Environmental Health Effects Research Series
ASSESSMENT  OF DISEASE  RATES  AMONG  SEWER
           WORKERS  IN  COPENHAGEN,  DENMARK
                                    Health Effects Research Laboratory
                                   Office of Research and Development
                                  U.S. Environmental Protection Agency
                                          Cincinnati, Ohio 45268

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                RESEARCH REPORTING SERIES

Research reports of the Offifie of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
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planned to foster technology transfer and a maximum interface in related fields.
The nine series are:

      1.  Environmental  Health  Effects Research
      2.  Environmental  Protection Technology
      3.  Ecological Research
      4.  Environmental  Monitoring
      5.  Socioeconomic Environmental Studies
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      7.  Interagency Energy-Environment Research and Development
      8.  "Special" Reports
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This report has been assigned to the ENVIRONMENTAL HEALTH EFFECTS RE-
SEARCH series. This series describes projects and studies relating to the toler-
ances of man for unhealthful  substances or conditions. This work is generally
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                                          EPA-bOO/1-78-007
                                          January 1978
       ASSESSMENT OF DISEASE RATES
AMONG SEWER WORKERS IN COPENHAGEN, DENMARK
                   by

                R.B. Dean
      LunDean Environmental Company
         Cincinnati, Ohio  45230
        Contract No.  CA-7-2761-A
             Project Officer

            Herbert R. Pahren
         Field Studies Division
   Health Effects Research Laboratory
         Cincinnati, Ohio  45268
   HEALTH EFFECTS RESEARCH LABORATORY
   OFFICE OF RESEARCH AND DEVELOPMENT
  U.S. ENVIRONMENTAL PROTECTION AGENCY
         CINCINNATI, OHIO  45268

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                                DISCLAIMER
     This report has been reviewed by the Health Effects Research Laboratory,
U.S. Environmental Protection Agency, and approved for publication.  Approval
does not signify that the contents necessarily reflect the views  and policies
of the U.S. Environmental Protection Agency,  nor does  mention  of  trade  names
or commercial products constitute endorsement or recommendation for use.

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                                  FOREWORD
     The U.S. Environmental Protection Agency was created because of increas-
ing public and government concern about the dangers of pollution to the
health and welfare of the American people.  Noxious air, foul water, and
spoiled land are tragic testimony to the deterioration of our natural envi-
ronment.  The complexity of that environment and the interplay between its
components require a concentrated and integrated attack on the problem.

     Research and development is that necessary first step in problem solu-
tion and it involves defining the problem, measuring its impact, and search-
ing for solutions.  The primary mission of the Health Effects Research Lab-
oratory in Cincinnati (HERL) is to provide a sound health effects data base
in support of the regulatory activities of the EPA.  To this end, HERL con-
ducts a research program to identify, characterize, and quantitate harmful
effects of pollutants that may result from exposure to chemical, physical, or
biological agents found in the environment.  In addition to valuable health
information generated by these activities, new research techniques and meth-
ods are being developed that contribute to a better understanding of human
biochemical and physiological functions, and how these functions are altered
by low-level insults.

     This report provides an assessment and discussion of the health of sewer
maintenance workers in Copenhagen, Denmark, and mortality statistics of such
workers.  With a better understanding of the health effects, measures can
be developed to reduce exposure to potentially harmful materials.
                                        R. J. Garner
                                        Director
                                        Health Effects Research Laboratory
                                     111

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                                  ABSTRACT
     Sewer workers in Copenhagen, Denmark have a higher death rate than the
comparable male population.  An alarmingly high proportion of the deaths
occur within the year that employment terminates.  Attempts to correlate the
statistics with sick leave records or chemicals in the environment have so
far not been successful.  Sewer workers experience a high rate of gastro-
intestinal tract disorders which they associate with chemical odors and in-
fectious agents.  They have elevated levels of gamma globulins.  Analytical
work has not yet identified any agents that might be responsible for the
observed death rates or the gastro-intestinal problems.  Biological ex-
aminations of stool specimens have not been made.

     This report was submitted in fulfillment of Contract CA-7-2761-A by
LunDean Environmental Company under the sponsorship of the U.S. Environmental
Protection Agency.  This report covers a period from May 1977 to August 1977.
                                     xv

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                                 CONTENTS
Foreword	iii
Abstract	iv
     1.   Introduction 	    1
     2.   Conclusions	    3
     3.   Analysis of Reports	    4
References	10
                                  TABLES
Number                                                                 Page

1.   Comparison of Sick Leave for Permanently Employed Sewer Workers
       (1959-1973) and City Office Workers (1964)	   5
2.   Death Statistics for Sewer Workers,

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                                 SECTION 1

                               INTRODUCTION

     The health and working conditions of sewer workers  in Copenhagen have
been investigated and reported in a series of documents  published and dis-
cussed over the period 1975-1977.  In April 1974 the union representing  the
sewer workers requested the University of Copenhagen to  investigate  environ-
mental and health problems of Copenhagen's sewer workers.   The study was
assigned to J. M{5rkholdt Andersen and Tage Egsmose MD, Associate Professors
at the University's Institute of Hygiene.  Some financial  assistance was
provided by the municipality from the sewer department's budget.

     The preliminary report came out in December 1975 (1), and was published
with minor corrections in April 1976 (2).  Additional death statistics were
presented later (4), and sick leave data were provided by  the Municipal-
ity (3) as a response to the original preliminary report.   In April  1977 a
second report was published based on medical consultations with sewer work"
ers (5), and a preliminary report of blood and urine chemistry was issued
about the same time (6).  Personal communications (7, 8) have greatly helped
to interpret the foregoing reports.

     In addition to the documents already referred to there have been many
news media articles and discussions over the past twenty years concerning
the health of sewer workers.  This report will attempt to  extract the hard
data as it applies to the health of sewer workers.  Conclusions based on
questionnaires will not be considered in detail.

     The municipality of Copenhagen serves 600,000 permanent residents,  ap-
proximately 200,000 transients and commuters and has an industrial load  equi-
valent, on a BODs basis, to 1,600,000 additional persons for a total equi-
valent load of 2.4 million.  The sewage is strong, of the  order of 750 mg/1
BOD.  At the present time sewage is screened to remove rags and large ob-
jects and discharged through two outfalls directly to the  waters between
Copenhagen and Sweden.  A modern treatment plant using high rate activated
sludge with the UNOX pure oxygen process is under construction and is ex-
pected to be in operation in 1979 (4).  One small plant uses primary treat-
ment and digestion (8).  Over the entire period covered by the reports sewer
work involved primarily cleaning and maintenance of sewers, manholes, screens
and pump stations.  It did not include sewer construction  or mechanical  shop
work such as repairing motors and pumps.  About eighty permanently employed
workers were classified as sewer workers in 1976.  Management of the sewers
is a division of the City Engineers office.  The sewer workers are members
of the Earth and Concrete Workers Union and the Highway Department Workers
Club.

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     "The Sewer Workers Report"  (2) is based on four separate studies:

     1.   Responses to a questionnaire to sewer workers about health and
          working conditions.

     2.   A study of sick leave records from January 1957 through December
          1973 for sewer workers and a control group of all city office
          workers.

     3.   A study of death records compared with national mortality statis
          tics (4) .

     4.   Assessment of reports of analyses of sewer atmospheres for toxic
          substances.

     The report "Sewer Work and Health" (5)  is based on clinical consulta-
tions with 82 out of 97 sewer workers in 1976.  The same group and two con
trol groups were subjected to a battery of tests on blood and urine (6).
The reports are considered together.

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                                 SECTION 2

                                CONCLUSIONS

     Mortality statistics show that sewer workers die earlier than Copen-
hagen males of comparable age, many of them soon after termination of their
employment.  The sewer workers complain of nauseating odors and a high in-
cidence of gastro-intestinal tract disorders.  They have elevated levels of
gamma globulin but no other significant differences from control groups.
The available evidence is insufficient to assign a specific cause for their
poor health and reduced life expectancy.  It seems probable that biological
and chemical insults, caused in part by lax observance and poor enforcement
of safety regulations and discharge restrictions have all contributed to
the adverse survival expectancy of this group.

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                                  SECTION 3

                             ANALYSIS  OF  REPORTS
 QUESTIONNAIRES  AND SICK LEAVE RECORDS

      Responses  to  the  questionnaires as well as the medical consultations
 clearly show that  sewer workers  consider  their job to be unhealthy and un-
 safe.   A detailed  analysis  of the  responses to the questionnaires is not in-
 cluded  because  the responses  are difficult to reproduce and are liable to be
 influenced  by local customs and  recent news items concerning the environment.
 Sick  leave  records are also difficult to  analyze because the decision to take
 sick  leave  is made by  the worker and not  on the basis of a medical examina-
 tion.   In Denmark  sick leave  pay for permanently employed Municipal workers
 is  100  percent  of  base pay  but does not include extra pay for "dirty work".
 Medical confirmation of  short illness is  seldom required.

     Table  1 compares  sick  leave for permanently employed sewer workers over
 the period  1959-1973 with male office workers of comparable ages in the year
 1964.   At all ages above 30 years  the sewer workers take more leave than of-
 fice workers.   Most  significant  is the high percent of sick leave taken by
 sewer workers over 50  years of age.  Workers over 60 years of age take an
 average of  one  day in  five  sick  leave.

     The rebuttal  from the  City  Engineers Office (3) gives the comparative
 sick leave  data shown  below,  unfortunately without age adjustment.

          Sick  leave rates  of unskilled wage earners in the City Engineers
          Office,  not  adjusted for age (3) .

                                     1973                 1974

Parking meter collectors             6.12%                6.48%
Street  cleaners                      7.07%                7.31%
Sewer workers                        7.63%                8.77%
Street  repairmen                     8.06%                9.42%
Garden  and park workers             10.64%               10.86%
Workshop and Warehousemen           10.30%               12.17%

There are relatively few transfers between work groups (8).   The high sick
leave of garden and park workers is attributed to hazardous  working condi-
tions, as in trees, rather than a selection of older workers for garden and
part work.  There is no evidence that sewer workers take more sick leave than
other manual workers although sewer workers certainly take more sick leave
than office workers  (2,7).

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TABLE 1.  COMPARISON OF SICK LEAVE FOR PERMANENTLY EMPLOYED SEWER WORKERS (1959-1973)  AND CITY
          OFFICE WORKERS (1964) (2, 7)
                    Sewer Workers
          Sick days    Year days*	%Sick days
         Office Workers
Sick days   Year days*
%Sick days
24
25-29
30-34
35-39
40-44
45-49
50-54
55-59
60-64
65+
6
65
564
1536
1954
1408
1382
1044
496
127
1032
9288
19608
33024
31992
27520
15480
10664
2408
688
0.6
0.7
2.9
4.7
6.1
5.1
8.9
9.8
20.6
18.5
345
510
840
915
1560
3107
3640
4116
6880
3072
23736
35088
48160
62952
89440
82216
96320
101136
118336
66048
1.5
1.5
1.7
1.5
1.7
3.8
3.8
4.1
5.8
4.7
AYear days equals number of working days per year times number of employees in age groups,
 i.e. days worked plus sick days.  Three weeks vacation not included.

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      The second study (5) was recommended by the authors of the first  report
 (2), and was financed by the municipality to investigate health problems
 among sewer workers.  Matched control groups from the city gardeners and
 from office workers were chosen by the Municipal personnel office and  their
 blood and urine chemistry were determined (6);  however not enough money was
 supplied for a medical examination of the controls.   This report confirmed
 the questionnaires of the first report (2)  and  concluded that  sewer workers
 have a higher than normal incidence of acute symptoms of gastro-intestinal
 disorders including nausea,  vomiting and diarrhea.   It further concluded
 that the disorders are directly related to  the  intensity of exposure to sew-
 er odors and splash.  Half of the workers have  had diarrhea in the past year
 and 10% say they have experienced it one or more times a week.   The fre-
 quency of the disorders is related to current exposure and not  to years of
 experience.  Few workers go  to their doctors for treatment for  gastro-intes-
 tinal disorders but seem to  consider them to be a part of the  job.  No ex-
 aminations of stool specimens were made.

      The doctors making the  81 examinations found 21 cases of  occupational
 disease which were reported  to the Health Service doctor.   An  additional  25
 cases were not reported because the workers did not  wish it.

      Many workers consider that odors rather than infectious agents cause
 their gastro-intestinal disorders,  e.g,  one told the doctor, "suddenly you
 get this stench in the face  and then you know you will have stomach trouble
 for the next few days" (5).

      In a publication from the Occupational Health Office  a steward said,
 "longer vacations  are necessary because  we  have a very special  problem get-
 ting  accustomed (to  the  sewer environment).  After a  vacation of  a week or
 more  one is almost always  sick the first two or three work days with vomit-
 ing,  nausea,  headaches and smarting of the  eyes.  We  don't  know what we owe
 it  to but  it is most likely  the chemicals in the sewer"  (10).

 ANALYTICAL  DATA

      The chemical  analyses reviewed (2)  provide  no evidence for toxic chemi-
 cals  that might be related to acute gastro-intestinal  problems.   Solvent va-
 pors  occasionally  exceeded hygienic standards for one  hour's exposure and
 hydrogen sulfide once  reached 13 ppm versus  a standard of  10 ppm.  There is
 little doubt  that  industrial  discharges  frequently contribute high levels of
 organic  vapors  to  the  sewer contrary to  regulations.  Many  of these dis-
 charges  are  of  short duration and are therefore  difficult  to identify.   The
 effect of these vapors on the health of  sewer workers  is at present only
 conjecture.  One station was  found  to have three times the allowable level
 of benzene when a  sick worker was replaced  (5).   There was, however,  no di-
 agnosis of benzene toxicity in  the  sick man, who is now dead (8).  One case
of high lead in the blood was  found  in a worker who had been cleaning heat-
 ing coils in a  sludge digester  (5,  8).  The job  was very dusty and the dried
sludge had a lead content over 100 mg/kg.  The worker was transferred to
another job and his blood Pb  levels  returned to   the normal range.  Masks are
specified for workers in dust or spray but the worker may not have been us-
ing his mask effectively.  The second study   (5)   includes photographs  of a

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worker who was using a high pressure spray to clean screens but was not using
a mask, and of a worker who was not using his gloves to handle a wooden ball
used to clean the sewer, again contrary to regulations.

     In the report of medical consultations with sewer workers (5), the doc-
tors conclude that the working environment is responsible for a high level
of acute disorders of the gastro-intestinal tract.  They also conclude that
sewer workers have a high level of chronic problems including fatigue, dif-
ficulty in concentrating, headaches, dizziness as well as psychic problems.

     The preliminary report of clinical laboratory analyses (6) showed little
essential difference over a wide range of chemical parameters between sewer
workers and the control groups chosen by the personnel office.  In many
cases the sewer workers, as a group, fell between office workers and garden
workers.  The only significant difference was an elevated level of gamma
globulins among sewer workers, suggesting that they have had more infections
than the other groups.  The biochemical examinations have not yet been com-
pleted.

DEATH RATES AMONG SEWER WORKERS

     The initial study (1) showed 24 deaths among 142 sewer workers who had
been employed for at least one year in the period 1957-1973.  This is sig-
nificantly greater than the death rate for all Copenhagen men of comparable
ages.  An updated report (4) added 9 additional deaths that had not been
supplied to the authors at the time of the original study.  Table 2 groups
the workers by years of employment and shows the comparable death rates for
Copenhagen males based on the 1975 statistical yearbook.  Death rates in
Copenhagen do not change very much from year to year.

     Workers who have spent 1 to 8 years in sewer work in the 15 year study
period have a death rate indistinguishable from the city rate.  For the next
8 years of employment the rate is more than twice the expected rate.  A
statistical analysis of the data shows the following:  The chi-squared test
on the two groups 1-8 years and 9-16 years is highly significant.  Individ-
ual groups were tested against the Poisson distribution.  Death rates for
workers with 9-12, 11-12, 15-16+ and 13-16+ years of employment were all
significant at the 5% level or better.  Therefore one can conclude that work-
ers who have spent more than 8 years in Copenhagen sewers have about twice
the death rate of all Copenhagen males.  The normal death rate during the
first 8 years of employment also reflects an adverse environment since sewer
workers are selected from healthy able-bodied males who should have a death
rate significantly below the city average (11).

     When the causes of death of the original 24 cases were examined (2),
the only outstanding difference from the national average was for cancer of
the pancreas.   Of 9 cases of cancer recorded on the death certificates there
were 3 cases of cancer of the pancreas, 2 cases of lung cancer and 1 each
of four other cancers.  The expected rate of pancreatic cancer was only 0.3
among 24 deaths of men over 25, therefore 3 deaths are highly significant.
There were no additional cases of pancreatic cancer among the 9 additional
deaths reported (4,7).  A recalculation based on an expected 0.414 deaths out

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  TABLE 2.  DEATH STATISTICS  FOR SEWER WORKERS  (4)*
Years of
sewer work
1-2
3-4
5-6
7-8
1-8
9-10
11-12
9-12
13-14
15-16+
13-16+
9-16+
Number
of deaths
N
1
2
3
2
8
6
8
14
4
7
11
25
Expected Chi squared Poisson Cumulative
deaths (N-E) ^/E Probability for N or
E more deaths in %
2.0
2.3
2.6
2.7
9.6 0.27
3.0 8.2
2.8 0.75f
5.8 0.25tf
2.5 24.
3.1 3.7f
5.6 2.6f
11.4 16.22
 1-16+
33
21.0
16.49
                                                tt
  Statistical calculations by R.B. Dean




  Significant at the 5% level
tt,,.
  Significant at the 0.5% level

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of 33 shows a Poisson probability of 0.8% for 3 or more deaths.   The death
certificates are currently being studied for other possible correlations (7) .

     Over 40% of dead former sewer workers died within the calendar year in
which they stopped working (2).  The calculation is based on 210 sewer work-
ers of whom 111 left the work force in the years 1959-1973.  Thirty-two of
these had died by the end of 1976, 13 of them in the year that employment
terminated.  The ages at death of 12 of the 13 men who died in the year that
employment terminated were evenly distributed between 51 and 58 years.  Some
of these men were ill when they stopped working.  Put another way, 12% of the
former workers died in the calendar year in which they terminated work.  For
comparison only 1% of Copenhagen males aged 55 and 3% of those aged 65 will
die within the twelve months following their respective birthdays.  Compara-
tive data for other occupations in Copenhagen is not available.

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                                 REFERENCES
 1.    Andersen,  J.M.,  L.  Egsmose and  T.  Egsmose.   "Unders^gelse af arbejdsfor-
      hold for kloakarbejdere  ansat ved  K^benhavns kommune"  (Study of working
      conditions of sewer workers employed by  the municipality of Copenhagen).
      University of Copenhagen Institute of Hygiene, Dec. 1975.

 2.    Andersen,  J.M.,  L.  Egsmose and  T.  Egsmose.   "Kloakarbejder rapporten"
      (The Sewer Workers  Report).  FADL's Forlag, Copenhagen, April 1976.

 3.    Gulstad,  E.   Unpublished communication.  City Engineers Office, Copen-
      hagen,  Feb.  1976.

 4.    Egsmose,  T.,  and J.  Nyboe.   "Verdr^rende d^delighedsunders^gelsen i Klo-
      akarbejder rapporten"  (Concerning  studies of death in the sewer workers
      report).   University of  Copenhagen Institute of Hygiene, Jan. 1976.

 5.    Jansson, P.,  and H.  Klausen.  "Kloakarbejde og Helbred" (Sewer Work and
      Health).   Eks-skolens Trykkeri ApS., Copenhagen, April 1977.

 6.    Lous, P.,  "Forel^big rapport til Stadslaegen" (Provisional report to
      the  Public Health Office).  Bispebjerg Hospital, Copenhagen, May 1977.

 7.    Egsmose, T.,  Personal communication.  Institute of Hygiene, University
      of Copenhagen, 1977.

 8.   Malchow-M«5ller,  0.  Personal communication.  City Engineers Office,
     Dept. of Sewage, Copenhagen, 1977.

 9.   "Sewage Treatment Plant Lynetten, City of Copenhagen".  City Engineers
     Office, Copenhagen, 1976.

10.   "Psykisk arbejdsmilj«$:   Trivsel i kloakr«5r og kontorlandskaber" (Psych-
     ic working conditions:   Thriving in sewer pipes and office landscapes).
     Arbejdstilsynet, Annual Publication of the Office of Occupational Health,
     p. 45-51, Copenhagen, 1976.

11.   Fox,  A.E. and P.F.  Collier.  "Low mortality rates in industrial cohort
     studies due to selection for work and survival in the industry".   J.
     Prev. Soc. Med. 30,  225-30, 1976.
                                    10

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                                   TECHNICAL REPORT DATA
                            (Please read Instructions on tlic rci-crsc before completing)
 1. REPORT NO.
  EPA-600/1-78-007
 4. TITLE AND SUBTITLE
  ASSESSMENT OF DISEASE RATES  AMONG SEWER WORKERS
  IN  COPENHAGEN, DENMARK
             3. RECIPIENT'S ACCESSI Of* NO.
             5. REPORT DATE
                January 1978  issuing date
             6. PERFORMING ORGANIZATION CODE
 7. AUTHOR(S)
         R.  B.  Dean
                                                           8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
         LunDean Environmental Company
         Cincinnati, Ohio  45230
             10. PROGRAM ELEMENT NO.

                   1BA607
             11. CONTRACT/GRANT NO.

                CA-7-2761-A
 12. SPONSORING AGENCY NAME AND ADDRESS
  Health  Effects Research Laboratory,  Cin-OH
  Office  of Research and Development
  U.S.  Environmental Protection Agency
  Cincinnati,  Ohio  45268
             13. TYPE OF REPORT AND PERIOD COVERED
                Final Report
             14. SPONSORING AGENCY CODE
               EPA/600/10
 15. SUPPLEMENTARY NOTES
               Project Officer:  Herbert R.  Pahren (513)684-7217
 16. ABSTRACT  Sewer workers in Copenhagen,  Denmark have a higher death  rate than the
 comparable male population.  An  alarmingly high proportion of  the deaths occur within
 the year  that employment terminates.   Attempts to correlate the  statistics with sick
 leave  records or chemicals in  the  environment have so far not  been  successful.  Sewer
 workers experience a high rate of  gastro-intestinal tract disorders which they as-
 sociate with chemical odors and  infectious agents.  They have  elevated levels of gamma
 globulins.   Analytical xrork has  not yet identified any agents  that  might be responsi-
 ble for the observed death rates or the gastro-intestinal problems.  Biological ex-
 aminations of stool specimens  have not been made.
      This report was submitted in  fulfillment of Contract CA-7-2761-A by LunDean
 Environmental Company under the  sponsorship of the U.S. Environmental Protection
 Agency.   This report covers a  period from May 1977 to August 1977.
                                              h.IDENTIFIERS/OPEN ENDED TERMS  C. COSATi rieki/Ooup
   Sewage Treatment",  Diseases*, Health,
   Waste Treatment, Mortality, Morbidity,
   Sewers, Epidemiology
   Denmark,
   Copenhagen,
   Sewer Workers
   Occupational Diseases
  57  U
  94  D
 ?. DISTRIBUTION STATEMENT
    RELEASE TO PUBLIC
19. SECURITY CLASS (This Report)
    UNCLASSIFIED
21. NO. OF PAGES

     17
                                              20. SECURITY CLASS (This page)
                                                  UNCLASSIFIED
                                                                         22. PRICE
EPA Form 2220-1 (9-73)
                                             11
                                                             £• US GOVERNMENT PRINTING OFFICE 1978-757-140'6659

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