United States Office of Water April 1983
Environmental Protection Regulations and Standards (WH-553) EPA-440/4-85-022
Agency Washington DC 20460
Water
£EPA Water-borne Routes of
Human Exposure Through
Food and Drinking Water
-------
DISCLAIMER
This is a contractor's final report, which has been reviewed by the Monitoring and Data Support
Division, U.S. EPA. The contents do not necessarily reflect the views and policies of the U.S.
Environmental Protection Agency, nor does mention of trade names or commercial products
constitute endorsement or recommendation for use.
-------
REPORT DOCUMENTATION *• «PORT •«• *•
PAGE EPA-440/4-85-022
4. Tttto and Subtitle
Water-Borne Routes of Human Exposure through Food and
Drinking Water
7. Authors) Perwak, J.; Adamson, F.; Gilbert, D. ; Scow, K. ; and
Wallace, D.
9. Performing Organization Nam* and Address
Arthur D. Little, Inc.
20 Acorn Park
Cambridge, MA 02140
12. Sponsoring Organization Nam* and Address
Monitoring and Data Support Division
Office of Water Regulations and Standards
U.S. Environmental Protection Agency
Washington, B.C. 20460
3. Raclpianf s Accession No.
s. Raport Dat* Final Revision
April 1983
6.
8. Performing Organization Rapt. No.
10. Projact/Task/Work Unit No.
11. ContracttC) or Grant(G) No.
{0 C-68-01-3857
C-68-01-5949
(G)
13. Type of Raport & Parted Covered
Final
14.
15. Supplementary Not**
Extensive Bibliographies
1ft. Abstract (Limit 200 words)
This report discusses methods for identifying and quantifying water-borne routes of
contamination of human food and drinking water. The work was performed for the U.S.
Environmental Protection Agency (EPA) as part of a program to assess exposure/risk of
65 classes of chemicals (129 "priority pollutants") in the water environment. It is
intended as a first step in developing methods for estimating levels of contaminants
in food and drinking water resulting from water-borne routes of migration. Points of
water contact with food in growth stages, processing, and preparation are identified.
A simplified methodology is presented for evaluating pollutant intakes during the
growth phase of crops, livestock, poultry, and fish, and information is presented on
water use in food processing and home preparation. The routes of contamination of
drinking water during treatment and distribution are identified.
17. Document Analysis a. Descriptors
Exposure
Risk
Water Pollution
Food Contamination
b. htantMara/Opan-Eiwtod Terms
c. COSATI Reid/Group 06H 06T
IS. Availability Statement
Release to Public
19. Security Class (This Report)
Unclassified
20. Security Class (This Page)
Unclassified
21. No. of Pag**
60
22. Price
$10.00
SeaANS»-Z39.1»
See Instructions en Reverse
OPTIONAL FORM 272 (4-77)
(Formerly NTIS-3S)
Department of Commerce
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EPA-440/4-85-022
December 1981
(Revised April 1983)
WATER-BORNE ROUTES OF HUMAN EXPOSURE
THROUGH FOOD AND DRINKING WATER
by
Joanne Perwak, Francis Adamson,
Diane Gilbert, Kate Scow,
and Douglas Wallace
Arthur D. Little, Inc.
U.S. EPA Contracts 68-01-3857
68-01-5949
Michael W. Slimak
Project Manager
U.S. Environmental Protection Agency
Monitoring and Data Support Division (WR-553)
Office of Water Regulations and Standards
Washington, D.C. 20460
OFFICE OF WATER REGULATIONS AND STANDARDS
OFFICE OF WATER
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
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I
I
FOREWORD
This report is part of a series of documents prepared under the
Monitoring and Data Support Division's pollutant exposure fate and risk
assessment program. This program is directed towards investigating the
risks due to presence of 129 Priority Pollutants in our nation's waters.
Sone of the reports prepared under this program address specific
pollutants. Others, such as this one, are generic in nature and are meant
to be tools for use when performing risk assessments on a wide variety of
pollutants.
This report investigates pathways through which waterborne pollutants
can enter or leave food during various phases of growth, harvesting,
processing, and preparation. It addresses the overall potential signi-
ficance of these pathways.
A companion report, Identification and Evaluation of Waterborne Routes
of Exposure from Other than Food and Drinking Water (EPA-440/4-79-016),
investigates other means of exposure to waterborne pollutants: inhalation
of vapors from polluted waters, and dermal absorption.
A related series of documents assesses the overall risks from 54 of
the most important Priority Pollutants. These documents compare the
importance of all known exposure routes, environmental pathways, and
sources of the particular pollutants.
Michael W. Slimak, Chief
Exposure Assessment Section
Monitoring & Data Support Division (WH-553)
Office of Water Regulations and Standards
111
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TABLE OF CONTENTS
LIST OF FIGURES
LIST OF TABLES ix
1.0 SUMMARY AND CONCLUSIONS 1_1
2.0 INTRODUCTION 2-1
3.0 WATER-RELATED CONTAMINATION OF FOOD DURING GROWTH 3-1
3.1 Food Crops 3_1
3.1.1 Principles of Irrigation and Crop Physiology 3-1
3.1.1.1 Irrigation 3-1
3.1.1.2 Crop Physiology 3-5
3.1.2 Contamination Model 3-5
3.1.2.1 Assumptions 3-9
3.1.2.2 Sample Applications 3-10
3.1.2.3 Limitations of Model and Comparison
of Model Results with Monitoring Data 3-12
3.2 Livestock and Poultry 3-13
3.2.1 Ingestion 3-13
3.2.2 Dermal Absorption 3-13
3.2.3 Comparison of Two Exposure Routes 3-20
3.3 Aquatic Organisms 3-20
4.0 WATER-RELATED CONTAMINATION OF FOOD DURING PROCESSING 4-1
4.1 Introduction ' 4_1
4.2 Utilization of Water in Food Processing 4-1
4.2.1 Introduction 4_1
4.2.2 Meat Products 4.3
4.2.3 Dairy Products 4_6
4.2.4 Preserved Fruits and Vegetables 4-6
4.2.5 Grain Milling Products 4-8
4.2.6 Bakery Products 4-9
4.2.7 Sugar, Confectionery Products 4-9
4.2.8 Fats and Oils 4-10
4.2.9 Beverages 4-10
4.2.10 Miscellaneous Foods 4-11
Summary of Water Use During Processing 4-11
5.0 WATER-RELATED CONTAMINATION OF FOOD DURING HOME
PREPARATION 5_!
6.0 DRINKING WATER CONTAMINATION DURING TREATMENT AND
DISTRIBUTION 6_]_
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TABLE OF CONTENTS (Continued)
6.1 Introduction 6_1
6.2 Chemical Additions at the Treatment Plant 6-1
6.3 Chemical Formations at the Treatment Plant 6-1
6.4 Pipe Corrosion 6-3
6.4.1 Metal Pipes 6-3
6.4.2 Asbestos-Cement Pipes 6-5
6.4.3 PVC Pipes * 6-5
6.5 Accidental Contamination in the Distribution System 6-6
6.6 Summary 6-6
7.0 REFERENCES 7_1
vi
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I
LIST OF FIGURES
Figure No. Page
3-1 Consumptive Use of Water by an Annual 3-7
Plant During Various Periods of Growth
3-2 Influence of Environmental Temperature on 3-17
Feed Consumption, Heat Production, and Feed
Utilization in Dairy Cattle
6-1 Sources of Contamination of Drinking Water 6-2
in Treatment and Distribution
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I
LIST OF TABLES
Table No.
Page
3-1 Common Water Capacities of Soil by Soil Types 3-3
3-2 Seasonal Consumptive-Use Requirements of Common 3-4
Irrigated Crops in Relation to the Requirements
for Alfalfa—Western States
3-3 Normal Crop Water Use. Central Coastal Plains. 3-6
Evapotranspiration (Consumptive Use) Table
3-4 Symbols Used in Food Crop Contamination Model 3-8
3-5 Comparison of Estimated and Measured Cadmium 3-14
Residues in Food Crops
3-6 Average Daily Water Consumption of Poultry and 3-15
Livestock
3-7 Representative Body Surface Areas and Weights 3-18
for Various Livestock Species
3-8 Estimates of Daily Water Absorption Through Skin 3-19
of Various Livestock Species
3-9 Regression Equations Correlating Bioconcentration 3-21
Factors (BCF) in Aquatic Species to Other Parameters
4-1 Water Intake of Major U.S. Industries, 1973 4-2
4-2 Process Water Usage by U.S. Food Industry 4-4
Groups, 1973
4-3 Water Requirements of Selected Canned Products 4-7
4-4 Direct Food/Water Contact During Processing by 4-12
Food Industry Group
5-1 Estimated Water Use in Home Preparation of Food 5-2
6-1 Metals in Drinking Water Resulting from Various 6-4
Types of Plumbing
6-2 Contamination of Drinking Water in Treatment 6-7
and Distribution
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1.0 SUMMARY AND CONCLUSIONS
The Monitoring and Data Support Division, U.S. Environmental
Protection Agency, is investigating the sources and distribution of
129 priority pollutants in the nation's environment in order to iden-
tify populations of humans and biota exposed to these pollutants and co
determine the associated health risks. In support of that effort,
this task was undertaken to identify and quantify major water-borne
routes of human exposure through food and drinking water.
Points of water contact with food have been identified and, to
the degree possible, the timing and volume estimated. While it was not
possible to arrive at an overall methodology for estimation of con-
tamination, the available information on the extent of water contact,
especially in growth, processing and preparation, suggests that this
source may be an important route of exposure to humans and livestock.
A simplified methodology has been developed for evaluating pollutant
intakes via the water-borne route for food in the growth phase, in-
cluding crops, livestock, poultry, and fish. Background information
on water use in food processing and home preparation is presented that
could form the basis for the development of an estimation model in the
future. Several steps (some exceedingly complex) are required before
actual levels of food contamination resulting from water contact can
be estimated:
• Relate yield of crop to total yield of biomass per acre
for a better estimate of concentration;
• Quantify pollutant loss rates from food during the
growth period;
• Quantify pollutant uptake and loss rates from food
during processing and home preparation.
However, in the process of considering food contamination, several
water-borne routes of contact were identified as being potentially impor-
tant, and could result in human exposure to pollutants.
• crop growth — rainfall or irrigation water
• water consumption of livestock and poultry
• uptake of pollutants from water by aquatic organisms
• water-mixing with food products
1-1
-------
The relative importance of these routes cannot be established at
this time. In addition, although food processing has been shown to
involve large quantities of water, the importance of this route cannot
be established since a detailed assessment of the surface area contacted
and the time of contact would be required. This would vary by crop and
process step.
The routes of contamination of drinking water in treatment and
distribution have also been identified. However, a model predicting
concentrations in drinking water from these sources was not considered
feasible at this time. It appears likely that only specific situations
of contamination (i.e., trihalomethane formation, or lead corrosion)
could be modeled due to the unique nature of each situation.
1-2
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r
2.0 INTRODUCTION
The Monitoring and Data Support Division, U.S. Environmental
Protection Agency, is conducting a systematic investigation of the sources
and distribution of 129 priority pollutants in the nation's environment
in order to determine the exposure and risks to man, fish, and other
biota. One part of this program is the preparation of exposure and risk
assessments, which identify the populations exposed to specific chemicals
and estimate 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-borne routes of human exposure to pollutants.
This task considers methods for identifying and quantifying water-
borne routes of human exposure. The objectives of this task'were to:
• Identify water-borne routes of contamination to food.
• Identify routes of contamination in drinking water
treatment and distribution.
• Develop a methodology for quantifying the contamination
of food and drinking water through the routes identified.
The project was focused primarily on the first two objectives;
data limitations meant that the third objective could be addressed only
in a very preliminary fashion. In addressing these objectives, several
simplifying assumptions were made:
• The pathways of pollutants to the water compartments were
not considered.
• The routes of contamination of drinking water supplies
were not considered.
• The quality of various sources of water used in food
production was not differentiated.
• Pollutant losses occurring in any phase of food production
or drinking water treatment and distribution were considered,
but not examined in detail.
This task was a first step in estimating inputs of contaminants
to food and drinking water. In order to estimate actual concentrations
in food, losses would need to be considered, as well as the specific
characteristics of each type of food and pollutant.
2-1
-------
In order to characterize the routes of contamination of food and
drinking water, several steps in the production of food and drinks
water were examined. For food, Chapters 3.0, 4.0, and 5.0 examine °
contamination during growth, processing, and home preparation. Of
these areas, contamination during growth is the one that can be charac-
terized most quantitatively at present. A simplified methodology is
developed for estimating water, and thus pollutant uptake fay crops.
Rates of water uptake for livestock, poultry, fish and shellfish'are
also discussed in Section 3.2.
Chapter 4.0 describes water use in food processing. It identifies
types of water contact and estimated volumes used in various processes
tor different rood groups. Water use in home preparation is considered
in a similar manner in Chapter 5.0. No attempt was made to develop a
methodology for estimating pollutant intake in processing or home
preparation, since a multifaceted model would be required, and the in-
formation presented in this report is only the first step in the develop-
ment of such a methodology.
The possible routes of contamination of water supplies during
treatment and distribution are considered in Chapter 6.0. Due to°the
nature of the contamination routes, the development of a general method-
ology tor estimating concentration was not attempted. S«^rax mecnoa
2-2
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3'° WATER-RELATED CONTAMINATION OF FOOD DURING GROWTH
3.1 FOOD CROPS
Principles of Irrigation and Crop Physiology
_ _ This section summarizes the key principles of crop phvsioloav and
zrr^atxon practice as background for constructing a preliminarv model
^or food crop contamination by irrigation water. In order to provide
aa-™^ : SlmPle rth°d °f aP?roximati^g uptake, pollutant ur>take is
Su TIL r* ^ Wlth WatSr UPtak£' alth°ugh this is often not the case.
Thus, tne resulting model is not an exhaustive theoretical model incor-
porating all pnysical and biological processes but rather a simplified
metnod o, approximating uptake. Its purpose is to determine the imoor-
tance of water-borne routes of contamination during crop c,rowth
3.1.1.1 Irrigation
Optimum plant performance results at least partiallv from an uninter-
rupted and adequate supply of water (Janick et al. 1969)'. The nature
of each agriculture site is defined by many factors, including soil
horizons, weather regimes, topography, and groundwater hydrologv
Because of the inherently wide variation in and numerous possible com-
binations or these factors, irrigation guidelines have been developed
experimentally for specific crops and soil types in various regions of
the t.S.^ The state Extension Services can supply irrigation data, cal-
culated ror the specific weather condition being experienced in the
region. As an aid to agriculturalists, the Extension Services also
r_ , kfdS °f w«er are associated with soil: hygroscopic, gravi-
tational and capillary. Hygroscopic water is the thin film of water
tightly bound to the soil particles. This bonding renders the water
unavailable _ to plants. Capillary water fills the spaces between soil
?^tlCr6?' 1S f" ln PlaCe by WSak molec^r forces, and is available
for uptake oy plant roots. The third type of water associaTed with soil
is gravitational. This is the water that will be drained by gravity down
to the water table or to an impervious sublayer once the spacfs between
the soil particles have been filled by capillary water. The "field
capacity of a given soil type is defined as the volume of capillarv
hf- follwin§ the Drainage of gravitational water. When
the field capacity _ is used up by withdrawal by roots or by evaporation,
the wilting point is reached and plants loose their turgor (the swollen
condition of the cell caused by internal water pressure). Since It inter-
rupts the plants' normal physiologic functioning (Janick et al. 1969)
loss of turgor is generally avoided. --
3-1
-------
Moisture is added to the soil by precipitation and irrigation. The
effectiveness of precipitation is a function of the intensity and dura-
tion of the storm, the air temperature, and the soil absorption capacity
at the time of the storm. Following a rainstorm, the resulting available
moisture is usually much less than the total precipitation because of
evaporative losses and slow infiltration rates of soils. Rain showers
delivering less than 1/4 inch are likely to result in high runoff losses
and minimal additions to soil moisture. The final soil moisture content,
therefore, is reduced by runoff during and following rain events, and by
evaporation caused by the action of wind and sun.
Irrigation has been shown to be most effective if applied when 60%
of the field capacity has been depleted. The rate of water use by field
crops is determined by hours of sunlight, the drying effects of wind,
humidity, wind speed and direction, the leaf area, root volume, and
temperature. Consumptive use, therefore, will vary widely among plant
species, and even widely for a given crop depending upon its growth
stage. For example, the highest water requirements for any crop are
usually during the flowering stages (Israelson and Hansen 1962)'.
i
The amount of readily available moisture is also a function of the
soil type. As shown in Table 3-1, the light sandy soils drain easily
and, therefore, contain less readily available moisture than the heavier
clay soils. The rate of water extraction by plant roots has been deter-
mined to be a function of the root density and the gradient in water
potential (determined by the concentration of solutes in the root cell
or soil and the turgor pressure). Usually the rate of extraction at the
surface is greater than subsurface rates because of the greater surface
area of roots in the topsoil layers (Janick _et ad. 1969). Experimental
observations indicate that when the depth of the root zone is divided
into four equal horizontal subsurface zones, the following fractions of
available water are extracted (where D = depth of the roots):
Zone 1 (surface to D/4) 40%
Zone 2 (D/4 to D/2) 30%
Zone 3 (D/2 to 3D/4) 20%
Zone 4 (3D/4 to D) 10%
To aid in making decisions regarding irrigation, indices of consumptive
use have been developed. Consumptive use, or evapotranspiration, is the
water loss from a unit surface of land directly (evaporation) and from
plant surfaces (transpiration) (Israelson and Hansen 1962). These
indices are empirically derived constants, which compare the water needs
of a variety of crops to one baseline crop for a given region. In
Table 3-2 the consumptive use indices of 26 crops are presented for the
Western States, using alfalfa as the baseline crop for comparison.
3-2
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r
TABLE 3-1. COMMON WATER CAPACITIES OF SOIL BY SOIL TYPES
Soil DescriDtion Readily Available Moisture
light, sandy - coarse to fine Q.7 - 0.9
medium, loamy - fine sandy loam 1.5
silt loam ]__g
heavy, clay - clay loam 2 1
clay
Source: Janick _et_ al. (1969).
3-3
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TABLE 3-2. SEASONAL CONSUMPTIVE-USE REQUIREMENTS OF COMMON IRRIGATED CROPS
IN RELATION TO THE REQUIREMENTS FOR ALFALFA—WESTERN STATES
Croos
Relation of Seasonal Consumptive
Use of Crops listed to the Season-
al Consumptive use of Alfalfa—
(Optimum Yield)
Alfalfa
Almonds3
Apricots3
Artichokes
Avocados3
Beans
Berries
Clover
Carrots
Corn
Citrus3
Cotton
Grain
Grain-Sorghum
Grapes
Hops
Lettuce
Melons
Pasture
Peaches3
Potatoes—Winter
Potatoes—Spring or Seed
Seed Peas
Sugar Beets
Strawberries
Tomatoes
Walnuts3
1.00
0.42
0.50
0.50
0.52
0.42
0.40
0.90
0.40
0.65
0.70
0.65
0.50 (variable)
0.35 to 0.40
(variable)
0.50
0.15 (Plant use only)b
0.40
0.90 (variable)
0.65
0.50
0.30
0.30
0.82
0.60
0.45 to 0.50
0.60
3Add 20-25% for permanent grass—legume cover.
bWater may be applied in addition to that required for growth for the
purpose of quality improvement.
Source: Israelsen and Hansen (1962).
3-4
-------
Table 3-3 presents data on water use by various crops. The data
given are the estimated monthly evapotranspiration amounts (in inche=)
for neld crops grown in the Sacramento Valley. These values do not
include water lost through deep percolation or runoff from the field
In trie Sacramento Valley, evaporation from the soil accounts for apDrox-
mately 10-20% of the seasonal total evapotranspiration (Henderson D.W
Professor of Agronomy, U.C. Davis, California, personal communication '
iy/y). mus, tne total amount of water actually utilized by a criven
crop over its growing season may be estimated from Table 3-3 bv°reducina
the figure to 80-90% of the seasonal total."
3.1.1.2 Crop Physiology
The rate of water intake by a plant varies with its growth stage as
noted above. As measured by evapotranspiration, the intake will inc-ease
steadily during the vegetative stage of the plant's growth, the flowerin*
stage occurs near maximum evapotranspiration, and during the fru^'tin*
stages, the evapotranspiration begins to drop. Transpiration (water"loss
from plant surfaces) is virtually at a standstill in annuals when the
iruit has completely matured, dried, or fallen from the plant. Figure
3-1 presents the curve for consumptive use of water over the life cycle
of an annual crop. The difference between the curves for consumptive
transpiration indicates the amount of water evaporated from the soil
surface. Note that as the plant matures and the leaf area increases,
the proportion of water evaporated from the soil surface diminishes.'
The amount of water a plant takes in through its roots is much greate^
than the amount finally retained by the plant; approximately 99% of the
water brougnt into the plant is vaporized from leaf surfaces. Loss
occurs^mostly through the stomata (80-85%) and through the cuticle
(10-15%). The rate of transpiration can be as much as 1.25 g per 100
cm^ of leaf surface (Israelson and Hansen 1962; Wilson and Loomis 1967).
3.1.2 Contamination Model
Much of the research necessary for a model that completely and
accurately follows all the biological and physical processes,' is either
lacking or ongoing. Hence the present contamination model for wate^-
contact through irrigation is extremely simplified. It estimates the
volume 01 water that can be associated directly with the plant. The
resulting estimated concentration of the contaminant in the edible por-
tion represents a (not necessarily the only.) worst case scenario, but is
primarily an attempt to determine the importance of the water-borne
route of contamination.
The assumptions made in this analysis are listed below, followed by
the resulting conclusions and necessary discussion. The symbols used
in the model are shown in Table 3-4.
3-5
-------
Croo and Growing Period — '
ArtichoKes
Broccoli
Brussels Sprouts
Carrots
5,15- 4/15
7/1 - 5/1
7/15- 5/15
2/1 - 5/15
3/15 - 7 '1
8/15 - 12/1
10/15- 3/1
4'15- 8/15
7/15- 3/1
12/1 - 3. "31
1/15- 5/15
Cauliflower
Ceierv
Cucumbers
Lettuce
Onions
Pepoers
Potatoes
Spmacn
Tomatoes
5/15- 8/1
3/1 -11/15
12/1 - 5/1
1/15- 7/1
8/1 - 1 /1
3/15- 6/15
7/1 - 8/31
12/15- 4/15
3/15- 7/15
8/15-11/15
2/15- 9/15
3/1 - 10/1
3/15 - 10/15
2/15 - 9/1
4/1 -11/1
4/1 - 8/31
6,15 - 12/1
9/15 - 11/15
11/15- 1 /31
1/15- 4/15
3/1 - 7/31
5/1 - 10/15
TABLE 3-3
NORMAL CROP WATER USE- '
CENTRAL COASTAL PLAINS £•'
EVAPCTRANSPIRATION .'CONSUMPTIVE USE) TABLE
ESTIMATED MONTHLY EVAPOTRANSPIRATION (inches)-
Jan
1.7
1.7
1.7
1.8
1.8
1.5
.5
1.5
.6
1.6
1.7
.6
Feo
2.2
2.2
2.2
1 .4
2.2
2.2
2.3
1 4
2.2
1 .5
2.1
.7
~f
1.8
Mar
3.1
3.1
3.1
2.5
.9
3.3
3.1
3.1
2.9
.8
3 .1
1.3
2.0
1.7
9
2.0
3.1
.8
Aor
1 .8
3.8
3.8
3.9
f\ O
s
4 .1
3.9
4.1
2.1
1.8
3.1
3.7
3-0
2.3
3.6
1.8
2.4
1.8
1.5
May
2.1
2.2
4.3
2.6
2.3
1 1
4.S
4.1
4.4
4.7
4.6
4.4
4.7
3.1
4.9
4.4
1.2
Jun
7
4.9
4.6
3.2
5 1
2.2
1 4.8
4.9
4.9
4.9
4.9
4.7
6.1
1 .4
| 5.6
1.9
Jul
2.1
1 .7
.8 '
5.3
1.2
1 .1
5.2
2.9
2.5
5.3
5.3
5.3
5.3
5.3
6.4
4.2
5.0
5.0
Auq
3.0
2 4
1 .9
* 1
2.3
2.4
2 5
2 1
2.0
4.4
1 .7
4.7
4.8
4.8
4.6
4.8
3.2
5.7
5.7
Seo
3.5
3.C
2.5
2.1
3 4
3.4
3.4
2.5
3.2
1 .8
3.6
3.9
3.9
4.8
.9
4.3
Oet
j
3.2 !
3.2
2.9
3.0
9 '
3.3
3.5
3.3
3.2
3.2
1.5
3.1
4.1
2.4
1.6
Nov Dec
2.2 1.4
2.2 1.4
2.2 1.4
2.2
1 .4 ' .4
2.2 1.5
1 0
2.3 ' 8
1.2
1 0
|
2.3 1.5
i
6
1.2 j
1.6
1.2
.6 1 .2
TOTAL
24.9
24.6
24.6
10. C
12 4
8.4
7.7
15.7
18.0
8.1
1 1 .4
13.6
9.5
10.0
11 7
19.1
11.5
9.2
7 .3
9.2
16.1
9.3
27.5
27.9
28.0
25.8
26.7
23.0
21.8
4.5
3.5
7.3
17.5
19.7
—' Estimated evapotranspiration (Consumptive Usei data were obtained from historic measurements, and from calculations basea on data in
Figure 8 Table 22 and 23. Crop Water Reauirements. No. 24 Food and Agricultural Organization of the United Nations.
- Coastal areas of San Mateo. Santa Cruz. Monterey. San Luis Obispo and Santa Barbara Counties.
—' Planting to narvest.
4/
— Other crops which have similar growing seasons ground cover, and growth characteristics nave similar ET requirements.
Source: Anonymous (und.)
3-6
-------
"ipt/ist ute
CT, g in inchti pfr day
If ioo?
o o»
40 50 60 7B
P*r:enf of entire Droning period
80
30 36 42
grcwmq pe-iofl m dovs
«-Tionrh growing period in days
49
90
)OC
60
c
0
0
9 " IB r
;nr,
36
Ef-mo-M
12 ?4 36 43
Four- month
'. ! I
'3 ;3 45 60
Five-mcnlh
: ; i
i3 36 54
72
45
' 9ro*!"9
60
75
growing
80
54
period ;n
72
period in
90
period in
ioe
63
floyj
64
days
lOS
days
126
72
96
120
144
81
ioe
135
162
90
120
:50
130
Source: Israelson and Hansen (1962).
FIGURE 3-1 CONSUMPTIVE USE OF WATER BY
AN ANNUAL PLANT DURING
VARIOUS PERIODS OF GROWTH
3-7
-------
TABLE 3-4. SYMBOLS USED IN FOOD CROP CONTAMINATION MODEL
Symbo1 Description
ET = total volume in liters of a crops consumptive use of
water or evapotranspiration for a given area in its
lifetime
VT = volume in liters of water utilized by the crop for a
given area in its lifetime (0.9 V )
P = concentration (mg/1) of the pollutant in irrigation
water or rainwater (assumed to be the same as in
groundwater)
p = mass in kg of a pollutant available in a given
area P = p V
[p]Fp = concentration of the pollutant in the plant and
thus in the food part
P (kg)
biomass per unit area (kkg)
concentration of the pollutant concentrated in
the food part
crop yield (kkg)
3-8
-------
1.1.2.1 Assumptions
Assumption: Farmers will seek to maximize yield by keeping the
water content of their fields above 60/1 of field
capacity.
Conclusion: The applied volume of water will be sufficient
to provide for drainage (gravitational water),
runoff, irrigation efficiency, and the volume
(in liters) equal to evapotranspiration (V^).
Discussion: While VET will obviously vary, depending upon
the cost of water, drought, irrigation practices,
accidents, etc., it is an adequate description
of the ideal situation.
Assumption: Approximately 10% of VET will evaporate.
Conclusion: VT = 0.9VET
where V =volume of water utilized by plants
Discussion: This value was found for the Sacramento Valley
area, and does not apply everywhere. It will
be used here as an example.
Assumption: The total mass of pollutant applied to a given field
is a function of its concentration in the total volume
of water applied (either irrigation water or rainfall).
Conclusion: The total amount of pollutant in the field that
is available to plants is that contained in the
volume (VEX). So, if the pollutant concentration
is [p], then the total amount of pollutant (P)
available to the plant is P = [p]•
Discussion: While P is the total amount of pollutant poten-
tially available to the plant, it does not take
into consideration adsorption of the pollutant
onto soil surfaces, release of pollutant from soil
into groundwater, biodegradation in the soil, etc.
Assumption: The transport of pollutant will occur at the same
rate as water transport.
Conclusion: The amount of pollutant entering the plants will
equal the amount available in VEj that is, P.
Discussion: Although pollutant transport rates are known to
vary, this method provides a simple way of
estimating pollutant uptake, and gives a rough
estimate.
3-9
-------
Assumption: Once the pollutant is in the plant, its mass will
not be diminished through evaporation or by metabo-
lism.
Conclusion: The concentration in the plant will be given
by P/biomass for the same area.
Discussion: Again, this is meant to be a worst case assump-
tion, since both volatilization and degradation
may occur. The relative importance of those
removal processes would depend on the chemical
and the particular plant considered.
Assumption: For the purposes of a simple model, it is assumed
that concentrations in the plant and the edible
portion are the same.
Conclusion: [p]__
- LKJ
— — /11 N
biomass (kkg)
where [?]pp = concentration in food part.
Discussion: This concentration may be too low in some cases.
As a maximum, or for lack of information on
crop biomass, the pollutant can be associated
with the food part:
[p]Fp* P(kg)
crop yield
3.1.2.2 Sample Applications
Cadmium Contamination of Cucumbers
Region: California Central Coastal Plains
Growing Season: 3/15-6/15
Procedure Example
a. Find the volume of water that is ET = 9.2 in-
taken up and transpired by the
crop plants on 1 acre, e.g., find V = 9.4x10 I/acre
V tr
VET'
• Find ET for crop and region
from Agricultural Extension
Service data.
3-10
-------
b. Determine (choose) concentration
of pollutant.
• Search STORE! or other
ambient water data files
for an average or high
concentration for the
region.
c. Find P — the amount of pollutant
carried into the plants on one
acre.
P = [p]'VT
0.03 mg/1 is maximum concentra-
tion of cadmium measured in
groundwater (Battelle 1977).
P = 0.03 mg/1 (9.4x10 I/acre)(0.9)
= 25 g/acre
= 0.9V
£T
d. Determine yield of crop (kg/acre)
for the growing seasons (USDA
1978).a
e. Associate pollutant load with
crop yield.
Y = 13.24 tons/acre
= 12011 kg/acre
[p]
FP;
25 g
12011 kg
2 mg/kg
From this example, at a concentration of 0.03 ppm (30 ppb) cadmium in
irrigation waters, cucumbers may accumulate cadmium to a level of
2.0 mg/kg.
Cadmium Contamination of Tomatoes
Region: California Central Coastal Plain
Growing Season: 3/1-7/31
a. ET = 17.5 in.
V£T = l.SxlO6 I/acre
b. [p] 0.03 mg/1
c. P - 0.03 mg/1 (l.SxlO6 I/acre)(0.9)
= 50 g/acre
d. Yield = 13.75 tons/acre = 12,473 kg/acre
3-11
-------
e. [?] * P 50
FP -
Y 12473 6/r^&
Di-2 Ethyl Hexyl Phthalate (DEPH) Contamination of
Iceberg Lettuce
Region: California Central Coastal Plain
Growing Season: 3/15-7/15
a. ET = 16.1 inches
V£T = 1.65xl06 I/acre
b. [p] =3.8 Mg/1 is the maximum found in ambient water in this part
of California according to STORET. The 50th percentile concentra-
tion for the country (the median) is 0.85 ug/1 (A.D. Little 1981),
but the maximum concentration is used as a worst case.
c. P * 3.8 yg/1 (1.65xl06 I/acre)(0.9)
=5.6 g/acre
d. Y * 11.75 tons/acre = 10,659 kg/acre
e. [p]Fp*=! = _
3.1.2.3 Limitations of Model and Comparison of Model Results with
Monitoring Data
The discussion above shows that there are many gaps in the data
necessary to develop a comprehensive model for uptake of waterborne
pollutants by food crops. The simple model developed is meant to
provide a first approximation of contaminant levels in field crops.
Though it is likely that the model will generally overestimate con-
centration, in some cases it may underestimate, for example,
for a compound that is actively taken up by a plant and is not lost
through volatilization or degradation.
In summary, the major assumptions, and sources of uncertainty,
are as follows:
• No losses or gains of the pollutant to the soil (through
leaching, dissolution, or adsorption) are allowed.
• The uptake of the pollutant is assumed to be
equivalent to the uptake of water.
• No losses from the plant are considered; i.e.,
all of the pollutant that enters the plant
remains there.
3-12
-------
• The pollutant is evenly distributed to the plant
parts (including the edible portion) .
The results of the sample applications of the model suggest that
waterborne routes of contamination can be very important for field crops,
Though the estimated concentrations are not expected to reflect accu-
rately real situations, it is useful to compare the model results for
cadmium with actual measurements shown in Table 3-5. The estimated
concentrations of cadmium are substantially higher than measured concen-
trations.
The possible reasons for this difference are numerous. First,
worst-case assumptions were made in many cases, especially with regard
to the concentration in irrigation water. In addition, cadmium is
bound to the soil to some extent and hence unavailable for uptake.
Measured concentrations of DEHP in lettuce were unavailable, but con-
centrations of this compound in other foods are generally less than
0.5 '^g/kg (Arthur D. Little 1980).
3.2 LIVESTOCK AND POULTRY
Livestock come into contact with water via two routes: ingestion
and dermal absorption. The following section estimates the total volume
of water to which four of the most common livestock species — cattle,
sheep, swine and poultry — are likely to be exposed. This provides a
first approximation of the mass of a priority pollutant potentially-
available to livestock over their lifetime as a function of water uptake.
In order to estimate tissue concentration, further information would be
necessary on distribution, metabolism, and excretion of the pollutant.
Again, the goal is to determine the potential importance of waterborne
routes of exposure by estimating the upper limit of the amount of a
pollutant via water each species can possibly be exposed to in their
lifetime.
3.2.1 Ingestion
Water intake must compensate for water loss in respiration, sweat-
ing, urination and defecation. Losses will be greater under certain
environmental conditions (low humidity, high temperature) and require
increased water consumption. Table 3-6 presents estimates of average
water consumption per day for several livestock species. The water
consumption figures given are approximate values, and represent average
rates over a variety of climatic and regional conditions.
3.2.2 Dermal Absorption
With the exception of horses, most livestock found in the U.S. have
only a slight ability to sweat (Brody 1964). When subjected to a high
ambient temperature, cattle and swine in particular are not very effec-
tive at lowering their basal temperature and respond only by panting,
a less efficient heat-loss process than sweating. As a result,
3-13
-------
TABLE 3-5. COMPARISON OF ESTIMATED AND MEASURED
CADMIUM RESIDUES IN FOOD CROPS
Crop
Cucumbers
Cucumbers
Cucumbers in
sludge/amended
soil
Garden fruits
Tomatoes
Tomatoes
Tomatoes
Method
Calculated
Measured
Measured
Measured
Calculated
Measured
Measured
Result
(mg/kg)
2
0.005
0.02
0.01 (max)
4
0.025
0.6
Source
This report
a
Stoewsand (1980)
FDA (1977)
This report
Stoewsand (1980)
Stoewsand (1980)
Includes green peppers, tomatoes, cucumbers, etc., in a composite
sample.
3-14
-------
TABLE 3-6. AVERAGE DAILY WATER CONSUMPTION OF POULTRY AND LIVESTOCK
Daily Consumntion
Species (Gallons) (Liters)
Beef Cattle (all ages; range and 10 38
feedlot, etc.)
Dairy Cows (in milk) 13 49.4
Lambs (on feed) 0.4 1.52
Swine (all but boars) 0.9 3.42
Chicken
Broilers 0.033 0.13
0.064 0.24
Turkeys 0.082 0.31
Source: Arthur D. Little, Inc., estimates.
3-15
-------
temperatures commonly encountered during summer will cause heat stress
and decreased productivities in these animals. Figure 3-2 shows a sharp
decline in various productivities in cattle at temperatures above 18°C.'
In hot environments, two management practices are commonly used to cool
animals: wet blankets and hosing down. Wet blankets, made of moisture-
holding material, are placed on animals during the middle part of the
day (at peak temperature) throughout the summer months. Hosing is the
direct spraying of animals with water.
In the hotter regions of the U.S., the exposure period to water
used for cooling purposes is estimated to be from 10:30 a.m. to 4:30 p.m.
for a total of 6 hours per day (Currie, B., Prof, of Environmental
Physiology, Dept. of Animal Science, Cornell Univ., Personal Communica-
tion 1980). As an upper limit, the maximum number of days per year when
cooling with water is required is estimated to be 90 days (July-September)
Therefore, the maximum period of exposure to water is 540 hours per year
per capita.
As a worst case, cattle, sheep and swine are all assumed to require
dermal contact with water for cooling purposes. Poultry are assumed to
find relief from the heat through panting or artificial temperature
regulation in their housing.
Calculating the amount of water absorbed through the skin during
the period of exposure to water requires data on the body surface area
and a skin absorption coefficient for each species. Table 3-7 presents
average surface areas calculated for swine, sheep, and dairy and beef
cattle. These values are based on a large, full-grown animal to provide
an upper limit.
Skin absorption coefficients for water uptake specific to each
species were not available. As an approximation of these coefficients,
data for human skin were used (U.S. EPA 1979), although the hairless
skin of man would presumably have a higher potential for absorbing
water than the hides of swine, sheep, and cattle. Hair cover acts as
an initial external barrier, and animals constantly exposed to water via
a wet blanket or hosing will have saturated fur, which will not prevent
water absorption. A more important parameter in determining absorption
may be the fiber weave pattern making up the skin collagen and this
varies according to the species (Yates 1971).
The water flux through human skin was estimated to be 0.2-0.5 mg/
cm2/hr (Scheulpein and Blank 1971). As a first approximation of water
absorption in livestock, a rate of 0.3 mg/cm2/hr was multiplied by the
surface area of each livestock species and the duration of daily water
exposure (1.5 hrs/day), in order to estimate daily water uptake through
skin. Table 3-8 presents the results.
3-16
-------
> » ftio 2> Jo'c
(NVItONMENTAt
Source: Brody (1964).
FIGURE 3-2
INFLUENCE OF ENVIRONMENTAL
TEMPERATURE ON FEED CON-
SUMPTION, HEAT PRODUCTION,
AND FEED UTILIZATION IN
DAIRY CATTLE
3-17
-------
TABLE 3-7. REPRESENTATIVE BODY SURFACE AREAS AND WEIGHTS
FOR VARIOUS LIVESTOCK SPECIES
Adult
Species
Swine
Equation to
Calculate
Surface Area
S = 0.10 (W)
0.63
Weight (kg) Surface (m2)
(W) Area (S)
250
3.24
Sheep
S = 0.12 (W)
0.57
70
1.35
Cattle (beef) S = 0.13 (W)°>56
700
5.10
Cattle (dairy) S = 0.12 (W)
0.60
500
5.00
Source: Brody (1964).
3-18
-------
TABLE 3-8. ESTIMATES OF DAILY WATER ABSORPTION THROUGH SK^
OF VARIOUS LIVESTOCK SPECIES ^^Oh =>K
Estimated
p£Cles Water Absorption fg/dav)
Swine , -
Sheen
o
Cattle (beef) 23
Cattle (dairy) 23
3-19
-------
3-2.3 Comparison of Two Exposure Routes
This analysis indicates that ingestion of water may be a far more
significant exposure route for swine, sheep and cattle than dermal
absorption (Tables 3-6 and 3-8): for beef cattle ingestion is about 36 kg
as compared to 23 g/day for dermal absorption. To the degree that water"
tlux across human skin represents a worst case for absorption across the
skin of the three animal species examined, dermal absorption can be ruled
out as a significant route.
By contrast, the water consumption by livestock and poultry appears
co be an important potential source of contamination. Water consumption
represents a larger mass than does food consumption for livestock. 'For
example, for beef cattle, water consumption is about 38 kg, and food
consumption (as corn equivalent) is about 7 kg. Thus, based strictly
upon considerations of mass intake, water consumption represents a larger
source. °
3.3 AQUATIC ORGANISMS
For fish and other edible aquatic species constantly immersed in
water, water is obviously a primary route of contamination. Consider-
able research has been conducted on pollutant uptake in aquatic species,
and methods have been reported to estimate pollutant uptake (bioaccumula-
tion) for certain groups of chemicals.
The bioconcentration factor (BCF), the chemical concentration in an
organism's tissue divided by the concentration in water, is commonly
used to express pollutant uptake by aquatic species. This is an equili-
brium expression assuming that any further uptake of pollutant is
balanced by the depuration, or excretion, rate of the substance. For
36 organic compounds, Kenaga and Goring (1978) derived regression equa-
tions relating each chemical's bioconcentration factor to its water
solubility and octanol-water partition coefficient. Table 3-9 presents
the two equations.
Using these equations to estimate contamination of edible fish
species requires that a number of assumptions be made (Kenaga and Goring
1978):
(1) Although considerable species variability in
pollutant uptake is common, these equations
average data from several fish species and it
is assumed that they are applicable to all fish
species as a first approximation.
(2) Although these estimation equations assume concen-
trations in the fatty portion of the fish, the
pollutant is assumed to be evenly distributed
throughout the body of the fish. This provides an
3-20
-------
TABLE 3-9. REGRESSION EQUATIONS CORRELATING BIOCONCENTRATION FACTORS
(BCF) IN AQUATIC SPECIES TO OTHER PARAMETERS
Regression Correlation
Equation Coefficient (r)
Parameter BCF Correlated
with Water Solubility Lo§ BCF = 2*791 ~ °'564 ~ 0-72
Octanol-Water Partition
Coefficient Lo§ BCF = 1'495 + °-935 (L°§ K ) 0.87
ow
Note:
WS = Water Solubility
K = Octanol-Water-partition coefficient
Source: Kenaga and Goring (1978)
3-21
-------
upper-limit estimate of tissue residue levels because ^
fat is usually discarded during evisceration and the
remaining muscle portion is eaten. I
(3) Variability in fish parameters likely to affect
pollutant uptake, such as fat content, was assumed |
to be expressed adequately in the equations. '
(4) All fish caught for consumption are assumed to have 1
been chronically exposed to the pollutant and to f
have reached equilibrium tissue concentrations.
For inorganics, no method exists at this time to estimate the I
BCF in fish or other aquatic organisms. Metals and other inorganics
are commonly detected in fish tissue at high concentrations, but
assimilation does not appear to follow a predictable pattern based on I
the current state of understanding. In addition, species variability |
in uptake patterns is high. For these reasons, no estimation of I
inorganic pollutant concentrations in fish was possible.
The waterborne route is very important in determining residues
in aquatic organisms. Residues of organics can be estimated from the
water concentration and a measured or estimated bioconcentration factor.
It should be pointed out, however, that consumption of contaminated food
items may also contribute to the body burden of aquatic species in some
situations.
3-22
-------
4.0 WATER-RELATED CONTAMINATION OF FOOD DURING PROCESSING
4.1 INTRODUCTION
Of the 15 trillion gal of water consumed by the manufacturing
industries of the United States in 1973, only 5% was accounted for by
establishments processing food and kindred products (Table 4-1), whereas
four other major industry groups accounted for a total of 85%. An
even smaller quantity, possibly about 1 1/2%, actually came into direct
or indirect contact with food products. However, when the nature of the
U.S. food processing industry is taken into consideration, it can be
seen that this use was spread over an exceptionally broad area of opera-
tions, involving a complex set of interrelationships.
The food processing industry in the United States is comprised of
nearly 30,000 establishments that run the entire spectrum from the manu-
facture of bulk commodities in huge quantities, such as fats and oils,
starches, and sweeteners, which are basic ingredients for the rest of'
the industry, to the production of highly processed convenience foods
for both retail and institutional markets.
While there are at least 50 food processing firms in the U.S. with
over $1 billion annual sales, nearly 50% of total food industry sales are
derived from about 22,000 establishments with fewer than 100 employees
each. In 1978 the food processing industry employed over 2 million
people, and produced shipments worth $230 billion.
In addition to this extreme fragmentation, the food industry is
also widely diversified in terms of types of products manufactured and
processes employed. The U.S. Department of Commerce has classified
this industry into 47 individual subsectors at the four-digit SIC code
level. Each of these subsectors is really a complete industry in itself,
with its own unique characteristics and distinctions. The "food industry"
is, therefore, structurally complex, differentiated and interrelated.
4-2 UTILIZATION OF WATER IN FOOD PROCESSING
4.2.1 Introduction
Water comes into intimate contact with foods during preparation
and preservation operations. It is universally used for washing fresh
raw foods at various stages of preparation; it serves commonly as a
carrier of raw materials between unit processes; and it is the medium
through which many unit processes such as soaking, blanching, qualitv
separation, and preheating are applied. Water also serves as an in-'
gredient of formulation or as a principal portion of the brine or syrup
added as a packing medium. Through its direct contact with raw foods
in preparation and processing, or its indirect contact with foods when
4-1
-------
TABLE 4-1. WATER INTAKE OF MAJOR U.S. INDUSTRIES, 1973
Industry
Primary metal industries
Chemicals and allied products
Paper and allied products
Petroleum and coal products
Food and kindred products
Transportation equipment
Total U.S. industries
Water Intake
(billion gal)
% of Total
4,941
4,176
2,415
1,283
804
242
15,024
33
28
16
9
5
2
100
U.S. Department of Commerce (1973).
-------
used to wash food processing equipment, water exerts influence upon the
efficiency of the processing operations and upon the quality of the
finished processed food.
The quantity of water used in food processing is subject to wide
variation, depending on the physical characteristics of the raw food-
stuffs, seasonality and changes in the product mix. Table 4-2 shows
the process water usage by U.S. food industry groups in 1973. For the
purposes of this discussion, process water includes water that comes
into direct contact with the food in addition to water that is con-
sumed in production. It can be seen that the largest users of process
water are the meat and poultry packers, processors of canned and frozen
fruits and vegetables, and brewers of malt beverages. Each of these
industry groups consumed over 20 billion gal of process water in 1973.
A more detailed review of amounts of process water used, and type of
use for each major food item, follows below.
4.2.2 Meat Products
The meat products group is the second largest user of process water
in the U.S. food industry, accounting for 28% of total usage.
The meat packing industry buys live animals and delivers primal
cuts, quarters and sides to meat cutting facilities, which reduce them
to retail film-wrapped packages. Use of process water in this sector
is mostly confined to washing the carcasses after de-hairing, and
washing viscera and major cuts. Much of the water is used for cleaning
the facilities and the processing equipment. In addition, water troughs
are provided for the animals prior to slaughter. Typically, a packing
plant uses about 550 gal of water for every 100 hogs slaughtered.
Water is also used quite extensively in poultry dressing plants.
To assist in defeathering the slaughtered birds, they are first immersed
in hot water to loosen the feathers. Following the defeathering operation,
which is carried out by a variety of machines, the birds are subjected
to a strong spray of water to rinse off detached but adhering feathers.
During the evisceration operation, both the interior and exterior
of the birds are frequently sprayed with water to remove debris. Follow-
ing evisceration, the birds are cooled by conveying them through a
chilled bath. The chilling is accomplished by either a refrigerated
jacket on the tank, or by adding water ice to the water bath. In some
operations, water is absorbed by the bird up to the legal limit of 8%
of the original weight.
The use of water in the manufacture of sausages and other prepared
meats is mostly confined to washing operations following meat cutting
and trimming; to curing for varying lengths of time in brine baths; and
to process line cleanup. Water is also used in production formulation
for the purpose of facilitating grinding, chopping and mixing, and to
prevent overheating of the mix. In this case, not more than 3% of water
4-3
-------
TABLE 4-2. PROCESS WATER USAGE BY U.S. FOOD
INDUSTRY GROUPS. 1973
Process Water Use
bic Code Industry Group (billion gal)
20 Food and kindred products 232.1
201 Meat Products 54.5
Meatpacking plants 36,2
Poultry dressing plants 22.8
Sausages and other prepared meats 3.2
Poultry and egg processing 2.3
202 Dairy Products 11.4
Fluid milk 6^0
Condensed and evaporated milk 3.0
Cheese, natural and processed 1.3
Ice cream, frozen desserts, butter l.l
203 Preserved Fruit and Specialties 74.0
. Frozen fruits and vegetables 27.0
Canned fruits and vegetables 20.5
Canned specialties 16.0
Dehydrated fruits, vegetables, soups 5.3
Frozen specialties 3.4
Pickles, sauces, salad dressings 1.8
204 Grain Mill Products 13.4
Corn wet milling 9.2
Dog, cat, and other pet foods * 1.4
Cereal breakfast foods 1.0
Flour, other grain mill products 0.9
Prepared foods 0.5
Rice milling 0.3
Blended and prepared flour 0.1
205 Bakery Products 1.7
Bread, cake, and related products 1.5
Cookies and crackers 0.2
206 Sugar, Confectionery Products 19.2
Raw cane sugar 8.6
Beet sugar 5 __ 7
Cane sugar refining 3.5
Confectionery products 1.8
4-4
-------
TABLE 4-2. PROCESS WATER USAGE BY U.S. FOOD
INDUSTRY GROUPS, 1973 (Continued)
Process Water Use
SIC Code Industry Group (billion gal)
207 Fats and Oils 2.8
Shortening and cooking oils 1.1
Animal and marine fats and oils 0.9
Soybean oil mills 0.6
Other vegetable oil mills 0.2
208 Beverages 34^3
Malt beverages 21.0
Bottled and canned soft drinks 6 4
Malt 4]5
Distilled liquor, except brandy 1.2
Flavoring extracts, syrups 0.8
Wines, brandy, and brandy spirits 0.4
209 Miscellaneous Foods 10.8
Canned and cured seafoods, other food
preparations n.e.c. 6.0
Fresh or frozen packaged fish 1.9
Roasted coffee ]_]g
Manufactured ice 1_0
Macaroni and spaghetti 0.1
Source: U.S. Department of Commerce (1973), and
Arthur D. Little, Inc., estimates.
4-5
-------
and/or ice may be added to uncooked sausage, while cooked sausage may
contain not more than 10% added water. I
4.2.3 Dairy Products "
Despite the high-volume production of the milk industry, dairy I
products account for a relatively low share of 5% in process water' '
usage. With a few exceptions, water only comes into direct contact
with the products during sanitation of processing equipment. 1
In the case of fluid milk, process pipes and pumps are primed with
water to facilitate startup. The first run of the water and milk mixture 1
is discarded. Process water in the form of steam comes into direct I
contact with milk when the latter is heated by direct steam injection
Applications of this process include the deodorizing of milk (mostly '
used in the South to avoid garlic-like flavors caused by feed) and the
heating of skim milk prior to drying. Culinary steam is also used in
the manufacture of processed cheese when the shredded cheese is cooked
with live steam for a weight gain of up to 6%. In these instances,
however, the risk of contaminant carryover into the steam is greatly
diminished.
Water may also be added directly during the processing of cheese
in order to control texture characteristics; and in the form of brine
during one continuous butter-making process.
4.2.4 Preserved Fruits and Vegetables
This category of food products accounts for the highest usage of
process water in the U.S. food industry, or about one-third of total
water used. The largest use is in the canning of fruits and vegetables
followed closely by freezing. This is no cause for surprise as much
of the processing equipment, insofar as raw material preparation is
concerned, is common to both industries.
Water is used to clean raw fruits and vegetables, and also to
transport them between various process steps. It is also used to
effect quality separation and facilitate further processing, and is
added directly to canned goods in the form of brine, syrup or sauce,
and to some frozen foods to prevent quality loss due to dehydration!
Water consumption can vary over wide limits, depending upon the
physical characteristics of the raw material. In the canning industry,
water use can range from a low of 300 gal/100 cases of finished product
in No. 2 cans for sauerkraut to 25,000 gal/100 cases for lima beans
(see Table 4-3). At a usage level of 7,000 gal/100 cases, tomatoes
are fairly representative of the group as a whole.
4-6
-------
TABLE 4-3. WATER REQUIREMENTS OF SELECTED CANNED PRODUCTS
Product TT Total
~~ ~ Water Consumption
(gal/100 cases
No. 2 cans)*
8,000
7,000
Beets
2,500
Corn
2,500
Grapefruit juice
500
Grapefruit sections .. fnn
5,600
Green beans
3,500
Lima beans
25,000
Peaches
6,500
Pears
6,500
Peas
2,500
Pork and beans
3,500
Pumpkin
2,500
Sauerkraut
300
Spinach
16,000
Squash
2,500
Succotash
12,500
Tomato products
7,000
Tomatoes, whole
750
*24 cans/case
Source: Jordan (1963).
4-7
-------
Water enters the tomato processing operation together with the I
tomatoes at the rate of about 2500 gal of water per ton of tomatoes.
About 10% of this water is initially used to soak the whole fruit so I
that contaminants are loosened on the surface. Following the soaking |
operation, about one-third of the water is used in a high-pressure spray
to remove the surface contaminants. About 5% of the water is used to •
generate steam, part of which is used in direct contact to scale the I
tomatoes prior to peeling or pulping. The balance of the water is
used to clean up the facilities and the processing equipment. The
residual water contained in solid packed tomatoes or tomato juice is J
extremely small. Water is added as an ingredient in tomato sauces. *
The quantities of water used in raw material preparation for j
dehydration compare closely with those for canning or freezing, on a 1
per unit basis. In the case of pickle manufacture, the product is
soaked in brine for a period of up to several weeks to ensure thorough
penetration of the pickling solution.
4.2.5 Grain Milling Products
Despite the high volume and diverse nature of the products in-
cluded in this industry group, process water usage accounts for 67,
of the total food industry use.
Seventy percent of the group total is accounted for by the corn
wet milling industry, which processes whole yellow corn into a wide
variety of products such as corn starch, chemically modified starches,
corn syrup, dextrose and high fructose corn syrup (HFCS); and by-products
such as corn oil and animal feed.
Water is used extensively throughout the process. Cleaned corn is
first steeped and softened in warm water tanks for several days. The
"steepwater" or water drained off from this process, containing about
900 Ibs solid matter per 1000 gal, is a good protein source, and is
converted to animal feed or used as a fermentation nutrient after con-
centration. The kernels are subsequently milled to remove the corn
germs, which are washed and separated by flotation.
After subsequent grinding operations, starch is removed from the
gluten by flushing with water. The starch is finally cleaned by a
series of washings and filtering processes; the wash water is re-used
in earlier stages of the process.
Rice milling is somewhat similar, insofar as a hot water steeping
process may be used to condition the product prior to milling.
Dog, cat, and other pet foods include moist and semi-moist product
categories. In both of these instances, water is used in product
formulation to a greater or lesser extent, as well as coming into in-
direct contact with the product during processing line cleanup operations.
-------
Cereal breakfast foods can also be classified into two general
types: those made from whole grains or their mill products, and those
made from fabricated cereal products. Considerable variations exist
within each type in regard to the cereals and other raw materials used,
and the type of processing employed. The grains may be cooked in steam,
while water may form part of the formulation in dough preparation or
flavoring system.
A small quantity of water is used in the flour milling industry
to wash the wheat, which is then passed through a centrifuge to remove
excess moisture. A further addition of water may be made to condition
the wheat prior to subsequent milling operations. This toughens the
bran and assists separation.
4.2.6 Bakery Products
Bakery products take only 1% of the total process water consumed
by the U.S. food industry. Process water usage is largely accounted
for by dough manufacture—typically about 40 Ibs of water are required
for every 66 Ibs of flour in order to prepare a bread dough. Similarly,
cakes and other bakery products incorporate water to a greater or lesser
extent in their formulation.
Water is also used in pan washing, and in cleaning other equipment
and utensils.
Cookie and cracker production is fairly similar to bread production,
except that in general stiffer doughs are prepared, and so the quantity
or process water used is less.
4.2.7 Sugar, Confectionery Products
This industry group accounts for 8% of total food industry use of
process water. Most of this occurs in raw cane sugar and beet sugar
processing operations.
Large quantities of water are used in raw cane milling. A typical
cane sugar mill processes about 2,000 tons of sugar cane per day
Around 22% of this quantity is required in inhibition water. This is
water that is added to the cane while it is being passed through the
crushing rollers. The water mixes with the raw juice, which is sub-
sequently concentrated by evaporators.
A cane sugar refinery produces white crystalline sugar from the
raw sugar resulting from the milling operation. Sugar cake is washed
in hot water, and the crystals are then dissolved in about one-half
their weight of hot water, prior to recrystallization. The process
requires a water consumption of about 0.5 gal for every pound of sugar
•L CX Juried •
4-9
-------
In the processing of sugar beets, the raw material is conveyed
to the initial stages of production by water channels or flumes.' Water
sprays are used in rotary beet washers, where gross contamination is
removed. The beets are then sliced and passed into a diffusor, where
the sugar is extracted with hot water. Flow rates are high, as a lar
-------
and in the preparation of cooled carbonated water, the other major
formulation component. Water also comes into direct contact with the
product through its use in can and bottle washing, as well as in the
sanitizing of equipment and utensils.
The production of distilled liquors generally involves mashing
the grain or other fermentable raw materials with hot water as the first
step in the process. After distillation, the beverage is adjusted to
the desired proof or alcoholic strength by the addition of plain or
distilled water.
In the case of wines and related products, the use of water is
limited to indirect contact applications such as bottle washing and
sanitizing equipment, with the exception of certain wines based on fruit
other than grapes, such as blackberries and peaches, where water is
used in product formulation.
4.2.10 Miscellaneous Foods
This final category accounts for 4% of total process water consump-
tion and is dominated by the processing of fresh, frozen, canned, and
cured seafoods.
Liberal use of water is made at all stages of fish processing,
including gutting, filleting, cooking, and canning in brine or sauce.
Water comes into contact with whole fish and fillets in the form of
.ice, which is added to slow down the rate of deterioration of the product
before the preservation process. Extensive use is made of water in
process line cleanup.
In addition to making ice for commercial fish harvesting and pro-
cessing operations, ice makers manufacture and sell ice for institutional,
wholesale and retail customers.
The coffee industry uses water in the manufacture of soluble
coffee. Ground, roasted coffee is extracted with hot water, and then
the resulting liquid is evaporated or spray dried to a powder.
Macaroni and spaghetti is produced from a dough containing semolina
durum flour, water, and other ingredients. This category represents
one of the lowest demands for process water in the U.S. food industry.
4-3 SUMMARY OF WATER USE DURING PROCESSING
Table 4-4 contains a summary of water use during processing by
food industry group. It identifies the process in which water has
direct contact with the food. The text has discussed quantities of
water associated with most of these particular steps and the conditions
of contact using representative examples. For instance, the following
breakdown was derived for tomatoes:
4-11
-------
FABLE 4-4. DIRECT FOOD/WATER CONTACT DURING PROCESSING
BY FOOD INDUSTRY GROUP
N. PROCESS
FOOD ^v
INDUSTRY \^
GROUP N^
Meat Products
Meatpacking
Poul trv
Sausages/Prepared Meats
(Dairy Products
J rluid Milk
C'.ieese
Fruits, Vegetables
Canned/rrozen
Pickles
Grain Milling
Corn wet Milling
1 Pet Foods
Breakfast Cereals
Flour Milling
IBakerv Products
i Bread
Cookies
(Sugar, Confectionery
Cane Sugar
Beet Sugar
Fats, Oils
Animal/Vegetable Oils
Beverages
Malt Bevt?rar:es
Soft Drinks
Distilled Liquor |
V, I n c' s
h — »~- — _.
Miscellaneous
Canned Seafood
rrozen Seafood
Roasted Coffee
Macaroni /Spaghetti
i
i
K
C
f-
y
•H
U
a
•
1
I
=
-— f
c
— t
en
en
OJ
y
1
•
1
1 •£
s
,
1
1
1
i
c
ra
•j
!
«
.
«
i •
f
,
• i
1 ,
.
»
•
•
•
•
•
•
•
•
-------
process water contact (gal/ton product)
soak 250
spray 800
steam 125
These values cannot be summed to obtain a total water contact
since these processes involve different types of contact. A model
could be developed as for food during growth, however, several factors
need to be taken into consideration before amounts of contaminants
entering food can be estimated.
• Detailed assessment of the surface area contacted, and
the time of contact. This would vary by crop and
process step.
• Consideration of the rates of absorption or adsorption
of water or the pollutant under the conditions specified
for each processing step.
Thus, although the opportunities for water contact can be specified,
this information cannot yet be used for calculating the resultant con-
centrations of a water-borne pollutant in processed food.
4-13
-------
o
substantial amounts ater Ire
of water consumption
in the
processas th" "l-ir.
« -
as wel1 as estimates
likelihood does not entail si^nTf- riC6' ^ PaSta) * StSamin§
Partly because ofthe stall oSntiti^ T^' °f f°°d C°
because ,any Inorg^ic'Sit^St.'^ n° t^po^^'rei h-
presents minimal potential for contamination T re^d^y- Washing
brief contact of the food with wate^ ' * " relati^ly
actuaf L^^J^^f a^f JJf ^f-e data as a basis for estimatin,
Processing. The data requirements ?or a ^dT'10^ Previ°us1^ ^ food
preparation as home preparation thS a moH^ ""i the Same f°r co^rcia
similar considerations. For products « h ^^ d ^ devel°Ped using
added directly (see water mLx'ngt ll*£ ? 5-1) Je^°' C° Wh±Ch Water is
concentrations in water to estimate ron, , v°lumes can be used with
foods. As an example, huLnTar* LnT n tratl°ns in those particular
2 I/day of tap water Is drinking Xfter an^ • C°nSidered to Consume about
tea). ' if a person wer£ ™JJat« a^d ln water-based drinks (coffee,
eggs, soup, hot cereal rice iello * S J &S drled milk' Peered
about 1.8 1 of water with th^s produc s Th" ^^ ^ mi^ht
from drinking water could be complrabl^ % ,' lntake °f a PoHutant
tion of these products. con>Parable to mtake resulting from conSump-
5-1
-------
TANLE 5-1. ESTIMATED WATER USE IN HOME PREPARATION OT E()()l)
Water Ust^ (oz) per Unit of Preparation
Food Group
Fresh Vegetables
Lettuces
Root vegetables
Spinach, cabbages,
b roc eo I i
Li j'uin-s
Torutoes, peppers
Sqnaslies
Corn
Frozen Vegetables
Canned Vegetables
Freeze-dricd Vegetables
Fresh Fruits
Herrles
Fresh Fruits
Dairy Products
Dried Milk
Condensed Milk
Powdered Egj;s
Boiling
32 oz./lb.
32 oz./lb.
32 oz./lb.
16 oz./lb.
32 oz./lb.
48 oz./lb.
8 oz./12 oz. pkg.
8 oz./can
Steaming
8 oz./lb.
8 oz./lb.
Water Mixing
16 oz./4 oz. pkg.
16 oz./4 oz. pkg.
32 oz./5 oz. pkg.
16 oz./can
16 oz./pkg.
Stewing
1
1
16 oz./lb.
16 oz./lb.
16 oz//lb.
48 oz./lb.
16 oz./lb.
Washing
— —
64 oz . /head
32 oz./lb.
64 oz./lb.
64 oz./lb.
32 oz./Jb.
32 oz./lb.
32 oz./lb.
32 oz./lb.
-------
TABLE 5-1. ESTIMATED WATER USE .N HOME PREPARATION OK KOOI, (Continued)
I
to
Food Group
Meats
Fronh (nil meats)
Poultry, fresh fish
Freoze-drlcd (.ill moats)
Prepared Foods
Dry Soup Mix
Condensed Soup
Single Serving Soups
Boullion Cubes
Hot Breakfast Cereals
Rice
Pasta
Baking Mixes
Gelatin, Instant Pudding
Drinks
Frozen Juices
Tea Bags
Loose Tea
Instant Tea
Ground Coffee
Instant Coffee
Powdered Mixes
, Source-: Arthur I). LiLtle, inc. estimate.
per Un U oj Preparat i on
Water Mixing
16 oz./4 oz. pkg.
24 oz./pkg.
11 oz./can
8 oz./pkg.
6 oz./serving
12 oz./pkg.
16 oz./pkg.
48 oz./12 oz. can
12 oz./bag
J6 02. /tsp.
oz./tsp.
12 oz./tsp.
6 oz./tsp.
48 oz./pkg.
04 oz./lb.
Wash ing
16 oz./lb.
-------
6-0 DRINKING WATER CONTAMINATION DURING TREATMENT AND DISTRIBUTION
6.1 INTRODUCTION
Much emphasis has been placed on the contamination of drinking
water supplies, and only recently has contamination in drinking water
treatment and distribution been considered as a source of human exposure
to hazardous chemicals. This Chapter examines such types of exposure.
Unlike food contamination, drinking water contamination during treat-
ment and distribution is generally limited to certain types of chemicals.
Chemicals introduced in water treatment and distribution come in direct
contact with the water supply and predicting the resultant contamination
requires specific information on water chemistry and other environmental
conditions. This Chapter considers qualitatively the types of such
contamination that may occur and the conditions that promote the occur-
rences.
Figure 6-1 shows the flow of drinking water from the water supply
to the consumer. Several sources of contamination have been identified,
including chemical additions at the treatment plant, chemical production
at the treatment plant, pipe corrosion, and leakage into pipes. These
types of contamination will be discussed individually below.
6.2 CHEMICAL ADDITIONS AT THE TREATMENT PLANT
Thousands of chemicals are used in water treatment in the U.S.
today. The U.S. EPA has compiled a long list of approved additives,
however, has no regulatory authority except through the individual
states. Thus, although the composition of some additives is very well
known, i.e., chlorine, the composition of others is largely unknown."
In addition, even the known chemical additives may contain trace con-
taminants that have not yet been identified.
With the exception of chlorine and florine, most chemicals added
at the treatment plant are not intended to remain in the finished
drinking water. Nevertheless, little is known about the fate of these
chemicals, and especially the fate of any contaminants.
6.3 CHEMICAL FORMATIONS AT THE TREATMENT PLANT
The chlorination of drinking water results in the formation of
chlorinated organics, particularly trihalomethanes. The production of
these compounds, especially chloroform, appears to depend primarily on
the available precursors. Arguello et al. (1979) reported that such
compounds in raw water as resourcinol, A-methoxyphenol, humic acid,
2,6-dimethylphenol, pentachlorophenol, hydroquinone and n.n-diethylaniline
in raw water resulted in a high production of chloroform. The production
of bromofonn was directly related to the bromide concentrations in raw
6-1
-------
Consumer
leaching
Water supply
ground or
surface
to
pipe
corrosion
chemical
1
Treatment!
chemical
formations
i
i
Pi;
CO]
r
ie
rros ion
Consumer
1.
chemi cal
addi tions
FIGURE 6-1. SOURCES OF CONTAMINATION OF DRINKING WATER IN TREATMENT AND DISTRIBUTION
-------
water. Temperature appears to influence the production of trihalomethanes,
usually resulting in a lower production at lower temperatures. In addi-
tion, trihalomethanes continue to be formed in the distribution system if
the water contains a chlorine residual, an appropriate precursor,'or
both (Brett and Claverley 1979).
The estimation of trihalomethane concentrations, based on these
variables is complex. While production ratios (from precursors) have
been calculated in the laboratory, these ratios are not useful in the
field for predictive purposes. The primary reason for this is that in
the field a composite of precursors will be available, and production
ratios are not likely to be the same as in the isolated laboratory-
situation.
6.4 PIPE CORROSION
Pipe corrosion is a well-known problem in water distribution,
and the release of metals from lead pipes into the drinking water'has
been studied extensively. However, other chemicals may be released in
the distribution, such as vinyl chloride and asbestos if PVC or asbestos-
cement piping is used. This section will discuss these types of dis-
tribution systems and the resulting contaminants.
6.4.1 Metal Pipes
The release of metals from distribution systems depends on the water
quality and the piping material used. Important water quality parameters
influencing corrosion are pH, alkalinity, hardness, temperature, dis-
solved oxygen and dissolved carbon dioxide (McFarren et al. 1977).
In general, soft waters containing dissolved oxygen and "carbon dioxide
promote corrosion, especially at higher temperatures (Karalekas et al.
1976). — —
Distribution systems have most commonly been examined from a
materials point of view, that is, the corrosion is measured as loss in
diameter in mils per year. Though this is a quantitative measure of
loss, it bears little relationship to concentrations of metals that
™aLiroSSVn thv WStfr* Jable 6-X Shows ^'P*3 of Plumbing used and the
metals that may be released. These types of materials corrode at
different rates under different conditions and the rate of corrosion
is not predictable.
Even for the same water system, concentrations vary depending
on the time of day. For example, the maximum sample taken in a survev
of homes in the Boston area showed 1.5 mg/1 lead in a standing sample'
(the water was standing in the pipes for several hours). In a running
sample (the water is run for several minutes before sampling) the level
of lead was 0.13 mg/1, a difference of a factor of ten (Karalekas
€ L 3.J.. j.9/0y.
6-3
-------
TABLE 6-1. METALS IN DRINKING WATER RESULTING FROM VARIOUS TYPES OF PLUMBING
o>
Type of Plumbing
Lead
Zinc-lined galvanized Iron
Alloys (solder, brass, bronze)
Iron and steel
Copper and brass
Stainless steel
Resultant Metal in
Drinking Water
Lead
Lead, zinc, cadmium
Copper, lead, silver, zinc
Iron, manganese
Copper
Chromium, nickel
Concent rations Found'
Pb - 170-1500 ug/1
Pb - 3.2-24.1 ug/1, Cd
<0.04-0.2 ug/i, 2n-280-
1400 ug/1.
aPipe exposed to corrosive water and standing water.
Sources: Karalekas et al. (1976) and McFarren £t al. (1977),
-------
While most metals are leached from the piping material, as is
shown in the example given above, small amounts of lead or other metal
may come from other sources such as lead joints, gaskets and lead-tin
solder used in the system. Though these sources probably represent
insignificant sources as compared with lead pipes, they may significantly
contribute to lead levels where other types of piping are used.
6.4.2 Asbestos-Cement Pipes
Asbestos-cement pipe is commonly used in the United States in
water distribution systems. Hallenbeck _et al. (1978) reported that
one-third of all water distribution pipe sold at that time in the U.S.
was asbestos-cement.
Recently, the release of asbestos into drinking water in the dis-
tribution has been observed (Sargent 1974; Peterson 1978, McFarren
et_ al_. 1977). The American Water Works Association Standard C400-77
sets criteria for quality of water that can be transported through
asbestos-cement pipe using the equation pH + log AH, where A equals
the alkalinity (mg/1 as CaCO^). This equation is used to determine
the agressiveness of the water. Values greater than 12 are non-aggressive,
10.0-11.9 are moderately aggressive, and less than 10 are considered
highly aggressive. The use of this equation implies that the release
of asbestos is related directly to these parameters.
While pH, hardness and alkalinity may influence the release of
asbestos from pipes, other factors are also important. For example,
Buelow e_t al. (1979) have shown that zinc, iron, and manganese in the
water can provide protection against asbestos release. On the other
hand, mechanical handling during installation and tapping for new users
promote release, if only temporarily. In addition, a high H2S content
in the source water was associated with higher levels of asbestos in
drinking water.
Obviously the release of asbestos from piping is a largely unpre-
dictable event. Levels may vary within a system at different times.
Therefore, calculating asbestos levels resulting in drinking water
would be extremely difficult.
Liners of concrete pipes can also be a source of pollutants in
drinking water. Tetrachloroethylene has been reported at levels up to
5 mg/1 in drinking water in Massachusetts. These levels were caused by
leaching from a resinous liner of concrete pipes used in distribution
systems (DEQE 1980).
6.4.3 PVC Pipes
Polyvinyl chloride (PVC) pipe has been used in distribution systems
for a number of years. Though it has not been studied extensively, PVC
pipe has generally been considered stable. Flexible PVC, however", has
been shown to release a number of organic materials, including numerous
6-5
-------
phthalate esters (Junk et al. 1974). In addition, Dressman and McFarren
(1978) nave ooserved the migration of vinyl chloride from PVC into water.
Little is known about the factors affecting such migration, but it does
not seem to depend as much upon water chemistry as does the migration
from metal pipes.
In addition to vinyl chloride, Wang and Bricker (1979) identified
MEK (2-butanone) and THF (tetrahydrofuran) in a water supply after PVC
pipes were installed. These solvents were used in the PVC pipe cement
used to join the tubing. The concentrations in this particular case
depended upon the residence time, up to an equilibrium concentration.
Clearly too little is known at present about the release of con-
taminants from the PVC pipe to describe even the conditions that promote
6-5 ACCIDENTAL CONTAMINATION IN THE DISTRIBUTION SYSTEM
Accidental contamination of drinking water in the distribution
system may occur in a number of ways, including cross-connections,
back-siphonage, and breaks in the system. The contaminants that may
result are limitless, and do not depend upon the characteristics of the
water, the distribution system, or the chemical. As a typical example
of what may occur, Craun and Gunn (1979) described an incident in which
Sitr?r?- C° a h°me f°r termitS C°ntro1 had entered a water
distribution system due to back-siphonage. It was hypothesized that
fnd rhSl PTaratl°n ^d dUUti0n °f the solution, back-siphonage occurred
and chlordane entered the distribution system.
Obviously, this type of incident cannot be predicted, nor can the
situations in which it would occur be described.
6.6 SUMMARY
Some of the important routes of contamination in drinking water
treatment can be described qualitatively as shown in Table 6-2. In
some cases the conditions that may promote release or contamination are
known but in no case can the estimated resulting concentrations of
water-borne pollutants be calculated.
6-6
-------
TABLE 6-2. CONTAMINATION OF DRINKING WATER IN
TREATMENT AND DISTRIBUTION
Contamination Route
Treatment:
Chemical addition
Chemical formation
Distribution:
Pipe Corrosion
Cross-connection, back-
siphonage
Chemicals Involved
Large number, chlorine and
fluoride common
Trihalomethanes, other chlorinated
organics
Metals, asbestos, vinyl chloride
Unknown
6-7
-------
7.0 REFERENCES
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Distributed by Interagency Agricultural Information Task Force; undated.
Arguello, M.D.; Chriswell, C.D. ; Fritz, J.S.; Kissinger, L.D.; Lee, K.W. ;
Richard, J.J.; Svec, H.J. Trihalomethanes in water: a report on the
occurrence, seasonal variation in concentrations, and precursors of
trihalomethanes. J. Am. Water Works Assoc. 71(9):504-508; 1979.
Arthur D. Little, Inc. An exposure and risk assessment for phthalate
esters. Washington, DC: Office of Water Regulations and Standards,
U.S. Environmental Protection Agency; 1981.
Battelle Columbus Laboratories. Multi-media levels of cadmium.
Washington, DC: Office of Toxic Substances, U.S. Environmental
Protection Agency; 1977.
Brett, R.W.; Calverly, R.K. A one-year survey of trihalomethane concen-
tration changes within a distribution system. J. Am. Water Works Assoc.
71(9) .-504-508; 1979.
Brody, S. Bioenergetics and growth. New York, NY: Hafner Publishing
Co.; 1964.
Buelow, R.W.; Millette, J.R.; McFarren, E.F. Field investigation of
the performance of asbestos-cement pipe under various water quality
conditions. Cincinnati, OH: Water Supply Research Division, U.S.
Environmental Protection Agency; 1979.
Craun, G.F.; Gunn, R.A. Outbreaks of waterborne disease in the United
States: 1975-1976. J. Am. Water Works Assoc. 71:422; 1979.
Department of Environmental Quality and Engineering (DEQE). Tetra-
chloroethylene update. DEQE, Commonwealth of Massachusetts; 1980.
Dressman, R.C.; McFarren, E.F. Determination of vinyl chloride migration
from polyvinyl chloride pipe into water. J. Am. Water Works Assoc. 20(1):
29-30; 1978.
Food and Drug Administration(FDA). Compliance program evaluation.
FY 74 total diet studies. Washington, DC: Food and Drug Administra-
Bureau of Foods; 1977.
Hallenbeck, W.H.; Chen, E.H.; Hesse, 'C.S.; Patel-Manklik, K.; Wolffe, A.H.
Is chrysotile asbestos released from asbestos-cement pipe into drinking
water? J. Am. Water Works Assoc. 70(2):97-102; 1978.
Israelson, O.W.; Hansen, V.E. Irrigation principals and practices.
3rd ed. New York, NY: John Wiley and Sons; 1962.
7-1
-------
Janick, J.; Schery, R.W.; Woods, F.W.; Ruttan, V.W. An introduction
to world crops. San Francisco, CA: W.H. Freeman; 1969.
Jordan, H.E. Industrial requirements for water. As cited in Heid, J.L.;
Joslyn, M.A. Food processing operations. Westport, CT: Avi Publishing
Co.; 1963.
Junk, G.A.; Svec, H.J.; Vick, R.D.; Avery, H.J. Contamination of water
by synthetic polymer tubes. Environ. Sci. Technol. 8(16):1100-1106•
1974.
Karalekas, P.C.; Cran, G.F.; Hammonds, A.F.; Ruan, C.R.; Worth, D.J.
Lead and other trace metals in drinking water in the Boston Metropolitan
area. J. New England Water Works Assoc. 90(2):150-179; 1976.
Kenaga, E.E.; Goring, C.A.I. Relationship between water solubility
soil-sorption, octanol-water partitioning, and bioconcentration of
chemicals in biota. Third Aquatic Toxicology Symposium, ASTM, October
1978, New Orleans, LA; 1978.
McFarren, E.F.; Buelow, R.W.; Thurnau, R.C.; Gardels, M. ; Sorrell, R.K.;
Snyder, P.; Dressman, R.C. Water quality deterioration in the distri-
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