tlAU-UlN-DOO/
 United States                             August, 1988
 Environmental Protection                        Revised April, 1991
 Agency
 Research and
 Development
  DRINKING WATER CRITERIA DOCUMENT FOR
  HEXACHLOROCYCLOPENTADIENE
Prepared for
  OFFICE OF WATER
Prepared by

Environmental Criteria and Assessment Office
Office of Health and Environmental Assessment
U.S. Environmental  Protection  Agency
Cincinnati, OH  45268

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                                  DISCLAIMER

    This document  has been  reviewed 1n  accordance with  the U.S.  Environ-
mental  Protection  Agency's   peer  and  administrative  review  policies  and
approved for  publication.   Mention  of  trade names  or commercial  products
does not constitute endorsement or  recommendation for use.
                                      11

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                                   FOREWORD
    Section  1412  (b)(3)(A) of  the Safe  Drinking Mater  Act,  as amended  1n
1986, requires  the  Administrator  of  the  Environmental Protection Agency  to
publish  maximum  contaminant  level  goals  (MCLGs)  and  promulgate  National
Primary  Drinking  Water  Regulations  for   each  contaminant,  which,  In  the
judgment of  the Administrator,  may have  an adverse effect on  public  health
and  which  1s known  or  anticipated to  occur  1n  public  water  systems.   The
HCLG 1s  nonenforceable  and 1s set  at  a  level  at which no known  or  antici-
pated  adverse  health  effects   1n  humans  occur  and  which  allows  for  an
adequate margin of  safety.  Factors considered  1n  setting the  HCLG  Include
health effects data  and sources  of exposure other than  drinking water.

    This document provides  the   health  effects  basis  to  be considered  1n
establishing the  HCLG.  To achieve  this objective,  data  on pharmacoklnetlcs,
human exposure, acute and chronic  toxldty  to animals and.humans,  epidemi-
ology and mechanisms  of toxldty  are evaluated.   Specific  emphasis  Is  placed
on  literature   data  providing dose-response Information.  Thus,  while  the
literature  search and evaluation performed  1n  support of  this  document  has
been comprehensive,  only  the  reports  considered most  pertinent  In  the  deri-
vation of  the HCLG  are cited 1n  the document.   The comprehensive  literature
data base  1n support of  this document  Includes  Information  published  up  to
1985;  however,  more  recent  data  may  have been  added  during the  review
process.   Editorial  changes  were  also  made  1n  1991  when  this  document  was
finalized.

    When adequate health effects  data exist,  Health Advisory  values  for less
than  lifetime  exposures   (1-day,  10-day  and  longer-term,   -10%   of   an
Individual's lifetime) are Included 1n  this document.   These  values  are  not
used 1n  setting the  HCLG, but  serve  as  Informal  guidance to municipalities
and  other  organizations when  emergency  spills  or contamination  situations
occur.
                                                 Tudor Davles,  Director
                                                 Office of Science and
                                                 Technology
                                                 James Elder,  Director
                                                 Office of Ground Water
                                                 and Drinking  Water
                                      111

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                             DOCUMENT DEVELOPMENT
Linda R. Papa, Document Manager
Environmental Criteria and Assessment Office, Cincinnati
U.S. Environmental Protection Agency
Scientific Contributors

David J. Relsman
Environmental Criteria and
  Assessment Office, Cincinnati
U.S. Environmental Protection Agency

James WHhey. Author of Chapter III and Reviewer
Environmental Health Directorate
Bureau of Chemical Hazards
Tunney's Pasture
Ottawa, Ontario  K1A-OL2
Scientific Reviewers

W. Bruce Pelrano
Environmental Criteria and
  Assessment Office, Cincinnati
U.S. Environmental Protection Agency

Annette M. Galchett
Environmental Criteria and
  Assessment Office, Cincinnati
U.S. Environmental Protection Agency

C. Ralph Buncher
Department of Environmental Health
University of Cincinnati
Cincinnati, OH

Fumlo Matsumura
Director, Pesticide Research Center
Michigan Stale University
East Lansing. MI

Charles 0. Abernathy
Yogendra Patel
Health Effects Branch
Office of Drinking Water
U.S. Environmental Protection Agency
Washington. DC
Larry ValcovU
Reproductive Effects  Assessment Group
Office of  Health  and  Environmental
  Assessment
U.S. Environmental  Protection Agency
Washington,  DC

Paul White
Exposure Assessment Group
Office of  Health  and  Environmental
  Assessment
U.S. Environmental  Protection Agency
Washington,  DC

Arthur Chlu
Carcinogen Assessment Group
Office of  Health  and  Environmental
  Assessment
U.S. Environmental  Protection Agency
Washington,  DC

Editorial  Reviewer

Judith Olsen
Environmental Criteria and
  Assessment Office.  Cincinnati
U.S. Environmental  Protection Agency
                                       1v

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                             TABLE OF CONTENTS

                                                                     Page
  I.   SUMMARY	      1-1

 II.   PHYSICAL  AND  CHEMICAL  PROPERTIES	     11-1

      ANALYSIS	     H-10
      SUMMARY	     H-16

III.   TOXICOKINET1CS	    111-1

      INTRODUCTION	    111-1
      INTRAVENOUS ROUTE  	    III-l
      ORAL ROUTE	    III-3
      INHALATION  ROUTE	    1II-8
      PERCUTANEOUS  ROUTE	    111-13
      COMPARATIVE STUDIES	>  .  .  .    111-13
      SUMMARY	    III-14

 IV.   HUMAN EXPOSURE	     1V-1
              (To be provided by the Office of Drinking Mater)

  V.   HEALTH EFFECTS IN  ANIMALS 	      V-l

      OVERVIEW	      V-l
      ACUTE TOXICITY	      V-l
      SUBCHRON1C  AND CHRONIC TOXICITY 	      V-7
      MUTAGENICITY	      V-15
      CARCINOGEN1CITY 	      V-16
      TERATOGEN1CITY	      V-17
      SUMMARY	      V-18

 VI.   HEALTH EFFECTS IN  HUMANS	     VI-1

      ACUTE EXPOSURE STUDIES	     Vl-1
      EPIDEM10LOG1C STUDIES 	     VI-8
      SUMMARY	     VI-10

VII.   MECHANISMS OF TOXICITY	    Vll-1

      SUMMARY	    VI1-?

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                           TABLE  OF  CONTENTS (cont.)

                                                                       Page
VIII.  QUANTIFICATION OF TOXICOLOGIC EFFECTS 	   V1I1-1

       INTRODUCTION	Vlll-1
       NONCARCINOGENIC EFFECTS 	   VI11-6
       QUANTIFICATION OF NONCARCINOGENIC EFFECTS 	   VI1I-11

            Derivation of T-Day HA  	   V1I1-11
            Derivation of TO-Day HA	VIII-12
            Derivation of Longer-Term HA 	   VI11-13
            Assessment of Lifetime  Exposure and Derivation of DUEL .   VI1I-14

       CARCINOGENIC EFFECTS	VIII-15
       EXISTING GUIDELINES, RECOMMENDATIONS AND STANDARDS	VII1-1S

            Occupational Standards	-. .  . .   V1I1-15
            Transportation Regulations  	   VI1I-17
            Solid Waste Regulations	V11I-17
            Food Tolerances	V1I1-17
            Water Regulations	V11I-17
            A1r Regulations	VI11-18
            Other Regulations	Vlll-18

       SPECIAL GROUPS AT RISK	VI1I-19
       SUMMARY 	   VI11-19

  IX.  REFERENCES	     IX-1
                                       vl

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                                LIST  OF  TABLES


 No.                                Title                               Page

 II-l     Identity of  Hexachlorocyclopentadlene  	     11-2

 11-2     Physical Properties  of  Hexachlorocyclopentadlene	     11-3

 11-3     Characteristics  of  the  Porapak* T  Collection  System  .  .  .       11-12

 11-4     Optimized GC Analytical Procedure  for  HEX	     11-13

111-1     Extractablllty of  [14C] HEX  and Radioactivity Derived
         from Saline  and  Various Biological  Preparations  	    111-12

III-2     Disposition  of Radioactivity Expressed as  Percentage
         of Administered  Dose from 14C-HEX  In Rats  Dosed  by
         Various Routes	    111-15

111-3     Fate of Radiocarbon  Following Oral.  Inhalation and
         Intravenous  Exposure to a«C-HEX In Rats Expressed
         as Percentage of Administered Dose	    111-16

1II-4     Distribution of  HEX  Equivalents In Tissues and Excreta
         of Rats 72 Hours After  Oral, Inhalation and Intravenous
         Exposure to  *«C-HEX  	    111-17

  V-l     Acute Toxlclty of  HEX	      V-2

  V-2     Subchronlc Toxlclty  of  HEX	      V-B

  V-3     lexicological Parameters for Mice  and  Rats Administered
         Technical Grade  HEX  In  Corn  Oil for  91 Days	      V-10

 Vl-1     Symptoms of  145  Wastewater Treatment Plant Employees
         Exposed to HEX (Louisville,  KY, March  1977) 	     VI-4

 Vl-2     Abnormalities for  18 of 97 Cleanup Workers at
         the Morris Forman  Treatment  Plant	     VI-5

 VI-3     Overview of  Individual  Exposure -  Symptomatology
         Correlations at  the  Morris Forman  Treatment Plant 	     VI-6

 VI-4     Hepatic Profile  Comparison of Hardeman County:
         Exposed Group (November 1978) and  Control  Group  	     Vl-9

 V1II-1  Summary of HAs and DWEL for  NoncarclnogenU Effects  ....   V1II-16
                                     vll

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                             LIST OF  ABBREVIATIONS
CDC
DMSO
DWEL
ECO
6C/MS
Gl
HA
HEX
*«C-HEX
HPLC
l.d.
1.v.
LAQL
LD50
LOAEL
LOEL
Mg
NAS
NIOSH
NOAEL
NOEL
NTP
OCCP
Radlolabeled carbon dioxide
Centers for Disease Control
Dlmethylsulfoxlde
Drinking water equivalent level
Electron capture detection
Gas chromatography/mass spectrometry
Gastrointestinal
Health advisory
Hexachlorocyclopentadlene
Radlolabeled carbon-14 hexachlorocyclopentadlene
High performance liquid chromatography
Internal diameter
Intravenous
Lowest analytically quantifiable level
Lethal dose to 50% of recipients
Lowest-observed-adverse-effect level
Lowest-observed-effect level
Megagrams equivalent to 1 metric ton
National Academy of Sciences
National Institute for Occupational Safety and  Health
No-observed-adverse-effect level
No-observed-effect level
National lexicology Program
Octachlorocyclopentadlene

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                        LIST OF ABBREVIATIONS (cent.)

RfD                Reference dose
S.D.               Standard deviation
SMR                Standard mortality ratio
sp. gr.            Specific gravity
SRI                Southern Research Institute
                                       Ix

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                                 I.  SUMMARY

    HexachlorocyclopentacMene  (HEX)   1s  an   unsaturated,  highly  reactive,
chlorinated cyclic hydrocarbon  of  low water  solubility.   HEX  1s a chemical
Intermediate used  1n  the  manufacture of  chlorinated  pesticides  and  flame
retardants with no end uses of  Its  own.   The major source of  environmental
contamination by  HEX  1s  the aqueous  discharge  from production  facilities,
with  small concentrations  present   as  contaminants  In commercial products
made from  It.   However,  HEX 1s not  frequently found  1n the environment and,
even when  present, H  1s rapidly degraded.  The degradation products  of HEX
have  not  been  Identified.   Because  of   recent  controls  on  environmental
emissions,  current  environmental  exposure to  HEX  Is  extremely low.   From
time  to  time.  Isolated  Instances, such as the sewer system disposal  of HEX
wastes In  1977  In Louisville,  KY, and the cleanup  of a large  waste  disposal
site  1n  Michigan  In  1983,  have  brought  this chemical  to the  forefront  of
environmental news.

    HEX  Is not  readily  absorbed  by  epithelial tissues  because  It  Is  highly
reactive,  especially  with  the  contents of the GI  tract.  HEX Is moderately
toxic  when given  orally,  but  has  been estimated to be  100 times  more toxic
when  Inhaled.   The  data  base for  the  long-term  toxlclly  of  HEX  Is very
limited.   A chronic   Inhalation bloassay   Is  being  conducted  by  the  NIP and
may provide data  regarding  any  carcinogenic potential of HEX.

    Several  literature  reviews  on  the health and  environmental  effects of
HEX  are  available.    Although each  of  these  reports   varies  In scope and
 03610                               1-1                               08/24/88

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emphasis,  a  large amount  of  the scientific knowledge about  HEX  1s  reviewed
In  these  documents.   To  avoid  unnecessary  duplication,  the  previously
reviewed  material will not  be  considered  at  great length,  except  where  H
Impinges directly upon present critical considerations.

    .HEX  Is  currently  produced  by  only  one company  In  the United  States,
Velslcol  Chemical Corporation.  Production  data  are  considered proprietary;
however, estimates  show  that  8-15  million pounds/year  are produced.   HEX can
enter  the environment  as an  Impurity/contaminant  In some of  the  products
using  HEX as  an  Intermediate or can  be released  during  the-manufacture  of
products requiring  HEX.   The  total  estimated environmental  release of HEX  Is
11.9 Mg  (13.1  tons).  Because of  Us  physical  and  chemical characteristics,
only a small  amount of this  total  can be expected  to persist.  In water, HEX
may undergo  photolysis,  hydrolysis  and blodegradaUon.  In shallow,  standing
water,  HEX  has  a photolytlc  half-life  of  <1  hour,  while  In  deeper  waters
where  photolysis 1s  precluded,  HEX  may persist for  several  days.   HEX  Is
known  to  be  quite volatile;  however,  the rate of volatilization from natural
waters can be  Influenced  by turbulence and  adsorption onto  sediments.

    In animal  studies, the absorption of unchanged  HEX 1s  reduced because of
Its reactivity with membranes and  tissues,  and  especially with the contents
of  the  GI   tract.   Radioactivity   from  *«C-HEX  1s  retained by  the kidneys
and  livers  of  animals  for   at least  72  hours   after  oral  or  Inhalation
dosing.   Absorbed HEX 1s  metabolized  and rapidly excreted, predominantly  In
the  urine   and   feces  with  <1X  of   the  HEX  found  In  expired  air.   The
metabolites  of HEX  have  not been Identified.
 03610                               1-2                              08/30/88

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    Subchronlc oral dosing studies have  been  conducted on rats and mice  for
91  days.   At 38  and  75  mg/kg/day  levels  In rats  and  mice, respectively,
adverse effects  were  noted,  which Included  Inflammation  and hyperplasla of
the  forestomach  and nephrosls.   In.  vitro  test  results  from three  species
have not  shown   HEX  to  be a  mutagen.   HEX was  also  Inactive  In  the mouse
dominant lethal  assay.

    Limited data are available on the health  effects  1n humans from exposure
to  HEX.   Isolated  Instances  have occurred  that  show Inhalation exposure  to
HEX  causes  severe  Irritation  of the  eyes,  nose,  throat  and lungs.   Human
exposures   from  other  routes  have elicited effects  that   Include  short-term
Irritations,  with  recovery  after  cessation  of  exposure.   The   long-term
health effects of continuous low-level and/or  Intermittent  acute exposure 1n
humans are not known.

    The data  base  Is  neither extensive  nor  adequate for  assessing the  car-
dnogenldty of  HEX.  The NTP has recently completed  a  subchronlc  Inhalation
animal study and will begin a lifetime animal  Inhalation  bloassay  using  both
rats and mice.   Several  epldemlologlc  studies were cited  1n  the literature;
however, no Increased Incidences of neoplasms  at  any  site  were reported  that
could  be  related  to  HEX.   Accordingly.  Velslcol  Chemical Corporation  has
on-going  programs  and  follow-up studies  In   order  to study  the   long-term
effects of HEX  exposure.   A  Judgment  of carcinogenic   potential will  be
deferred  until  the  results  of  the  NTP  long-term  bloassay  are  available.
Using  the  International  Agency  for Research  on  Cancer (IARC) criteria,  the
available   evidence  would place  HEX  In the Group 3 category.  According to
the  U.S.  EPA  Guidelines for  Carcinogen  Risk  Assessment,  based upon  present


03610                              1-3                               08/24/88

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data,  this  chemical  Is  classified  In  the Group  D  category.   A  U.S.  EPA
carclnogenldty Group  0 classification was verified by the CRAVE Work  Group
on 10/05/89.   This  classification Indicates that the available data base  1s
Inadequate to assess the carcinogenic potential of this substance.

    Using  a  gavage  study  on  rats,  the  1-day  health  advisory  (HA)  for
children  has   been  calculated  to be  15  mg/l.   The   10-day  HA was  derived
using a repeated-dose  toxlclty study on  both rats and mice,  and for children
the level Is recommended  to  be  2  mg/i.

    The longer-term HAs were developed  from  the  SRI  13-week  study  also used
for  the  derivation of the  Drinking Water  Equivalent  Level (DWEL).   The
recommended  longer-term  HA  for  adults  1s  3  mg/8.  and for children  the
longer-term  HA  1s  0.7  mg/i.   The  DWEL  Is  0.3  mg/i,  which  1s  calculated
using  an  RfD  of  0.007 mg/kg  bw/day  (verification  date  10/09/85)  based on a
NOAEL of  10 mg/kg for  absence of  adverse effects  In rats.
 03610                              1-4                               06/11/91

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                    II.  PHYSICAL AND CHEMICAL PROPERTIES

    Hexachlorocyclopentadlene  (HEX,  HCCPD,   C-56)  Is  a  nonflammable  liquid
with a characteristically pungent, musty  odor.   The  pure compound Is  a  pale
yellow but  Impurities may produce  a  greenish tinge  (Stevens. 1979).   HEX  Is
a  dense  liquid  with  a  specific  gravity  of 1.7019  at  25°C and  low water
solubility  (0.80S-2.1  mg/i)  (U.S.   EPA,  1978).   Studies  by  Nalshteln and
Llsovskaya  {1965}  have  Indicated  an odor  threshold for HEX  of 0.002  mg/i
and  a  "taste"   threshold  of  0.007   mg/i.   HEX  1s  a  liquid  with  a  high
boiling  point  (239°C)  and a  vapor  pressure of  0.08 mm Hg  at  25°C.  Table
II-l presents  Information on the Identity  of  the chemical  while Table  11-2
lists Its physical properties.

    HEX  Is   stable  under moisture-free  and Iron-free  conditions  (Stevens,
1979).   Chemically,  HEX  Is   a  highly reactive  dlene that  readily  undergoes
addition  and substitution  reactions and  also  participates  In  Dlels-Alder
reactions  (Ungnade  and  McBee,  1958).   The  products  of   the  Dlels-Alder
reaction  of  HEX  are  generally 1:1  adducts containing a hexachlorobicyclo-
(2,2,1Jheptene structure; the  monoene derived  part  of  the  adduct  is  nearly
always  1n  the endo-posltlon.  rather  than the  exo-posltlon  (Stevens,  1979).
Look (1974)  also  reviewed the  formation of  HEX  adducts  of aromatic  compounds
and  the  by-products  of   the  Dlels-Alder  reaction.   Two early reviews  of the
chemistry  of HEX  were   publUhPd  by Roberts  (1958) and Ungnade  and  McBee
(1958).

    HEX  has  an absorption band  In  the  ultraviolet  range at  322 and  3?3  nm
(log  e  = 3.17)  1n ethanol   (U.S. EPA,  1978).   This  absorption  band  reaches


03620                              11-1                               04/12/91

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                                  TABLE II-l

                     Identity  of Hexachlorocyclopentadlene*
  Identifying Characteristic
          Name/Number/Structure
IUPAC Name:

Trade Names:

Synonyms:
CAS Number

CIS Accession Number:

Molecular Formula:

Molecular Structure:
1.2>3,4.5t5l-Hexachloro-l,3-cyclopentad1ene

C56; MRS 1655; Graph!ox

Hexachlorocyclopentadlene
Perchlorocyclopentadlene
HEX
HCPD
HCCP
HCCPD
C-56
HRS 1655
Graphlox

77-47-4

7800117
                         Cl,
JC1
                                                          Cl
                                   Cl
'Source:  U.S. EPA. 1984
03620
  II-2
 10/16/85

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                                 TABLE  11-2

               Physical  Properties of Hexachlorocyclopentadlene
     Property
 Value/Description
                                                           Reference
Molecular weight

Physical form (25°C)

Odor

Odor threshold: air
                water

Electronic absorption
  maximum [(1n 50%
  acelon1tr1le-water)]

Solubility 1n water
  (rag/l)
  Organic solvents

Vapor density (air  =  1)

Vapor pressure
  (mm Hg, °C)


Specific gravity



Melting point ("CJ*
 Boiling  point  (°C)
 Conversion  Factor
272.79

Pale yellow liquid

Pungent

0.03 ppm (v/v)
0.0077 ppm (w/v)

313 nm
3.4 (20°C)
2.1 (25°C)
1.8 (28°C)

Mlsclble  (hexane)

9.4
                           0.08 (25°C)
                           0.975 (62°C)

                           1.717 (15°C)
                           1.710 (20°C)
                           1.7019 (25°C}

                             9.6-11.34
 239
 234
Stevens, 1979

Hawley, 1977; Irish.  1963

Hawley, 1977; Irish.  1963

Amoore and Hautala, 1983




Wolfe et al.. 198?


Horvath, 1982
Dal Monte and Yu,  1977
Wolfe et al.. 1982

U.S. EPA, 1978

Verschueren, 1977
 Irish.  1963
 Stevens,  1979

 Hawley, 1977
 Stevens,  1979
 Weast  and Astle,  1980

 U.S.  EPA, 1978;  Hawley,
 1977;  Stevens.  1979
 Weast  and Astle.  1980
 Aldrlch Chemical
 Company,  1988

 Hawley, 1977;  Stevens,  1979
 Irish, 1963
 1  ppm =  11.17  mg/cu.m   Irish,  1963
 03620
         11-3
                                                                     04/12/91

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                              TABLE II-2 (cont.)
Property
Octane! /Hater partition
coefficient (log P)
(measured)
(estimated)
Kow
Latent heat of vapori-
zation
Henry's Law constant
(atm-mVmole)
Value/Description
5.04+0.04
5.51
1.1x10*
176.6 J/g
2.7xlO'2
Reference
Wolfe et al.,
Wolfe et al.,
Wolfe et al.,
Stevens, 1979
Atallah et al
Wolfe et all,
1982
1982
1982

., 1980;
1982
*A wide  range  of melting  points have been  reported  for  this  chemical;  this
 variation may be due to chemical Impurities and/or Isomerlc structure.
03620
11-4
06/19/90

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Into the visible  spectrum,  as  evidenced  by the yellow color of HEX.   Facile
carbon-chlorine  bond  scission  might  be  expected  In   sunlight   or   under
fluorescent light.  The 1R  spectrum of the  dlene  has  two  absorption bands  at
6.2 and 6.3 ym In the double bond region  and  three bands at 12.4,  14.1 and
14.7  ym  1n  the  C-C  region.   The  mass  spectrum  of  HEX  shows  a  weak
molecular  Ion  (M) at M/e 270,  but also a  very  Intense (H-35)  Ion making this
latter Ion suitable for sensitive,  specific Ion monitoring.

    HEX Is produced for commercial use only by  Velslcol Chemical Corporation
(SRI, 1987; USITC,  1986).   Current  production  data are not available.   U.S.
EPA  (1984)  estimated that  between  8  and  15  million pounds/year  {4000-7500
tons) are produced.   In a  report prepared for  the  U.S. EPA, Hunt  and  Brooks
(1984} estimated that 8300  Hg  (9130 tons)  of HEX  were produced  In  the  United
States In  1983.

    Commercial HEX  contains various  Impurities depending  upon the  method  of
synthesis.   The  three  primary  processes  commonly  used for the production  of
HEX  are  chlorlnatlon  of   cyclopentadlene,  dechlorlnatlon   of  octachloro-
cyclopentene and  the  dehydrochlorlnatlon  of hexachlorocyclopentane.   In  the
first process, cyclopentadlene  Is  mixed  with alkaline hypochlorlte  at  40°C.
HEX  1s  recovered  by  fractional   distillation,   and  contains  appreciable
quantities  of lower  chlorinated  cyclopentadlenes.  In  the dechlorlnatlon
process, HEX  Is  produced by thermal dechlorlnatlon  of octachlorocyclopentene
at  470-480eC   (Stevens,   1979).    Technical   grade  HEX  usually  . contains
contaminants  such  as  hexachlorobenzene,  octachlorocyclopentene,   PCBs and
mlrex.  The nature  and levels of contaminants  will vary  with the  method  of
production.   Commercial HEX produced by Velslcol  Chemical Corporation  at  the


03620                              11-5                               08/25/88

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Memphis, TN  plant,  which  1s  used  Internally and sold to other users, has a
97% minimum purity (Velslcol  Chemical Corporation, 1984).

    Although HEX  has  essentially no end use  of  Us own,  It  has been  used  as
a chemical  Intermediate In the production  of several  Insecticides/pesticides
Including  aldrln,   dleldrln,  endrln,   chlordane,   heptachlor,   endosulfan,
pentac, mlrex  and others and  1n the  manufacture of  flame retardants  such  as
wet  add  chlorendlc  add,  and Dechlorane  plus* (Stevens,  1979).  With  the
exception of endosulfan and pentac,  the use of HEX-based  pesticides  has  been
banned,  suspended  or  severely  restricted  (U.S.  EPA,  1980).    Figure  11-1
Illustrates  synthetic pathways for  the various  chlorinated  pesticides.   HEX
1s also  used to a lesser  extent  In  the manufacture  of  resins  and dyes (U.S.
EPA, 1980), and has been used previously as a general bloclde (Cole,  1954).

    When  studying HEX  1n water, there  are  numerous  physical  properties  that
Influence  Us  ultimate fate.  In  the event  of release  Into  shallow  or flow-
Ing  bodies  of  water, degenerative processes  such as photolysis, hydrolysis
and  blodegradatlon,  as well  as transport processes Involving volatilization,
evaporation  and other physical loss  mechanisms,  are  expected to be prominent
1n  HEX dissipation.   In  deeper,  nonflowlng  bodies of  water,  hydrolysis and
blodegradatlon  may become  the predominant fate processes  (U.S. EPA, 1984).

     Zepp  et  al. (1979, 1984) and Wolfe et al. (1982) reported the results of
U.S.  EPA studies on  the rate of  HEX phototransformatlon 1n  water.   Under a
variety  of  natural  sunlight  conditions, 1n both distilled and natural waters
of   1-4  cm  depth,   phototransformatlon  half-life  was  <10  minutes.   Rate
constants  were also computed for various times  of the day at 40°N latitude.


03620                               11-6                             08/25/88

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                                                                                                    iNtMlN
o
GO
IV)
o
o
OS
CO
CD
                                                                                                                     INOO1UITM4
                                     «'Clj. I.Oj Oi 'Ullllt

                                      UIIN IN CCI«OI CtIV

                                      Ot »0,CI, . IINIOVt
                                                     Mill II
                                     FIGURE  II-l


Synthesis of Chlorinated Cyclodlene Pesticides from Hexachlorocyclopentadlene


                              Source:   U.S.  EPA, 1984

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The  rate  constant for  near-surface photolysis  of  HEX was estimated as  3.9
hour"1.   This  corresponds  to a   half-life  of  -11   minutes.   Addition  of
natural sediments  to  distilled water  containing HEX had  little  effect  on the
phototransformatlon  rate.   These  findings  Indicated that  the  predominant
mechanism  of  HEX  phototransformatlon  (decomposition) was direct  absorption
of light  by  the chemical, rather  than photosensltlzatlon reactions Involving
other  dissolved or suspended materials.   Although no product  was Identified,
Zepp  et  al.  (1984)  and  Wolfe  et al.  (1982)  speculated  that  the  primary
phototransformatlon  product  was hydrated tetrachlorocyclopentadlenone,  which
dlmerlzes  or  reacts  to form higher molecular weight products.   The dlmerlza-
tlon  of hexachlorocyclopentadlene  to  form  higher  molecular  weight products
represents  a  minor   pathway  according  to  Butz et  al.  (1982)  and Yu  and
Atallah  (1977b).  According  to Chu et al.  (1987),  the  photolysis half-life
of  HEX 1n  water  was  <4  minutes  when exposed to sunlight.    These  authors
positively   or   tentatively   Identified   at   least  eight   photoproducts:
2,3,4,4,5-pentachloro-2-cyclopentenone;   hexachloro-2-cyclopentenone;   hexa-
chloro-3-cyclopentenone  (primary products);  pentachloro-ds-2,4-pentad1eno1c
acid;  1-  and E-pentachlorobutadlene,  tetrachlorobutyne  (secondary products)
and  hexachlorolndenone (minor product).

     Studies  of  the  hydrolysis of  HEX Indicate  that  at 25-30°C  and  1n  the
environmental   pH  range  of   5-9,  a  hydrolytlc half-life of  -3-11  days Is
observed   (Wolfe  et  al.,  1982;   Yu   and  Atallah,  1977a).   In  comparison,
hydrolysis  Is  much  slower  than  photolysis, but may  be a significant  load-
reducing  process  1n waters  where photolysis and  physical  transport processes
are  not  Important (I.e., In  deep, nonflowlng  waters).   Wolfe  et al.  (1982)
found hydrolysis  of  HEX  to  be Independent of  pH over an  environmental  range


03620                              11-8                             08/25/88

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of 3-10.  Also, the addition of natural sediments, sufficient to adsorb <92%
of the  compound,  caused  the rate  constant to vary by  less  than  a  factor of
2.   It  was  therefore  concluded   that   sorptlon  to  sediments  would  not
significantly affect the  rate  of  hydrolysis  (Wolfe  et  al.,  1982).   In both
studies  (Wolfe  et al., 1982;  Yu  and  Atallah,  1977a)  the authors  concluded
that the  hydrolysis  rate  was higher as  temperatures  Increased  and although
the  hydrolysis   products  were  not   Identified,   high  molecular  weight
polyhydroxyl compounds  appear to be  major  products.

    The  rate  constants  for  the   oxidation  of   hexachloropentadlene   with
singlet  oxygen   ^O.)   and  penoxy   radicals  1n   water   were  estimated   at
<103  and  12  M~a  hour'1,  respectively  (Mabey   et  al.,   1982).    If   the
concentrations  of  10.   and  ROp   radicals   In  water   are  assumed   to  be
10'"  and 10'9 M,  respectively (Mill  and  Mabey,  1985), It  1s  likely  that
under  ordinary  environmental   conditions,   oxidation  of  HEX  will  not  be
significant.

    The   Intermedia   transport  of  HEX   from   water   may  occur   through
volatilization  Into  air,  adsorption onto suspended partkulate matters  and
subsequent  sedimentation  and  uptake  by  plants  and animals  In  water.   The
significance  of  HEX sorptlon  In water was  predicted by  Wolfe et  al.  (1982)
using  a computer  simulated Exposure  Analysis Modeling  System  (EXAMS).   The
distribution  of  HEX  1n  the   sediments  of  a  river,   pond,  eutrophlc  and
ollgotrophU  lake was  estimated to be 98.8,  86,  87  and 97.IX,  respectively,
of  the  total  HEX In  the  system.   Johnson and  Young   (1983)  observed  that
adsorption  plays  an Important  role 1n reducing the concentration  of  HEX In
aqueous  solutions.  The  predicted  strong  sorptlon  of  HEX  In  sediments  is
also supported by experimental  sorptlon data  1n soils.

03620                               11-9                              08/25/88

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    However,  the   main   removal   of  HEX  from  water  bodies   comes   from
volatility.   Weber  (1979)   measured   the   volatility   of   "C-HLX   from
distilled   water   following  the   Incubation   of   the   glass-stoppered   and
unstoppered  test  bottles  shaken at room temperature for 24 hours.   From the
full  glass-stoppered bottles  containing  0.41  mg/s. HEX.  only  4-5% of  HEX
was  lost,  while 1n  the  half-full  stoppered bottles, 15-16% of  the  chemical
was  missing.   The  volatilization  of  HEX from  the half-full,  unstoppered
bottles  was 45-47%  over  the 24-hour period.   Other researchers  (Kllzer  el
al.,  1979;  Atallah  et  a!.,  1980) have determined  very  high  rates  of
volatilization  for HEX.   Kllzer et  al.  (1979) reported that  the volatility
of  HEX  ranged from  4.7-8.8%/hour  from  a  static aqueous solution containing
50  yg/a  HEA.   Atallah  et  al.  (1980)  observed  >80%  volatilization  In  24
hours from  unlnoculated media containing 45 mg/8. HEX.

    Blodegradation  may  also  be   a   significant  process  1n  certain  waters
(Tabak  et al.,  1981),  although  the evidence 1s limited.  Tabak et al.  (1981)
observed  complete  degradation  of  HEX  at  concentrations  of   5  and 10  mg/a
within   7   days    In   a   settled   domestic   wastewater   culture   system.
Blodegradation  of  <2.5%  14C-HEX  by  acclimated   mixed  microorganisms  was
observed  1n 2-3 weeks  by  Atallah et al.  (1980),  while Wolfe et  al.  (1982)
observed  no  difference  In  degradation   rate  when  sterile  and  nonslerile
natural  sediments  were added  to HEX  solutions.

Analysis
    Gas  chromatography  Is  the  preferred  method  for   analyzing  HEX  In  air
using   either   flame  lonlzatlon   collection   or   GC-63Ni   electron  capture
03620                               11-10                             04/12/91

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detection (ECD) (Chopra et al.t  1978;  Neumelster  and Kurlmo, 1978; HhHmore
et al.,  1977;  NIOSH.  1979).   GC/MS  Is  necessary  for confirmation  (Elchler,
1978).

    Several   sorbent  materials  were  evaluated  for collection  of  HEX  vapor:
Amber 1 He®   XAD-?   (20/50   mesh),   Porapak®   R   (50/80  mesh).   Amber sorb®
XE-340   (20/50  mesh}.   Chromosorb®  104  (60/80  mesh).  Tenax-GC®   (35/60
mesh),  Porapak*  T  (80/100  mesh)  and  Porapak®  T (50/80  mesh).    According
to the  NIOSH criterion  for  acceptable  methods, a sorbent material  must  have
a  demonstrated sorptlon  capacity  for  the  analyte  that  Is  adequate  for
sampling a reasonable volume of workplace air  at  an  established rate.   Table
II-3  enumerates  additional  factors related   to  the Porapak®  T   collection
system.

    Gas  chromatography  with ECO was  determined  to  be  the  most  sensitive
analytical  technique   (Boyd  et  al.,  1981).   For  HEX  the  chromatographlc
response  was  stated   to be  a   linear  and  reproducible  function  of  HEX
concentration  1n  the  range  of  -5-142  ng/mi  (25-710 pg  Injected),  with  a
correlation  coefficient  of   0.9993  for  peak  height  measurement.    The
optimized operating conditions  for this method  are shown In  Table  11-4.

    Validation  tests  were  conducted  according  to   NIOSH  guidelines.   The
accuracy and  precision  of  the  overall  sampling and analytical  procedure for
HEX  were  evaluated   1n   the   concentration   range   of  -13-865   yg/m3  at
25-28°C  and  a  relative  humidity  >907..   The LAQL  of HEX was  determined  to be
25 ng/sorbent  tube,  assuming  1 ma.  of  hexane-desorblng  solvent and a  1  hour
desorptlon  time  by ultrasonlfUatlon.   The  upper  limit  of  the  method  was


03620                              11-11                             08/25/88

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                                  TABLE II-3
             Characteristics of the Porapak* 1 Collection  System3


         Characteristic                          HEX Type/Value

       Sorbent material                      Porapak* Tb
                                             (80/100 mesh)
       Breakthrough t1mec                    >8 hour (0.2  l/mlnute)
       Breakthrough volume0                  >100 fi.
       Tube capacity0                        >100 g
       Average desorptlon                    0.94 (27.4 ng)
       efficiency of Indicated
       quantity of analyte
       Sorbent tube                          75 mg sorblng layer,
       configuration0"                        25 mg backup  layer
       Extraction solvent                    Hexane

aAdapted from Boyd et al.,  1981
bTh1s material required cleaning by Soxhlet extraction (see text).
cFor  these  tests the  temperature of  the generator effluent was  maintained
 at  25-28°C and  the relative  humidity  at  >9054.   The concentration  of  the
 analyte 1n the generator effluent was  1  mg/m3 of HEX.
      sorbent  tubes  were  Pyrex  (7  cm long  by 6  mm o.d. and  4 mm  1.d.).
 Sllanlzed glass wool plugs  separated  the sections.
03620                               11-12                             08/11/88

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                                 TABLE  II-4

                 Optimized GC Analytical  Procedure  for HEXa-b
        Characteristic
              Type/Value
        Detector

        Column
         Electron capture

         354 OV-1 on Gas-Chrom Q
         (100/120 mesh) 1n glass
         (4 mm  1.d. by 2 m)
                             OPERATING CONDITIONS
        Carrier  gas
          (20 ml/minute]

        Temperatures
          Injection  port
          Column
          Detector

        Detector parameters
        Solvent For compound0
         5% CH4, 95% Ar
          150°C
          135°C
          250°C

          Detector  purge,  5% CH4  with
          95% Ar  (80  mi/minute)

          Hexane
aAdapted from Boyd et al., 1981

bA Hewlett-Packard 5750A gas chromatograph was used.

cThe Injection volume was 5 pi of sample and 1 yi of solvent flush.
03620
11-13
08/11/88

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2500 ng/sorbent  sample.   This 2500  ng  level represents the  smallest  amount
of  HEX  that  can  be  determined with  a  recovery  of  >80%  and  a  relative
standard  deviation  (RSD)  of <10X.   The desorptlon  efficiency  of  100% was
determined  by  averaging the  levels  ranging from near  the  LAQL  of  25 ng  to
1000 times the LAQL.

    For  analysis  of HEX  1n  water,  adequate precautions must  be  taken since
HEX 1s  sensitive  to light 1n both  organic  and aqueous solutions; therefore,
the water samples,  extracts and standard  HEX solutions must be protected.
The rate  of degradation  1s dependent upon the Intensity and wavelength,  with
the half-life  of  HEX being  -7 days  when the solution 1s exposed to ordinary
laboratory  lighting  conditions.   Storing   the  HEX-conta1n1ng solutions  In
amber  or red  (low  actinic)  colored glassware  1s  recommended  for  adequate
protection  (Benolt  and Williams,  1981).

    The  XAD-2  resin extraction  has  been used  to  concentrate HEX from large
volumes  of  water.   Solvent  extraction  of water has  also  proved successful.
The detection  limit used for the organic solvent extraction technique was  50
ng/8.  vs.  0.5  ng/fc  for  the  XAD-2  method.  Using  the  solvent extraction
method   under  subdued   laboratory  lighting  conditions,  the efficiency  of
recovery  for  an  artificially loaded water sample was In the  range of 79-88%.
The  authors concluded  that  the  XAD-2 resin could  not  be  used to accurately
sample  HEX  In water,   but  could  be used  to screen  samples qualitatively
because  of  the poor detection limit  (Benolt  and Williams, 1981).

    DeLeon  et al.   (1980)  developed a  method for determining  volatile and
semlvolatlle  organochlorlne  compounds   In  soil  and  chemical  waste disposal


03620                               11-14                            08/25/88

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site  samples.   This  procedure  Involves  hexane  extraction  followed  by
analysis  of   the  extract  by  temperature-programmed  gas  chromatography  on
high-resolution  glass   capillary  columns  using   ECD;   GC/HS  Is  used  for
confirmation   of   the  presence  of  the  chlorocarbons.    The method  has  a
detection limit of 10 vg/g.

    When a soil  sample  was spiked with a  10  pg/g concentration  of HEX, the
recovery  was  59.8%  (S.D.  6.1};  at  100   vg/g,  95.9%  (S.D.  15.9);  at 300
yg/g,  90.2%   (S.D.  4.1).  Of  the  11  different  compounds tested,  the 100
vg/g  HEX  sample   had   the   highest   standard  deviation  Indicating  that
utilizing this method for HEX may  have  limitations  (DeLeon et al.,  1980).

    Velslcol   Chemical  Corporation  (1979)  has  developed analytical methods
that  have been  used for  detecting HEX   1n  urine,  adipose  tissue,  liver,
kidney  and   muscle   tissues.   The   respective   recoveries  and  standard
deviations for these tests  were (1n percentages):   80+10 (1-50  ppb),  85+_2,
69*4, 71+3 and 76+4.  The  level  of  fortification  for the  tissue samples was
10  ppb.   For  urine, <31% HEX  could  be  degraded when  the  fortified  urine
sample was stored overnight 1n a  cooler.

    Urine  was extracted with  hexane,   the hexane passed through  anhydrous
sodium  sulfate,  and evaporated  to  1  ma.   The  limit  of  detection  for HEX
without concentrating the extract was 0.5  ppb.  For cattle, poultry and fish
tissues,  the  tissues were extracted with 2:1  pentane/acetone, the  homogenate
diluted  with  10%  sodium chloride  solution,  centMfuged, and  the pentane/
acetone layer transferred  Into a  separatory  funnel.   The residues were then
partitioned Into  acetonltrUe  (3  times),  water diluent  added  to  the aceto-
nltrlle,  and  then  back-extracted  with  pentane.  The   pentane  extract was

03620                              11-15                             08/25/88

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treated with  concentrated  sulfurlc acid and then water,  and  concentrated  to
~3  ma.   Upon  dilution  to  10  ml  with hexane,  the  solution  was  treated
with a  1:1  concentrated sulfurlc  add/fuming  sulfurlc  acid  solution,  water.
and  a  9:1   mixture  (solid)  of  sodium sulfate/sodlum  carbonate.   Packed
columns  (3%  OV-1  on  Gas  Chrom Q-100/120  mesh-1n  2 m  x  2  mm 1.d.  glass
column) or  capillary columns (30 m  x  0.25  mm  SE-30  WCOT) can be used  for  GC
using a 63N1-electron capture detector.

Summary
    HEX  1s  an  unsaturated,  highly  reactive,  chlorinated cyc-l1c hydrocarbon
of  low water  solubility and  high volatility.  HEX  1s  used  primarily  as  a
chemical  Intermediate  In the manufacture of chlorinated pesticides  and flame
retardants  with essentially  no  end  uses  of Its own.  Low levels of HEX have
been  detected  1n  the   environment;  however,   when  present,  1t Is  rapidly
degraded  by a  number of  physical processes.

    Several analytical  methods  have  been  developed  for   Identifying  and
quantifying HEX  In various media.   Although  HEX  may  be  found  In  water,
because  of  Us  physical and  chemical  characteristics,  only  a  small  amount
can   be   expected  to   persist.   In  water,   HEX  may  undergo  photolysis,
hydrolysis  and  blodegradatlon.   In  shallow   water,  HEX  has  a   photolytlc
half-life of  <1  hour.   In  deeper water where photolysis  Is precluded, the
hydrolytlc   half-life   of  HEX  Is  several days,   while  blodegradatlon  1s
predicted  to  occur more  slowly.   The rate  of volatilization of  HEX from
distilled water may be as high  as 4.7-8.854/hour.  The rate of volatilization
from  natural  waters  will  depend  upon  depth, turbulence  and  wind   speed.
Adsorption  to  sediments will  also  greatly reduce  the  rate of evaporation
from  natural  waters.
03620                               11-16                            08/25/88

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                             111.  TOX1COK1NETICS
Introduction
    Limited studies on  pharmacoklnetlc parameters  of  HEX have been reported
In the  literature.   Those studies  that  have addressed  the  disposition and
fate  of  HEX  have  been  conducted with  the  1«C-labeled  compound  and  dealt
wUh  the total radioactivity  rather  than HEX per se.  Ho metabolites of HEX
have  been  unequivocally Identified; however,  some  characteristics, such  as
their volatility  and solubility,  have been recorded.

    The principal route of HEX entry Into  the  human  body as  a. contaminant  In
water  would be  by  the oral  route, although  In Industrial  settings   H  Is
conceivable that HEX  could  form an aerosol mist or exist at  fairly low con-
centrations as  a  vapor;  therefore,  there  Is  the  potential  for  pulmonary
uptake.   Dermal  exposure  during  handling procedures  or accidental  spills
should also be considered as a possible route of HEX uptake.

Intravenous Route
    Yu  and Atallah  (1981)  administered  a dose  of  0.25 mg  (-0.75  mg/kg)  of
»«C-HEX  (with an  activity  of  10.b mCl/mmole)  as  0.3  mi  of a  solution  1n
20%  Emulphor  EL620/sal1ne  1rt  the  lateral  caudal  vein  of  male and   female
Sprague-Dawley   rats  weighing  between  240  and  350 g.   Sequential  blood
samples,  taken  over  a  period  of  24  hours  post-dosing, revealed  that   the
elimination of  HEX  followed  a  two-compartment .open  pharmacoklnetlc  model
with  a half-life of -0.7 and -32 hours  for  the Initial and terminal phases,
respectively.

     Following the  administration of  the  l.v.  dose,  Yu and  Atallah  (1981)
 found that -18% of  the "C-labeled HEX  was  excreted In the  feces and -21%

03630                               II1-1                            08/15/88

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1n  the  urine.   The  radlolabel  was  found  In  all  examined animal  tissues.
However, at  24 hours  post-dosing,  the bulk  of the radlolabel was  still  1n
the blood  (-20%), with  lower  amounts In the liver  (-5%),  kidneys  (-2%)  and
the fat  (-2%).   Also, 9% of the  administered radlolabel  was  found  In  the GI
tract (duodenum,  large  and  small Intestine),  which  1s  consistent  with  the
earlier observation  by Mehendale (1977) that some  excretion  occurred  In  the
bile.   Of  the  total  administered  dose.  67% was  recovered within  24  hours
post-dosing.   Metabolites  were  not  characterized   In  the  part of  the  study
concerned with the fate  of HEX after  1.v. administration.

    Lawrence and  Dorough (1982)  examined the uptake, deposition and elimina-
tion  of  HEX following l.v.  exposure  of  female albino  Sprague-Dawley  rats.
Intravenous  doses  of 0.01  mg/kg of  14C-HEX  were  administered  In DMSO or
10:4:1  sallne-.propylene glycol :ethanol  1n  0.2  ml  of  solution.   Recovery of
radiocarbon  Immediately after  treatment was  101.2+4.7%,  based on calculated
doses.   Elimination of  the  dose occurred  predominantly during the  first 24
hours In  the feces  and urine.  Within 72  hours  following  treatment,  22% of
the radiocarbon  was excreted  1n  the  urine,  31.4% was found In the feces and
31%   was retained In the body.  Of the 31% retained  In the body, the kidneys
(22.3%),   lungs   (14.9%)  and   liver   (9.6%)   were  the   sites  of  residue
accumulation.   Accumulation  In  adipose  tissue  was not significant.  Biliary
excretion  was  <14%,  Indicating  that  -50%  of  the radiocarbon excreted  1n the
feces was  unabsorbed.

    In  a  similar  study, El Dareer  et al.  (1983)  administered male Fischer
344   rats  doses  of   0.59  mg/kg  "C-HEX   In  Emulphor  EL-620:ethanol:water
(1:1:4  v/v) In  a  volume  of  0.15  ma/150 g  bw.   A specific  activity  of 18


03630                               III-2                            08/15/88

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vCVmg HEX was  used  for the 1.v.  dose.   At 72  hours  after  treatment 34.0,
15.8 and 39.0%  of  the  dose was found In  the  feces,  urine and body tissues,
respectively.   Of the 39% retained In the body,  13.9 and  18.4% were found In
the   liver   and  carcass,   respectively.    About  0.1%   was   excreted  as
"C-carbon  dioxide  during the observation  period.

Oral Route
    In  the  same communication  In which  the  pharmacoklnetlcs of  HEX after
l.v. administration was  reported, Lawrence and Dorough  (1982) also described
the  results  of  administering  a  single  oral  dose  of  HEX to rats.    Female
Sprague-Dawley  rats  (175-250 g  bw)  were administered  5 vg/kg  14C-HEX by
Intubation as  0.5  ml of solution  1n  corn oil.  Recovery  of  the  radiocarbon
Immediately after oral  treatment  based  on calculated dose was 98.0%.  At 72
hours,  68.2%  of the 5  vg/kg of  14C-HEX  had  been  eliminated 1n the  feces,
24.4%  In the  urine and  2.8% of  the  dose  was  retained  In  the body.   Biliary
excretion  accounted  for 18% of  the  oral dose,  Indicating  the  radiocarbon
eliminated  In  the feces (-50%  of  the dose)  was not  absorbed  from  the  Gl
Irtct.

    Mehendale  (1977)  administered i4C-HEX  (5 pmole;  6  mg/kg)  In corn  oil
to  four  male  Sprague-Dawley rats by oral Intubation.   Dally  urine and fecal
samples  were  collected.   After  7  days  -33% of  the  administered dose  was
excreted 1n  the  urine,  87% of  which  was  eliminated within the first  24 hours
after  treatment.   Fecal  excretion was  equivalent to 10% of the  dose,  -60% of
which  was  excreted  within  24  hours.   Only  a  small  amount  (-0.5%)   of  the
original  dose  was  recovered  In the  kidneys and  liver.  Hehendale  (1977)
speculated  that. 1n  view of the low  total recovery of  the administered dose,


03630                               III-3                            08/15/88

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a  major  part  of  the  dose   (>50?4)  had  been  excreted  through  the  lung.
Subsequent  studies by  Dorough  (1979)  found  that  <1X of  an  oral  dose of
**C-HEX was  excreted  1n  the  lungs.   El Dareer et al.  (1983)  reported  that,
after oral  dosing, HEX  and  Us  volatile metabolites can be readily  lost If
the samples were  dried and powdered In  their analysis.

    Dorough  (1979)  and  Dorough and Ranlerl  (1984)  Investigated the accumula-
tion, distribution and excretion  of  radlolabeled HEX  following  Us  adminis-
tration to  male and female Sprague-Dawley  albino rats  and  mice,  either  as  a
single  oral  dose  or  as a component  of their diet.  To  effectively  account
for  the radiocarbon administered  to  the test animals, two  female rats  were
dosed  by  gavage  with   14C-HEX  at 20  mg/kg  In  0.9  ma  of  corn oil.   The
animals were Immediately  placed In  separate  metabolism  cages  through  which
air  was drawn  at  600  ml/minute.   Passing the  expired  air  through, toluene
traps  showed that  <1%  of  the  administered  dose  was  voided  as  respiratory
gases.

    Single  dose  studies  (Dorough,   1979;  Dorough   and  Ranlerl,   1984)  were
conducted  by administering  14C-HEX  at  doses  of either  2.5  or  25  mg/kg  bw
dissolved  In 0.9 ma  of  corn  oil  for  rats and  0.2-0.3  ma  to mice  using  a
feeding needle.   Animals  were  killed  at  1.  3  and  7 days  post-dosing and
samples of muscle,  brain, liver,  kidney,  fat and  either  ovaries or testes
were  removed  and  analyzed  for   14C-act1vUy.  Urine  and  feces were  also
collected  during the  period between  dosing and tissue sample collection.  No
appreciable  differences  due  to sex  or species  were  found  In the excretion
patterns.   After 7  days, animals  administered 2.5  and  25  mg/kg  HEX had
eliminated  an average  of  16.4 and 15.8% of the dose  In  urine,  and 63.3 and


03630                                1II-4                            08/15/88

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75.2% In  the  feces,  respectively.   The liver,  kidney  and  fat  were the most
Important sites  of  deposition for  l4C-res1dues In both rats  and mice, the
levels In the kidneys of rats  and  liver  for  mice being  the  highest.

    In the same  study,  rats and mice were also  placed  on diets  containing  0,
1,  5  or   25  ppm of   14C-HEX  for  30 days.   Assuming a dally  Intake of  15 g
for rats  and  5  g  for  mice,  this would give  dose rates  of 0, 0.066,  0.330 and
1.666 mg/kg/day for   rats  and 0,  0.182, 0.910  and 4.55  mg/kg/day  for  mice.
Feed  was replaced In the  feeders  every 12  hours to minimize the loss  of
»4C-HEX  (from volatilization) and  killed  at 1,  3, 7, 12, 1'5 and 30  days.
The surviving animals were then  returned to a  normal  diet for  <30  days and,
during this  post-treatment  period,  animals  were killed at  1,  3, 7,  15  and  30
days  after the  last day of treatment.

    The  total  excretion  (urine and  feces}  of  the  radlolabel  ranged from
63-7954  of the  consumed 14C-HEX.    In  all  cases,  the  liver,  kidney and   fat
contained the  highest  amounts of  14C-label  and  a  steady-state  for  these
levels  appeared to  be  reached after  15 days  of the  feeding  phase.   A good
correlation   was  observed  between  the  level   of   HEX  1n  the  diet and   the
14C-levels  found In  all  of  the  tissues examined.   In a  separate experiment
with  male rats,  1n  which  the bile  duct was cannulated and a  single  dose  of
25 mg/kg of  »*C-HEX  was  administered orally,   only  16% of  the dose   was
excreted 1n  the bile.

     The   extraction   characteristics  of  the  radiocarbon  compounds   In   the
excreta  showed that  they were largely  polar  metabolites,  some of which were
capable  of  being changed  to organic  soluble  compounds  after  add catalyzed
hydrolysis.
03630                              III-5                            08/15/88

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    In  a  comparative  study of  the pharmacoklnetlcs of  14C-HEX  after  l.v.
and oral  dosing, Yu and  Atallah (1981) administered single oral doses  of  3
or  6  mg  of  J*C-HEX (specific  activity.  0.267 mC1/mmole)  to  Sprague-Dawley
rats   (240-350 g   bw).    The   doses   ranged   from  8.5-25.6  mg/kg.    The
l*C-act1v1ty  appeared  1n the  blood within 30 minutes of  dosing  and  reached
a maximum after  -4  hours.

    Tissues  were analyzed  for "C-HEX at  8,  24, 48. 72,  96 and  120 hours
post-dosing.   The  kidney and  liver  had higher  residue levels  than  any other
tissue  after  oral  dosing,  although  these  were generally  much lower  than
those  observed  after   l.v.  dosing.   The kidneys  and  liver  were  found  to
contain  0.96 and  0.7554,  respectively, of  the administered oral dose while
these organs  retained  2.92 and 4.68%, respectively,  of  the administered l.v.
dose  at  24  hours  post-dosing.  Significantly,  a higher  proportion (15.07%)
of  the  J4C-act1vHy was  found  1n  the  digestive  system  (duodenum,  large and
small  Intestines)   after  oral dosing.  In  addition, the  Increased  rate and
extent  of fecal  excretion after oral administration (-72%), as compared with
that  after  l.v. dosing  (-20%),  would suggest  that  only a fraction  of the
orally  administered  dose  was  absorbed.   About 17%  of   the  oral   dose was
excreted  In  the  urine.

    Both  urinary  and  fecal metabolites  were  characterized as  polar  due  to
their   lack   of  solubility   1n  organic  solvents.    Unchanged  HEX  was  not
detected  In  any of the  samples examined.  Only 11% of  the 14C-content was
soluble  In  organic solvents  and  a further 32%  was rendered organo-soluble
after   acid   catalyzed  hydrolysis  Indicating,   perhaps,   the  formation   of
metabolic ester-conjugates.


03630                                111-6                           08/15/88

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    Yu and  Atallah  (1981)  also examined  the  capability of liver,  fecal and
gut  homogenates  to  metabolize  HEX  ^ vitro.   In an  apparent  first-order
process.  HEX  was metabolized  by  gut  content,  fecal  and  liver  homogenates
with  half-lives  of  10.6, 1.6  and 14.2 hours,  respectively.   When  mercuric
chloride  (HgCl.)  was added  to  the  gut  and fecal  homogenates,  as a  bacte-
rlodde,  the half-lives  were  Increased to 17.2 and 6.2  hours,  respectively,
Indicating  that  there was  an  Important  contribution of  the  gut  and  fecal
flora  to  the  metabolism of  HEX.   Denaturatlon of  the  liver homogenate  had
virtually no  effect on  the  ^ vitro  metabolic  rate.  Indicating  that  there
was limited Involvement of  enzyme-dependent processes.

    Lawrence  and Dorough  (1982),  In a  comparative  study  of  the  uptake,
disposition and elimination of  HEX,  by the  1.v..  Inhalation  and oral routes,
orally  dosed  Sprague-Dawley  rats (175  and  250  g)  with  either   5  vq or  6
mg/kg  of  radlolabeled HEX.   Doses  1n the mlcrogram range  were  useful  for
monitoring  the urinary and  fecal  excretion of HEX; however, an oral dose of
6 mg/kg,  250  and 600  times  the  Inhaled and  1.v.  doses, respectively,  was
necessary to measure  tissue  residue  levels.  The authors  attributed this  to
the poor  b1oava1labH1ty of HEX when administered by the oral route.

    The  total  recovery of  the  radlolabel  Immediately following the adminis-
tration  of  the  oral  dose  was  98.0*5.3%  (mean *.  standard deviation).   Rats
dosed  orally  voided  2-3  times more  of  the  dose  In  the  feces  than  those
animals  dosed  by the  l.v.  or   Inhalation route.   Blood levels  were measured
<6  hours  after  dosing and  reached a  maximum  at  2 hours.  The  low level  of
radiocarbon  (-1   ng/mi)  appearing  1n  the  blood  as  compared  with  animals
dosed  l.v.  and  by Inhalation Indicate that  there was poor absorption of HEX


03630                                111-7                            08/15/88

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from the GI tract.   The  data  were not  obtained over  a sufficient  post-dosing
period to allow any estimate of the elimination rate.

    Biliary excretion  accounted  for  18% of the administered dose after  oral
exposure as  compared  with  -13X after  l.v.  and -8%  after  Inhalation.   This
observation agreed  with  the  report of Yu and  Atallah (1981) who  adminis-
tered comparable dose  levels  by  the  oral  route.   Lawrence  and  Dorough (1982)
also  reported  that  the fecal  material  contained   predominantly  polar  or
unextractable  material.   This was  the case  even  In animals where  bile  was
collected,  Indicating  that  degradation of  HEX to polar products was  taking
place  1n the  gut.   The  authors  suggested that  the poor  absorption of  HEX
from the GI  tract  may be partially  related to Us high affinity  for binding
with the stomach contents and gut mucosa.

    In  a  more  recent  comparative  study  (El Dareer  et  al.,  1983),  male
Fischer  344 rats  (169 g)  were dosed  at  4.1  and  61 mg/kg  with  -1  ma  of  a
solution  of   14C-HEX  dissolved  1n   a  1:1:4  mixture  of  Emulphor  EL620,
ethanol  and   water.    Little   radioactivity  (-1X)   appeared   as   exhaled
14C02,  2.4% remained  1n the  tissues   at  72  hours,  <79.5X was  excreted  In
the feces, and <35.5 was  eliminated  In the  urine.

Inhalation  Route
    In  a report originally produced  for  the Velslcol  Chemical  Corporation,
(Dorough,  1980)  and later  reported  by Lawrence  and  Dorough (1981,  1982). on
the comparative  uptake of HEX when administered by  various  routes,  rats were
exposed  to  14C-HEX vapor  In  a  specially  designed single animal  exposure
system.   Essentially, a  known amount  of  14C-HEX was  applied  as  a solution
 03630                                III-8                           08/15/88

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In  hexane   to  the  Inside  of  a  3.7  l  generating  flask.   Air   was  drawn
through the flask that was  slowly  rotated  to allow the deposition of HEX on
the  walls  of  the  flask  as  the  hexane  evaporated.   The animal  was   then
exposed to the vapors In a  rodent  respirator and  the  exhaust  vapors  from the
system were  passed  through a  filter  pad  made  from  expanded polyurethane
foam.   The  polyurethane   foam  was  demonstrated  to  entrap  all  of   the
14C-HEX,  which could then be solvent extracted  for analysis.

    Rats  were exposed  for  a period of 1 hour  to  the  HEX  vapors and  received
doses  that  ranged  from  1.4-37.4   yg/kg  bw  (Lawrence and  Dorough,  1981).
Immediately  following  this  1-hour exposure,  the  recovery  of the  retained
dose  was  found  to  be 91.8+8.5%  (mean £  standard deviation).   Tbe exposed
animals  were Immediately  placed  In  metabolism  cages  for  72 hours  during
which  time expired air,  feces and urine  were collected.  The animals  were
then  killed and  specific  tissues  analyzed  for  14C activity.  Less than 1%
of  the retained  radiocarbon was expired during  a 24-hour period   Immediately
following  exposure  and  no  radiocarbon  was  detected  as 14C02-   Only  -69%
of  the Inhaled  dose was recovered, which  was  much lower   than that  recovered
after  1.v. or oral  dosing  (85% and  82%,  respectively).  Since  recovery of
the dose  Immediately following the administration of the  Inhalation dose was
-92%,  the  reduced recovery  during the  72-hour post-dosing period led to  the
speculation that a volatile metabolite was formed during this post-exposure
period,  but  attempts  to  collect and  Identify  such a material  were  not
 successful.

     Blood  concentration-time data  during  a 1-hour exposure and  for >6  hours
 postexposure were  also  presented.  It would  appear  that the levels in  the


 03630                               1II-9                             04/12/91

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systemic  circulation  had  barely  reached  steady state  during  the exposure
period.   Elimination  during the subsequent 6  hours  appeared to relate to a
complex  pharmacoklnetlc model  with  a  terminal  rate  comparable  wHh thai
reported  for the l.v.  route, with a half-life of -30  hours.

    The  elimination  In  the bile appeared  to  be low,  with  only  -8% of  the
administered  dose  being eliminated  by  this route,  as  compared with 13  and
18% after 1.v. or  oral administration, respectively (Lawrence and  Oorough,
1981, 1982).

    The  trachea and  lungs contained  the  highest concentrations  of  14C-HEX
when  the  tissues  from  animals  killed at  72  hours   after  exposure were
analyzed.   These  concentrations were  higher  In these  tissues  than when  the
dose  was administered  by  other  routes.  The  kidneys  were  also a  site  for
residue  accumulation.   Lawrence  and  Dorough  (1981,  1982)   concluded  that.
Irrespective  of  the  route  of  administration,  the  lung appeared to  be  the
primary  target organ  for  toxIcHy.

    The  fraction  of  the  dose recovered In the  feces and  urine (23  and 33%,
respectively)  was  about  the  same  as  that recovered  after the  l.v.  dose,
except  that more  was recovered In  the urine   than  from  the feces after  the
Inhalation  exposure,  while the  reverse was  observed  after  the 1.v. dose.

     In a  comparative  study  of the  uptake,  disposition  and  elimination of
i-C-HEX, El  Oareer  et al.  (1983) placed  Fischer  344  rats  (125-190 g) In
Delmar-Roth  type metabolism  cages;  1.1   mg   of  14C-HEX (15  pCI)   In  0.05
ma of  elhanol was  then  placed  In glass  U-tubes   situated  1n the  Incoming


 03630                               111-10                           04/12/91

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air line of  the  metabolism cages.   After  2 hours, >90% of the  radioactivity
had volatilized  and  the dose  received  by each  rat  was  calculated from  the
total  amounts of  radioactivity  recovered  from the tissues, feces, urine  and
exhaled air.  The fur of the animals was  not  Included.  The dose  received by
the exposed animals was  between 1.3 and  1.8 mg/kg bw.

    The animals  were  killed at either 6  or  24 hours after removal from  the
Inhalation  exposure.  Whole blood, plasma,  liver,  kidney, voluntary  muscle
(gastrocnemlus).   subcutaneous   fat,  brain,   skin  (ears)  and  the residual
carcass (except  for  the skin and  fur)  were analyzed for  14C activity.   The
principal  sites of deposition were  the  lungs,  kidney  and  liver.   Only  -1J4 of
the radlolabel  was  Identified  as   14CO?.   No  Intact  HEX was  found   1n  any
of the  tissues.   The majority  of  the  radlolabel extracted from  the  tissues
was polar  (water-soluble).

    In  a  separate  experiment,  El  Dareer  et  al.  (1983) Incubated  1*C-HEX
with homogenates  of  liver, feces  and  Intestinal (large  and  small)  contents
as  well  as with whole  blood  and plasma.   These  _1n  vitro  studies  were
designed  to  assess  the  binding of  HEX  to  substrates  present  1n the  homogen-
ates.    The  mixtures  were   Incubated at  37°C  with  gentle shaking.   Samples
were taken  at 0,  5 and  60  minutes  and  extracted twice, first  with chloroform
and then,  after   acidification  with 1  ml  of  IN HC1,  with chloroform:metha-
nol (2:1  v/v).    The  radiocarbon  content  of  each  of the  samples  was  deter-
mined  and selected samples were also  analyzed  for  HEX,  per  se,  by an  HPLC
method.   The results,  presented   1n Table  III-l,  demonstrated  the  chemical
reactivity of HEX and Its ability  to bind components of biological material.
03630                               III-ll                           08/15/88

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o
u>
                                                   TABLE III-l
o Extractablllty of [14C] HEX and Radioactivity Derived from Saline and Various Biological Preparations3

Percent
Total Radioactivity In Fraction
First Extraction
Preparation Time
(minutes)
Saline 0
5
60
- Liver 0
« 5
h 60
Plasma 0
5
60
Whole Blood 0
5
60
Feces 0
5
60
_ Intestinal contents 0
§ 5
£ *°
m _^ — ^^ _ _
Organlcb
99.6 (92.4)
99.1 (92.8)
98.8 (94.6)
55.0 (74.4)
42.8 (49.7)
11.1
22.2 (61.7)
19.7 (66.3)
1.4
16.2 (60.4)
2.8
0.6
90.0 (93.7)
83.4 (87.8)
40.5 (61.0)
93.7 (94.7)
82.8 (89.5)
66.3 (87.0)
Aqueous
0.4
0.9
1.2
8.0
15.2
18.8
7.2
25.0
43.4
3.8
21.6
27.4
0.6
0.8
2.8
0.6
1.6
4.6
Second Extraction
Organic

24.5
15.0
5.9
50.2
33.6
21.
27.9
13.4
12.0
8.0
9.0
31.3
4.6
8.6
15.4
Aqueous

1.0
4.7
2.4
0.8
2.0
3.9
1.2
1.6
1.4
0.2
0.6
3.0
0.2
1.0
2.4
Pellet

11.6
22.2
51.8
19.6
19.6
30.2
50.8
60.6
58.6
1.2
6.2
22.4
1.0
5.9
11.3
   aSource:  El  Dareer  et  al..  1983


      mbers  In  parentheses  represent  the percent  of  the
Inactivity In the fraction as  HEX.

-------
Percutaneous Route
    There  were no  studies  on  the  pharmacoklnetlcs  or  disposition  of  HEX
found An  a survey of  the published literature or 1n the  technical  research
documents  provided  to the  U.S.  EPA by  Industry  under  the Toxic  Substances
Control   Act  reporting  requirements.    While  no  quantitative   studies   or
estimates  of  the  uptake of  HEX through  skin  were  found, studies have  been
reported In which discoloration, edema and necrosis of  the  skin  was  observed
following  the  dermal  application  of  HEX (Treon  et  a!.,  1955;  IRDC.  1972).
In  these  reports,  a  toxic  response,   leading  to  death,  was  observed  In
several   Instances,  which would suggest  that  HEX was absorbed  transdermally
Into the systemic  circulation.

Comparative Studies
    It was  evident,  from the available  published literature,  that  the  four
principal  studies  on  the uptake  and disposition  of  HEX each  Involved  more
than one  route of uptake and  that the  comparison of the exposure  route  was
at least one objective of the  study.  The principal  comparative  observations
were as  follows:
    1.  Irrespective  of  the  route  of  application,  the  lung  was  the
        target organ for toxlclty.
    2.  The principal  routes  of  elimination  were the urine  and  feces.
        Considerably more  of  the administered dose was  excreted  1n the
        feces after  oral administration  than  after  dosing by  the  1.v.
        or  Inhalation   route.    More   of  the  administered   dose   was
        excreted  In  the  urine than  the feces  after  Inhalation  exposure
        while the reverse was the case after l.v. administration.
    3.  Biliary  excretion  occurred  after administration  by  all  three
        routes.   For  similar doses,  elimination was  In  the  following
        order: oral > l.v.  > Inhalation.
03630                               111-13                           08/15/88

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    4.   Results of  distribution  studies  are presented  1n Tables  III-2,
        I1I-3  and  III-4.    The  highest  HEX  accumulation  was  In  the
        kidneys,  lung  and  liver  following oral and  l.v. exposure.   Ihe
        lung  and   trachea  contained  the highest  concentration  of  HEX
        after Inhalation exposure.
Summary
    A number  of  studies  are available regarding the absorption,  distribution
and excretion  of  HEX  and Us metabolites following oral.  Inhalation  and  l.v.
exposure.    Comparative   pharmacokineUc  studies  of  laC-HEX   have   shown
higher  levels  of  fecal  excretion   following  oral  exposure  than  l.v.  or
Inhalation  exposure  (El  Career  et al.,  1983;  Lawrence and Dorough,  1982).
Increased  elimination of  radiocarbon following oral  exposure  is consistent
with  toxlcity data  that  Indicate that HEX Is more  toxic following Inhalation
than    oral    exposure.     Following    Inhalation   exposure   to   iaC-HEX,
considerable  amounts  of  the  radlolabel  remain  In   the  lung   and  trachea,
Indicating  that HEX  reacts with  biological  material In  the  lung (Dorough,
1980).

    The  low  level  of   1«C02  or  14C-HEX   (<1%)  exhaled  from the   lungs
following Inhalation  or oral  exposure  Indicates  that the respiratory  tract
does  not play a major role  In the excretion  of  HEX (Dorough, 1979).  Urinary
excretion predominates following Inhalation  exposure.

     Following  oral exposure,  the highest  levels of  HEX are  found  In  the
kidney  and  liver.   Poor  absorption  of  HEX   from  the   GI  tract  has   been
attributed  to  the low  bloavallabllHy of  HEX  In   the  gut  and  Its   rapid
metabolism  by  Intestinal  flora  following  oral exposure  (El  Dareer  et  al..
 1983).   Dietary  exposure  to  HEX  for  30  days  showed   a  good  correlation
 03630                               IH-14                           04/12/91

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o
CJ
to
o
                            TABLE  II1-2

       Disposition of Radioactivity Expressed as Percentage
of Administered Dose from "C-HEX In Rats Dosed by Various foutesa

Feces
Urine
^ Tissues
en
Other volatile
TOTAL RECOVERY
Oral Dose
Lou Doseb High Doseb
(4.1 mg/kg) (61 mg/kg)
79.4 * 2.9 65.3 * 6.9
35.5 * 2.5 28.7 * 4.2
2.4 * 0.6 2.4 ± 0.1
0.8 f 0.0 0.6 f 0.0
0.2 i 0.0 0.3 * 0.0
118.3 i 3.0e 97.3 i 7.0
aSource: Adapted from El Oareer et al., 1983 (The
tlon for three rats.)
Intravenous Doseb Inhalation Dose
Group Ac Group Bb
0.59 mg/kg (1.3 mg/kg) (1.8 mg/kg)
34.Oil.Qd 28.7^4.3 47.5*6.4
15.8 i 1.4 41.0 i 4.8 40.0 » 6.6
39.0 * 1.0 28.9 * 1.6 11.5 * 0.8
0.1 * 0.0 1.4 * 0.3 1.0 * 0.5
0.1 * 0.0
89.0 * 2.0 (100) (100)
values represent the mean X of dose i standard devta-
bAt 72 hours after dosing or exposure
cAt 6 hours after
dplus Intestinal
o
OO _fc
exposure
contents


j    cent  recoveries  for  this dose are "normalized" to 100X.  differences  In  disposition  for  the two doses are
     minimal, an  Indication that no saturable process is operative In this ilosc range.


-------
                                  TABLE  I1I-3

              Fate of Radiocarbon Following Oral,  Inhalation  and
                    Intravenous  Exposure to 14C-HEX  1n Rats
                 Expressed as  Percentage of Administered Oosea
                                    Cumulative Percent of Dose
                    Oralb                Intravenous0             Inhalat1ond

Urine
Feces

Urine
Feces

Urine
Feces
Body
Total Recovery

22.2 + 1.8
62.2 ± 8.0

24.0 * 1.9
67.7 * 5.1

24.4 + 1.9
68.2 * 5.1
0.2 + 0.2
92.8 + 4.7
24-Hour
18.3
21.1
48-Hour
20.7
30.4
72-Hour
22.1
47.4
15.7
85.2

+ 5.2
± 7.1

+ 5.6
± I-?

* 5.7
* 1.9
* 7.8
+ 4.8

29.7
17.0

32.5
21.0

33.1
23.1
12.9
69.1

* 4.5
± 7.5

+ 5.1
± 7-5

+ 4.5
+ 5.7
+ 4.7
* 9.6
aSource:  Adapted from Dorough. 1980, and Lawrence and Dorough, 1982

bDoses administered  In 0.5 ml corn oil at 7 yg/kg bw

cDoses  administered  1n  0.2 ml  10:4:1  sallne-.propylene glycol-.ethanol  by
 Injection Into the  femoral  vein at 5 vg/kg bw.

dDoses  administered  as   vapors  over  a  1-hour  exposure  period  to  achieve
 doses of -24 yg/kg  bw.
03630                                111-16                           08/15/88

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                                  TABLE  III-4

        Distribution of HEX Equivalents In Tissues and Excreta of Rats
   72 Hours After Oral, Inhalation and Intravenous Exposure to 14C-HEXa'D-c
     Sample
Oral Oose
(6 mg/kg)d
Inhaled Dose
(-24
Intravenous Dose
   (10 ug/kg)
Trachea
Lungs
Liver
Kidneys
Fat
Remaining carcass
                                           ng/q of Tissue
292 + 170
420 7 250
539 7 72
3272 7 84
311 7 12
63 +• 40
107.0 * 65.0
71.5 * 55.2
3.6 + 1.9
29.5 * 20.2
2.8 +• 0.4
1.3 «• 0.6
3.3 * 1.7
14.9 * 1.1
9.6 * 1.1
22.3 + 0.6
2.3 +• 0.2
0.5 «• 0.1
                                          Percent of Dose
Whole
Urine
Feces
Total
Body
Recovery
2
15
63
81
.8
.3
.6
.7
+ 1
7 3
I 8
7 6
.1
.3
.5
.7
12
33
23
69
.9 *
.1 7
.1 *
.1 *
4.7
4.5
5.7
9.6
31
22
31
84
.0 «•
.1 7
.4 *
.6 «•
7.8
5.7
1.9
4.6
^Source: Adapted from Dorough, 1980 and Lawrence and Oorough, 1982

bOne  HEX  equivalent  Is  defined as  the amount  of  radlolabel  equivalent  to
 one nanogram of HEX based on the specific activity of the dosing solution.

CA11 values are -the Mean ± S.D. of three replicates.

dNote  that  the oral  dose was  250 and  600  times  that  of  the  Inhaled  and
 1.v.  doses,   respectively.   That  was  necessary  since  residues  were  not
 detected In  Individual  tissues of animals  treated orally at  doses  of  5-25
03630
             111-17
                            08/15/88

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between  14C  levels  found  1n  all  tissues  and  levels  of  HEX  In  the diet;
steady-state levels were reached after 15 days of exposure.

    There  1s  very  limited  data  available regarding the pharmacoklnetlcs of
dermal  exposure  to HEX.   Harked  discoloration  of  the skin  has  resulted
following dermal application of HEX.

    Metabolites  of HEX  have not  been  characterized.    At  least  four polar
metabolltles were  separated  from  I issues  and  excreta  regardless of  the route-
of  admlnstratlon.   Fractions  of  the  polar  metabolites could  be  rendered
organo-soluble  by  treatment  with  an aqueous  strong  acid,  which  suggested
that  these are  conjugated metabolites.   Very  IHtle  of  the radlolabel  In
tissues  or  excreta was  extractable with  organic  solvents  and no  unchanged
HEX was detected  1n any of these fractions.

    The  available  studies  not  are adequate  for  assessing  the  nature  and
mechanisms Involved In the uptake,  metabolism,  distribution  and  excretion of
HEX  by  the   l.v.,  Inhalation  and  oral  routes.   Insufficient  data   are
available  to  make  any  quantitative estimate  of dermal  uptake.   The precise
characterization  and  chemical  nature  of  the  metabolites  of HEX  are  not
available.
03630                                111-18                           06/19/90

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                             IV.   HUMAN EXPOSURE
   Text to be provided by the Office of Drinking Water
03640                                IV-1                            10/16/85

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                        V.  HEALTH EFFECTS IN ANIHALS
Overview
    Hexachlorocyclopentadlene  toxlclty has  been  reported In many  shorl-term
studies, several  of  which have been  reviewed  In other  documents.  Including
NAS  (1978)  and  U.S.  EPA (1980,  1984).   Although  different   1n  scope  and
emphasis  (earlier  U.S.  EPA   documents   addressed  ambient water  and  air
toxlclty.   respectively)   a   large   amount   of   the   scientific   knowledge
pertaining  to HEX  1s  Included  In  these  documents.   To avoid  unnecessary
duplication,  studies  previously discussed  1n  the above  dcc-jrscr.ts  will  not be
reviewed  In great detail  In  this  section,  except when  they are  used  In the
presentation  of critical health effects of HEX.

Acute Toxlclty
    An  approximate  oral lethal  dose  (ALD)  for  female  rabbits  was determined
to  be  420-620 mg/kg.   The oral  ALDs for  male and  female rats  were <280 and
>280  mg/kg,  respectively.   An  oral LD5Q  of 505  mg/kg  for  male  rats was
also  calculated  (Treon  et  al.,  1955).    IRDC   (1968)  determined  the  oral
L05Q  for male albino  rats to  be  926 mg/kg for  HEX  given In corn oil.   In  a
later  study,  IRDC  (1972)  reported oral  LD^s of  630,  530  and  584 mg/kg  for
male,  females,  and  male  and  female  rats  combined,  respectively.  In  a  more
recent  study, Dorough  (1979)  reported an approximate lethal dose  of 65 mg/kg
for male and female Sprague-Dawley  rats  and  approximate lethal  dose  of  180
and 600 mg/kg for Sprague-Dawley  male and  female mice,  respectively.

     The acute toxlclty studies of HEX are  summarized  1n Table  V-l.  Treon et
 al. (1955) conducted  a series  of oral toxlclty  studies using  female  rabbits
 (strain unspecified)  and  Carworth rats  of both  sexes.   HEX was  administered
 03650
v_-|                               04/12/91

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o
OJ
o»
171
o
                    TABLE V-l

              Acute Toxlclty of HEX*
Study
Oral LDjQ
Oral LDso
Oral LDcn
Species/Age
rat,
rat,
Rat.
young adult
adult
young adult
l»50:
LD50:
L050:
males
males
males
Results
- 505
- 926
- 630
mg/kg
mg/kg
mg/kg
Reference
Treon
I ROC.
IRDC.
et al..
1968
1972
1955


    Oral  1050


    Oral  1050


    Inhalation 1059


    Inhalation LCso


    Inhalation LCjo


    Primary eye Irritation
rat. young adult
mouse, young adult
rat. young adult
rat. young adult
guinea pig.
young adult

rabbit, adult
      females - 530 mg/kg
      males and females -
      584 mg/kg

LDso: males and females -
      300-600 mg/kg

LDso: males and females -
      600-1200 mg/kg
3.5-hour LCso: males and
females - 3.1 ppm

4-hour LC5Q,: males - 1.6 ppm
             females - 3.5 ppm

3.5-hour LCso: males and
females - 7.1 ppm

Severe eye Irritant (0.1 ml lor
5 minutes or 24 hours); all dead by
day 9 of study
                                     SRI. 1980a
                                     SRI. 1980a
                                     Treon et al.. 1955
                                     Rand et al.. 1982a
                                     Treon et al.. 1955
                                     IRDC. 1972
CD
CO

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o
u>
o»
en
                                                 TABLE  V-l  (cont.)
             Study
Species/Age
Results
Reference
   Primary dermal Irritation    rabbit, adult
   Primary dermal Irritation    rabbit, adult
   Primary dermal Irritation    monkey, adult
                    Moderate skin Irritant  (250 mg/kg)

                    One application


                    Severe skin Irritant  (200 mg/kg)

                    All males died In study


                    Skin discoloration and  necrosis

                    (0.05 mt of 10X HEX solution)
                         Treon et al..  1955
                         IRDC,  1972
                         Treon et  al..  1955
   'Source: U.S. EPA.
oo
CO

-------
as  a  5%  solution  In peanut oil  by gavage.  In addition,  Southern  Research
Institute  (SRI.  1980a)  reported  the  oral  LD5Q for male  and  female  weanling
B6C3F1  mice to  be 600-1200 mg/kg and  the oral  LD,Q  for weanling  Fischer
344 male and female rats to be between 300 and 600 mg/kg.
    Treon  et  al.   (1955)  reported  an approximate  dermal   lethal  dose  for
rabbits  between 430  and  610 mg/kg  while  IROC (1972)  reported that  1n  male
New Zealand  white  rabbits,  an approximate  lethal  dose  for dermal  exposure
was <200 mg/kg.

    Treon  et al.  (1955)  reported  a 3.5-hour LC5_  of  3.1  ppm for  Carworth
rats  of  both  sexes, and  2.1  and  7.1  ppm  In male  and  female guinea  pigs.
respectively.   Rand  et  al.  (1982a)  reported a  4-hour IC™  of  1.6  ppm for
male Sprague-Dawley  rats and 3.5 ppm for female rats.

    Treon  et  al.   (1955)  reported  HEX to   be  a  primary  skin  Irritant  1n
rabbits  (strain unspecified) at a  dose level of  250 mg/kg.  Monkeys (strain
unspecified)  were   also  tested  by  Treon  et al.  (1955).   Discoloration,
necrosis  and  edema  of  the  skin  were noted when 0.05   mi  of   a   10%  HEX
solution  was  applied for  3 consecutive  days.   Application  of  0.01 ma  of
0.1-10%  solutions  of  HEX  resulted  In  no  skin   Irritation.   IRDC  (1972)
reported HEX to be a dermal Irritant 1n New  Zealand white  rabbits based upon
edema  observed following  the  application  of  200 mg/kg HEX.   In  this study.
Intense  discoloration of the skin was  also noted.

    In a Russian study. Nalshteln  and  Llsovskaya  (1965)  studied  the effects
of  HEX applied  to  the shaved  area of the  skin of  rabbits (strain  unspeci-
fied)  dally  for 10 days.  According to the  authors, no effects were noted In
03650                               V-4                              08/25/88

-------
control  and  test  animals given  dally  doses  of  0.5-0.6 ml  of a  20 mg/a.
solution of HEX.

    The  acute  oral  toxlclty of  HEX was tested  1n  male CD-I mice  (6/group)
following a single gavage dose  of 0. O.OS, 0.1, 0.5, 1.0 or 5.0 g/kg  HEX  In
DHSO (Litton  Blonetlcs,  1978b).   Mortality was  observed 1n 6/6 mice exposed
to both  the 1.0 and 5.0  g/kg dose.   At  doses  of 0.05,  0.1  and  0.5 g/kg. 1/6,
1/6  and  3/6  deaths  were  observed,  respectively.  In  a  follow-up  study,
exposures of  7.6,  25.3 or 76 ing/kg HEX for  5  consecutive days resulted  In
6/10, 9/10 and 10/10  deaths,  respectively.

    Fischer  344 rats  and  B6C3F1  mice  (5/sex/group)  were  administered  a
single  gavage dose of  0,  75, 150.  300, 600  or  1200 mg/kg HEX  and  observed
for 14  days  (SRI.  1980a).  Treatment-related  mortality was seen In  5/5 male
and 5/5  female  rats at >600  mg/kg and  In  2/5  females  at the 300 mg/kg dose
level.    No other treatment-related  deaths  were  recorded.   Animals exposed  to
>300  mg/kg  HEX  also   experienced  decreased   activity,   ruffled   fur   and
diarrhea; the severity and duration was directly related  to the dose  level.
Animals  In  the  75  and  150 mg/kg  dose groups  experienced  none  of the effects
observed at the higher exposure levels  with the exception of  "wet fur  In  the
anal area",  which  the  authors  suggested  may  be  an  Indication of  mild  Gl
disturbances.

    In  the  mice,  all  animals  exposed  at  1200  mg/kg   died, while  only  one
female  and  one male  died at  the  600  mg/kg  level.   At  the other  exposure
levels  (<300 mg/kg) only minor  effects  were observed.
03650                              V-5                               08/25/88

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    In  a  follow-up  range  finding  study  (SRI,  1980b), rats  and  mice were
administered HEX  In  corn oil at 25. 50,  100,  200  and  400  mg/kg  for  rats and
50,  100,  200,  400  and  800  mg/kg  for  mice  on a 12-day schedule  (days 1-5,
8-12,  15  and 16).   Five mice and five  rats  of  each sex were dosed at each
level,  with at  least   two  consecutive dosing days  before sacrifice.   Body
weights were taken  on  days  0,  7  and  17.   All  animals were  observed  twice
dally for signs of toxlclty  and clinical  symptoms.

    In  the  rat experiment (SRI,  1980b).  all  males and  4/5  females  at the 400
mg/kg  HEX  dose level  died,  while  at  the  200  mg/kg  dose,  1/5 males and 4/5
females died.  For  the remaining males,  there  was a  dose-related decrease  1n
body  weight gain of  8,  17,  43  and  135% for  the  25,  50,  100 and  200  mg/kg
dose  groups, respectively.   Significant  gross  changes  In the  stomach Includ-
ing  ulceratlon  and  thickening of  the  stomach wall were observed  1n all  the
surviving  animals at  doses  >100 mg/kg and  1n 5/5 males and  2/5  females  at
the 50 mg/kg dose level.

    In  the  mouse  experiments (SRI,  1980b),  all of the treated animals  at  the
400 and  800 mg/kg dose  level  died.  No  treatment-related  mortality was seen
at  <200 mg/kg  and  only minor effects  were observed at  <100  mg/kg HEX.  The
weight  gain depression  seen  1n  the  rat  study  was not  evidenced  In the mouse
study.

    Rand  et al.   (1982a) conducted  a  range-finding study  1n  which groups  of
10  male and 10 female Sprague-Dawley  rats were exposed  to atmospheres 0.022.
0.11  or 0.5 ppm  HEX.  6  hours/day,  5  days/week  for a  total  of 10 exposures.
Nine  male rats and  one female rat  exposed  to  0.5 ppm HEX  were dead or morl-

03650                              V-6                              04/12/91

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bund after  5-7  exposures.   Prior  to death,  these  rats had  dark red  eyes,
labored breathing,  and paleness of extremities.  No deaths were  noted  \r\  the
other exposure groups;  however,  the males  In  the  0.022 and 0.11 ppm  groups
experienced a  significant (p<0.05)  concentration-related  reduction  In mean
body weight.  Mean  lung  weights  were  significantly  Increased  1n males  and
females exposed  to  0.5 ppm.   Significant reduction  In  kidney,  adrenal  and
ovary weights  were  also  observed  In  the 0.5  ppm  group.   In  males,  liver
weight was reduced 8-9% of  control at  >0.022 ppm dose  levels and  1n  females
in the 0.11 and  0.5  ppm groups.

SubchronU and Chronic Toxldty
    Subchronlc toxlclty studies  of  HEX  are summarized  In  Table V-2.   Oral
toxlclly studies In B6C3F1 mice  and Fischer 344 rats  have  been  conducted by
SRI (1981a,b;  Abdo.  1984)  under contract  with  NIP.   In the  mouse study (SRI,
1981a). dose  levels of  0. 19. 38, 75.  150 and  300  mg/kg HEX (94.3-97.4%) In
corn oil were administered by  gavage to  10  mice of  each sex. 5  days/week  for
13  weeks  (91  days).   At  the highest dose  level  (300 mg/kg), all male mice
died by day 8 and  three  females died by  day 14.  In  female  mice,  there  was
significant  dose-related   enlargement  of  the   liver.   Toxic  nephrosis  In
females at doses  of  >75  mg/kg was characterized by  lesions  In  the  terminal
portions  of  the convoluted  tubules,  with basophllla  In the Inner  cortical
zone and cytoplasmlc  vacuollzatlon.  Nephrosis  was  not observed  In  male mice
at  any  dose  level.   Levels   of  >38 mg/kg  HEX  caused  lesions   In the fore-
stomach,  Including  Inflammation  and  hyperplasla In  both males  and  females
and  a  decrease  In  relative  body  weight gain.   These  lesions  Increased in
severity and  Incidence  with  Increased  dose.  At the  19  mg/kg dose  level, no
significant hlstologlc  changes were  seen  In  any  of  the  organs  examined.


03650                              V-7                                04/12/91

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o
CO
 CO
                                                                               TABLE  ¥-2


                                                                      Subchronlc loxtclty of HEX*
Study Species
90-Day feeding study rat
90-Day feeding study mouse
14 -Week Inhalation rat
toxlclty study
14 -Meek Inhalation monkey
toxlclty study
Dose
10. 19. 3B. TS. 150
mg/kg (by gavage)
19. 38. 75, 150 or
300 mg/kg (by gawage)
0.01. O.OS and 0.? ppn
IS days/week)
0.01. 0.05 and 0.2 ppn
(5 days/week)
Results
NOAEL
LOAEL
NOAEL
LOAEL
NOEL
LOEL
NOEL
LOEL
- 10 mg/kg
- 19 mg/kg
- 19 ng/kg
- 38 wj/kg
- 0.2 ppcn
- NE
- 0.2 ppm
- NE
Effects at LOU or Reference
Lowest Dose
Lesions of forestonuch In SRI. 1981b
female rats at 19 mg/kg
Lesions of forestonuch In SRI. 1981a
both sexes at 38 mg/kg
No statistically slgnHI- Rind et al.. 1982A
cant effects
No effects noted Alexander et al.. 1980
           •Source: U.S. EPA. 1984


           NE • Not established
  CO
  co
  CO

-------
Slight Increases In organ  weights  were noted.   A dose level of 38 mg/kg was
considered a LOAEL 1n mice based on  the  Increasesd  Incidence and  severity  of
nephrosls  In  females  and  an Incidence  of  hyperplasla  and  Inflammation  in
males and females.   The  19 mg/kg dose level  was  considered  a NOAEL  for  mice.

    In the rat study (SRI. 1981b;  Abdo et al.,  1984),  dose levels  of  10, 19,
38, 75 and ISO mg/kg  HEX  1n corn  oil  were  administered  by gavage to  groups
of 10 male  and female  F344 rats, 5 days/week for 13 weeks.  At doses  of >38
mg/kg  HEX,  epithelial   hyperplasla  and  Inflammation  of  the  forestomach,
Increased mortality and  toxic  nephrosls  were observed In  males and  females.
A  significant  (p<0.05)  dose-related  depression  1n  body weight  gain was
observed   In  males  at   levels   of  >38  mg/kg  and  females  at  >75  mg/kg.
Liver-to-brain  weight   ratios   were   significantly   (p<0.05)   Increased   1n
females  at  >38 mg/kg  and k1dney-to-bra1n  weight ratios  at  >75 mg/kg.   At
doses >19  mg/kg, epithelial  hyperplasla  and focal Inflammation of the fore-
stomach,   and   toxic  nephrosls  were  noted  In  females.    Decreases  In  body
weight gain  relative to the controls  were observed  1n  males  at all  dose
levels;  however,   these  were not  significant   at  the 10  or  19  mg/kg  dose
levels.   In  females,   dose-related   decreases   In  body  weight   gain  were
observed   at  doses >38   mg/kg/day.    No  significant  adverse  effects  were
observed   In rats at the  10 mg/kg dose  level.   A summary  of these results  are
presented In Table V-3.

    Fourteen-week  Inhalation studies 1n  rats and  monkeys  have  been performed
(Rand  et  al., 1982a,b;   Alexander  et al.,  1980).   Groups  of 40  male  and  40
female Sprague-Dawley  rats,  weighing  160-224 g  or  groups of  12  cynomolgus
monkeys  (6/sex),  weighing 1.5-2.5 kg,  were exposed  to  HEX.   6  hours/day.  5
days/week,  for  as  long  as 14  weeks.   Levels of exposure  were  0,  0.01,  0.05

03650                              V-9                               04/12/91

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o
u
in
O
                       TABLE V-3


Toxlcologlcal Parameters for Mice and Rats  Administered

     Technical  Grade HEX  In Corn  Oil for 91 Daysa
o
CO





Pathology
Forestomach
Species/
Strain

Hale mice/
B6C3Fi




Female mice/
B6C3F]




Male rats/
Fischer 344




Dose
(mg/kg)

0
19
38
75
150
300
0
19
3B
75
150
300
0
10
19
38
75
150

Mortality

1/10
0/10
0/10
0/10
0/10
10/10
0/10
0/10
0/10
0/10
0/10
3/10
3/10
1/10
1/10
1/10
3/10
7/10
Relative
Weight
Galnb

f36X
t 9X
- 9X
-45X
--
	
f!3X
-13X
-13X
-25X
-38X
„ _
- 4X
- 8X
-20X
-49X
-57X

Inflammation

0/10
0/10
2/10
7/10
7/10
7/10
0/10
0/10
2/9
6/10
10/10
7/9
0/10
0/10
0/10
4/10
9/10
8/9

Hyperplasta

0/10
0/10
2/10
8/10
9/10
8/10
0/10
0/10
2/9
9/10
10/10
9/9
0/10
0/10
0/10
5/10
9/10
8/9

Kidney

Toxic
Nephrosls
0/10
0/10
0/10
0/10
0/10
0/10
0/10
0/10
0/9
10/10
10/10
7/10
0/10
0/10
4/10
10/10
9/10
8/10
00
CO

-------
0                                                 TABLE  V-3 (cont.)


en





Pathology
Forestomach
Species/
Strain

Female rats/
Fischer 344




Dose
(mg/kg)

0
10
19
38
75
150

Mortality

1/10
2/10
1/10
1/10
3/10
5/10
Relative
Weight
Gain6
OX
«• 4X
- 5X
- 2%
-30X
-33X

Inflammation

0/10
0/10
2/10
2/10
9/10
9/10

Hyperplasla

0/10
0/10
2/10
5/10
9/10
9/10

Kidney

Toxic
Nephrosls
0/10
0/10
0/10
10/10
10/10
10/10
"Source:  SRI. 1981a,b


^Relative weight gain Is calculated as:
                                       ou

                                          Control  Group Value
                                   Dose Group  Value  -  Control  Group  Value
o
CD
oo
00

-------
and  0.20 ppm  HEX.   In monkeys,  there were  no  deaths,  or adverse  clinical
signs,  or  significant  changes  In  weight   gain,  pulmonary  function,  eye
morphology,  hematologlc  parameters, clinical chemistry or  hlstopathology  at
any dose  level tested.

    Hale  rats  had  a  transient appearance of  dark-red  eyes at 0.05  and  0.2
ppm" HEX.  At  12  weeks,  there were marginal but not statistically significant
Increases  1n  hemoglobin   concentration  and  erythrocyte  count  1n  0.01  ppm
males,  0.05  ppm females,  and  0.20 ppm males and  females.  There were  small
but nonsignificant  changes 1n mean liver  weight  of  all  treatment  groups  and
similar   changes  In  the  kidneys  of  all  treated  males.   There  were  no
treatment-related  abnormalities  1n gross  pathology  or  hlstopathology.   On
this basis,  the  NOAEL  1n  rats  was  0.2  ppm  HEX.

    In  another  study  by  Rand et  al.  (1982b),  no  treatment-related ultra-
structural changes  were  observed In monkeys exposed to HEX vapors.   Exposure
was  Identical  to that described  In the  previous  study (Rand  et al., 198?a).
This  study took  an  1n-depth look at the Clara cells of the lung; the results
showed  a statistically significant (p<0.01)  Increase  In  the  mean  number  of
electron-lucent  Inclusions  In the apex and  base  of the  Clara  cells In the
exposed   animals   as   compared  with  the   controls.    According   to  some
researchers  (Evans  et al.,  1978), Clara  cells respond  to Injury  by regres-
sion  to a more  primitive cell type.   Rand et al. (1982b) noted that some of
the  ultrastructural changes  In  the  exposed  animals resembled  those of the
Evans  study.   The  biologic   significance  of these results  are  not  known;
however,  Clara  cells  play an  Important part  In  producing the extracellular
lining  of the  peripheral airways.  Alteration of  this  lining may result In
subsequent  Impaired breathing (Rand et al..  1982b).

03650                              V-12                              04/12/91

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    Treon et al.  (1955)  exposed  two  guinea pigs, six rabbits, four  rats and
five mice  to  a concentration of  0.34  ppm HEX  for  7  hours/day,  5  days/week
for 25-30 exposures.  Guinea  pigs  survived the 30 exposures, while  only two
rabbits  survived  and no  rats or  mice survived  5  exposures.   Degenerative
changes  were   observed   In   the  brain,  heart,  liver,   adrenal   glands  and
kidneys.  Severe  pulmonary edema,  hyperemla and  acute necrotlzlng  bronchitis
was also  observed.   Using a  lower concentration (0.15  ppm HEX),  2/2  guinea
pigs,  3/3 rabbits and 4/4 rats survived IbO seven-hour  exposure  periods.   In
mice,  only  1/5  animals  survived.   Slight  renal and hepatic  degeneration was
noted  In  all   species  and rats,  mice and  guinea pigs  also developed  lung
lesions.

    In  an  NTP-sponsored study (Battelle  Northwest  Laboratories,  1984;  Abdo
et al.,  1986),  F344  rats and B6C3F1  mice  (10/group/sex)  were exposed  to HEX
(99.4254)  at 0, 0.04, 0.15,  0.4.  1  or 2  ppm  (0, 0.45, 1.67, 4.46,  11.1  or
22.3  mg/m3) 6 hours/day,  5 days/week  for  13  weeks.   All  rats  and  mice
exposed  to  >1  ppm died; 5/10 male and 2/10  female  mice at  the  0.4 ppm  also
died.    In   male  rats,   there   were  statistically   significant  (p<0.05)
reductions  1n  body  weight  and Increases In relative  lung weight at 0.4  ppm.
Similar   but   less   severe   effects   were   seen  In  females.   Dose-related
hlstopathologlc changes  were  observed  In  the  respiratory tract epithelium of
males   and  females  at  >0.4  ppm.    Changes  Included  necrosis  and  acute
Inflammation.   No statistically  significant adverse effects were observed In
rats at <0.15  ppm.

    In  mice (Abdo et al., 1986),  exposure  to  >0.4  ppm  HEX resulted in a 10%
reduction   1n   body  weight   gain  In  males   and   females.   Dose-related


03650                              V-13                              04/12/91

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hlstopathologlc   alterations  1n   the  respiratory   epithelium,   including
hyperplasla  and  metaplasia,  were  observed  1n  all  treated  mice  at  levels
>0.15 ppm.  No adverse effects were seen In mice exposed at 0.04 ppm.

    A chronic  oral  toxlclty study of  HEX  being  conducted  by  SRI  for  the  NIP
was  terminated In  April  1982  because Inhalation was  determined  to be  the
more  relevant  route of  exposure.   No other chronic oral  toxldty  data  were
available  for  this  report.   There were  no  chronic  dermal  toxlclty  studies
found In the available literature.

    A 30-week  Inhalation study  1n rats of technical  grade HEX, 9654 pure with
hexachlorobuta-1,3-dlene  and   octachlorocyclopentene  as   Impurities,   was
conducted  by  Shell  Toxicology  Laboratory (D.  Clark  et  al., 1982).   Four
groups  of  8  male and  8  female  Wlstar  albino  rats were  exposed to HEX at
nominal concentrations  of 0, 0.05. 0.1 and  0.5  ppm  for  6 hours/day,  5  days/
week, for  30 weeks  and  were observed for a  14-week  recovery period  without
HEX  exposure.   At  the   highest dose  level 4  males  and  2  females  died.   In
males,  there  was  a depressed body  weight  gain In the  0.5 ppm group relative
to  controls  beginning at  7  weeks of  exposure and persisting throughout  the
remainder  of   the   study.   In   females,  body  weights  were  significantly
Increased  during  the  first half  of   the  exposure period  but  were signifi-
cantly  (p<0.01) decreased at  the end of  the  recovery period  at  0.5  and 0.1
ppm.   At  0.5  ppm,  there  were  pulmonary  degenerative changes  noted  In both
sexes although the males  were affected  more  severely.   At the 0.5 ppm dose,
there were mild degenerative changes  In the liver and kidneys at 30 weeks In
a  few rats and  kidney   weights were  significantly Increased  In the females.
After  30  weeks  of  study,  there was  no biologically  significant  toxldty
noted In animals  exposed to  concentrations of  0.05 or  0.1  ppm  HEX.

03650                               V-14                              04/12/91

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HutagenUUy
    Goggelman et al. (1978) found that HEX was not mutagenlc wUh  or without
liver mlcrosomal  activation  at ?.7xlO"3 H  1n  an Escherkhla  con K12. back
mutation  system.   In this  test there  was  70%  survival  of bacteria  at  72
hours.  HEX was not  tested at  higher  concentrations because  It was cytotoxlc
to E.. coll.  A previous report  from  the  same  laboratory  (Grelm et  al.. 1977)
Indicated that HEX  was  also  not mutagenlc 1n Salmonella typhlmurlum strains
TA1535 (base-pair mutant)  or  TA1538  (frame  shift mutant) after  liver mlcro-
somal  activation;   however,  no details  of  the  concentrations  tested «cie
given.   Although  letrachlorocyclopentadlene  Is  mutagenlc  In these  systems,
probably  through  metabolic conversion  to  the  dlenone,  It  appears that  the
chlorine  atoms  at  the  C-l  position   of  HEX  hindered  metabolic  oxidation  to
the corresponding acylatlng dlenone  (Grelm et  al., 1977).

    A  study  conducted  by  Industrial  B1o-Test  Laboratories  (IBT,  1977) also
suggests  that  HEX  Is  not mutagenlc  1n S.  typhlmurlum.   Both  HEX and  11s
vapors were  tested  with  and  without metabolic  activation.   The  vapor  test
was done  In desiccators with  only the TA100  strain of  S.  typhlmurlum.   It  Is
not clear from  the  data whether sufficient amounts of HEX  or  adequate  times
of exposure were used.   Exposure limes of 30,  60 or  120 minutes were studied.

    At  concentrations   of  <1.25xlO"3  ug/ml  In  the   presence   of an   S-9
liver  activating  system,  HEX was not mutagenlc  In the mouse  lymphoma muta-
tion  assay.   MutagenUHy could  not be  evaluated  at higher  concentrations
because of the cytotoxlclty of HEX (LHton Blonetlcs,  Inc..  1978a).
03650                              V-15                              04/12/91

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    Williams  (1978)  found  that  HEX  (10"* M)  was   Inactive  in  the  liver
epithelial  culture  hypoxanthlne-guanlne-phosphoMbosyl  transferase  (HGPR1)
locus/mutation  assay.   At  10"5 M  H  also  failed  to  stimulate  DNA repair
synthesis  In  hepatocyte  primary  cultures.   Negative  results  were  also
obtained In an additional unscheduled DNA synthesis  assay  (Brat.  1983).

    Two  recent  studies provided by  NTP  (Haworth et al.,  1983) also did not
demonstrate the mutagenlclty  of  HEX.   In  S.  typhlmurlum strains  1A98, TA100,
7A1535  and  TA1537.  levels   of  <3.3  yg/plate  were  not  mutagenlc  without
activation  and  levels  of <100.0  yg/plate  were  not  mutagenlc after micro-
somal  activation.   Higher levels  could  not  be  tested  because of excessive
killing  of  the bacteria.    In  the DrosophUa  sex-linked  recessive lethal
test,  HEX  was not  mutagenlc.   The doses used  1n this  study  were 40 ppm by
feeding  for 3 days  or  a single  Injection of 2000 ppm.

    HEX  has  also   been  assayed In  the  mouse  dominant lethal  test  (LHton
Blonetlcs,  Inc.,   1978b).   In  this assay,  0.1, 0.3  or  1.0  mg/kg  HEX was
administered  by gavage to 10 male  CD-I  mice for 5 days and  these mice were
then  mated  throughout  spermatogenesls   (7  weeks).    This  test  determines
whether  the  compound   Induces  lethal  genetic  damage  to the  germ  cells of
males.   There was   no  evidence  of  dominant  lethal activity  at  any dose  level
by  any  parameter   (e.g.,  fertility Index,  Implantations/pregnancy,  average
resorptlons/pregnancy).

CardnogenlcUy
    An  NTP bloassay  of HEX  for  cardnogenlclty by  the  Inhalation  route  In
rats  and  mice  Is  In  progress  (NTP,  1991).  The  ability  of HEX to  Induce

03650                              V-16                              04/12/91

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morphologic transformation  of  BALB/3T3 cells  \t\ vitro  has  been studied  by
LHton BloneUcs, Inc. (1977).  Evaluation of  the potential  for  carcinogenic
activity was based on the following criteria:
    The endpolnt of  carcinogenic activity  Is determined  by  the  presence
    of f1broblastlc-l1ke colonies, which are altered  morphologically  In
    comparison to the cells observed  In normal  cultures.  These (trans-
    formed) cells  grow  In  criss-cross,  randomly oriented  fashion  with
    overlapping  at  the  periphery  of  the  colony.   The  colony  exhibits
    dense  piling  up  of  cells.   On staining the  foci  are deeply stained
    and  the cells are  basophlllc In  character and  variable  In  size.
    These  changes are  not  observed  1n  normal  cultures,  which  stain
    uniformly.
    Assays   were  performed    at    levels   of   0.0,    l.OxlO'5,   ?.OxlO's.
3.9xlO~5,   7.8xlO"s   and   1.56xlO"4   pi/ml.    The   cultures   were  exposed
for  48 hours  followed  by  an  Incubation  period  of   3-4  weeks.   The  doses
selected  allowed  an 80-100%  survival of  cells  as   compared   with  solvent
negative  controls.    3-Methylcholanthrene  at  a  dose  level of  5  pg/mi  was
used  as  a positive control.  Results  Indicated  that  HEX was not responsible
for any significant  malignant transformation.

Teratogenlclty
    The  teratogenlc  potential  of  HEX was  evaluated In pregnant  Charles River
CD-I  rats  administered  HEX (98.25%)  In  corn  oil. by gastlc  Intubation, at
dose  levels of  3, 10 and  30 mg/kg/day from days  6 through 15  of  gestation.
A control  group received  the vehicle  (corn   oil)  at  a  dose  volume  of 10
mt/kg/day.   Survival  was   100%,  and  there   was  no  difference   In   mean
maternal  body weight  gain  between dosed  groups  and  controls.   A  persistent
anogenHal staining  was observed  In dams at the highest dose.   There were no
 differences  In   the  mean   number   of  Implantations,  corpora  lutea.   live
 fetuses,  mean fetal   body weights  or male/female sex  ratios among  any of the
 03650                              V-17                              04/12/91

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groups.   There were  no statistical differences  In  malformation  or  develop-
mental  variations  compared with the controls when  external,  soft  tissue  and
skeletal examinations were  performed (IRDC, 1978).

    Murray et  al.  (1980)  evaluated the teratogenlc  potential  of  HEX  (98%)  In
CF-1 mice  and  New Zealand  white rabbits.  Mice were dosed  at  0.  5,  25  or  75
mg/kg/day  HEX  by gavage  from days 6-15 of  gestation  while rabbits  received
the  same dose  from days  6-18 of  gestation.   In  the  mice,  no  evidence  of
maternal  toxlclty,  embryotoxIcHy  or  teratogenlc  effects  was observed.   A
total of 249-374 fetuses  (22-33 litters) were examined 1n each dose group.

    In  rabbits,  maternal  toxlclty was  noted  at   75 mg/kg/day  (diarrhea,
weight  loss  and mortality),  but  there was no  evidence  of  maternal  toxlclty
at  the  lower levels.   There  were  no  embryotoxlc effects at  any  dose  level.
Although  there  was  an  Increase In  the proportion of  fetuses  with 13 ribs  at
75  mg/kg/day,   this  was   considered   a  minor  skeletal   variation,  and  the
authors concluded that  HEX  was not  teratogenlc at the levels tested.

    Studies  on  the  teratogenlc potential of  Inhaled HEX  were not located  In
the  review  of  the  scientific   literature.   No  data  were  located   that
addressed the reproductive  effects  of  HEX.

Summary
    Although  there  are  some  Interspecles  differences  among  guinea  pigs,
rabbits,  rats  and  mice,  HEX  vapors  are toxic  to  all species  tested.   HEX
appears  most  toxic  when  administered by  Inhalation, with oral  and  dermal
administration  being  less  toxic   routes.   The  acute lethal  concentration


03650                               V-18                              06/19/90

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      )  of  1.6 and 3.5  ppm In male and  female  rats, respectively, has  been
demonstrated.   The oral  LD5Q  for  adult  animals  Is  >500  mg/kg; however,
approximate  lethal doses  of 180 and  280 mg/kg  were determined for mice  and
rats, respectively.

    Subchronlc  oral  dosing of  rats  (38 mg/kg/day)  and  mice (75  mg/kg/day)
for  91  days  produced  nephrosls  and  Inflammation  and  hyperplasla  of  the
forestomach.  No overt  signs  of toxUHy were noted when mice and  rats  were
exposed by  Inhalation at 0.2 ppm  of  HEX (6  hours/day,  5  days/week)  for  14
weeks.  However, Inhalation exposure  of  rats  at 0.5 ppm for  30 weeks caused
degenerative changes  In  the  liver,  respiratory  tract and kidneys,  in  vitro
test results from  three species have  not  shown  HEX  to  be a  mutagen.   HEX was
also  Inactive   1n  the mouse  dominant lethal  assay.  In  rabbits, maternal
toxlclty has been  noted at high oral  levels of  HEX  (75 mg/kg/day}.  but  there
was no  evidence of maternal  toxUUy at lower  levels.   Other research  has
not shown any  maternal  toxlclty to mice.   Long-term studies of  HEX  Inhala-
tion are presently being conducted  by  the NTP.
03650                              V-19                              06/19/90

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                        VI.  HEALTH EFFECTS IN HUMANS

    According to  a  NIOSH estimate. 1427  workers  are occupatlonally exposed
to HEX  (NIOSH,  1980).   VelsUol officials estimate  that  -157  employees are
potentially  exposed  to  HEX  In their  production facilities.   Acute   human
exposure  has  been reported  In homes  near  waste  sites  where HEX  has been
disposed (C. Clark et al..  1982; Ella  et  al.,  1983).

    Very  little  detailed   Information   Is  available  concerning  the   human
health effects  of HEX  exposure.   The  most noticeable effect Is  the  pungent,
Irritating  odor  produced  by  HEX.   Levins  (1980)  reported  that  the odor
threshold  of  0.0017  mg/m3  (0.00015 ppm) represented  the recognition  level
for 100%  of the  Individuals on a  test  panel.   The study design and method-
ology  were  not  given.   Based  upon  animal  studies  and   observations   by
researchers, HEX  vapors are very Irritating to all mucous membranes, causing
tearing, sneezing and  salivation; skin contact can cause  blisters and  burns.
Inhalation  of vapors or  mist  can result  In the secretion of excess  fluid  In
the   lung,  while  Inhalation   or   1ngest1on  may cause  nausea,   vomiting,
diarrhea,  lethargy,   respiratory   Impairment  and Injury  to  the  liver   or
kidneys.

Acute Exposure Studies
    Treon et al.  (1955) reported that members of  a group  conducting toxldty
tests  developed  headaches  when they  were  accidentally  exposed to unknown
concentrations  of HEX,  which  had escaped  Into   the  room when an aerated
exposure chamber was  opened.
03660                               VI-1                             08/25/88

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    A well-documented  Incident of  acute human exposure  to  HEX occurred  In
March 1977  at  the  Morris Forman Mastewater  Treatment  Plant In  Louisville,
KY.  The  Incident  has  been described and  reviewed  1n several papers  (Wilson
et  al.t  1978;  Morse et  al.t  1979;  Komlnsky et  al..  1980).   The complete
details  of   the  original  NIOSH  Hazard  Evaluation  and  Technical  Assistance
Report Number TA-77-39 are found In Komlnsky and Wlsseman  (1978).

    In 1977,  the Louisville  treatment facility was  contaminated with  -6  tons
of  HEX  and  smaller  amounts of OCCP.  a waste by-product  of HEX  manufacture
(Morse et al.,  1979).   The contamination  was  traced  to one  large  sewer  line
that passed  through  several  populated areas.   Concentrations of  HEX detected
In  the  sewage water at  the  plant  ranged <1000 ppm, and  levels In  the  sewer
line  ranged  <100   ppm.    Air  samples  from  the   sewer  line  showed   HEX
concentrations  <400 ppb.   Although  airborne concentrations of  HEX  at  the
time of  the  exposure  were unknown,  airborne concentrations In  the  primary
treatment areas  (screen and grit chambers) ranged  between  270  and 970  ppb 4
days after   the  plant   had  closed.    (The  ACGIH TWA  for  HEX was  10 ppb  In
1977.)    During  the  cleanup,  when   workers  used  steam  to   remove   the
contamination,  levels of  19.2  ppm HEX were  reported (Komlnsky et al.,  1980).

    The  Centers for  Disease Control  (CDC) and NIOSH developed  questionnaires
regarding the type  and  duration of symptoms  (Morse et al., 1979; Komlnsky et
al., 1980).   A total  of 193  employees  were  Identified as those potentially
exposed  for   2  or  more  days during  the 2 weeks before the  plant  was closed
(Morse  et al.,  1979).   Of  the  193  employees  exposed, 145  (75%)  responded.
Physical  examinations   and  blood  and  urine  samples  were  collected  from
workers  reporting  symptoms  of  mucous  membrane Irritation.


03660                                VI-2                            08/25/88

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    Results of  the  CDC  and  NIOSH questionnaires showed  that  the  odor  of  HEX
was detected  before the onset of  symptoms  by 94% of the workers.   The most
common  symptoms reported  were  eye  Irritation  (59%),   headaches  (45%)  and
throat  Irritation  (27%)   (Table   VI-1).    Of   the   41   workers   physically
examined, 6 had physical  signs  of eye  Irritation  (I.e.,  tearing  or  redness)
and 5  had  signs of  skin Irritation.  Laboratory analyses of  blood and urine
specimens from  these workers  showed  elevations  of  lactic dehydrogenase (LDH)
In  21% and  protelnurla In  15%.   However,  no  clinical abnormalities were
reported by  the plant  physician,  the  local  hospital, or by  the  Independent
laboratory 3 weeks later (Horse et a!.,  1978, 1979).

    During  clean-up procedures,  clinical  chemistry parameters  were  moni-
tored.  The  only abnormalities  noted  were  several   minimal-to-mild  altera-
tions  In liver  function tests (Komlnsky et  al., 1980).   These  abnormalities
are  listed  In  Table  VI-2.  All  workers  showing  these symptoms also  had
physical signs  of  mucous  membrane  Irritation.   Table  Vl-3  summarizes data
for nine workers exposed  at the site (Komlnsky  et al..  1980).   The  exposure
levels could  not be estimated accurately because of  possible prior  exposure
and because the workers had used protective equipment.

    A  questionnaire  was also given to a  selected  sample of  residents of  a
48-block  area  surrounding  the  contaminated sewer  line.  A  total  of  212
occupants were  surveyed.   Very few  residents  noted  an  unusual  odor  (3.8%).
The most  prevalent  symptoms  were  stomachaches  (5.2%),  burning  or  watering
eyes  (4.7%) and headaches  (4.7%).   There was no association  between symptom
rates  and  the  distance of  households  from the  contaminated  sewer  line.
03660                               VI-3                             08/11/88

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                                  TABLE  VI-1

             Symptoms of 145 Wastewater  Treatment  Plant  Employees
                 Exposed to HEX (Louisville,  KY, March  1977)*
Symptom
Eye Irritation
Headache
Throat Irritation
Nausea
Skin Irritation
Cough
Chest pain
Difficult breathing
Nervousness
Abdominal cramps
Decreased appetite
Decreased memory
Increased saliva
No. of Employees
with Symptom
86
65
39
31
29
28
28
23
21
17
13
6
6
Percent of Employees
with Symptom
59
45
27
21
20
19
19
16
14
12
9
4
4
*Source:  Morse et al., 1978
03660
VI-4
09/19/85

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                                  TABLE  VI-2

                  Abnormalities  for  18 of  97  Cleanup Workers
                    at the Morris Forman Treatment Plant3
                                                           Abnormal Results.

                                                                            b
Laboratory Test Normal Range
Serum Glutamate-
Oxalacetate Transamlnase (SG01) 7-40 mil/mi





Serum Alkaline Phosphatase 30-100 mU/ms.


Serum Total B1l1rub1n 0.15-10 mg/%
Serum Lactate Dehydrogenase 100-225 mU/mi
Range

40-49
50-59
60-69
70-79
80-89
90-99
100-109
110-119
120-129
1.0-1.9
230-239
No.

5
1
4
0
1
1
3
1
1
lc
1
aSource: Komlnsky et al.,  1980

bFor  Individuals  with  more  than  one  serial  blood   test,  only   the   most
 abnormal result Is tabulated.

Associated with serum glutamate-oxalacetate transamlnase  of  66

U = Units of enzyme activity
03660
VI-5
08/11/88

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o
CO
                                                                 TABLE  VI-3

                     Overview of  Individual Exposure  - Symptomatology Correlations at  the Morris Forman Treatment Plant9
       Case
       No.
Estimated Airborne Exposure
Immediate Symptoms
Persistence of Symptoms
Laboratory Abnormalities
                19.200 ppb HEX and  650  ppb
                OCCP  for  several  seconds  (No
                protective equipment)
       2.3.4     7083 ppb  HEX and  446 ppb
                OCCP for  several  seconds.
                (Half-face  respirator)

       5.6      40-52 ppb HEX and 9-21 ppb
                OCCP (Half-face respirator)

       7,8      Exact exposure unknown
                (Half-face  respirator)
                980 ppb  HEX  for  15
                minutes;  OCCP  not measured
                (No protective equipment)
                                 Lacrlmatlon; skin Irritation on face and
                                 neck; dyspnea and chest discomfort;
                                 nausea (several minutes later)
                                 Lacrlmatlon; Irritation of exposed
                                 skin
                                 Slight eye Irritation
                                 Slight skin Irritation
                                 Irritated eyes
                                 Nasal Irritation and sinus  congestion
                                 after 2 weeks of Intermittent  exposures
                                   1.5 hrs.  post-exposure:   Fatigue;
                                   erythema  of  exposed  skin;  eye
                                   Irritation subsided  In  1  day;  chest
                                   discomfort persisted several days.

                                   Asymptomatic at  2 hours,  except
                                   for soreness around  eyes
                                   No residual  after  cessation  of
                                   exposure

                                   Faces  felt  'puffy* and  •wlndburned"
                                   for 1-2 days after exposure.  This
                                   was noted also  by  friends and
                                   family.  No  residual  skin lesions.

                                   Eyes felt "dry  and Irritated1 for
                                   2-3 days after  exposure.  Nasal
                                   Irritation ceased  within 1-2 days
                                   of cessation of exposure.
                                     Lab work 4 days post expo-
                                     sure was normal1'
                                     Lab work 7 days post  expo-
                                     sure was normal on one
                                     workerb

                                     Normal  7 days later on one
                                     None available
                                     None  available
       aSource:  Adapted  from Komlnsky et al.. 1980

       (•Laboratory work  was same as done on cleanup crew
 CO
 CO
 CO

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The authors  slated that  no significant  ambient  air  concentrations  of  HEX
were found 1n these areas  (Komlnsky and Hlsseman,  1978).   Residents  reported
the same types and frequency of  symptoms  reported  by  workers  associated with
HEX exposure,  which  led   the  authors to  suggest   that  these symptoms  were
unrelated to  HEX  exposure or may  be  due to other  confounding  environmental
factors (Horse et al., 1978}.

    Several   papers  have  documented  a similar  Incident of  HEX exposure  1n
Hardeman  County,  TN.  1C.  Clark  et  al.,  1982; Meyer, 1983;  Ella et  al.,
1983}.   In  1978,  workers   at the  treatment  plant began  complaining  of  acute
symptoms similar to those  found  In  the  Louisville  plant.  Air and wastewater
levels  were  monitored,   and  urine,  blood  and liver   function  tests  were
analyzed, as  well  as  data obtained  from an Illness  symptom questionnaire.
In  the original study design,  workers  were compared  with a  control  group
from another  Memphis  treatment  plant, which did not  receive  wastes from the
pesticide manufacturing  plant.   In  a  later  survey, workers  at  two  other
municipal  facilities   were used  for  comparison.   In  the  analysis  of  the
various  monitoring  tests,  C.  Clark  et  al.   (1982)  found  no  statistical
difference  In  urine  samples from  both  of the  Memphis  treatment facilities.
In  the  liver  function   tests,  there  were   no   statistically  significant
differences among the  values obtained for all survey  groups.

    At   the   same  time   the  wastewater  treatment   plant  study  was  being
performed,  an  Investigation of  residential  wells  In  Hardeman  County  was
conducted  In  response to  complaints of  foul  odors  and  bad  taste (Meyer,
1983).   In   this  area also  lies a  200  acre  chemical   land  dump,  which was
operated  from 1964-197?.   In 1978,  the  U.S.  Geologic Survey  {Sprinkle, 1978;
Rlma,  1979)  confirmed the  contamination of  wells.    However,  HEX was  not

03660                               Vl-7                             04/12/91

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detected  In any  samples.   Urine  surveys  and  liver  function analyses were
conducted on  residents.   A summary of this  data  1s  presented  1n  Table  VI-4.
The situation  at the Memphis  treatment  facility  Is the only  known  existing
case of  essentially  continuous  low-level  chronic  exposures  with  Intermittent
higher  acute  exposures, especially  during  an accidental  discharge  from  the
nearby pesticide manufacturing facility (Ella et al., 1983).

Ep1dem1olog1c Studies
    Mortality studies have  been  conducted on workers  Involved  In  the produc-
tion  of HEX  or  formulation  of  HEX  products.   The SMndell  and  Associates
(1980)  report  was  a  cohort  study  of  workers   employed  at  the  Velslcol
Chemical Corporation  plant  at Marshall.  Illinois  between 1946  and 1979.   The
purpose  was  to  evaluate  the vital  statistics  of  all former  and  current
employees (>3  months) who were present during  the  manufacture of chlordane.
In preparing  the cohort, the authors noted  the  difficulties  In  tracing some
of  the  employees.   In   the  final  cohort of 783  Individuals,  97.4% of  the
employees were  located  and  their  vital  status  Included  1n the  study.   The
analysis  showed  no significant differences  1n  mortality rates between  these
employees  and the  U.S.  population.   The  observed  deaths  for  all  causes,
Including heart  disease and cancer, were fewer than  the calculated  expected
deaths among members  of  the U.S. population  (SMndell and  Associates, 1980).

    Wang and MacMahon (1979)  conducted  a  study of 1403 males employed at  the
Marshall  and  Memphis plants for >3 months.  There were 113  observed deaths
compared with  157  expected,  yielding a  standardized  mortality  ratio  (SMR)  of
72.  The  two  highest  SMRs  were  134 for  lung cancer and 183 for cerebrovascu-
lar disease,  but  only   the  latter was statistically  significant  (p<0.05).


03660                                VI-8                             08/11/88

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                                                     TAl    )J-4

           Hepatic  Profile  Comparison  of  Hardoman  County:  Exposed  Group  (November  1978)  and  Control  Group3
o>
o
                  Parameter1*
                                                                          Results
                                                              November 1978
                                                              Exposed Group
                                    Control
                                     Group
  Significance of
Difference (t lest)
Alkaline phosphatase (32-72 mil/ml
  age 21. 25-150 mil/ml age 21}
    Serum gamma glutamlc transamlnase
      (SGG1) (5-29 mU/ml)
i>   Albumin (3.5-5.0 g/dft)
    Total blllrubln (0.1-1.1 mg/dft)
    Serum glutamlc pyruvlc transamlnase
      (SGOT)  (8-22 mil/ml)
Meant                  88.1         61.5
Range                  34-360       31-220
No. above normal/      17/36        8/56
total tested

Meanc                  9.47         11.56
Range                  2-54         4-56
No. above normal/      3/36         3/56
total tested

Heanc                  4.35         4.93
Range                  3.9-4.8      4.2-6.2
No. above normal/      0/36         0/57
total tested

Meant                  0.240        0.51
Range                  0.1-0.8      0.2-1.7
No. above normal/      0/31         4/52
total tested

Meanc                  19.5         16.08
Range                  12-36        9-140
No. above normal/      11/36        7/56
total tested
                                                                                                   0.016
                                                                                               0.430
                                                                                               0.0001
                                                                                               0.0001
                                                                                               0.001
§   aSource:  Meyer.  1983
^    Normal  range Indicated In parentheses

S   cGeometrlc  mean

    U =  Units  of  enzyme activity

-------
The authors  suggested  that these effects were  unrelated  to  exposure  because
the deaths  showed  no consistent pattern with  duration  of  employment  or  with
duration of follow-up.

    A study  of  >1000 employees  (93%  of  the  cohort)  at  the Memphis, TN  plant
from  1952-1979  was  conducted  by   Shlndell  and  Associates  (1981).    The
researchers  found  no significant difference  1n mortality  between  the  control
and exposure  groups  and fewer deaths  In  the study group  than predicted from
vital statistics rates.   The  Investigators  also reported  there  was  no excess
mortality by job function.

    Buncher  et  al.   (1980)  studied  the  mortality  rates  of  workers  at  a
chemical  plant  that  produced  HEX.   The  Investigators   reviewed  personnel
records  for  those who  worked for at  least  90 days between  October  1,  1953
and December  31,  1974.  There were  341  workers (287 male and 54  female) who
fit the  criteria.    Health  status  was ascertained through 1978 and  expected
numbers  of  deaths  were  calculated  based  upon  the  U.S.  population  and
specifics  for  sex,  age  and  calendar  year.   The  SMR was  69  showing  the
workers  to  be  healthier   than  the  general  population.    Deaths caused  by
specific  cancers,  all cancers, disease  of  the circulatory  and  digestive
systems  were fewer  than  the  expected  numbers.  The authors noted  that the
time  since Initial  exposure, <25 years,  reduced the  power   of the  study to
detect cancers, which  may  have a 10-40 year  latent period.

Summary
    There  1s  only  limited  Information  on  the  effects   of  HEX  In  humans.
Acute Inhalation  exposure has resulted In headaches and severe Irritation of
the eyes,  nose,  throat and lungs.  Dermal contact may cause  severe burns and

03660                                VI-10                            08/25/88

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skin Irritation.   Epldemlologlc  studies  have generally shown  no  significant
differences  In  mortality rates  of  workers exposed  to  HEX In  the  workplace
and  the  general population.  Although  a  significant excess  of deaths  from
cerebrovascular disease was reported 1n  one  study, no consistent  pattern was
observed with duration of employment or  follow-up.

    Current  human  exposure  1s  limited  to  Improper handling and  disposal and
proximity to either manufacturing sites  utilizing  HEX or  disposal  sites.  No
other chronic  human  health  effects  data from HEX  exposure  have been located
In the literature.
 03660                                Vl-11                            08/25/88

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                         VII.   MECHANISMS  OF TOXICITY

    The mechanisms  underlying  HEX toxlclty are  not  well understood, mainly
because of  Its  high chemical  reactivity  and ability  to polymerize even at
low temperature.  HEX has been shown to react with oleflns and  other organic
molecules, such as aromatic compounds.  In vitro studies by El  Dareer et  al.
(1983) have  Indicated that  HEX readily binds  to organic material and can be
easily extracted.

    While the available  literature  does  not  provide any single mechanism to
account for  HEX  toxlclty, Lawrence and Borough  (1982)  showed  that  all  routes
of exposure  caused  necrotlc  lung tissue.   Exposure to HEX vapors  results In
Irritation  of  the  respiratory tract  and  may  lead  to  bronchopneumonla  and
respiratory  failure  (D.  Clark et al.,  1982).   In comparison,  the  degenera-
tive changes 1n  the  liver and  kidneys  are mild  and unlikely  to contribute to
the chemical's toxlclty  (NAS,  1978;  SRI, 1980a,b).

    Absorption  from  the  Gl  tract was  reported  to  be  relatively Inefficient.
This may  be due to  the  poor  bloavallabllHy  of  HEX  when administered  by the
oral  route  or  to  Us   rapid  hepatic  metabolism  and  biliary  excretion  (El
Dareer et  al.,  1983; Lawrence  and Dorough, 1962).   Studies  by Yu and Atallah
(1981)  Indicate that the gut  and fecal  flora  may  have  a major  role  1n the
metabolism   of  HEX  and  that  enzyme  dependent  processes  may be  limited.
Absorption   following  dermal  exposure  resulted  In  marked  distinct   skin
discoloration,  and  In some cases, mortality.  This might  suggest  a "site of
uptake"  Interaction, which  may be similar to that observed In  the lung after
pulmonary  uptake.


03670                              VII-1                             08/25/88

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    Following Inhalation and  the  diffusion  of  HEX  through  the  lung tissue to
the blood, metabolism to water-soluble compounds may occur, but attempts to
collect  and   Identify metabolites  have  been  unsuccessful.   The relatively
slow elimination  of  the radlolabel from the systemic circulation after  l.v.
dosing  with  14C-HEX  (approximate terminal half-life of  30 hours)  suggests
potential  for  bloaccumulatlon  or  repeated  dosing  (Lawrence  and   Dorough,
1981, 1982).

    Rand  et  al.  (1982b)  showed  that  significant  changes at  the  cellular
level  In  lung tissue  occurred  after  HEX Inhalation.  HEX  vapors affect  the
extracellular  lining,  and  In  some  cases, cause  significant  Increases  In
hemoglobin and  red  blood cells.  Although  more  severe effects  seem  to  occur
by Inhalation,  Impaired  breathing was  seen  1n  most experiments  regardless  of
the route of exposure.

Summary
    Little  Is known  about  the  mechanism  of  HEX  toxldty.  Because of  Us
high  reactivity  and  volatility, attempts  to  Identify  the reactive  metabo-
lites  of  HEX  and  to characterize Us  mechanism of toxldty have been largely
unsuccessful.   Data   gaps  remain  1n  several  areas:   1) the  question  of
whether  similar  metabolites are formed following administration by  different
routes;  2) comparison of toxldty of  the parent compound  and  Its metabolites
1n  eliciting the  toxic effects  seen  following HEX  exposure;  and  3) Inter-
action  of HEX  with organic  compounds  such as  hemoglobin.  Finally, HEX  Is
often  contaminated  by products used 1n Us manufacture  or  In  the manufactur-
ing of  other  products; therefore,  the  possibility for co-exposure may exist.
03670                               VI1-2                             08/30/88

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                 VIII.   QUANTIFICATION  OF  TOXICOLOGIC  EFFECTS

Introduction
    The  quantification  of  toxlcologlc effects  of  a chemical  consists  of
separate  assessments  of  noncardnogenlc   and  carcinogenic  health  effects.
Chemicals that  do  not  produce  carcinogenic  effects  are  believed to have  a
threshold dose below which no adverse, noncarclnogenic health  effects occur.
while carcinogens are  assumed to act without  a  threshold.

    In  the   quantification   of   noncarclnogenic  effects,  a  Reference   Dose
(RfD),  [formerly  termed  the  Acceptable  Dally  Intake (ADI)]  1s  calculated.
The RfD  Is  an  estimate (with  uncertainty spanning perhaps an  order magni-
tude)  of a  dally  exposure   to the  human  population  (Including  sensitive
subgroups)  that  Is  likely to be  without  an  appreciable  risk  of deleterious
health  effects  during a  lifetime.   The  RfD  Is  derived  from  a  no-observed-
adverse-effect   level   (NOAEL),   or  lowest-observed-adverse-effect   level
(LOAEL),  Identified  from a  subchronlc or chronic  study, and divided  by  an
uncertainty  factor(s)  times  a  modifying  factor.   The  RfD is calculated  as
follows:
     RfD . 	
-------
U.S.  EPA  (1991)  employs  a  modification  to  the  guidelines  proposed by  the

National Academy of Sciences (MAS, 1977, 1980) as follows:


Standard Uncertainty Factors (UFs)

        Use a 10-fold  factor when extrapolating from valid experimental
        results from studies using prolonged exposure to average healthy
        humans.   This  factor  1s  Intended  to account for  the  variation
        In sensitivity among the members of the human population.  [10H]

        Use an  additional  10-fold factor when  extrapolating  from valid
        results  of  long-term  studies  on  experimental  animals  when
        results of  studies of  human  exposure are not  available  or  are
        Inadequate.  This  factor  1s Intended to  account for  the uncer-
        tainty  In  extrapolating  animal  data  to the  case  of  humans.
        [10A]

        Use an  additional  10-fold  factor  when  extrapolating  from  less
        than  chronic  results  on  experimental animals when there  Is  no
        useful  long-term  human  data.   This  factor  1s   Intended  to
        account  for  the  uncertainty  In extrapolating  from  less  than
        chronic NOAELs to chronic NOAELs.  [10S]

        Use an  additional  10-fold  factor  when  deriving an  RfD  from  a
        LOAEL  Instead  of  a  NOAEL.   This factor  Is  Intended  to account
        for  the  uncertainty  In  extrapolating   from  LOAELs  to  NOAELs.
        [10L]

Modifying Factor  (MF)

        Use  professional  judgment  to  determine  another  uncertainty
        factor  (MF) that  Is  greater than zero and less  than or equal to
        10.   The  magnitude of  the  MF  depends  upon  the professional
        assessment  of  scientific  uncertainties  of  the study  and  data
        base  not  explicitly  treated above,  e.g.,  the  completeness  of
        the overall data  base and  the  number  of species  tested.   The
        default value  for  the  MF  1s  1.


    The  uncertainty  factor  used  for  a  specific risk  assessment  Is  based

principally   upon  scientific   Judgment  rather  than  scientific  fact   and

accounts   for   possible   Intra- and  Interspecles  differences.   Additional

considerations  not Incorporated  In the NAS/ODW  guidelines  for  selection of

an  uncertainty factor  Include the  use of  a  less  than  lifetime  study  for

deriving  an  RfD,   the  significance of  the  adverse  health  effects and  the

counterbalancing  of beneficial  effects.
03680                                VII1-2                           04/12/91

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    From  the  RfD,  a  Drinking Water  Equivalent Level  {DUEL}  can be  calcu-
lated.   The  DVIEL  represents  a  medium  specific  (I.e.,   drinking  water)
lifetime  exposure  at  which adverse,  noncardnogenlc  health effects are  not
anticipated to  occur.   The DUEL assumes  100% exposure from drinking  water.
The DUEL  provides  the  noncardnogenlc health effects  basis  for  establishing
a  drinking water  standard.   For  Ingestlon  data, the  DUEL  1s  derived  as
follows:
                       IRfDl  x  (Body weight  In  kg)
                       	'	 — = 	 mq/8.
                      Drinking  Water Volume  In  I/day  	
where:
        Body weight = assumed to be 70 kg for an adult
        Drinking water volume = assumed to be 2 ft/day for an adult

    In addition  to the RfD  and  the  DUEL, Health Advisories  (HAs)  for  expo-
sures  of  shorter  duration  (1-day, 10-day  and longer-term)  are  determined.
The  HA values  are  used  as  Informal  guidance to  municipalities and  other
organizations when  emergency spills  or contamination  situations  occur.   The
HAs are calculated using an  equation  similar  to the  RfD and DWEL;  however,
the NOAELs  or  LOAELs are Identified  from acute or  subchronlc  studies.   The
HAs are derived as follows:
                   HA . (NOAEL or LDAEL) x (bw) =
                          (UF) x (	 a/day)       	  y
    Using the above equation, the following  drinking water  HAs  are  developed
for noncardnogenlc effects:

    1.  1-day HA for a 10 kg child Ingesting 1  I water  per  day.
    2.  10-day HA for a 10 kg child  Ingesting 1 ft water per day.
    3.  Longer-term HA for a 10 kg child Ingesting 1  I  water per day.
    4.  Longer-term HA for a 10 kg adult Ingesting 2  ft  water per day.
03680                               VII1-3                           04/10/88

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    The  1-day  HA  calculated  for  a  10  kg  child  assumes  a  single acute
exposure  to  the chemical  and  Is  generally derived  from  a  study of <7 days
duration.  The  10-day  HA assumes  a limited exposure period of  1-2  weeks and
Is generally  derived  from a study of <30  days  duration.  The  longer-term HA
1s  derived for  both  the 10  kg  child  and a  70 kg  adult and  assumes  an
exposure  period  of  -1  years   (or  10%  of an  Individual's  lifetime).  The
longer-term  HA  Is  generally  derived  from a  study of  subchronlc  duration
(exposure for 10% of animal's lifetime).

    The U.S.  EPA  categorizes the  carcinogenic  potential of  a chemical, based
on the overall welght-of-evldence, according to the following  scheme:
        Group  A:  Human   Carcinogen.   Sufficient   evidence  exists  from
        epidemiology  studies   to  support  a  causal  association  between
        exposure to the chemical and human cancer.
        Group  B:  Probable Human  Carcinogen.   Sufficient  evidence  of
        carclnogenlclty  In animals with  limited   (Group  Bl)  or  Inade-
        quate (Group B2)  evidence 1n humans.
        Group   C:   Possible  Human   Carcinogen.    Limited  evidence  of
        carclnogenlcUy 1n animals In the absence  of  human data.
        Group  D:  Not  Classified  as  to Human CarclnogenlcUy.   Inade-
        quate human and  animal  evidence of carclnogenlcUy  or  for  which
        no data are available.
        Group   E:   Evidence  of  Noncarclnogenklty  for   Humans.    No
        evidence  of  carclnogenlcUy  1n  at least  two  adequate  animal
        tests  1n different  species  or  In both  adequate  epldemlologlc
        and animal studies.

    If  toxlcologlc  evidence leads  to  the classification  of the  contaminant
as a  known,  probable  or  possible human carcinogen,  mathematical models are
used  to  calculate  the  estimated  excess  cancer   risk  associated  with  the
Ingestlon  of   the  contaminant   In drinking water.   The  data  used In these
03680                               VI11-4                           04/12/91

-------
estimates  usually  come  from  lifetime  exposure studies  using  animals.   In
order to predict the  risk  for  humans from animal data, animal doses must  be
converted  to  equivalent human  doses.   This  conversion Includes  correction
for  noncontlnuous  exposure,  less than  lifetime studies and for  differences
In  size.   The factor  that  compensates  for the  size  difference  Is the  cube
root of  the ratio  of  the animal and human body  weights.  It Is  assumed  that
the  average  adult  human  body  weight  1s  70  kg and  that  the  average  water
consumption of an adult human  Is 2 a of  water  per day.

    For  contaminants   with  a  carcinogenic  potential,  chemical  levels  are
correlated with  a  carcinogenic  risk estimate  by employing  a cancer  potency
(unit  risk)  value  together with  the assumption  for  lifetime  exposure  from
Ingestlon of  water.   The  cancer  unit risk 1s  usually derived from a  linear-
ized multistage model with a 95%  upper  confidence  limit providing a low dose
estimate;  that  1s,  the true risk  to humans,  while not  Identifiable,  Is not
likely  to  exceed  the  upper  limit  estimate  and.  In  fact, may  be  lower.
Excess cancer  risk estimates may also be calculated  using  other models  such
as  the  one-hit, Welbull,  loglt and  problt.   There  1s  little  basis  In the
current  understanding  of   the  biologic  mechanisms  Involved  In   cancer  to
suggest that  any one  of  these models Is  able  to predict risk more accurately
than any other.  Because each model  1s  based  upon  differing assumptions, the
estimates derived for each model can differ by several orders of  magnitude.

    The  scientific  data base used   to calculate and  support the  .setting of
cancer  risk   rate  levels has  an  Inherent  uncertainty  that Is  due  to the
systematic and random errors 1n  scientific measurement.  In most cases, only
studies  using  experimental  animals  have been performed.   Thus, there  Is


03680                                VI11-5                           04/12/91

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uncertainty  when  the  data  are  extrapolated  to  humans.   When  developing
cancer risk  rate levels,  several  other  areas of uncertainty exist, such as
the  Incomplete  knowledge  concerning  the  health  effects  of contaminants 1n
drinking  water,  the  Impact  of   the  experimental  animal's  age,  sex  and
species,  the  nature  of  the target organ  system(s) examined and  the  actual
rate of  exposure of the Internal  targets  In  experimental  animals  or humans.
Dose-response data  usually  are  available  only  for  high  levels of  exposure
and  not  for  the lower  levels  of  exposure  closer to where a standard  may be
set.   When  there  1s  exposure  to  more  than  one  contaminant,  additional
uncertainty results  from a lack  of Information about possible  synerglstlc or
antagonistic effects.

NoncarclnogenU  Effects
    Limited quantitative Information  1s  available regarding the human  health
effects  resulting from HEX exposure;  however, transient  or acute exposure  to
HEX  vapor  has  been  associated with Irritation to the eyes,  nose and throat,
as  well  as  headaches  and  nausea.    In  animals,  comparative   studies  have
Indicated  that   HEX  exposure  Is  more toxic  following Inhalation  than  oral
exposure.

     Short-term  studies  by  IROC  (1978)  and   SRI  (1980a,b,  1981a,b)  provide
substantial  data on  oral  toxldty to rats and  mice.   The Southern Research
Institute  (SRI. 1981a,b)  studies  are  of  longer  duration  and  provide  NOAELs
and  LOAELs.    A Russian   study   by   Nalshteln   and   Llsovskaya   (1965)   was
conducted  for   6 months and also yielded  no-effect  levels; however, an  HA
cannot  be  recommended since  the complete study design  was not reported.
 03680                                VIII-6                          06/19/90

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    More recent  studies  have been  published  (SRI,  1980a.b, 1981a,b), which
provide  greater   detail,  use  more  appropriate  toxlcologlc  endpoints   and
define NOAELs and LOAELs  than  the earlier study by Nalshteen  and  Llsovskaya
(1965) which served as the basis  for  the  1980  Ambient  Hater Quality Criteria
Document (U.S. EPA,  1980).   These  studies are reviewed below and  have  been
used  In  the calculations of  the 1-day,  10-day  and  longer-term HAs  and  the
lifetime DUEL.

    SRI (1980a) conducted a gavage  study  using HEX with male and female F344
rats  and  B6C3F   mice.  Dose  levels  of 0, 75,  150,  300, 600  and  1200 mg/kg
HEX In corn  oil  were  administered to both rats and  mice by gavage.  One dose
at  each  of  the five levels was  given  to  five  animals  of each sex.. Clinical
observations  related  to  the  administration of  HEX  Included  a decrease In
activity,  ruffled  fur,   wet   fur  In  the  anal  area   and   diarrhea.   These
alterations  occurred  within 6-24 hours of dosing;  severity and duration were
related  to  the dose  level.  All  rats  In  the  600 and  1200  mg/kg dose groups
died,  while  In the 300 mg/kg  dose  group, two female  rats  died.   In the 150
and  75 mg/kg rat dose groups,  ruffled fur occurred,  but  no deaths.  In the
mouse  study,  all  1200  mg/kg  dose  group animals  died.   At  the  600 mg/kg
level,  only one  female  and  one  male mouse died.  At  the  other  levels,  only
minor  effects  were  observed.   The 150 mg/kg rat level was  observed  to be the
NOAEL  In rats, while  the  300 mg/kg  was chosen  as the NOAEL  In  mice.

    The  SRI (1980b)  conducted a repeated-dose study  In which F344  rats and
B6C3F]  mice were  exposed to  0,  25, 50,   100.  200  and  400  mg/kg  HEX and 0,
50,  100, 200, 400  and  800  mg/kg  HEX  1n rats  and  mice,   respectively.  All
doses were  administered  by  gavage  with  corn  oil  used as  the vehicle.   Five


03680                               VIII-7                           04/12/91

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mice and  five  rats of each  sex  were  used for each dose  level on  a  schedule
of  12  dosing days (days  1-5,  8-12,  15 and 16), with at  least  2  consecutive
dosing days before the terminal  sacrifice began.

    In  the rat  study (SRI.  1980b),  all  males  and 4/5  females  at  the  400
mg/Jcg  HEX dose level  died,  while at  the  POO mg/kg dose, 1/5 males  and  4/5
females died.   Clinical  observations  were performed twice dally.   At  the  100
mg/kg  dose  level,  ruffled fur  occurred 1n all rats.  The Investigators noted
that  there  was  significant  weight  depression  In  both  the  males   and  the
females  at  this  dose  rate,   but  there were  no deaths  or  life-threatening
clinical  and gross  observations.  At  the 50 mg/kg HEX dose level, there were
no  significant clinical  signs,  but  there were  gross changes  to  the  stomach
wall  and  a  depression  In  weight gain.   The gross  observations  at  the  50
mg/kg  dose  level  Included discolored  raised  areas  on  the mucosal surface of
the  stomach In 3/5  females  and  3/5  males.   The decrease In  weight  gain 1n
males  was -17% and  females  -22%.  At  the 25 mg/kg level,  the  clinical  and
gross  observations   did  not   find   any   Irregularities.   The  weight  gain
depressions  were  8%  for  males  and  11% for females.  The 25 mg/kg dose level
was selected as the  NOAEL for  rats.

    In the mouse  study  (SRI.  1980b), all of  the  animals treated at  the 800
and  400  mg/kg dose  level  died.   However, one of these deaths was attributed
to  Improper  gavage technique.   At the 200 mg/kg dose level, two animals died
because  of Inappropriate experimental techniques,  as did one at  the  50 mg/kg
level  and  two of the controls.   One animal's death at  the  200  mg/kg level
was  attributed to chemical  toxldty.   The 100 mg/kg HEX dose was determined
to  be  the NOAEL,  since there were effects but none  considered  adverse.

03680                                VI1I-8                           04/12/91

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    In a 13-week oral  toxUHy  study  (SRI,  1981a,b; Abdo et al..  1984),  HEX
was administered In  corn  oil by  gavage  to  groups  of  10  male and 10  female
F344 rats at doses of  0,  10,  19,  38,  75  and  150 mg/kg  and to 10  mice  of  each
sex at  doses  of 0,  19,   38,  75,  150 and  300 mg/kg.   The  doses were  glve'n
dally,  5  days  a week  for 13 weeks.   Compared with the  previously-reviewed
shorter-term studies,  HEX  was  found  to be  more  toxic  at  the lower  dose
levels.   All  10  male  and  3 female  mice died at  the  300  mg/kg HEX  dose
level.  At  the  150  mg/kg  level, six male rats  died, while  one rat  In the 75
mg/kg  group  died  as a result  of  chemical toxlclty.   Other  deaths  occurred,
but  these  were  attributed  to  Improper  gavage  technique  by   the  Investi-
gators.   Stomach  lesions  (hyperplasla and focal  Inflammation) were  observed
1n  male and female  rats  at  the  38.  75 and  150 mg/kg dose groups  and only
female  rats  at  the  19  mg/kg dose  level.  At  higher doses (>150  mg/kg)  toxic
nephrosls  In females  was observed.  According to  the  Investigators,  these
lesions  decreased  In  severity  with decreasing  dose,  with  hyperplasla  being
the  primary  lesion.   One  female  rat   at  the  19  mg/kg dose  level  had a
squamous  cell papllloma of  the  epithelial  surface.  The only effect  reported
for  the 10 mg/kg dose was  a slight depression  In  body  weight  In both  males
and females.

    In mice (SRI,  1981a),  the  stomach  lesions  occurred  at  the  38 mg/kg  and
higher dose  levels,   Including  deaths   at  the  two highest  levels.   In  the
published results  (Abdo  et al.,  1984),  the  "no observed toxic  effect  level"
of HEX was  stated  to  be at  the  19 mg/kg level for rats.   In  addition,  the
authors stated  that   rats  of  both  sexes  and  female  mice  are  approximately
equally susceptible to the  toxic  effects  of  HEX administered by  gavage over
a 90-day  period.   Therefore,  the NOAEL was  10  mg/kg HEX for  rats and  19

 03680                               VIII-9                            04/12/91

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mg/kg  for  mice.   The  lower level  In  rats  was selected  because  the  lesions
were still  considered  toxic effects, but In  the  long-term  may  or  may  not  be
adverse.   Therefore,  by  using  this  level,  an  added  margin  of  safety  1s
Inherent  In the  calculation of  the DUEL.   Because  HEX toxlclty  Increase's
with duration,  this  NOAEL  would  accommodate the possibility of  these  effects
becoming adverse over  the  longer-term.

Quantification of  Noncarclnogenlc Effects
    Although there Is  some question as  to  the  route  of  HEX transport  In the
body,  the   kidneys,  liver  and lungs  appear  to  be  the major  target  organs.
Investigators have observed  sex  and species differences  1n  toxic response  to
HEX.   In addition, some observed effects In  these  studies  may have resulted
from a combined  exposure  to HEX  and  other  compounds.   In the Abdo  et al.
(1984)  study,  hexachloro-l,3-butad1ene  (HCBD)  was  present  as  a contaminant
of  HEX.   Since HCBD  Is  a  known  nephrotoxln  In  rodents,  some  of the  adverse
effects seen In the  study  may be attributed to either or  both compounds.

    Derivation  of  1-Day  HA.   In  the  range-finding  study  by SRI  (1980a)
rats exposed  to a single  oral dose of  150  mg/kg HEX  experienced "wet  fur  In
anal  area"  and  ruffled  fur  when  observed  for  14  days.   No  other   toxic
effects  were  seen  at  this  dose  level.  At  higher  doses,   mortality and
diarrhea were  observed.   A  NOAEL  of 150 mg/kg  can be derived  based  on the
absence of  adverse effects seen at  this  level.

The 1-day HA for  a child Is  calculated as follows:
                           HA m 150  mq/kq x  10 kq  =
                                  100 x 1 I/day


03680                                VII1-10                         04/12/91

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where:
         ISO mg/kg = determined  to  be the NOAEL  of  the SRI  (1980a)  rat
                    study
         10 kg     = assumed body weight of a child
         1 l/day   = assumed water consumption by a child
         100       = uncertainty   factor  chosen   In   accordance   with
                    NAS/ODU and  Agency  guidelines  1n using a NOAEL from
                    an animal study
 This  HA  Is  equivalent  to  15  mg/day or  1.5  mg/kg/day.  It  should  be noted
 that  this  level  (15 mg/i)  1s above  the reported  water  solubility  of  HEX
 (1.2-3.4  mg/l)  under  normal  ambient  conditions;   however,   under  certain
 conditions  (e.g.,  Increased   temperature)  the water  solubility of  HEX  can
 Increase.

    Derivation  of 10-Dav  HA.   The  SRI  (1980b)  repeated-dose toxlclty study
 was  used.   In  this  study a  NOAEL  of  25  mg/kg,  based  on  no significant
 decreases   In  weight  gain In  male and  female  rats   was  defined  following
-exposure  to 25, 50,  100,  200  and  400  mg/kg HEX for  12 days (days 1-5, 8-12,
 and 15  and  16).

 The 10-day  HA for  a  child 1s calculated as  follows:
      10-day  HA = 2S  m(l/kq  x 10 kq x °'714 = 1.8 mg/l (rounded to 2 mg/a)
                       100  x 1 l/day
 where:
     25 mg/kg  = determined to  be  the NOAEL  of  the  SRI  (1980b)  female
                 rat study
     10 kg     = assumed body  weight  of a  child
     0.714     = the correction  factor (5/7)  to adjust  for  continuous
                 exposure from a 5- to 7-day exposure
 03680                               VIII-11                           06/11/91

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    100       = uncertainty  factor  chosen  in accordance  wHh  NAS/QDW
                and  Agency  guidelines  for  use  with  a  NOAEL  from  an
                animal study

    1 l/day   = assumed water consumption by a child

This HA 1s equivalent to l.B mg/day or 0.18 mg/kg/day.
    Derivation  of  Longer-Term HA.   The 13-week oral  toxicity  study by  SRI

(19Blb)  is  the only   longer-term  oral  study  of  sufficient  duration  and

experimental  design  that  can  be used  for  calculating longer-term HAs.   In

this study,  HEX was  administered in corn oil  by gavage to  groups  of  10 male

and  female  f344  rats  at  doses   of   0,  10,  19,  38,   75  and  150  mg/kg.

Treatment-related  dose-dependent adverse effects  Including  Inflammation  of

the  stomach  were  seen  with  increasing  severity at  >19  mg/kg.   The  only

effect reported at the 10 mg/kg dose  was a  slight depression  in  body weight

in males and  females.



The longer-term HA for a child Is calculated as follows:

              i       •    u*    10 mg/kq  x 10 kg x 0.714   ., _ m..
              Longer-term HA  =  	a , *	•—a	 =  0.7 mg/J.
                                    100 x 1  i/day



This HA is equivalent  to 0.07  mg/kg/day.
where:
        10 mg/kg  = NOAEL  from the  SRI  (1981b;  Abdo et  al.t  1984) study
                    based  on absence  of  stomach lesions

        10 kg     = assumed body weight  of a child

        0.714     = the    correction   factor   (5/7)    to   adjust   for
                    continuous exposure  from a 5- to 7-day exposure

        100       = uncertainty  factor   chosen   In   accordance  with
                    NAS/ODW  and Agency  guidelines  for  use  with a NOAEL
                    from an animal  study
03680                                VJII-12                          04/12/91

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        1  a/day   =  assumed  water  consumption  by  a  child

For an adult:
                              10 mg/kg  x  70 kg x  0.714    9  c    .
             Longer-term HA  .  	2 i/day  x 100    (rSundSfto  3 mg/i)
where:
        10 mg/kg  =  NOAEL from the SRI (1981D; Abdo et al.. 1984)  study
                    based on absence of stomach lesions
        70 kg     =  assumed  body weight of an  adult
        0.714     =  the   correction   factor   (5/7)   to   adjust   for
                    continuous exposure from a 5- to 7-day  exposure
        2 ft/day   =  assumed  water  consumption  by an adult
        100       =  uncertainty   factor   chosen   In   accordance   with
                    NAS/ODW and Agency guidelines  for use with  a  NOAEL
                    from an  animal study

    Assessment  of Lifetime  Exposure  and Derivation of  DWEL.   In a  13-week
oral  toxlclty  study  by  SRI  (1981b),  rats  (10/sex/group) were  exposed  by
gavage  with  0.  10,   19,  38,  75  or   150 mg  HEX/kg  bw  Tor  5  days/week.
Epithelial  hyperplasla, focal  Inflammation  of  the forestomach and  stomach
lesions,  and nephrosls  were  observed  with Increased  Incidence  and  severity
1n both sexes  at >38  mg/kg  bw.   At  the 19  mg/kg/day  dose  similar  effects
were  observed In males only.   A slight but nonsignificant  depression In body
weight  gain  was seen  at  10  mg/kg  1n  males  and 1n  females  at  19  mg/kg.
Therefore  the  10 mg/kg dose  was  considered a NOAEL and the  19  mg/kg  dose a
LOAEL.
        Step 1:  Determination  of  RfD
     RfD = 10 mq/kq x 0.714 = Q Q0714 mg/kg/day (rounded to 0.007 mg/kg/day)
               100 x  10
 03680                               VIII-13                          06/11/91

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where:
    10 mg/kg  = NOAEL  from the  SRI  (1981b;  Abdo  et al..  1984)  study
                based on a lack of adverse effects
    0.714     = the  correction  factor  (5/7)  to adjust  for  continuous
                exposure from a 5- to 7-day exposure
    100       -= uncertainty  factor  chosen  In accordance  with  NAS/OOW
                and  Agency  guidelines  for  use with  a  NOAEL  from  an
                animal study
    10        = uncertainty  factor appropriate  for  use  with study data
                that are significantly less-than-Hfetlme 1n duration
       Step 2: Determination of the Drinking Water Equivalent Level  (DWEL)

       DWEL __ 0.007 mq/kq/dayx 70 kq = Q ^           M t() Q 3
                     2 a/day
where:
    0.007 mg/kg/day  = RfD
    70 kg            = assumed weight of an adult
    2 l/day          = assumed water consumption by an adult

A summary of noncarclnogenU effects Is listed In Table VIII-1.

Carcinogenic Effects
    The  data  base  Is   neither   extensive  nor  adequate   for  assessing  the
cardnogenldty  of HEX.   The National  Toxicology Program  (NTP) has  completed
a subchronlc  animal Inhalation study and  Is  presently  conducting a lifetime
animal   Inhalation bloassay   using  both  rats  and  mice.   A  judgment  of
carcinogenic  potential  will be deferred  until the results  of  the  long-term
NTP bloassay  are available.  Using the IARC criteria, the available evidence
matches  the  overall Group  3 category.  According  to  the  U.S.  EPA Guidelines
for Carcinogen Risk Assessment,  this  chemical Is classified  In  the  Group D

03680                                VIII-14                          06/11/91

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                                 TABLE  VIII-1
             Summary of HAs and  DUEL for Noncarclnogenlc Effects
                                     Drinking  Water
                                     Concentration
                                       (mg/i)
                       Reference
1-Day HA (10 kg child)
10-Day HA (10 kg child)
Longer-term HA (10 kg child)
Longer-term HA (70 kg adult)
DUEL
    15
     2
     0.7
     3
     0.3
SRI, 1980a
SRI, 1980b
SRI. 1981b
SRI, 1981b
SRI. 1981b
03680
VIII-15
         06/12/91

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category,  which  Indicates  that  the  available  data  base  Is  Inadequate  to
assess the carcinogenic potential of this substance (U.S.  EPA,  1986).

ExIsUIng Guidelines. Recommendations and Standards
    EPA  Guidelines.   An  RfO  of  0.007  mg/kg/day  was  verified by  the  RfD
Work  Group  orr 10/09/85  (U.S.  EPA, 1991).   The  CRAVE  Work Group verified a
classification  of  Group  D  (not  classifiable   as  to  cardnogenldty  for
humans) for HEX on  10/05/89 (U.S. EPA. 1991).

    Occupational  Standards.   There 1s  no   current  Occupational  Safety  and
Health  Administration  (OSHA)   standard  for  HEX  levels   In  the  workplace.
However,  the   American  Conference  of  Governmental  Industrial   Hyg1en1sts
(ACGIH,  1986)  has  adopted  a  TLV.  expressed as   an  8-hour  TWA of*0.1  mg/m3
(0.01  ppm).   The levels are based  on the data  from the  Inhalation  study by
Treon et al. (1955).

    The  National  Institute for Occupational Safety and Health  (NIOSH,  1978)
classlfed  HEX   In the  Group II  pesticide  category and recommended  criteria
for  standards   for  occupations 1n  pesticide manufacturing and  formulating.
These  standards  rely  on  engineering controls,   work  practices and  medical
surveillance  programs,  rather  than workplace air  limits,  to  protect  workers
from  the  adverse effects  of  pesticide exposure   In manufacturing  and  formu-
lating (NIOSH,  1978).

    Transportation   Regulations.    The  Hazardous  Materials   Transportation
Act  specifies  the  requirements  to  be observed  1n  the  preparation  for  ship-
ment  and transport of hazardous  materials.  The  transport  of HEX by  air,


03680                               VIII-16                          04/1?/91

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land and water  Is  regulated  by these statutes, and  the  Department  of  Trans-
portation has designated HEX as  "hazardous material,"  a  "corrosive  material"
and  a  "hazardous  substance."   The  maximum  net  quantity  for  transport  by
passenger-carrying  aircraft  or  rallcar  has  been  set  at  10  gallons  per
package.   Transport on deck or  below deck by  cargo vessel 1s also  permitted.

    Solid Haste  Regulations.   Under  the Resource Conservation and Recovery
Act  (RCRA),  the  U.S.  EPA has  designated HEX  as a  hazardous toxic  waste,
Hazardous Waste  No. U 130,  subject  to  disposal  and permit  regulations  (40
CFR 262-265 and 122-124).

    Food  Tolerances.   Under the Federal  Insecticide  Fumlgant and Rodentl-
clde Act  (F1FRA),  a tolerance  of 0.3  ppm has  been established for chlordane
residues, which are not to contain >1X of HEX {40 CFR 180.122).
    Water  Regulations.   Under  Section  311  of  the Federal  Hater  Pollution
Control Act,  the  U.S.  EPA  designated HEX as a hazardous substance and estab-
lished  a  reportable  quantity  (RQ)  of 1 pound (0.454 kg) for HEX.  Discharges
equal  to or  greater than  the RQ  Into or  upon U.S.  waters  are prohibited
unless  the  discharge 1s  In compliance  with applicable permit programs.

    Under  the Clean Water  Act,  the U.S.  EPA  has designated  HEX  as  a  toxic
pollutant  (I.e.,  priority pollutant).   Effluent limitations  guidelines,  new
source  performance  standards, and pretreatment  standards have been developed
or  will be  developed for the  priority  pollutants for  21  major  Industries.

    Under  the Clean Water  Act,  an  ambient  water quality criteria level  for
HEX was also  developed  (U.S. EPA,  1980).   Based on available  toxlclty  data

03680                               V11I-17                           04/12/91

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for  the  protection  of  public  health  the  level  derived  was  206
Using  organoleptlc  data  for  controlling  undesirable   taste  and  odor   of
ambient water, the estimated  level was  1 pg/a.  (U.S. EPA,  1980).

    AU  Regulations.   HEX  1s  not  regulated  under  the  Clean A1r Act.   The
U.S. EPA, after  evaluating the current  exposure  data  and ambient air levels
of HEX, Issued a decision not  to  list HEX as a hazardous  air pollutant.

    Other Regulations.   Pursuant  to  rules  under  sections  8(a)  and  8(d)  of
the  Toxic  Substances  Control Act  (TSCA),  all  manufacturers   of  HEX  are
required  to  report health  and safety  Information  on  HEX to the  U.S.  EPA's
Office  of Toxic  Substances.   The  deadline  for  submission of  Preliminary
Assessment Information Manufacturer's Report on HEX was November  19,  198?.

    In 1979, the  Interagency  Testing  Committee (ITC)  recommended  that HEX be
considered for  health and  environmental effects testing  under  Section  4(a)
of  the TSCA  (44  FR  31866).   This  recommendation was based  on   evidence  of
potential human  exposure and a potential  for environmental  persistence  and
bloaccumulatlon.   The U.S.  EPA  (1982) responded  In  the  Federal  Register.
The following Is the  statement  from that notice:

    EPA  has  decided  not  to  Initiate  rulemaklng  to require  testing  of
    HEX under section 4  of  TSCA because EPA does not believe that there
    Is a  sufficient  basis  to  find that  current  manufacture, distribu-
    tion  In commerce,  processing,  use  or disposal of HEX may present an
    unreasonable  risk of  Injury to the  environment  or of mutagenlc  and
    teratogenlc  health  effects.   Neither  has  the  EPA   found  evidence
    that  there  1s  substantial or significant environmental  release  of
    HEX.  In  addition, certain new studies  have  become  available since
    the  ITC's  report or  are  underway,  making  additional  testing  for
    chronic and oncogenlc effects  unnecessary.
03680                               V1II-18                          04/1P/91

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Special Groups at Risk
    While  very   little  data  are  available  concerning  the  effects  of  HEX
exposure on  humans,  It  Is apparent  that  those Individuals with  respiratory
problems or  diffidences  will be  most sensitive  to  HEX exposure.   Workers
repeatedly exposed to HEX vapors  are also at high  risk.
 03680                               VIII-19                          04/12/91

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                               IX.  REFERENCES

Abdo, K.. C.A. Montgomery. W.M. Kluwe, D.R. Farnell and J.O. Prejean.  1984.
Toxlclty  of  hexachlorocyclopentadlene:  Subchronlc  (13-week) administration
by gavage to F344 rats  and B6C3F1  mice.  J.  Appl.  Toxlcol.  4(2): 75-81.

Abdo. K.M..  C.A. Montgomery.  J.  Roycroft,  H.A.  Ragan. R.A.  Renne and W.E.
Glddens.     1986.     Subchronlc    (13    week)    Inhalation    toxldty    of
hexachlorocyclopentadlene  (HCCPD)  1n F344  rats and  B6C3F1  mice.   Abstract
Toxlcol.  (V): 57.

ACGIH  (American  Conference  of Governmental  Industrial  Hyglenlsts).   1986.
Documentation  of Threshold  Limit  Values  for  Substances  1n  Workroom  Air.
Cincinnati. OH, 4th ed.  p. 20.

Aldrlch  Chemical  Company.  1988.   Handbook  of  Fine Chemdals.   Aldrlch Chem.
Co.. Milwaukee. Wisconsin,  p. 800.

Alexander,  D.J..  G.C.  Clark,  G.C.  Jackson,  et  al.  1980.   Subchronlc Inhala-
tion  toxldty of  hexachlorocyclopentadlene In  monkeys  and rats.   Prepared
for  Velslcol  Chemical  Corporation, Chicago, IL.  373 p.

Amoore,  3.E.  and E.  Hautala.   1983.   Odor as an aid to chemical safety: Odor
thresholds  compared  with  threshold  limit values  and  volatltles  for   214
Industrial  chemicals  1n  air  and  water   dilution.   J.  Appl.   Toxlcol.   3:
272-290.
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Atallah,  Y.H.,  O.M.  Whltacre,  R.G.  Butz.   1980.   Fate  of  hexachlorocyclo-
pentadlene  In  the  environment.   Paper presented at 2nd  Chemical  Congress  of
the North American Continent. American Chemical Society. Las  Vegas.  NV.

Battelle  Northwest  Laboratories.   1984.   Inhalation  Carclnogenesls  Bloassay
Study:  Subchronlc   Study  Report  on   Hexachlorocyclopentadlene   1n   Rats.
Submitted National Toxicology Program.

Benolt, P.M.  and  D.T.  Williams.    1981.   Determination  of  hexachlorocyclo-
pentadlene  at  the  nanogram  per   liter   level  In  drinking  water.   Bull.
Environ. Contam. Toxlcol.  27: 303-308.

Boyd.  K.W.. M.B.  Emory  and  H.K.  Dillon.   1981.   Development  of  personal
sampling  and  analytical  methods  for organochlorlne  compounds.   ACS  Symp.
Ser.  149: 49-64.

Brat, S.V.  1983.   The hepatocyte  primary  culture/DNA repair assay on  com-
pound  hexachlorocyclopentadlene  using  rat  hepatocytes  In culture.   Naylor
Dana Institute for Disease Prevention.  Am. Health Foundation, Vahalla.  NY.

Buncher,  C.R.,  C.  Moomaw and E.   Slrkoskl.   1980.   Mortality study of  Mon-
tague  Plant-Hooker  Chemical.   Univ.  Cincinnati   Med.  Center,   Dlv.   Epl.
Blostat.  Unpublished report prepared for Hooker Chemical Corp.

Butz. R.G., C.C. Yu  and Y.H.  Atallah.  1982.  Photolysis of  hexachlorocyclo-
pentadlene  In water.  Ecotox. Environ. Safety.  6:  347-357.
03690                               IX-2                             04/12/91

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Chopra, N.H.,  B.S.  Campbell  and  J.C.  Hurley.   1978.   Systematic  studies  on
the  breakdown  of  endosulfan  In tobacco smokes: Isolation and  Identification
of the degradation products from  the pyrolysis of  endosulfan  I  in  a  nitrogen
atmosphere.  J. Agric.  Food Chem.   26:  255-258.

Chu.  S.J.,  R.A.  Griffin,  M.H.  Cheu and  R.A.  Larson.   1987.   Products  of
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03690                               IX-3                             04/12/91

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03690                               IX-4                             04/12/91

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03690                               IX-6                             04/12/91

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Komlnsky, J.R., C.L.  Hlsseman  and D.L. Morse.  1980.  Hexachlorocyclopenta-
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1978, Revised August 1978.  Kensington, MD.   13 p.


03690                               IX-7                             04/12/91

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Look, M.   1974.   Hexachlorocyclopentadlene  adducts  of  aromatic  compounds and
their reaction products.  Aldrlchemlca Acta.  7(2):  1974.

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03690                                IX-8                             04/12/91

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Murray, F.J..  B.A.  Schwetz, M.F.  Balmer  and  R.E.  Staples.   1980.   Terato-
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03690                               IX-11                            04/12/91

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03690                                1X-12                            04/12/91

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