Organic micropollutants in drinking water: An overview

Organic micropollutants in drinking water: An overview

The Science the Total Environment, of Science Elsevier Organic Publishers B.V., Micropollutants Joseph Office A. of -Printed Drinking Wate...

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The Science

the Total Environment,

of Science

Elsevier

Organic

Publishers

B.V.,

Micropollutants

Joseph Office

A. of

-Printed

Drinking

Water:

in

Cotruvo, Drinking

U.S. Water

47 (1985) 7-26

Amsterdam

Environmental

7 in The Netherlands

An Overview

Protection

Agency

ABSTRACT Biological contamination is still the most significant public health risk from drinking water even in industrialized countries. High potential for organic chemical transport to drinking water continues to exist even with source protection because of the multitude of chemical types and quantities. Drinking water is usually not a unique source nor the most significant contributor to total exposure from synthetic organic chemicals but it might be one of the most controllable. The major public concern with drinking possible contribution to cancer risks from though the actual risks are probably small the public interest to prevent adulteration their quality for the future so that these A risk assessment/management assist the process of making problems and control decisions data in a consi.stent manner.

with

The

U.S.

the

Netherlands

Hygiene,

and

and

the

on

Organic

of

immediate

and

among

tion

of

public

World

synthetic finished some

Protection

National Netherlands

Health

and all

in

continuing

in

is

suggested which may of these contamination consider all of the available

(1)

Water

and

and

production

of

and

in

associated

Environmental Institute

Ltd. Symposium

This

is

a subject

industrialized concerned

drinking

be

International

Health.

are

to

Research

this

especially that

pleased

Health

organizing

organizations

is

Public

Testing

Drinking interest

and

resources,

of

Waterworks

Organization

persons

water

Agency

Institute

Micropollutants

water,

countries with

and

the

protection

protecof

health. Within

ologies

the

decision model assessments consciously

rational that

Environmental

water contamination has been organic micropollutants. Even in most cases it is clearly within of water supplies and to protect concerns or risks can be avoided.

the

to

water

last has

organic drinking substances

ten

at

years

resulted

the in

extension

constituents

waters.

These per

trillion

analytical

identification

chemical

parts

of

of in

techniques levels.

detection

hundreds

rivers,

lakes,

are

now It

is

of

method-

natural

and

groundwaters

capable

of

likely

that

and

detecting many

of

these

recent

existed

detections

for

quite

low

some (parts

detected

in

per

but

from

dermal

from

direct

human

health

to

large

avoid

exposure

to As

the

with

demand to

to the

improper

protect

the

management

and

ideas

concerning

ation

between

cancer

risks.

sources control

egregious

waste

disposal of that

the

be

at

purged

risk volatile

in

the

volatiles

the

water

transported

home,

and

ultimately

exposure in

general

disease to

per

public

water

it

water

may

be

is

and

per

safety.

contamination

that

There

is for

associated

likely

persons

health

resources

to not

million

practices.

our

relative

great the

with

have

future

involuntary

contaminants. to of

the

Symposium

these

this

organic

risk

management based

upon

paper

will

micropollutants

opportunities,

a regulatory substances

of

of

risks

in

substances

water.

but

risks

quality

unnecessary

introduction and

other

examples

environmental

an

types

are

to

cases

may

of

contaminant

known,

of

accumulate

inhalation uses

of

quality

of

may

usually

unpredictable.

which

that

is

generally the

has

variety

inhalation

drinking

completely of

and

health,

water

of

and

of

residues

that

substance

number

large

public

other

numbers

given

protection

source

relative

there

be

contaminated

not

the

water,

and

any

from

air,

this

of

large

associated

public

of is

the

processed

of

terms

nor

Nevertheless

and

showering

risks

can

of

the

from

but

contaminants

into with

in

lifetime,

been

to

water

significance

both

contamination

of

less),

protection

consumption

The

be

in

identifying

body

in

contact air

or

lies

exposures

substances

indoor

concentration

water

also

excessive

to

The billion

interest

environment

fish,

actually

a particular

Public

from

time.

are

their

in

assessment decision possible

briefly drinking

issues, model

describe waters.

and

some

regarding

contributions

recent

differentito

human

9 Sources ---

of

Organic

Micropollutants

Contamination occur

from

numerous

chemical the

of

treatment and

Water butor

to

the

is

exposure

by-products

and

neither

of

these

Occupational

exposures

orders

of

greater

than

general

source

is

a continuing

and

hydrocarbons foods

often

is

an

exposure

- Natural These to

which

are

sulfur water

acids

and

0.1 20

unidentified

degree

include

and

mg/l to

25 mg/l

and

industrial

contriof

treatment

chemi-

be

three

of

ambient

halogenated

and

many

in

exception

may

of

the

used

significant

Inhalation

to

six air

petroleum

pesticides

in

population.

and

usually such

not

in

of

a variety of

their

highly

of

colored

such

as

natural humic

waters or

decomposition: other

and

variety

and

but (TOC),

rather total

concentrations

5 mg/l surface

fulvic tannins;

nitrogen

carbon Total

1 to

all

individually

organic

to

of

complexity.

identified

spectra.

groundwaters some

classes

as total

absorbance

deep

components

by-products

Because

or in

products

Residues

broad

proteins

are

color,

principal

to

general

mostly

parameters

(TON),

the

production

exposure

refractory

these

general

about

the

and

most

water.

areas.

substances.

solubility

in

agents

the

with

of

Water

relatively

containing

nitrogen

waters

lesser

amino

surrogate

from

and

(2)

drinking

for

in

disposal.

natural

of

oxidizing

nor

may

by-products

commercial

chemicals

rural

source

diverse or

terpines;

in

Products

a greater

acids

even

to

the

source

between

cals.

magnitude

waste

micropollutants

water,

substances,

interaction

organic products,

and

waste

a unique

to

by

natural

and

activities,

Water

sources

products

water

usually

human

water

natural

drinking

use

Drinking

including:

between of

production

drinking sources

reaction

in

in and

many

in organic

range surface

groundwaters.

10 - Treatment The

By-products

most

studied

chlorination:

however,

ozone,

chlorine

products

in

and

other

picrin,

water.

finished

products active

and

most

aldehydes

drinking

water to

and

which

often

and

a few

known

produce

micrograms

per

including produce

reaction

include

undesirable

chloroform chloro-

tastes that

hundred liter

from

acetonitriles,

Quantities

several

to

substances

brominated

from

derived

chemicals

are

ketones.

range

those

treatment

identified

chlorinated

acids,

are

chloramines

familiar

phenols

and

have

been

micrograms

or

less

detected

per

for

odors,

most

liter of

the

substances. - Industrial

Products

A large and

number

refrigerants

billion

found

synthetic

tion,

highly

kilograms

Table

Results

trations Principal

of

and

per

year.

in

drinking

freons

tend

water

to

and

soils

and

ug/l

to

several

the

Water

most Supply

worldwide

be

because

to

being

1982 Ground

the

propellants carbon

produced

chemical

0.1

groundwater

are

They

patterns,

from

aerosol

the of

most

sediments.

huge

produc-

stability, Drinking

milligrams significant Survey

rates

frequently

their

biological

at

per

liter

and are

recent

contained

in

have

re-

I (3). Literally

ported

with

solvents, tetrachloroethylene,

adsorption

ranging

reported

concern.

use

negligible

contamination been

chloride

contaminants

and

hydrocarbon

trichloroethylene,

delocalized

volatility,

has

halogenated

methylene

several

water

of including

tetrachloride, of

iodine

The

trihalomethanes

other

generated chemically

trihalomethanes,

numerous

for

all

dioxide,

halogenated

and in

treatment

at

hundreds least are

once usually

contamination

of

other

in

drinking

at

parts potential

synthetic

organic

water. per

Individual

billion seems

chemicals

or to

be

less

frequencies in

associated

finished with

been and

drinking surface

concenwater. waters

11

TABLE 1 surmacy

of raxnd

water

supply

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survey

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m-xylene o+p-xy1ere

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ToherE 1,2-Dichlorcqcpane p-Dichlorobenzene BPZlKJbe"ZSN Ethylbenzene Benzene 1,2-Dichlorcethane vinyl chloride 1,2-Dib-3chlorqropane

1,1,2-Trichloroethane 1,1,1,2-~etrachlorethane 1,1,2,2-Tetrachlorcethane ChlOKObXlZ~W "-Prcpylbe"ZeW o-allorotoluene p-ullorotolue"e m-Dichlorobenzene o-Dichlorobenzane styrene Isoprcpylbe"zene

i:: 0.5 0.5

Lata

Positives NLmber

Tetrachlorcethylene Trichlorcethylene l,l,l-Trichloroethaw 1,2-Dichlorcethane 1,2-Dichloroethylenes (cis and/or trans) Carbon tetrachloride l,l-Dichloroethylene

0.2

crxlxre"ce

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15 9 B a 6 6 5 4 3 3

Msdian (USA)

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1 0 0 0 0 0 0 0 0 0 0 0

18 3.2 2

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16 6.3 1.5 .9 2.9 21 1.3 5.8

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12 receiving

industrial

disposal

discharges

Water

in

the

vicinity

of

waste

and

its

in

non

Products

contamination

becoming

from

a more

leaded

such

blems

appear

to

storage.

be In

tamination

the

than

they

are

for

to

we

be

from

environmental

pesticides

totaling

which

highly

are

mobile

(spills

and

leaks

from

just

beginning

to

Storage storage stress

contamination

pipelines)

in

the as

use

corrosion is

pro-

known

are

and

many

assess

Tanks

tanks

enriched than

significant

mechanical

and

gasoline

most

Underground

solvents

especially

xylenes

more

and

The

are

gasoline

fuels

include

environment.

Leaking

damage

leaks

tend

States

underground to

refined

and

transportation

from

subject

potential

which

United

l,OOO,OOO

toluene

aquerous

during

other These

benzene,

the

potential

More

as and

in

and

occurrance.

gasoline,

hydrocarbons

gasoline

frequent

components

other

and

groundwaters

sites. - Petroleum

is

and

conLUST.

and the

since ultimate

great.

- Pesticides Hundreds are

in

they in

use

may

worldwide. migrate

are

such

in

surface

being

found

be

the

from

manufacturing

that

many

degraded would

of or

not

as

in

these

are

runoff can

waters. that

are

disposal.

in of

were soils those

of

are

applied

above

by

of

as

assumptions

water and

water

recently

was

must

deposition

and

groundwaters.

are

or

and

groundwater

now

be

frequently

appears rather

mistakenly

biologically

and

dibromochloropropane

acceptable it

surface

and

year

and

contamination

legally

sufficiently so that

in

per

ground

surface

aldicarb,

this

pounds

evaporation

contaminate

currently Until

millions

mobile

such Most

of

or

highly

Nematocides

chemicals

Many

by

atrazine

immobilized

occur.

alachlor

waters

uses or

as

return

ground of

hundreds

waters

waters.

result

such

surface

Irrigation

herbicides

found

Some to

rainfall.

Some

to

of

reexamined.

than assumed

chemically contamination

13 -

In

Situ

Transformation

Biological

and

environment

is

a well

a detoxification

relied

upon

as

always

the

case.

and

then

to

and

the

sulfone

Of more

chemical known

For

aldicarb

widespread

nated

compounds

interest

are

The

all recent

be

(vinyl

is

not to

more

these

DDE)

than are

indications

result

of

and

that

the

of

chloride)

generation

in

vinyl

chloride,

of

from

of

less

water.

found

higher

a product

toxic

parent

found

trichloroethylene

a case

sulfoxide

when

degradation

the

often

aldicarb

toxic

forms

in

necessarily

trans-1,2-dichloroethylenes the

would

risk

disposal

been

and

this

is

l,l,l-trichloroethane,

of

chemical

Contamination

future

identified

in

chlorior

tetra-

of

signifi-

precursors.

wastes of

as the

is

a mounting

groundwaters

most

from

significant

problem improper

source

of

in

industrialized

disposal

practices

their

present

and

contamination.

Management

water

of

Contamination

- Source

Protection

The

desirable

most

would

harmful

to

cis

DDD and

readily

sulfoxide toxic:

chemicals

Disposal

countries.

not

as

DDT

oxidizes

the

principally

This

- Waste

has

be

carcinogenic

The

synthetic

However

aldicarb

less

such

chloroethylene. cant

example

and may

(eg.

process.

somewhat

l.l-dichloroethylene

of

phenomenon

sulfone.

is

groundwaters

transformations

be to

organic always

the

be

potentially

means

prevent

However, for

large

assuring

contamination

chemicals. possible

of

these number,

the of

source

source

and waters

The and

quantity

safety by

protection

substances. variety

quality

at problem of

the

drinking

potentially

a high is

of

level

attributable contaminants

may

14 and

ubiquitous

waters to

in

sources solution

groundwater

the

and in

Treatment

Drinking

water

to

the

finished

surface

organic

such Aeration

are

constant.

designed of

and

need

a highly

include

such vinyl

to

for

removal

migrate

soils.

processes the

normally

safety

applied

involving of

sediments. biphenyls

to coagu-

a number

These

of

may

of

include

and

some

pesti-

dioxins. technology

i.e.

those

Packed

operated

to

routinely

achieve

results

in

transport

of

volatile

be

raised

a high

removal

of

Henry's

Law

as trihalomethanes, tower

up

for

with

contaminants

chloride.

can

assure

stage

surface

treatment

to

removal

effective

common

on

source

chlorinated

chemicals,

by

rely

polychlorinated

is

organic

to

the

to

Others

processes

bound

technology

migrating

retarded

effective

readily

even

and

to

aeration 99%

benzene,

systems

removal

of

can

those

be

types

substances. Aeration

the from

ambient

air

so questions

inhalation.

Both

strated

that

results

in

decline

rapidly

and

are

of

not

in

reasonably

and

trichloroethylene

but

a particulate

chlordane,

These

particulates.

always

hydrocarbons,

synthetic

to

treatment

of

that

as

volatile

will

consisting

aromatic

capable

suspended

Conventional

chemicals

cides

or

are

contaminants

filtration

polynuclear

Some adsorbed

supplies

water.

and

others

potential

waters,

lation

uses.

solution

- Water

tailored

and

total

1 million efficiency

except

results

cases risks

within

loadings liters

theoretical

for

negligible

could

are per

on

calculations of

to

extreme

desirability

and

field

groundwater

persons

in

the from

the

very

small

at

same

time.

total

emission

into

and studies

vicinity.

meters

containing

water

source

100

ug/l

of

of

only

about

For

concentrations

and

initial

example

g/day.

demon-

aeration

Air

trichloroethylene 100

risks

have

contamination,

a few

the

from

its

only

day in

substances

quantities aeration at

99%

of

15 Granular carbons

(PAC)

water

are

used

being GAC can

chemicals GAC must

prevent

be

organic

time

and

affinities

of

the

expected

currently

effective tap

external

some or

using of

full

which

scale

management

the

contact

have

particular

isotherms

to

can

predict

be

the

design

plants.

and

units

containing

point-of-use

and

a GAC system

processes

resins,

water

chemicals of

to

weight

chemicals.

Treatment

future

removal

molecular

including

produced

activated public

volatile

factors

can

have

low

performance

techniques

for

a household

be

and

small

accumulated

treatment

may

applications

for

can

adsorption

treatment but

The

powdered

and

many

remove

substances.

point-of-use

be

mentioned

potential

for

oxidation

of

which

with

been

chemicals

supply.

Cases

exist

approach

is

effective

an

not

selective ozone

GAC have organic

are

and

ultra-

shown at

where

use,

to

the

with

be

coneffective

and

efficient

supplies

and

measure. - Legislative

Controls

Legislation sources For

of

high

numerous

Carbons

macroreticular

Small in

control

of

used on

light.

sumer's

a function

additional

adsorption

violet

is carbon.

large

many

to water.

degree

both

including

finished

laboratory

widely

remove

hydrophobic.

types

a lesser in

into

performance

Numerous

to

reactivated

certain

in

and

increasingly

periodically

type for

simulated

eg.

are

chemicals the

(GAC)

effectively

that

breakthrough

for

and

carbon

systems.

organic The

activated

and example

Clean through regulated drinking

Water

and to

control

in

the

Act)

both

waste USA the

requires

technology

through water

regulations

criteria source.

to

protect

disposal Water control

have

been

Pollution of

and to

water installed

Control

effluent

requirements related

drinking

Act

many

countries.

(also

called

the

to

surface

discharges

permits.

ultimate

in

Ambient use

eg.

water

agricultural

their

waters quality or

is

16 Prevention the

Underground

and

the

Act.

of

The

Superfund

contaminated

that

cases

to

date

updated

in

Drinking

sents

the

Water level

does

not

Canada organic

Quality

of

in

revised

its

chemicals

with

USEPA

has

six

are

development synthetic

that

interim and for

(5).

It

organic

four

up

to

to

Guidelines is of

regulations

in

60 organic and

been of

current

recently

or

prepared

or

countries. water

quality

published

was Guidelines

A WHO guideline esthetically

repre-

pleasing

health 1978

water

of

the

to

include

21

further

revisions

considering

consumer.

chemicals. for

ten

(6).

organic Revised

chemicals solvents

on

fourths

protect

1984

organic effect

have

individual

in now

a tax

three

or

the

trihalomethanes

chemicals

that

drinking

an

Water

number

from

sites

in

ensures risk

the

Recovery

chemicals.

significant

in

on

organic

and

been

Organization

20

Conservation provided

and

Directive

pesticides

pesticides

have

by Act,

recover

guidelines

Drinking

increase

including under

Guidelines

for

any

and

an expected The

and

a constituent

result

to

U.S.A. Water

Approximately

supplies.

Health

the

Drinking

clean

organizations

World

in

Safe

a fund and

water

Communities' The

is

actions

international

1975.

the

wastes.

and

regulated

Resource

mitigate

involved

Standards

Economic

the

chemical

standards

of

U.S.A.

to

drinking

several

European

proposed

volatile

have

water

by

the

used of

Water

Drinking

under in

is

groundwater - Drinking

and

program

is

programs

controls

by disposal

potential

for

Control

waste

products

these

contamination

Injection

hazardous

chemical

The

groundwater

with and

chemicals regulations

emphasis

on

the

pesticides.

- Monitoring Monitoring

for

costly

as the

number

levels

become

lower

organic of with

chemicals chemicals improvements

becomes of

interest in

increasingly increases

analytical

complicated and

and

the

concentration

and

detectable tech-

17 With

niques. it

is

essential

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up to

paid In

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1986

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time.

Risk

Management Risk

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decisionmaker

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22 is

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IARC animal

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the

are

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Criteria

Group

1 - Chemical

is

carcinogenic

epidemiological Group

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Group

2A

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Group

28

- Usually

Group

is

least

probably

the

IARC

categories animal

has

evidence

a combination data

evidence

from

humans.

sufficient

to

humans.

in

animals

evidence

and

humans.

proposed (11).

as

a five

The

distinguish of

evidence

carcinogenicity

be classified

recently

not

(sufficient

to

of of

in

cannot

criteria do

humans

carcinogenic

limited

3 - Chemical USEPA

to

studies).

inadequate

of

and

Classifications

toxicology

evidence

classes

primary between

carcinogenicity

to

carcinogenicity

category

scheme

difference

is

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its

chemicals

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with

no

to

that

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humans.

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IARC

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with

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genicity.

Group

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Group

B - Probable

carcinogen human

Group

Bl

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Group

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human in

the

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carcinogen.

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of

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sufficient

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to

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in

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(limited of

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evidence data).

of

carcinogenicity

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23 Group

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classified

Group

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Both of

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in

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carcinogenicity).

based term

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tests:

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term

metabolism;

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the

evidence,

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fication

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step

o

EPA Group

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IARC

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II

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animal probable been

Group

EPA Group

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exposure

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could

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2A or

28

based

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to

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as

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a 3 level

classi-

RMCLs

human carcinogens: carcinogenicity.

evidence

of

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o

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ranked

C

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Setting

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or

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E

3

I includes of

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carcinogenicity The

carcinogens. to contribute

to

exhibit

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finite

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level

sufficient

their

carcinogenicity

a threshold some

have

thus of

it risk.

human

or

known

or

control

as

these

compounds

can

be

assumed

has that

not any

24 Category cient

II

evidence

reflect

of

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has

been

that

reported

of

chemicals.

two

To

additional

factor

some

value).

lifetime

risk

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linear

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III

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for

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the

be

applied

range

chemicals data

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III

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AD1 consists

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is

intended

compounds

that

are

not

have

raised

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depending II

and is

more

of

substances

would

be

a method

for

determining

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is acceptable

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with

calculated well

to

accepted exposure

be

an

less

10 or

based

upon

effects. data.

and

for

of

the

no evidence

chronic scientific

for

Category

quality

or

upon the

than

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inadequate

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carcinogens,

conservative

quantity

a

such in

as

the

than

levels

of

protective

of

in

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method

treated

based

non-carcin-

a factor

potential

be

these

carcinogenicity

quality

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and

a conservative

conservative

reflective

those

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animals

for

upon

a calculation

being

should

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ADIs.

in

data

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concerning on

chemicals

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of using

available.

using

insuffi-

should

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divided

10-G

Goals

Goals

based

of

to

this

but

carcinogenicity

evidence

are

carcinogenicity.

of

adequacy

(e.g.,

10-S

employed

that

data.

calculations

equivocal

I chemicals

and

limited

a quantitative

of

option

of

Category

some

animal

obtaining

model.

be

for

Category

data

for

second

for

Category

toxicology

of

the

for

to

The

which

evidence

according

questions

option

from

consists

multi-stage

which

exists

first

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manner

for

for

verified.

options

account

in

conservative but

main

(ADI)

principles.

chemicals

experimental not

The

endpoints

other

some

although

are

ogenic

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carcinogenicity

fact

There types

as

includes

threshold

toxicity community toxicants.

25 VOCs

Category

Using

Three

I - Known or evidence

Category

Regulatory

Probable Human of carcinogenicity.

Approach

Carcinogens:

Strong

Benzene Vinyl chloride 1,24ichloroethane Trichloroethylene Category

II

- Equivocal

Evidence

of

Carcinogenicity.

Tetrachloroethylene l,l-Dichloroethylene Category

III

- Non-Carcinogens: of carcinogenicity

Inadequate in animals.

or

no

evidence

l,l,l-Trichloroethane p-Dichlorobenzene

The vides

suggested

a rationale

reasonable in

foregoing

the

considered

and

judgements environment. along

assessment/management

methodology

for

for

decisions

The with

risk

control quality

technological

and

using

all

and

of

on

quantity economic

decision the

experimental

potentially of

the factors.

model data

harmful toxicology

pro-

chemicals data

are

and

26 REFERENCES 1.

2.

3.

The opinions expressed in do not necessarily reflect Protection Agency. Cotruvo, Drinking Agency Risks,

this the

paper policies

are of

those the

of the author, U.S. Environmental

and

they

J.A., "Risk Assessment and Control Decisions for Protecting working paper prepared for the International Water Quality", for Research on Cancer Working Group on Drinking Water and Lyon, December 14, 1985. In press. National Chemicals,

Proposed Regulations: tile Synthetic Organic June 12, 1984.

4.

Guidelines Geneva,

5.

Guidelines Government

6.

National 68624-68705,

for 1984.

Drinking

Water

Primary Federal ___--

Quality,

for Canadian Drinking Printing Centre, Hull, Interim 1979:

Primary and

Drinking Register

Vol.

1,

Water Vol.

World

Health

Water Quality, H 48 Quebec, Canada.

Drinking 1975.

Water

Regulations; 49, No.

Regulations:

Cancer

Vola114,

Organization,

10/1978,

Vol.

Canadian

44(231)

pp.

7.

Cothern, C.R., Coniglio, W.A. and Marcus, W.L., in Assessment of Carcino genie Risk to the U.S. Population due to Selected Volatile Organic Compounds from Drinking Water via the Ingestion, Inhalation and Dermal Routes. Draft Report, USEPA, Officr of Drinking Water, Criteria and Standards Division 1984.

8.

Ruckelshaus April 1984.

9.

Proposed Regulations: Volatile Synthetic 114, June 12, 1984.

10.

11.

"Evaluation Monographs U.S.E.P.A. Request

William

D.

Organic

"Risk

a Free

National Primary Chemicals,

of the Carcinogenic Supplement 4, Lyon,

for

in

Risk France

1984, Proposed Guidelines Comments Federal Register

Society",

Drinking Federal

of pp.

Chemicals 1114,

EPA Journal,

Water Register

P.

Regulations: Vol. 49,

to Humans", October 1982.

for Carcinogen Risk 49(227): 46294-46301

No.

IARC

Assessment;

12.