0.1  (hands and forearms)  for each activity with
the exception  of ironing,  which  is an inhalation route  exposure.
Frequency/duration of  household  activities were estimated by ADL staff
as  follows:
          Ironing—2 hours per week
          Cleaning—2  hours per week
          Dishwashing—7 hours per week
          Clothes  Washing—1/4 hour per week
          Outdoor  activities—1  hour per  week
In all cases  the water source is water supply.
      Two sources of artificial household  humidity were  considered:
humidifiers  and dishwashers.  Clothes dryers, steam heat systems and
washing machines were  excluded  from analysis  because venting or covers
usually prevents  the  escape of more than  a  small amount of vapor.  Infor-
mation on the number  of  humidifiers,  the  hours per  year in use,estimated
at 776 hours (in Akron,  OhioX and  quantity  of water released was  found
 in a  Federal Energy Administration report on  energy efficiency.   '   It
was assumed  that  each humidifier exposed  three people  to humid air and
 that  Akron,  Ohio was  representative of  the  average  of different humidi-
 fier usage patterns  in the U.S.   The  potential  total U.S. exposure to
 humidified air was calculated to be 59,000,000,000  person/hours/year.
                                   22

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     Information on the number of homes with dishwashers was  found  in
              (4)
Merchandising,    and again, a three-person exposure was assumed  for
each appliance.  Duration  (30 minutes) and number of annual events  (365)
were estimated by case team members.  The potential total U.S. exposure
to humidified air was calculated to be 16,000,000,000 hours/year.   The
source of water used by both appliances is water supply.
     2.  Personal Activities
     For each of the personal activities the population involved  was
estimated on the basis of  age, as follows:
     •  toothbrushing:  the total U.S. population; ages 5 to 64;
     •  hand and face washing:  the total U.S. population; and
     •  shaving:  che total U.S. population; males 13 years of age
        and older.
                (6)
U.S. Census data    was used to obtain the population number for each
activity.  Duration estimates for the activities were made by the Technical
                                                        (7)
Services staff of the American Water Works Association.     ADL staff
then estimated the frequency and extent of each exposure.   The source  of
water used for personal activities is water supply.
     Activity          Duration (per event)  Frequency          Extent
     Toothbrushing     1 minute              12 hours per year    0.1
     Hand and Face     1 minute              18.25 hours per year 0.2
     Washing
     Shaving           2 minutes             12 hours per year    0.1
                                                                        (8)
     The 1975 data on dental visits from the Vital and Health Statistics
were updated for the 1976 population by assuming that an individual still
makes 1.6 dental visits per year.  Duration was estimated at 10 minutes
exposure to water.  Thus, in 1976 the total U.S. population, 215 million,
made 344 million dental visits for a total exposure of 57  million hours
annually.  The water source is water supply.   The extent of  skin absorption
was estimated to be .1 assuming some facial contact with water spray.
Although realistically this is a negligible exposure relative to activities
such as swimming or bathing, it is representative of the lower range of
                                   23

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exposures encountered by a large number of people.  Exposure was calculat-
ed in order to determine the magnitude of such a low exposure activity
where data were available.
     Bathing and showering are generally treated as one activity in the
literature so the assumption was made that their exposures are equal
(duration, number of annual events).  We assumed that the total U.S.
population engaged in this activity.  Only bathing/showering in water
supply sources was considered.  Salt water and fresh water showering were
                               (9)
excluded.  A previous ADL study     estimated  the time duration to be 15
minutes  per event and the number  of events per week to be 3.5 (182 events
per year).  Based on this information, an individual spends 46 hours
annually bathing and/or  showering and the total population spends 9.9
billion  hours annually.  The  extent of the body exposed is considered
to be  1.0  (total body).
     An  estimate was made of  the  number  of person-hours spent in some
form of  hospital-administered hydrotherapy  (for instance, whirlpools,
Hubbard  tanks,  swimming  pools).   Persons receiving water  therapy at home
or at  sports  facilities  were  excluded from consideration  because of lark
 of available data.   Personal communication with physical  therapists at
 five Boston area hospitals      provided  the  basis for a quantitative
 estimate of number of person-events at  hospitals.   Neither the  actual
 number of individuals treated annually  nor the number of  treatments per
 individual is easily retrievable by hospital personnel or from literature.
 The total number of hospitals and physical therapy departments  in  the
 U.S.  was obtained from Hospital Statistics.    '   According to the  physical
 therapists we talked to, the standard duration of one hydrotherapy session
 is 20 minutes.   It was estimated that 18.7 million person-events occur
 annually.   Hence the total U.S.  exposure is  6.2 million hours per  year.
 Extent was averaged at  .6 since the degree of exposure may range  from
 .1 for a hand whirlpool to 1.0 for the more common total  body whirlpool.
 The water source is water supply.
                                    24

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      3.   Recreational Activities
      A  reasonable amount of  information was  found on  recreational
activities.  Greater detail  on subpopulations  (by age,  sex,  region)  ex-
posed was available for most of the activities.  The  subpopulation expos-
ure  estimates are presented  in Appendix R.   The following discusses the
more general results.
      Information on boating was found  in a publication  of the U.S.
                                                      (12)
Department of Interior's Bureau of Outdoor Recreation.       The activity of
boating includes canoeing, sailing, and other boating.  A total of 68
million people participate in all boating activities, each on the average
of six  activity days per year.  Total  population exposure was computed
to be Id,000 million hrs annually. The duration of one  boating event was
estimated by case team members to be four hours.  Extent of  dermal expos-
ure  was  considered to be part of  the body or .4.  For each type of boat-
ing,  further data are presented in Appendix  B for sex, age, residence
and  region.  No information was available on boating  in specific water
sources.  Included in the total number,  therefore, is boating  in oceans,
lakes,  streams and rivers.
      The data source for information on fishing was a U.S. Department of
Interior publication, the  1975 National Survey of Hunting, Fishing and
Wildlife.     A total of 54 million people engage in recrea-
tional  fishing.  Each angler spends an average of 25 days fishing annually.
The  case team estimated the time spent per day as five hours.  The total
number  of hours of exposure annually for all participants is 6600 million.
Dermal  exposure was estimated to be hands and feet (0.2) which may come
into contact with water during fishing.  Information was also available
on exposure by sex, age and water source presented  in Appendix B.   The
sources  of water  for which  data were  available  were  salt water  (oceans  and
estuaries) and freshwater (lakes, rivers and streams, ponds).
      All information on swimming was found in a publication on outdoor
recreation from the U.S. Department of the Interior, Bureau of Outdoor
           (12)
Recreation.      The total population swimming annually is approximately
181  million.  An individual participates in swimming an average of nine
                                  25

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activity days per year for roughly two hours per day (case team assump-
tion) totaling 18 hours per capita annually.  The total population swims
3.3 billion hours per year.  The extent of dermal exposure was considered
to be 1.0, the entire body.  The available data also allowed subpopulations
to be distinguished in terms of sex, age, residence, and region (see
Appendix B).    Information was available for swimming in two water sources:
outdoor pool swimming and outdoor swimming in natural bodies of water
(ocean, lake, river and stream).  No information was found on indoor pool
swimming.
                                                     (12)
     Literature  from the Bureau of Outdoor Recreation    documented water
skiing as an activity with 20 million participants annually.  Each person
engages in water skiing an average of six activity days per year.  Dura-
tion was  estimated by the case team to be two hours per day.  Extent was
estimated to be  total body (1.0).  No information was available on water
skiing by water  sources so the presented data include skiing on lakes,
rivers and streams, and oceans.  Total U.S. exposure equals 260 million
hours per year.   Exposure estimates for subpopulations are presented  in
Appendix B by sex, age, residence and region.
                                    26

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                          V.  EFFECTIVE DOSE  RATE

A.   INTRODUCTION
     As explained earlier, the risk to a given subpopulation  is  a  func-
tion of the average daily intake of the pollutant and  the  toxiclty asso-
ciatiated with the exposure route.  The average daily  intake  was defined
as the product of the degree of exposure  with the effective  dose  rate.
In this section we will discuss methods of estimating  the  effective dose
rate when persons breathe  air contaminated by vapors from solutions contain-
ing priority pollutants, or are in contact with water  containing priority
pollutants.  General calculational methods are presented,  and the  critical
parameters which influence the effective dose rate are discussed.
B.   VAPOR INHALATION
     In this analysis, we assume that persons exposed to water containing
priority pollutants breathe air that is in equilibrium with the water.
The amount of priority pollutant inhaled is then equal to  the inspiration
rate times the concentration of pollutant in the air, or:

Effective Dose Rate = Ventilation Rate x Concentration Pollutant in Air
(Inhalation)
                         EDRI = (VR)  * Cp,  air                         [1]

     To be conservative, we assume that all of the pollutant inhaled is
absorbed in the lungs and remains in the body.  Data on breathing rates
for persons performing various activities are available in the literature,
and for worst case exposure estimates  one can use  the inspiratory flow rate
at strenuous exercise of 6 nr/hour as  an upper limit in calculations.
     The key variable influencing the  effective dose rate is the concentra-
tion of priority pollutant in the air  above the water source.
     The concentration can be determined by several methods:
     •  Measurement of typical pollutant concentrations in air in repre-
        sentative, field situations;
                                      27

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     •  Measurement of concentrations of pollutants in air in controlled
        laboratory tests and extrapolation to field conditions; and
     •  Estimation based upon the physical and chemical properties of the
        pollutant.
     There are limited data available from field or laboratory measurements
of priority pollutant concentrations so that estimates based upon physical
and chemical properties and thermodynamic principles will most often have
to be used.
     The concentration of priority pollutants in air in equilibrium with
water containing the pollutant in solution is given by the following
general equation:

                         P Y   =  Y  P   X                              [2]
                          t p      p  vp  p

where:
     P   =  total pressure of the gas phase  (usually one atm in this
            analysis) (atm)
     p   =  vapor pressure of the pure priority pollutant at the system
      ^    temperature  (atm)
     Y   =  mole  fraction in the vapor phase of priority pollutant
      P
     X   «  mole  fraction in the liquid phase of priority pollutant
      P
     Y   =  activity  coefficient of priority pollutant in solution

     The term P Y   equals P  , the partial pressure of the priority pollu-
               t  p         p
 tant  in the vapor phase  (air) and can be related to weight concentration
 by  the  ideal  gas  laws as follows:

                         'p, air ~  ~RT
          P Y M
n  a-i •*•     t»T!                                 *•  J
 where:
     C   .    =  concentration of  pollutant  in air  (gm/liter)
      p, air
      M      =  molecular weight  of pollutant (gin/mole)
                                    28

-------
     T  =  system temperature (°K)
     R  =  gas constant (liter-atm/mole °K)

Combining equations [2] and [3] one obtains:

                              Y P  X M
                   c       =   P vg P P                                [4]
                    p,air         RT

     In most cases of practical significance, equation [4] can be further
simplified by relating the mole fraction of pollutant in the liquid, X  ,
                                                                      P
to the weight concentration of pollutant in the liquid, C      (the
usually measured quantity) as:
c
_P-J
, /M
liq P
C
+ M
w
C 1± M
1000
18
0.018 C . .
p,lz
M
P
where:
    C  ,.   =  concentration of pollutant in liquid phase (gm/liter)

     C      =  concentration of water in liquid phase - 1000 gm/liter
      wat
     M      =  molecular weight of water = 18 gm/mole

     In developing equation [5] we have assumed that the sum of concentra-
tions of all pollutants in the water is small, i.e., negligible compared
to the concentration of water.  This certainly is true for pollutants which
are typically in the parts per million range.
     Combining equations [4] and [5] we obtain:

                        .018y P  C
             C       =  	P VP PiUq                               [6]
              p.air            RT                                      l J
                                    29

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     Thus the key physical parameters which influence the weight concentra-
tion in the air are:  (1) the liquid activity coefficient, (2) the liquid
concentration of the pollutant, and (3) the vapor pressure of the pollu-
tant.  Within the range of exposure conditions encountered, the absolute
temperature does not vary much (say from 255°K to 311°K or 0°F to 100°F),
although it must be remembered that the vapor pressure is a strong function
of temperature.
     In using equation  [6], vapor pressure data are available in the
literature for most of  the priority pollutants.  Similarly the weight
concentrations of priority pollutants  in water are available from screen-
ing and other  data.     Unfortunately, data are most likely not readily
available on activity coefficients of  priority pollutants.  In this method-
ological study, we did  not thoroughly  review the chemical literature on
this subject.
     Some further simplifications can  be made to enable order of magnitude
estimates of vapor concentrations.  Certain combinations of fluids are
considered "ideal solutions," and Raoult's law can be used to estimate
vapor  concentration.  Raoult's law states:

                    P Y  =  P  X                                       [7]
                     t  p      vp p

Basically this infers a value of unity for the liquid phase activity co-
efficient in equation  [2].  Raoult's law is usually  followed by:   (1)
members  of homologous series in combination  (e.g., propane, butane,
straight chain alcohols,  etc.);  (2) combination of substances with similar
hydrogen bonding characteristics; and  (3) all mixtures for any component
as it  approaches 100 percent concentration.  Thus Raoult's law would hold
for the  water  concentration  in dilute  solutions of priority pollutants  in
water  since  the water mole fraction  (or concentration) approaches  1.  As
a first  approximation,  however, Raoult's law can be  used  for other sub-
stances  at  lower concentrations, recognizing there may be substantial
positive or  negative deviations  (activities of 0.3 to 20  are not uncommon).
More detail  on estimating activity coefficients and  deviations from
                                      30

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 Raoult's law is given in the Chemical Engineers Handbook     and in
 The Properties of Gases and Liquids.
      For dissolved gases in solution, or for dilute solutions of a volatile
 solute in a solvent, Henry's law states that the partial pressure of the
 solute in the gas phase is directly proportional to the concentration in
 the solution or:

                          P   =  K,, C  . .                               [8]
                           p     TI  p,liq

 where:  K   =  Henry's law coefficient

      Although this law would hold  for most of the priority pollutants in
 dilute solution, there are only few data  available for coefficients for
 priority pollutants. (Note that equation [8]  is the same as equation [2]  if
 the Henry's law coefficient is the same as y  p  •)   Additional  information
                                             P vp
 on the applicability of Henry's law is given in the two references  cited
 above.  Methods  for  estimating Henry's law coefficients are also  available
in the literature.

      From the methods  described above, one can make rough  estimates of
 the  vapor phase  concentrations  of  priority pollutants  and  thus the effec-
 tive dose rate  for some  representative priority pollutants  at a range of
 concentrations  in  water.  Some  typical results  are  shown in Table 5.
High vapor pressure  compounds and  those with high water concentrations
could result in  significant  inhalation values,  if exposure  is continuous.
Note that  many of  the priority  pollutants, pesticides, PCB's, metals, have
low  vapor  pressures and, in  general, only the low molecular weight or
short  chain compounds have vapor pressures of one mm Hg or more.   Thus for
most priority pollutants at  concentrations of 1 ppb or less, inhalation in-
take even for continuous exposure should be below 1 ug/day. However,  each individual
chemical and exposure condition should be examined independently in risk
assessments.
                                     31

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                                                      Table 5
       Chemical

       Chloroform
       Benzene
to
       Phenol
       Chlordane
Estimated Vapor Concentration and Inhalation Intake
for Representative Conditions
Vapor
Pressure
(mmHg @
approx 25°C)

200




100



0.35



io-5





Water
Concentration

1 PPt
1 PPb

1 ppm
10 ppm
1 ppt
1 ppb
1 ppm
10 ppm
1 ppt
1 ppb
1 ppm
10 ppm
1 ppt
1 ppb
1 ppm
10 ppm

Estimated
Vapor
Concentration
(gm/liter)
1.93 x 10~13
1.93 x IO"10
_7
1.93 x 10 '
1.93 x 10~6
.966 x IO"13
.966 x 10~10
.966 x 10~7
.966 x IO"6
.338 x 10~15
.338 x 10~12
.338 x 10~9
.338 x 10~8
.966 x 10"2°
.966 x IO"17
.966 x IO"14
.966 x 10~13

Estimated
Vapor
Concentration
(mg/m3)
1.93 x 10~?
1.93 x 10~4
_i
1.93 x 10
1.93
.966 x 10~7
.966 x 10~4
.966 x 10"1
.966
.338 x 10~9
.338 x 10~6
.338 x 10~3
.338 x IO"2
.966 x 10~14
.966 x 10~U
.966 x 10~8
.966 x 10~7
Daily
Inhalation
Intake*
  (mg)
2.78 x 10
2.78 x 10
27.8
278
-5
-2
1.39 x 10
1.39 x 10
13.9
139
-5
i
-2
                                                                                            4.87 x 10
                                                                                            4.87 x 10
                                                                                            4.87 x 10
                                                                                            .487
         -8
         -5
         -2
                                                                                            1.39 x 10
                                                                                            1.39 x 10
                                                                                            1.39 x 10
                                                                                            1.39 x 10
         -12
         -9
         -6
         -5
        Assumes 24-hour exposure at a ventilation  rate of  6 m3/hr.

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     In addition to breathing vapors from water containing priority
pollutants, persons may be exposed to priority pollutants by breathing
fog or mist generated from polluted water sources.  The quantity of
pollutant inhaled by an individual will depend upon the ventilation rate,
duration of exposure to fog or mist, and the quantity of pollutant in
the fog or mist.  The inhalation rate has already been considered.  To be
conservative, one can assume that any pollutant inhaled in a fog or mist
remains in lungs and is absorbed into the body.  The duration of exposure
to fog or mist will vary greatly depending upon occupational, geographical,
and climatological factors.  In this program we could not develop gener-
alized exposure estimates because of this variability.  However, one can
make estimates of the quantities of pollutants contained in fog or mist
for subsequent use in specific exposure/risk calculations.
     The quantity of priority pollutant contained in a fog or mist depends
upon both the number and size of droplets or particles of water in the
fog or mist and the concentration of the pollutant in the droplets or
particles.  Each of these factors will depend upon the mechanism of
generation of the fog or mist.  For example, if contaminated water
vaporizes and subsequently condenses into a fog or mist,  the size and
loading of the particles will depend upon atmospheric conditions.  Further-
more, the concentration of pollutant in the droplets or particles will,
in general, be less than that of the original contaminated water because
of the fractionation process that has occurred.  If contaminated water
is mechanically formed into a fog or mist, the particle size and loading
might be different from a condensing fog and the concentration of the
pollutant in the particles or droplets might be the same as in the
original source.  The latter case represents an upper limit of the
quantity of pollutant inhaled, assuming that the pollutant  generally has
a lower vapor pressure than water and is initially in a relatively low
concent rat ion.
     The water content of fog has been studied by Radford     who related
liquid water content to visibility.   In practical terms,  Radford finds,
as expected, an inverse relationship between liquid water content and
                                 33

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horizontal visibility.  Visibility of 3000 ft is consistent with a liquid
water content of 0.02 gm/m3; visibility of 100 ft is consistent with a
water content of 2 gm/m .  Another estimate of the maximum moisture content
of fogs can be obtained by assuming the air to be saturated at
some temperature between the ambient air temperature and the water
temperature from which the fog is formed.  For example, saturated air
                               Q
at 35°F contains about 5.8 gm/m  water vapor whereas saturated air at
90°F contains about  36 gm/m  .  Thus if a 90°F saturated air stream were
cooled to  form a saturated fog at 35°F, the water particles in the fog
could amount to almost 30 gm/m   if the water droplets do not settle out.
For estimating purposes, we  might consider fogs  to  contain a maximum
          o
of 5 gm/m  liquid  water  (corresponding to Radford's horizontal visibility
                                                     3
of 55 ft  or 16.7 meters).  Thus  a person inhaling 6 m /hr of fog or mist
might inhale 30  gm of water  per  hour  (clearly much  of this will be ex-
haled) .   At a pollutant  concentration in the mist or fog equal to that
 in the polluted water (a maximum case) the amount of pollutant inhaled
 could be  0.03 mg/hr at a concentration of 1 ppm  or  .03 ug/hr at a pollu-
 tant  concentration of 1  ppb.
      Comparison with Table  5 shows  that  inhalation  of fog of water drop-
 lets  containing phenol at  1 ppm for  one  hour would  give about the same
 order of magnitude intake  as breathing vapor for 24 hours from a water
 source  polluted with 1 ppm phenol.   For  lower vapor pressure pollutants,
 breathing a mechanically produced  fog for a short period of time could
 result in a higher intake  than prolonged breathing  of vapor from the
 contaminated source.
      Clearly these estimates are not very precise but suggest that fog
 or mist inhalation could be a significant  source for some pollutants
 and exposure conditions.
                                   34

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C.    SKIN ABSORPTION
      A  great deal of research has been  done  over  the  years  on the process
of percutaneous  transport of compounds; however,  much of  the  work has  been
clinically oriented and very little physical/chemical data  have  been
developed to enable accurate prediction of the  rates  of penetration and
permeation through the skin.  From a brief review of  the  literature we
conclude the following.
      The process of percutaneous absorption  results from  a  combination of
adsorption onto  the stratum corneum (the thin coherent membrane  of
epithelial cells that comprise the "dead" surface layer of  the epidermis).
diffusion through it and through the viable  epidermis, and  through  the
papillary dermis into the microcirculation.
      In general, diffusion through the stratum corneum is the rate-limit-
ing step.
      The diffusion of solutes in water solution through the stratum corneum
may result from  two mechanisms:  (a) diffusion concurrent with solvent
transport or (b) a combination of preferential absorption on the stratum
corneum and diffusion through it.
     A review article by Scheuplein and BlaiR    provides equations and
data  to estimate the order of magnitude of transport through the skin.
Considering the first mechanism,  the diffusivity of the skin has been
measured and found to vary with location on the body.   However, the thick-
ness of stratum corneum also varies, and the complementing effect of in-
creasing diffusivity with increasing thickness seems to yield a relatively
uniform steady state permeability and flux through the skin.  The water
                                                       2   ^18)*
flux  through the skin is approximately 0.2 to 0.5  mg/cm hr.        The flux
of the solute (priority pollutant)  could be estimated  by multiplying this
water flux by the weight fraction  of pollutant in the water.   Thus at a  con-
centration of 1 ppm, the flux of pollutant would be 0.2 x 10   to 0.5 x 10
*In this review article, several references to water flux through the skin
 show different values ranging from 0.2 to 0.9 mg/cm^ hr for the abdomen,
 back, forearm, etc., and even higher values for the palm, sole, scrotum, etc.
 In another article, Galey (et al.)^) report the diffusivity of water in
 whole human skin to be 4.4 + 1.7 x 10~7 cm/sec.  The corresponding flux
 value would be about 1.6 mg/cnn hr.
                                    35

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     2                                         —9             —9       2
mg/cm  hr; at 1 ppb, the  flux would be  0.2 x  10    to  0.5  x  10  mg/cm /hr.
                                                        2             42
Since a representative body  surface area  is about  1.8 m  or 1.8 x 10 cm ,
the pollutant flux  for twenty-four hour exposure might be on the  order  of
8.6 x 10"  to 21.5  x  10~2 mg/day  or 8.6 x 10~5 to  21.5 x  10~5 mg/day  at
pollutant concentrations  of  1 ppra and 1 ppb,  respectively.
     Considering  the  second  mechanism which includes  preferential absorp-
tion on the  stratum corneum, and  diffusion  through it, the flux of solute
(priority pollutant)  through the  skin is  given by  the following equation:
                             K DAC
                      J
                       s       6        p  s

 where :

                                                  2
      J    =  steady state flux of solute (moles/cm hr)
      S
      K    =  membrane/solvent partition coefficient =
      m
             solute sorbed per cc tissue _
             solute in solution per cc solvent
                                                       2
      D    =  average membrane diffusion coefficient (cm /hr)
      5    =  membrane thickness (cm)
      AC  =  concentration difference of solute across membrane
             (moles /cm^)
      k   =  permeability constant for solute (cm/hr)
       P

      In examining equation [9] we see that the key variables affecting
 the flux of pollutant through the skin are the concentration of pollutant
 in the water (for practical purposes we can assume that the concentration
 of the pollutant in the body is zero, so that the flux is directly propor-
 tional to the pollutant concentration in the water) , and the permeability
 constant for the solute.  As noted above,  the membrane diffusion co-
 efficient and the skin  (membrane) thickness seem to be mutually dependent,
 so that the key variable may be the membrane (skin) /solvent (water)
 partition coefficient.
                                    36

-------
     If data were available, equation [9] could be used to estimate the
flux (effective dose rate) of priority pollutants.  In our brief litera-
ture search, we could not find the needed permeability or diffusion data
for the priority pollutants, and only limited data for other substances.
(The data seem to be of interest primarily to the pharmaceutical/cosmetics
industry and to the military.)  Some typical values of the diffusion and
permeability coefficients and ranges of values of flux rates for several
water concentrations are given in Table 6.  Note that the values estimated
by transport of solute through the stratum corneum by equation [9] are the
same order of magnitude (actually both smaller and larger depending upon
the chemical) as those estimated from diffusion of the solvent containing
the solute.  This suggests that accurate estimates of the skin absorption
must take into the importance of K , the membrane (skin)/water partition
                                  m
coefficient.
     Since octanol seems to have a very high value of K. ,  it is plausible
that substances similar to octanol would also have a high value of K   and
                                                       0             m
a possibly high permeability constant,  k .  This also suggests that
                                        P
chemicals with a high octanol/water partition coefficient,  might also have
a high membrane/water partition coefficient and a high permeability constant
for human tissue.  Unfortunately, sufficient data are not  available on
chemicals other than straight chain alcohols to support this hypothesis.
                                   37

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                                                     Table  6


Chemical
Aqueous Solutions
Methanol
Ethanol
Butanol
Octanol
Ethyl Ether
2-Butanone
2-3 Butane diol
Progesterone
Cortisone
Hydrocortisone
Estradiol

Amphetamine
Ouabain
Representative Values of Skin Absorption Parameters and Rates
Tissue/
Permeability
Constant (k )
(cm/hr) p
0.5 x IO"3
0.8 x 10~3
2.5 x 10~3
52 x 10~3
16 x 10~3
4.5 x 10~3
.05 x 10~3
1.5 x 10~3
.01 x 10~3
.003 x IO"3
1.1 x 10~6
-,-j
0.039 x 10
0.011 x 10~7
Diffusion Co-
efficient (D)
(cm2/sec)
.62 x IO"9
.66 x 10~9
.74 x 10~9
.77 x 10~9
io-9
io-9
io-10
2 x ID'11
1 x IO-12
3 x 10~13
_

-
-
Solvent
Cone. Ratio

0.6
0.9
2.5
50
12
3.4**
.37**
55**
7.4**
7**
_

-
—
Flux through Skin at
1 ppm 1 ppb
(mg/cm^hr)
.5 x 10"6 .5 x 10~9
.8 x 10"6 .8 x 10"9
ft Q
2.5 x 10 2.5 x 10 *
fi Q
52 x 10" 52 x 10~
-6 -Q
16 x 10 16 x 10
4.5 x 10~6 4.5 x 10~9
.05 x 10~6 .05 x 10~9
£. Q
1.5 x 10~b 1.5 x 10
-ft -9
.01 x 10 .01 x 10
f Q
.003 x 10 .003 x 10
1.1 x 10~9 l.l x 10"12
-10 -1?
0.39 x 10 U l.l x 10.
0.011 x 10"10 1.1 x 10'12


Effective Dose Rate at
1 ppm 1 ppb
(mg/day)*
2.16 x Hf1
3.45 x 10~L
1.08
22.5
6.9
1.9
_o
2.16 x 10
•I
6.5 x 10
-3
4.3 x 10
Q
1.3 x 10 °
4.7 x 10~4
-4
4.7 x 10
4.7 x 10"4
2.16 x 10~4
3.45 x 10~4
1.08 x IO"3
-3
22.5 x 10
6.9 x 10"
1.9 x IO"3
-5
2.16 x 10
-4
6.5 x 10
. _ _ «~6
4.3 x 10
-6
1.3 x 10
4.7 x 10~7
-7
4.7 x 10
4.7 x 10~7
 *                                                            2
  Calculated for continuous exposure of the entire body (1.8 m ) for 24 hours.
**
  Estimated using a tissue thickness of 27 microns.
 Source:  References 18 and 19.

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            VI.  APPLICATION OF METHODOLOGY TO CHLORDANE AND
                      HEPATACHLOR RISK ASSESSMENTS

     The methods described above can be used to estimate the "average
daily intake" of chlordane and heptachlor by inhalation and skin adsorp-
tion and compare these values to the average daily intake of these chemi-
cals by food and water ingestion.  In this way one can determine the
significance of the non-ingestion routes.
     Table 7 gives data from earlier assessments pertinent to the discussion.
The average daily intakes of heptachlor from food and chlordane from
drinking water were 0.3-0.64 ug/day and 0.01-0.02  ug/day. respectively.  The
range of ambient water concentrations of the same chemicals was 5-50 ppt
and .01 to 1 ppb, respectively.
                                Table 7
                 Data From Chlordane and Heptachlor
                           Risk Assessments
       Chlordane
       Heptachlor
       Heptachlor Epoxide
                                                   Average Daily Intake
                                                        (ug/day)
Ambient Water
Concentration Range
.01-1 ppb
5-50 ppt
7-70 ppt
Food
.002-. 007
-.3 to .64
-
Drinking
Water
.01-. 02
<.006
—
     Assuming that a person was continuously exposed to vapor from water
containing these chemicals, the effective dose rate for inhalation can be
estimated from equation [6] in Section V, and assuming Raoult's law to
                           *
hold with the following results:
                                   39

-------
                        25°C
     Chlordane
     Heptachlor
     Heptachlor
     epoxide
                    ~
       mmHg
        -4
  3 x 10   mmHg
   2.6 x  10
   mmHg
                          -6
Estimated Vapor    -
Concentration (mg/m )
.966 x 10~13 at
.01 ppb liq cone
1.45 x 10~12 at
5 ppt liq cone
2.5 x 10~14 at
10 ppt liq cone
                                            Daily
                                            Inhalation
                                            Intake
                                              (ug/day)
1.39 x 10
                                                                     -8
2.1 x 10
                                                                    -7
3.6 x 10
                                                    -9
     Thus inhalation of vapor in equilibrium with ambient water containing
low levels of chlordane, heptachlor and heptachlor epoxide yields only
negligible intakes of the chemicals compared to that obtained from food
ingestion.  Even if the activity of the compounds in water were high (say
50 to 100) the quantity inhaled would still be small.  Only if a mist or
fog from water contaminated with chlordane were breathed continuously were
breathed continuously could this inhalation source of pollutant be significant.
     For skin adsorption of these chemicals, several estimates can be made.
It was shown in Section V that the adsorption flux of water (for entire
body surface) would range from about 3.6  g/hr to 9 g/hr.  At ambient
concentrations of chlordane, heptachlor and heptachlor epoxide, the follow-
ing effective dose rates could occur.
 Chlordane
 Heptachlor
 Heptachlor
 epoxide
3.6-9 x 10 6 mg/hr @ 1 ppb to 3.6-9 x 10 8 mg/hr @ .01  ppb
1.8-4.5 x 10~8 mg/hr <§ 5 ppt to 1.8-4.5 x 10~7  mg/hr @  50 ppt
2.5-6.3 x 10"8 mg/hr @ 7 ppt to 2.5-6.3 x 10~  mg/hr @  70 ppt
      Thus for total exposure for 24  hours/day,  skin absorption rates would
 be as follows:
 Chlordane      .08 ug/day to .22 ug/day @  1  ppb
                .0008 ug/day to .0022 ug/day  @  .01  ppb
 Heptachlor     .0004 ug/day to .0011 ug/day  @  5  ppt
                .004 ug/day to .011 ug/day  @  50 ppt
                                     40

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                              -4                   -3
Heptachlor epoxide    5.6 x 10   ug/day to 1.5 x 10   ug/day @ 7 ppt
                      .0056 ug/day to .015 ug/day @ 70 ppt

Thus continuous exposure to water containing heptachlor or heptachlor
epoxide at ambient levels might result in daily skin adsorption intakes
only about 1 to 5% of that from food ingestion, i.e., .015 ug/day skin
absorption compared to 0.3-0.64 ug/day food ingestion.
     For chlordane, however, skin absorption seems to be a potentially
significant mechanism if the ambient water contains 1 ppb chlordane.  The
estimates above were based on continuous 24 hour total surface exposure
to water containing chlordane.  Using the exposure data of Section 4, one
could develop better estimates of average intake by skin absorption.  For
example, for bathing the exposure was 46 hours/year or .126 hrs/day; thus
the average daily skin absorption of chlordane from bathing would be from
        -4            -3
4.2 x 10   to 1.1 x 10   ug/day.   This may be as much as 10% of the average
daily intake from food and drinking water.  Dishwashing for 365 hours per
year, i.e., 1 hour/day would give about the same average daily skin absorp-
tion intake because only about 10% of the body is exposed.   Although the
"average" daily intake by skin absorption seems to be only as much as 10%
of the average daily food intake, certain activities could give high
specific daily intakes.   For example, if one swam for 4 hours in any given
day in water containing 1 ppb chlordane, from .013 to .036 ug chlordane
might be adsorbed, an amount comparable with the average dally food intake.
     In Section V another method  was given for estimating  skin absorption,
i.e., use of equation [9].   If chlordane had the same permeability constant
as cortisone (they have  similar molecular weights but very different
structures) about .004 ug/day could be absorbed for total  continuous 24-
hour exposure at 1 ppb,  a value somewhat smaller than the  .08 to  .22 ug/
day estimated above,  but still not negligible compared to  chlordane
food and drinking water  ingestion.  If chlordane had a permeability constant
more nearly equal to that of progesterone or an alcohol,  from .6  to
1 ug/day might be adsorbed at concentrations of 1 ppb for  24 hours total
exposure.
                                   41

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     These results indicate that skin absorption of chlordane cannot be
neglected entirely, and suggests that additional effort be devoted to
understanding the mechanisms of skin absorption and developing data for
absorption of priority pollutants.  It becomes particularly important
when considering subpopulations who have high exposure for prolonged periods
to water which may be contaminated with  priority pollutants.
                                    42

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                                REFERENCES
 1.  Day, R., "Regional Heat Loss," pp 240-261 in:  Newburgh, L.H.  (ed.)
     (1949) Physiology of Heat Regulation and the Science of Clothing.
     W. B. Saunders Co., Philadephia.

 2.  U.S. Bureau of Census (1975), Current Housing Reports, Series H-lll.
     As quoted in Statistical Abstract (1976).

 3.  U.S. Bureau of Census (1975), Annual Housing Survey;  1975, Part A,
     Series H-150-75.  As quoted in Statistical Abstract (1976).

 4.  Anon. (1976) Merchandising.  Annual Statistical issues.  Billboard
     Publications, Inc., New York, N.Y.

 5.  Federal Energy Administration (1977) Energy Efficiency Program for
     Appliances.  Final Report.  By Booz-Allen and Hamilton, Inc.

 6.  U.S. Bureau of Census (1976) Current Population Reports, Series P-25,
     Nos. 310, 371, 519, 643 and 704.  Dept. of Commerce, Washington, D.C.

 7.  Craft, George (May 30, 1978), Personal communication.   Technical
     Services, American Water Works Association,  Denver, Colorado.

 8.  U.S. National Center for Health Statistics (1975), Vital and Health
     Statistics, Series 10, No. 115.

 9.  Arthur D. Little (1977)  Study of Energy-Saving Options for Refrigerators
     and Water Heaters, Vol.  2:  Water Heaters.   Prepared for Federal
     Energy Administration, Washington, D.C.

10.  Personal communication with staff at New England Rehabilitation Center,
     Woburn; Otis Hospital, Cambridge; Tufts-New  England Medical Center,
     Boston; Syrames Hospital, Arlington;  Milton Hospital, Milton.

11.  American Hospital Association (1977), Hospital Statistics 1976,
     Annual Survey.

12.  U.S. Dept.  of Interior (1973) Outdoor Recreation;  A Legacy for
     America.  Bureau of Outdoor Recreation, Washington, D.C.

13.  U.S. Dept.  of Interior (1977), 1975  National Survey of Hunting. Fishing.
     and Wildlife—Associated Recreation.  U.S. Fish and Wildlife Service,
     Washington, D.C.

14.  Comroe, Julius H. (1966), Physiology of Respiration, Year Book Medical
     Publishers, Inc., Chicago, Illinois.
                                     43

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15.  Perry, J.H. (edit) (1950), Chemical Engineer's Handbook, 3rd Edition,
     McQraw Hill, New York.

16.  Reid, R.C. and Sherwood, T.K. (1958), McGraw Hill, New York,
     The Properties of Gases and Liquids.

17.  Houghton, H.G. and Radford, W.H., "On the Measurement of Drop Size
     and Liquid Water Content in Fogs," Pap. Phys. Ocean Meteor. Mass.
     Inst. of Tech., Woods Hole Ocean. Instn., Vol. 6, No. 4 (1938) as
     reported in "Compendium of Meteorology," ed. by Thomas F. Malone,
     American Meteorological Society, Boston, Mass. 1951.

18.  Scheuplein, R.J. and Blank, I.H. (1971), "Permeability of the Skin,
     Physiological Reviews, 51, No. 4, p702.


19.  Galey, William R., Lonsdale, H.K., and Nacht, Sergio, "The In Vitro
     Permeability of Skin and Buccal Mucosa to Selected Drugs and Tritiated
     Water."  The Journal of Investigative Dermatology, 67^713-717, 1976

20.  Forbes, W.H., "Laboratory and Field Studies"  (Chapter 11), pp320-388,
     in:  Newburgh, L.H.  (ed.)  (1949) Physiology of Heat Regulation and the
     Science of Clothing.  W.B. Saunders Co., Philadelphia.
                                     44

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                             APPENDIX A




                        MATHEMATICAL APPENDIX




Definitions of Symbols




B       = normal breathing




A       = activity leading to exposure (e.g., swimming)




P       = demographic subpopulation (e.g., children)




G       = environmental category (e.g., coastal)




H       = habitational category (e.g., urban)




J       = occupational category (e.g., farmers)



W.(G,H) = source of water to which activity A is exposed.




MT(G,H) = fraction of total population having occupation J.
 J



FA(P)   = frequency of exposure for subpopulation P via

          activity A. (hours/day)



F ,E *  = frequency and extent of exposure for occupation J.
 J  J


EA*(P)  = extent of exposure for P via A.



N(P)    = fraction of general population falling in subpopulation P.




POP     = total population of U.S.




Q(G,H)  = fraction of general population falling in this category.




R(P)    = ventilation rate for subpopulation P (m.  /hr.)
* For dermal route, extent = dermal factor (0-1)
                                 A-l

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Exposure Computations

1.  Activities
D (P) = degree of exposure  for member  of P  through  activity A.

      = EA(P) ' FA(P)   for  dermal
         A       A
      = R(P)  • FA(P)    for  inhalation
X.(6,H,P) = exposure of subpopulation  P in  situation G,H as percent

            of total population  exposure

          = N(P)'Q(G,H)'DA(P)


 T
X.        = total exposure  of  general  population to water source T via
 A
            activity A

          = POP  •  E.  [X (G,H,P):  W (G,H)  - T]
                 G.H.P   A
 XA
= total exposure via activity A (person-hours/day)
=  E  x?
 2.   Occupations

 DT         = degree of exposure in occupational category J.
  u
             EJ   j           for dermal
           = R (adult) •  Fj   for inhalation
 X,         = exposure in occupational category J to water Source T
             POP        [MT(G,H)D. :  WT(G,H) = T]
                  G,H     J      J    J
 X.        = total exposure in occupation J (person-hours/day)
              •%      T

               T     J
                                   A-2

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3.  Inhalation (Adjustment for Occupational Exposure)
F0(P)     - 1 - Z»F.(P)  where the summation includes only  activities
                 A
                          for which inhalation occurs
DBR(P)1
                             J
x£        = POP •  £    [XB(G,H,P) : WB(G,H) = T]
                G.H.P

XB        =   Z *B      (person-m.3/yr.)
              T
4.  Total exposure by water source
 T
X         = total exposure to water source T (person-hours)
       ET*   v*  T
      X. +  2-r X      f°r dermal  (person-hr . /yr . )
       J        A
                  J       A   A
     V        V
T    /   I     /    T
   -f    x    +      X
                    j  j
                                                                 "\
                                        for inhalation (person-m. /yr.)
Inhalation exposure through occupations and activities has been sub-
tracted from total exposure through breathing, so that there is no
redundancy in the above calculation.
X       = total U.S. water exposure
               XT
                                   A-3

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    Effective Dose Rate and Risk Computations


Let physical/chemical properties of interest  be  designated as

(z   z,...) = z
CT - Pollutant concentration in water source T
S(C ,30 = Effective dose rate
Y = Toxicity coefficient (excess risk/ppb)
then V. = average daily intake via A and T


        = X*  • S (CT,Z) and
     R. = Risk from activity A
          T   A
                    Y
                   ' Y
 Similarly R  = Risk in occupation J
            J
-E*  '
~ T   J
                                   . Y
      Also R_ = Risk from normal breathing
                   X  B   .  S  (CT,Z)  . Y
      Also R  = Risk from water  type T
                                  )   - S(CT,Z)  -
        or R
                                                  (dermal)





                                                 (inhalation)
                                  A-4

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Hence, total risk to U.S. population is given by

     R=£RT   or    R-5 RA
 Note that if the concentration C  depends on location, the
 above computations may be suitably modified.
                              A-5

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                             APPENDIX B
BOATING
       (12)
   Sailing
   Canoeing
RECREATIONAL SUBPOPULATION EXPOSURES*
Population
Sex ,
males 5 x 10
females 3 x 106
Age (yrs1*
12-17 2 x 106
18-24 2 x 106
25-44 2 x 106
45-64 2 x 106
65+ .3 x 106
Residence
in SMSA 5 x 106
not in SMSA 3 x 10*
Region
Northeast 3 x 106
North Central 2 x 106
South 2 x 106
West 1 x 106
Sex
males 6 x 106
females 4 x 10&
Age (yrs)
12-17 2 x 106
18-24 3 x 106
25-44 4 x 106
45-64 1 x 106
65+
Residence f
in SMSA 6 x 10°
not in SMSA 4.8 x 106
Total
Exposure
(person-hours)
150 x 106
114 x 106
83.2 x 106
40.8 x 106
52.8 x 106
99.2 x 106
2.4 x 106
136.0 x 106
136.8 x 106
139.2 x 106
33.6 x 106
29.6 x 106
52.4 x 106
120 x 106
46.4 x 106
41.6 x 10J?
45.6 x 10?
44.8 x 10*
32.8 x 10°
1.36 x 10
91.2 x lOJ?
76.8 x 10°
T*he subpopulations may not add up  exactly to the total given in Table 5
 because of rounding errors.   Further,  the precision of the estimates is not
 as great as might be perceived from the values  given here.   Most likely, the
 the estimates are only precise to  two  significant figures.

                                   B-l

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                            Population
                  Total
                  Exposure
                  (person-hours)
  Other  Boating
Region          ,
Northeast 3 x 10
North Central 4 x
South 2 x 10°
West 1 x 10°

Sex          ,
Males 25 x 10b
Females 25 x 106

Age  (yrs)     ,
12-17  11 x 10
18-24  9 x 10*
                            25-44
                            45-64
                            65+
19 x 10
11 x 10*
2 x 106
                                                      74.4 x 10*
                                                      44.8 x 10°
                                                      32.8 x 10°
                                                      12.0 x 10°
                                                      630.0 x 10
                                                      480.0 x 10
                             6
224.4 x 10
144.0 x 10:
448.4 x lO;
268.4 x 10*
57.6 x 10°
                            Residence
                            in SMSA 31 x 10°
                            not in SMSA 19 x 10*
                   669.6 x 10,
                   425.6 x 10*
FISHING
       (13)
                            Region           ,
                            Northeast 11 x 10
                            North Central 13 x
                            South 17 x 106
                            West  10 x 106
                            9-17 years     t
                               men 8.9 x 10  ,
                               women 3.4 x 10

                            18-24 years    ,
                               men 4.2 x 10
                               women 2.2 x 10b

                            25-34 years    ,
                               men 7.9 x 10  ,
                               women 3.8 x 10

                            35-44 years    ,
                               men 5.1 x 10  ,
                               women 2.5 x 10

                            45-54 years    ,
                               men 4.7 x 10°
                               women 1.9 x 10e

                            55+ years      ,
                               men 3.5 x 10  ,
                               women 2.5 x 10
                   224.4 x 10'
                   306.8 x 10'
                   367.2 x 10*
                   220.0 x 10*
                   1090.3 x 10
                   416.5 x 10

                   514.5 x 10*
                   269.5 x 106

                   967.8 x 10*
                   465.5 x 10

                   624.8 x 10*
                   306.3 x 10

                   575.8 x 10*
                   232.8 x 10°

                   428.8 x 10*
                   306.3 x 10
                                   B-2

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SWIMMING
        (12)
   Outdoor pool
   swimming
                            Population
 Sex          6
 male  31  x  10  ,
 female 34  x 10
                           Total
                           Exposure
                           (person-hours)
 477.4  x 10
 693.6  x 10
Age
12-17
18-24
25-44
45-64
65+
6
21 x 10°
12 x 10^
21 x lg6
9 x 10^
1 x 106
                                                       537.6  x 10'
                                                       160.8  x 10f
                                                       331.8  x 10;
                                                       117.0  x 10
                                                       10.8 x 106
                            Residence       ,
                            in SMSA  46 x 10°
                            not in SMSA 19 x 10*
                          901.6 x 10;
                          269.8 x 10*
                            Region
                            Northeast  20 x 10°
                            North Central 16 x 10e
                            South 18 x 106
                            West 10 x 106
                          368.0 x 10C
                          313.6 x 10*
                          252.0 x 10:
                          220.0 x 10e
   Other swimming
   outdoors
Sex
male 57 x 10  ,
female 59 x 10
1071.6 x 10"
1038.4 x 106
                            Age (years)
                            12-17
                            18-24
                            25-44
                            45-64
                            65+
       30 x 10;
       24 x 10*
       44 x 10*
       16 x 10*
        2 x 10*
672.0 x
446.4 x 10
712.8 x 10
256.0 x 10
32.4 x 106
                            Residence
                            in SMSA  79 x 106
                            not in SMSA  37 x 10°

                            Region
                            Northeast  38 x 106
                            North Central 24 x 10e
                            South  34 x 106
                            West  20 x 106
                          1311.4 x  10
                          799.2 x 106
                          767.6 x 10°
                          350.4 x 106
                          598.4 x 106
                          392.0 x 106
                                  B-3

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                                                   Total
                                                   Exposure
                         Population                (person-hours)

Waterskiing<           Sex            ,
                         male  10.8 x 10?          159.8 x 10°
female 9.1
                                                       .
                                    x 10           96.5 x 106
                         Age (years)  ,
                         12-17  5 x 10°            97.0 x 10°
                         18-24  6 x 10°            67.2 x 10b
                         25-44  8 x I0j            91.2 x 10°
                         45-64  1 x 106            7.8 x 106
                         65+    Ox 106            0
                         Residence        ,                    ,
                         In  SMSA  12 x  10°  ,        168.0 x  10
                         not in SMSA 8  x  10        92.8 x 10b
                         Region                              ,
                         Northeast  4  x 10°          44.0  x 10°
                         North Central 5  x  106      48.0  x 10b
                         South 7  x  106             84.0  x 106
                         West 4 x 106              87.2  x 106
                                 B-4

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                                  TECHNICAL REPORT DATA
                           (Please read Instructions on the reverse before completing)
1. REPORT NO.
 EPA-440/4-79-016
                                                           3. RECIPIENT'S ACCESSION NO.
». TITLE AND SUBTITLE
 Identification and Evaluation  of Waterborne Routes of
 Exposure -From Other Than  Food  and Prinking Hater
                                               5. REPORT DATE

                                                  January.  1979
                                               6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
 Kate Scow1
 Melba Wood
i
Alfred E. Wechsler1,   Janet Stevens1,
 Michael A. Callahan2
                                                          8. PERFORMING ORGANIZATION REPORT NO
». PERFORMING ORGANIZATION NAME AND ADDRESS
 Arthur D.  Little, Inc.
  Acorn Park
  Cambridge, Massachusetts 02140
                                                           10. PROGRAM ELEMENT NO.
                                               11. CONTRACT/GRANT NO.
                                                EPA-68-01-3857
                                                Task #4
12. SPONSORING AGENCY NAME AND ADDRESS
 2U.S.  Environmental Protection Agency
  Office of Water Planning and Standards
  Monitoring and Data Support Division  (WH-553)
  Washington. D.C. 20460	
                                               13, TYPE OF REPORT AND PERIOD COVERED
                                                Final Task Report
                                               14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
      The purposes for this task were  (1)  to identify major human exposure routes
 (other than food and drinking water)  for  waterborne pollutants; (2)  to  develop a
 methodological framework for establishing the significance of these  routes for
 quantifying the risks to humans associated with these routes; and  (3) to incorporate
 this framework into a risk assessment methodology and test its usefulness for risk
 assessments of chlordane and heptachlor.   Inhalation of vapors from  polluted water
 and absorption of pollutants through  the  skin during direct contact  with water were
 chosen as the most significant alternative exposure routes for consideration In this
 report.   The process of estimating water  exposure consists of (1)  identifying human
 activities that can result in exposure; (2) identifying subpopulations  involved in
 these activities; (3) assessing activity  duration or degree of daily exposure to
 the different sources of water; and (4) summation of average daily exposures for
 different subpopulations.  Seventeen  exposure activities (bathing, dishwashing, etc.)
 in  personal, recreational, and household  categories were identified.  Estimates for
 these activities were made of average daily exposure by inhalation or skin absorption
 routes,  exposure extent, and total national  yearly exposure, with subpopulations
 identified by age, sex, and geographic location in several cases.  Calculations for
 chlordane and heptachlor showed inhalation to be negligible compared to other Intakes,
 but for  chlordane, skin absorption may be  a significant exposure route.	
7.
                               KEY WORDS AND DOCUMENT ANALYSIS
                 DESCRIPTORS
                                             b.lDENTIFIERS/OPEN ENDED TERMS
                                                            c.  COSATI Field/Group
 Risk
 Exposure
 Water pollution
 Public health
 Chlordan
 Heptachlor
                                                              06F

                                                              G8G
                                                              57H
8. DISTRIBUTION STATEMENT
           Release Unlimited
                                  19. SECURITY CLASS (ThisReport)
                                     Unclassified	
                                                         21. NO. OF PAGES

                                                         	58
                                             20. SECURITY CLASS (Thispage)
                                                 Unclassified
                                                                        22. PRICE
PA Form 2220-1 (t-73)
                                                    -- U.S. GOTDWMlin FKINTWGOfTICE 1979-281-147/49

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