Municipal sewage sludge application on Ohio farms: Health effects

ENVIRONMENTAL

RESEARCH

Municipal

38, 332-359 (1985)

Sewage Sludge Application Health Effects’

C. RICHARD DoRN,*,~

on Ohio Farms:

CHADA S. REDDY,*.~ DAVID N. LAMPHERE,*,~ AND RICHARD LANESET

JOHN V. GAEUMAN,~ Departments

of *Veterinary The Ohio State

Preventive University,

Medicine Columbus,

fpreventive Ohio 43210

and

Medicine,

Received February 27, 1984 A 3-year prospective epidemiologic study was conducted on 47 farms receiving annual applications of treated sludge (average of 2-10 dry metric tons/ha/year) and 46 control farms in three geographic areas of Ohio. On the sludge-receiving farms 164 persons (78 families) and on the control farms 130 persons (53 families) participated by cooperating with monthly questionnaires concerning their health and their animals’ health, annual tuberculin testing, and quarterly blood sampling for serological testing. The estimated risks of respiratory illness, digestive illness, or general symptoms were not significantly different between sludge farm and control farm residents. Similarly, there were no observed differences between disease occurrence in domestic animals on sludge and on control farms. No conversions from negative to positive tine test results occurred after sludge had been applied to the farms. The frequency of serological conversions (fourfold or greater rise in antibody) to a series of 23 test viruses and the frequency of associated illnesses were similar among persons on sludge and control farms. The absence of observed human or animal health effects resulting from sludge application in this study of Ohio farms was associated with low sludge application rates which were in accordance with Ohio and U.S. Environmental Protection Agency guidelines. Caution should be exercised in using these data to predict health risks associated with sludges containing higher levels of disease agents and with higher sludge application rates and larger acreages treated per farm than used in this study. 0 1985 Academic Press, Inc.

INTRODUCTION

The amount of sewage sludge requiring disposal has increased greatly since the U.S. Government required that all publicly owned sewage treatment plants include secondary treatment. Furthermore, the Water Pollution Control Act Amendments of 1972 require that an assessment of alternative treatment technologies, including sludge recycling to the land, be considered before construction grants could be awarded. The Marine Protection, Research and Sanctuaries Act of 1972 curtailed the routine practice of dumping sludge into the ocean (Galen, 1980). The alternative of incinerating sludge requires large amounts of energy and it must be done in compliance with the Air Quality Act of 1967. Therefore land application and landfills have been used more in recent years. Suitable landfill sites are, however, being exhausted. Thus, sludge is now being applied to farm’ This study was supported by the Ohio Farm Bureau Federation-U.S.EPA Cooperative Agreement CS805189. 2 To whom correspondence should be sent. 3 Present address: Department of Veterinary Anatomy and Physiology, University of Missouri, Columbia, MO 65211. 4 Present address: Box 18, Arkansaw, WI 54721. 332 0013-9351/85 $3.00 Copyright D 1985 by Academic Press, Inc. All rights of reproduction in any form reserved.

SLUDGE

SPREADING-HEALTH

EFFECTS

333

land by many municipalities. There are also economic advantages for the farm owner and operator who uses the sludge as a fertilizer and as a soil conditioner. Municipal sewage sludge has been applied to farmland for many years: however, there remain questions about the human health and animal health consequences of this practice. Potentially harmful microbiological agents and chemical substances in sewage sludge have been described in several reviews (Burge and Marsh, 1978; Epstein and Chaney, 1978; Pahren et al., 1979; Jones, 1980; Kowal and Pahren, 1980; World Health Organization (WHO). 1981). Sewage treatment employees who were occupationally exposed to sludge, in addition to raw sewage, were the subjects of several investigations; however, many of these studies can not be adequately evaluated due to lack of controls (Clark et nl., 1976). A study of Paris sewage plant workers found that they had a higher risk of amebiasis and giardiasis compared to the general population (Doby et al., 1980). Hepatitis A infection in Copenhagen workers has also been correlated to sewage exposure (Shink et al., 1981). The health of sewer workers, sewage treatment workers, and their families was monitored in several U.S. cities and no evident adverse health effects were observed as a result of sludge exposure (Clark et al., 1980). A seroepidemiologic study of sewage treatment workers failed to show any evidence of increased risk of infection as measured by an increase in antibody titers (Clark et al., 1978). Epidemiologic studies of persons living near sewage treatment facilities have also been conducted. In a study of acute illness among population groups at varying distances from the Tecumseh Wastewater Treatment Plant in Michigan, the higher illness rates were related more to socioeconomic status of the families than to proximity to the wastewater treatment plant (Fannin et al., 1980). A study of persons living near a new activated sludge plant in Illinois found a higher incidence of skin disease and severe gastrointestinal symptoms after the plant became operational (Johnson et al., 1980). However, antibody tests for 3 1 human enteric viruses and attempted isolations of many pathogenic bacteria, parasites. and viruses yielded virtually no clinical evidence of infectious disease effects associated with the sewage treatment plant. Sewage treatment aerosol had no adverse effect on communicable disease incidence as discerned from total school absenteeism in children living near a wastewater treatment facility in Oregon (Camann et al., 1980). The health effects of aerosols emitted from an activated sludge plant in Skokie, Illinois, were studied over an 8-month period (Northrup et al., 1980). No correlations were observed between the exposure indices and self-reported rates of illness or of bacterial or viral infection rates. Of the 246 families studied only a few were exposed to the highest pollution levels. Several epidemiologic reports provide accounts of enteric infections resulting from the use of untreated wastewater in the cultivation of crops that are subsequently eaten raw (Geldreich and Bordner, 1971; Hoadley and Goyal, 1976; Sepp, 1971). A large retrospective study of 77 kibbutzim in Israel exposed to slow-rate land treatment with nondisinfected oxidation pond effluent and 130 control kibbutzim was reported (Shuval and Fattal, 1980). The 1983 final report of this study did not confirm the 1980 findings of increased incidence of typhoid fever, salmonellosis, shigellosis, and infectious hepatitis in the exposed kibbutzim. How-

334

DORN

ET

AL.

ever, a small significant excess risk of total enteric disease was found during the 1983 effluent irrigation period (Shuval et al., 1983). There have been no previously reported studies of the human health effect of land application of treated municipal sewage sludge. The health of livestock on farms where sludge is applied is also a concern. The major pathogenic agent of concern is Salmonella acquired by animals grazing on sludge-treated land. Calves became infected when grazing pastures to which a slurry containing lo6 Salmonella dublin organisms/ml had been applied the previous day at a rate of 10 gal per 40-yd2 strip (13.6 kl/ha) (Taylor and Burrows, 1971). A later study using lo5 S. dublinlml failed to infect calves when allowed to graze 7 days after spreading at a rate of 11.2 kuhectare (Taylor, 1973). Goats raised on corn silage grown on sludge-amended land did not become infected with Salmonella even though Salmonella were present in the sludge (Ayanwale et al., 1980). Studies of carrier rates and serotypes of Salmonella in cattle grazing on sludge-treated pastures in Switzerland have indicated a positive association and a cycle of infection from humans to sludge to animals to humans (WHO, 1981). Similar evidence was reported from the Netherlands, but not from the United Kingdom where reporting of salmonellosis is compulsory. Cattle serve as the intermediate host for Tueniu suginutu of humans. The Tueniu ova can survive from several days to 7 months (Babayeva, 1966). T. suginutu cysticercosis in cattle due to ingestion of T. suginutu ova has been associated with exposure to human sewage in Australia (Rickard and Adolph, 1977) and in the United Kingdom (Macpherson et al., 1978), and to sewage sludge in Virginia (Hammerberg et al., 1978). Thirty-seven cysticerosis cases were found among calves exposed to raw sewage flooding pastures on a farm on which sewage sludge had also been applied (Fertig, 1982). Seven cysticercosis cases occurred 2 years later on the same farm when sewage sludge was the only likely source of infection (Fertig and Dorn, 1985). Livestock are also exposed to chemicals in sludge by direct ingestion of sludge adhering to vegetation or by ingestion of feeds grown on agricultural lands where sludge was applied. Animal food products consequently serve as an avenue for the translocation of chemical compounds, such as heavy metals, to human beings. One study reported significantly higher (P < 0.05) levels of cadmium in the livers and kidneys of cows exposed to a publicly owned sludge recycling site compared to controls (Kienholz et al., 1977). Fitzgerald (1980) reported that the average kidney cadmium level in 39 cows grazing on sludge-treated pastures was as high as 40.7 kg/g. Several studies have examined tissue residue levels in cattle (Kienholz et al., 1979; Bertrand et al., 1980; Boyer et al., 1981), swine (Hammell et al., 1977; Hansen and Hinesly, 1979; Beaudouin et al., 1980), and sheep (Smith et al., 1977) fed sewage sludge or sludge-fertilized feed as part of their ration. Several heavy metals, primarily cadmium and lead, were reported in significantly higher concentrations in the livers and kidneys of treated animals than in the controls. Mycobacterium is another pathogen which is isolated from sewage sludge (Jones et al., 1981). Mammalian as well as atypical Mycobucterium strains in sludge could infect or sensitize exposed human beings and animals. Even though

SLUDGE

SPREADING-HEALTH

CO”WTIES:

CIWk Franklin

=c

EFFECTS

Meana

= F

FLG. I. Location of counties with participating

Pioksway=

q

33s

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sewage treatment facilities and farms.

sensitized individuals may not become ill, they would react to the tuberculin test resulting in diagnostic and possibly economic problems for livestock owners. Since no systematic investigation of human and livestock health effects of sewage sludge application on privately owned farms has been conducted, the study described in this report was initiated. The study was a cooperative undertaking between the U.S. Environmental Protection Agency (U.S.EPA), the Ohio Farm Bureau Federation, the Ohio Department of Health, and The Ohio State University. The research objectives were to: (1) monitor the health status of humans and animals living on sludge-receiving and control farms, (2) determine if sludge application on farms is associated with conversion of tuberculin reactions from negative to significant, and (3) determine if sludge application is associated with higher illness rates. METHODS

Selection of Participating Farms Three different locations in Ohio were selected for the health study. These Iocations were selected because they represented different geographic areas of the state, treatment facility officials were interested in disposing of their sludge via farmland application, and each facility produced enough sludge to accommodate large numbers of participating farms. The three locations were Medina County, the Columbus area (Franklin and Pickaway Counties), and Clark County (Fig. 1). The Ohio State University Cooperative Extension staff in each county compiled a listing of all farms over 20 acres (8.1 ha) that might participate in the project. The recruitment of farms began in the Spring of 1978. The farm owners and operators were contacted and invited to attend an educational meeting conducted

336

DORN ET AL.

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456769101112123456769101112123456769101112123456769101112~2345~ 1976

1979

FIG. FI IG. 2. Participation date of first interview;

1990

1961

1982

YEAR AND MONTH BY NUMBER

;

of each sludge-receiving farm, by county and date of sludge application; A, date of sludge application; 0, date of final interview.

0,

by the project staff. At that meeting, those persons interested in having their farms considered for sludge application completed a detailed questionnaire about their farming operation and livestock. From these respondents, certain farms were eliminated because of their distance from the sewage treatment facility, their proximity to a stream, or other environmental considerations, and a list of eligible farms was developed. All dairy farms were excluded in accordance with an Ohio Department of Health recommendation based on their interpretation of regulations which prohibit human fecal waste from being applied to farms producing Grade A milk. For each location, each farm in the eligible pool was randomly assigned to either receive sludge (sludge farm) or serve as a control farm. Thus for each sludge farm, except one in Medina County, there was a control farm from the same county further matched in the sense that their pre-sludge and post-sludge periods of observation corresponded (Figs. 2, 3). Since the farms which were chosen to receive sludge benefitted economically from the fertilizer and soil conditioning properties of the sludge, each control farm received incentive payments of $150, one at the beginning and the other at the end of the study. The farms designated to receive sludge were visited by an agronomy team which collected soil samples, reviewed present and planned crop rotations, and made recommendations concerning time, location, and amount of sludge application. Each proposed site of sludge application was inspected by the Ohio EPA and approved prior to receiving sludge. Source and Application

of Sludge

The sludges used in Franklin and Pickaway Counties and in Clark County were anaerobically treated and in Medina County the sludge was aerobically treated.

SLUDGE

SPREADING-HEALTH

337

EFFECTS

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,,,1i,,,,,lli,lllll1~1111~~11111111111illlllrll,lil

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FK;. 3. Duration of participation of final interview.

1979

1980 YEAR ANDMONTH BY NUMBER

234567691011121 I981

23456 I982

of each control farm by county: l . date of first interview; 0. date

The sludge was spread by applicator equipment at the rate of 2-10 dry metric tons/ha. The amount of sludge applied to each farm was based on the soil phosphorus requirements, according to the Ohio and U.S.EPA guidelines (Miller et (II., 1979; U.S.EPA, 1979). The means (and ranges) of application rates were 2.0 (1.3-4.81, 4.5 (3.2-7.0), and 9.9 (4.0-12.1) dry metric tons/ha/year for Medina. Clark, and Franklin-Pickaway Counties. respectively. Only selected fields or parts of fields received sludge. Applications were confined to less than 20 ha on all of the farms in Medina and Clark Counties (mean 15 ha) and on 18 of the 25 farms in Franklin and Pickaway Counties (mean 47 ha). Sludge applications were repeated approximately once a year.

The farm owners and operators were visited prior to sludge application by a health team consisting of an epidemiologist and a nurse. The health studies were then explained in greater detail, informed consent forms were signed, and a baseline health questionnaire was completed for each farm resident. The questionnaire consisted of the following components: I. Family form. This contained information on the location of the farm, a list of people living and/or working on the farm on a regular basis, and information on the farm environment. 2. Human exposure form (I). This contained an individual participant’s work schedule both on and off the farm, nature and source of food, contact with animals, and previous medical history including illnesses and vaccinations. Additional information on immunization history, smoking history, and chronic illnesses was collected on an annual basis.

338

DORN

ET

AL.

3. Human illness form (II). This recorded symptomatology and course of a participant’s illness. 4. Animal exposure form (I). This described the environment, source of feedstuffs, time spent on the sludge field and illnesses for each livestock production unit. A livestock production unit was defined as a group of animals of the same species and type of operation under the management of a single family or individual . 5. Animal illness form (II). This showed the nature and duration of illness in each livestock unit. Followup questionnaires on animal and human health were completed by telephone at approximately l-month intervals, beginning with the initial interview. Tuberculin

Testing

Each participant was given a tuberculin tine test (Tuberculin, Old, Tine Test; Lederle Laboratories, Pearl River, N.Y.) by the project nurse. The test was read by the test subject at 72 hr post-injection. The mail-back postcard provided with the tuberculin tine test kit was used for recording and reporting the results. A significant tine test reaction was defined as any induration of 5 mm or more. Prior to September 1979 those reporting a reaction to the tine test were referred to their family physician for further evaluation, After September 1979 individuals who reported a significant reaction to the tine test were given a Mantoux test using human strain purified protein derivative (PPD; Connaught Laboratories Ltd., Willowdale, Ontario, Canada). In subsequent testing only the Mantoux test was given to these individuals. The significant Mantoux test reaction was defined as an induration of 10 mm or more. Those positive to the Mantoux test were examined by thoracic radiography for confirmation. The tuberculin testing was performed on all participants at yearly intervals to evaluate possible conversions from negative to positive (significant). Sludge application on these farms was coordinated so that the first (baseline) tuberculin testing was done within 1 week before the date of first sludge application. Serum Neutralization

Testing

When the first tuberculin test was administered, blood samples were collected to obtain serum specimens. Subsequent samples were collected approximately every 3 months. The serum was separated by low-speed centrifugation and then stored at - 20°C for later testing. Twenty-three enteroviruses and two cell culture systems, rhabdomyosarcoma (RD) and buffalo green monkey (BGM), were used to measure neutralizing antibody titers for each person sampled. The sera were inactivated at 56°C for 30 min. Three to four serial sera from one individual were tested simultaneously. The challenge virus doses were between 30 and 300 TCD,,. A back titration was done on each challenge dose. The serum titer was the highest dilution of serum that completely inhibited the cytopathogenic effect of a given enterovirus. A seroconversion was a fourfold rise in antibody titer to a specific test virus between two consecutive serum samples tested simultaneously. Each of the first two sludge applications were analyzed separately, yielding 46 and 29 pairs of farms, respectively. The baseline serum for the first sludge application

SLUDGE

SPREADING-HEALTH

339

EFFECTS

was taken before sludge was applied. For the analysis of the effect of the second sludge application, the baseline serum was a serum taken before or no more than 15 days after the second application of sludge. It was considered that any antibody rise occurring within that 15-day period probably would not have been due to sludge exposure. Every rise considered a seroconversion was confirmed by at least one repeat test.

Questionnaire responses were coded and entered into an Amdahl470 computer for future retrieval and analysis. The questionnaire data and comparable demographic data obtained from the 1970 Census of Agriculture were displayed descriptively. Because human beings, animal production units, and the numbers of animals remained on the farms varying length of time, person-years at risk, unityears at risk, and animal-years at risk were computed. Person-years at risk values were calculated by adding participation periods for all individuals at risk. The period of observation started on the date of the first interview following sludge application and ended at the termination of the study on that farm. This descriptive examination of the data used the longest possible observation period in order to include illnesses due both to infectious agents and chemical agents which accumulate with additional sludge applications and remain in the environment for long periods. Subsequent data analyses focused on the infectious disease transmission hypothesis and were limited to the period immediately following sludge applications, e.g., 7 weeks or up to 3 months. For controls, participation started on the date of interview following the date of sludge application on its corresponding sludge farm. The number of unit-years at risk was calculated by adding the number of weeks of data contribution by each production unit for each interview and dividing by 52. The number of animalyears at risk was calculated by adding the total number of weeks of data contribution by all animals within each unit at the time of each interview and dividing by 52. These values were then used as denominators in calculations of illness rates. The following equations were used.: human illness rate per 100 person-years at risk animal illness rate per 100 = unit-years at risk

no. of new illnesses x 100: no. of person-years at risk no. of units, affected no. of unit-years at risk

x 100:

animal illness rate per 100 no. of animals ill animal-years at risk = no. of animal-years at risk x 100. Two panels of persons having no knowledge of the actual data being collected were asked to group the illness symptoms and signs mentioned in the human and the animal questionnaires into clinical entities suitable for data analysis. The panel for the human data consisted of two infectious disease specialties, a toxicologist, and an epidemiologist. The human symptoms were combined into four groups: (1) general: fever, headache or generalized muscular aches and pains: (2) diges-

340

DORN

ET

TABLE NOTATION

FOR MATCHED

PAIR

AL. 1

CASE-CONTROL

STUDY,

THE n -

rz,, CONCORDANT

Pair

WHERE

THE n‘, DISCORDANT

PAIRS PRECEDE

PAIRS

Case

Control

1

(x,,,

.

till3

.

1 YIR)

2

(x,,,

. . . . XZR)

cv*,,

. .

, Y?R)

n

(x,,.

. . . 1 x&J

c.?J“,, .

2 X,R)

3 YnR)

tive: nausea or diarrhea; (3) upper respiratory: runny nose, sore throat, nasal congestion, or hoarseness; and (4) lower respiratory: chest congestion or cough. The panel for the animal illness data consisted of a veterinary clinician and an epidemiologist. Selected animal signs were combined into two groups (1) digestive: constipation, diarrhea, or blood in feces; and (2) respiratory: cough, nasal discharge, or difficult breathing. The human illness data were subjected to statistical analysis using the multiple logistic regression method (Breslow and Day, 1980; Kleinbaum, 1982) using both the individual and the combined symptom categories. The multiple logistic regression model has been one of the approaches used to investigate the effects of independent variables on the risk of developing disease symptoms. Most of the time, in these studies, the dependent variable is binary in nature (d = 1 for the presence of the response variable (illness or symptom) and d = 0 for the absence of the response variable). The independent variables can be defined as x1, x2, . . * ) x,, then Pr(d = 11x1, x2, . . . , xR) =

where p represents the regression parameters and (Y is the intercept. Pairwise matching was used in this study to investigate the effects of certain independent variables on the risk of developing a symptom. The sludge farms were matched with control farms on the basis of entry date into the study. There were 46 matches for this analysis; one farm in Medina County was eliminated because there was no match. Table 1 shows the notation scheme of the matched pair study in which R risk variables are under evaluation, x refers to the risk variables for the cases, and y to those for controls. The first subscript indexes the pair while the second subscript denotes the risk variable. For matched pair case-control data, the conditional likelihood is determined by computing the product of fld conditional probabilities, i.e., one conditional probability for each discordant pair. The product of these nd probabilities, is the conditional likelihood. Since in this study only one control farm is matched to each sludge farm, the conditional likelihood can be written as follows:

SLUDGE

SPREADING-HEALTH

EFFECTS

341

1

Holford ef al. (1978) treated this as a conventional likelihood function applying standard likelihood results to make inferences on pi, . . , PR. The coefficients can easily be interpreted in terms of odds ratios, which are estimates of the relative risk. In the present study, the exponentiated p is the odds of reporting a symptom with each unit change of the independent variable. The human data were analyzed separately for the first and the second sludge applications. This analysis used a farm as the unit of observation rather than individuals to avoid bias due to clustering of illnesses within farm families. The period of observation following sludge application was 3 months (or approximately three interviews) and corresponded to the period when infectious diseases due to sludge exposure might be expected. The following variables were accounted for in the multiple logistic analysis: sludge or control farm, number of weeks of observation, and number of persons in each age group (O-4, 5- 13. 1321, 22-59. and 260). The response variable was one or more reported illnesses in the farm family during the period of observation. The statistical analysis of the animal illness data was limited by small numbers of some types of animal units and the absence of livestock, pets, or both on some farms. Therefore it was not possible to perform a matched-pair analysis. Using the animal unit as the basis of measurement, the x’ test was used to screen the data for possible associations between illness signs (single or combined) and use of sludge on the farm. For this calculation, illnesses experienced during the first 3 months following the first sludge application and during the 3 months following the second sludge application were analyzed separately. A program for testing of followup data with animal unit-time denominators was also applied to illness rates per 100 unit-years at risk to determine if any rates were significantly different on sludge farms compared to those on control farms (Rothman and Boice, 1979). Comparisons were also made between sludge farms and control farms to explore other independent variables which might have resulted in significant confounding effects on human and animal illness. For these comparisons the x’ test was used for categorical variables and the F test (analysis of variance) was used for continuous variables. The 5% level of significance was used for all statistical tests. RESULTS

For the three combined locations, a total of 47 farms received sludge and 46 farms served as controls (Table 2). As more than one family was often associated with a single study farm, the sludge farms had 78 families with 200 eligible persons and the control farms had 53 families with 174 eligible persons. A person eligible to participate was one who resided on or regularly visited a designated project farm. For the sludge farm group, eligible persons had to reside on or visit regularly the site where the sludge was applied.

342

DORN ET AL. TABLE 2 NUMBEROF FARMS ANDPARTICIPANTS IN SLUDGEANDCONTROLGROUPSBY YEARS OF PARTICIPATION Study group

Unit All counties Farms

Number started

Number participating‘ 1 year

2 years

3 years

Sludge Control

47 46

47 46

36 37

13 13

Sludge Control

78 53

77 53

56 40

21 13

Eligible personsb

Sludge Control

200 174

200 174

153 124

59 44

Participants

Sludge Control

165 130

165 130

126 109

53 37

Sludge Control

31 26

31 26

20 21

18 19

Sludge Control

101 76

99 76

82 72

35 18

Sludge Control

35 28

35 28

20 16

Medina County Participants Franklin-Pickaway Participants Clark County Participants

Counties

-c -

a Participation is calculated from the date of first sludge application for each sludge farm; for each control farm participation was calculated from the date of interview closest to the date of first sludge application on the corresponding sludge farm. b A person eligible to participate was one who resided on or regularly visited a designated project farm. (In the case of sludge-receiving farms, residence or visits must not be on a site remote from sludge.1 c Blank indicates that none of the participants were in the project during the third year because of late recruitment.

Of the eligible persons, 16.5 persons on sludge farms and 130 persons on control farms initially participated (Table 2). Thirty-five individuals that refused to participate were from sludge-receiving farms; 18 were males and 17 were females. Forty-four individuals from control farms refused to participate; 26 were male and 1X were female. Factors including delays in sludge applications and withdrawal from participation due to personal reasons changed the duration of participation among farms. Considering the date of first sludge application as the beginning of the project (the same date for the time-matched control), all farms and participants completed at least 1 year of participation. Thirty-six sludge farms completed 2 years and 13 completed 3 years. Thirty-seven control farms completed 2 years and 13 completed 3 years. The small number of participating farms and persons completing 2 and 3 years is due primarily to late start up times and voluntary withdrawal from the study (Figs. 2 and 3). The farms in Medina County started first, followed by farms in Franklin-Pickaway Counties and then by Clark

SLUDGE

SPREADING-HEALTH TABLE

3

DISTRIBUTIONOFPOPULATIONINSLUDGEANDCONTROLGROUPS -

BY AGE ANDSEX. ALL COUNTIES Control

Sludge

0 Column

343

EFFECTS

Age (yr) and sex

Number

All ages M F

16.5 91 68

100.0

130 73 57

100.0

O-9 M F

17 7 10

10.3

13 7 6

10.0

IO-19 M F

22 14 8

13.3

19 12 7

14.6

20-29 M F

24 I5 9

14.5

12 8 4

9.2

30-39 M F

24 14 10

14.5

24 14 10

18.5

40-49 M F

24 13 I1

14.5

IO 6 4

7.7

SO-59 M F

28 19 9

17.0

37 I2 15

20.8

60-69 M F

16 9 I

9.7

23 I3 IO

17.7

370 M F

10 6 4

6.1

2 1 1

I.5

does

not add to 100.0%

Percentage”

Number

Percentage

due to rounding.

County farms. The largest numbers of participants were in Franklin-Pickaway Counties; both Medina County and Clark County had approximately the same number of participants (Table 2). None of the Clark County farms participated the third year due to late recruitment. Human Population Characteristics There were more males than females in both the sludge and control groups, 1.37: 1 and I .28: 1 respectively (Table 3). The total Ohio rural farm population sex ratio also slightly favors male (Table 4). Most of the people on both sludge and control farms were in the 50-59 age groups (Table 3). In the O-19 age interval there were proportionately fewer persons on both sludge farms and control farms than enumerated in the 1970 census

344

DORN ET AL. TABLE DISTRIBUTION

OF TOTAL

RURAL

FARM ALL

4

POPULATION OHIO

BY AGE AND SEX (1970

CENSUS),

COUNTIES

Age (v-1 and sex

Number

Percentage

All ages M F

23,877 12,040 11,837

100.0

o-9 M F

3,884 2,003 1.881

16.3

10-19 M F

4,976 2,602 2,374

20.8

20-29 M F

2.137 1,052 1,085

9.0

30-39 M F

2,499 1,237 1,262

10.5

40-49 M F

2.982 I.430 1,552

12.5

50-59 M F

3,300 1,668 1,632

13.8

60-69 M F

2,186 1,184 1,002

9.1

210 yrs M F

1,913 864 1,049

8.0

(Table 4). Conversely, there were proportionately more persons in the 50-69 age group than enumerated in the 1970 census. As shown in Table 2, there were 47 sludge-receiving farms and 46 control farms; however there were 78 families in the sludge group compared with 53 in the control group. It therefore becomes important to consider the distribution of persons in each farm and in each family unit. There were far more single-person families in the sludge group compared to the control group, 31 vs 12 (Table 5). This disparity was due in part to a plant nursery farm which regularly employed seven male laborers. Three of these persons, but not their family members, were exposed to the sludge. Therefore they were considered to be single-person family units for the purpose of the study. All of the participants on both sludge and control farms were white Americans.

SLUDGE

SPREADING-HEALTH TABLE

NUMBER

OF FARMS

Size of family (persons) Total

8 9

AND FAMILIES

345

EFFECTS

5

IN THE SLUDGE-RECEIVING

AND CONTROL

Sludge

GROUPS,

ALL

COUNTIES

Control

Farms

Families

Farms

Families

46 4 16 I 5 3 I 3 0 I

78 31 28 4 9 4 3 0 0 0

46 I ‘2. 3 6 4 3 0

53 I? 24 6 5 4 z 0 0 0

0

Immunization history. One person on a sludge farm in Medina County had poliomyelitis (polio) prior to the start of the study on that farm. No other sludge farm or control farm participant had a history of polio. Approximately 90% of both combined sludge and control groups had been immunized. No cases of polio were reported during the study. Approximately one-fourth of the sludge and control groups had been immunized for common measles (rubeola). No cases of measles were reported during the study. The immunization level for rubella was approximately the same as for measles. No cases of rubella were reported during the study. Distribution of time spent on and off the farm. Each participant was asked about the amount of time he/she spent in field work, in livestock work, and in off-farm activities during each monthly interview. Their monthly responses were averaged for each 3-month season over the 3-year period. On the sludge farms the amount of the field work that was on sludge-treated land was also determined. Approximately 13% of their field work was performed on sludge-treated land over all seasons (Table 6). Most of the field work was performed in Spring, Summer, and Autumn on both sludge and control farms. The amounts of time spent in field work on sludge and control farms were similar, 9.1 and 10.9 hr/week, respectively. The amount of time spent in livestock work was approximately one-half the amount of time spent in field work. The amount of livestock work for the three combined locations was similar in the sludge and control groups. Home-produced food consumed. The percentage of meat consumed which was home raised was higher for the sludge farm residents than for the control farm residents (Table 7). This difference was contributed by participants mainly from Franklin-Pickaway Counties; however, it was not statistically significant using the analysis of variance. For fruit and vegetable consumption, the percentages that were home grown were similar in sludge and control groups (Table 7). By analysis of variance there was a significant season effect on the percentage of homeproduced meat and fruits and vegetables consumed (P < 0.05).

346

DORN ET AL. TABLE 6 SEASONAL ON- AND OFF-FARM WORK PROFILESOF CONTROL AND SLULXE POPULATIONS, ALL COUNTIES Average hours/week” Type of time

All seasons

Winter

Spring

Summer

Sludge farms Total Field work On sludge land Livestock work Off-farm time School Job Other

168.0 9.1 1.2 4.6 39.5 4.9 10.4 24.2

168.0 2.1 0.4 4.8 41.2 5.6 10.1 25.5

168.0 11.3 1.5 4.7 37.1 5.5 10.4 21.2

168.0 10.8 1.5 5.0 39.8 1.7 10.1 28.0

168.0 12.4 1.5 3.9 40.2 6.9 11.1 22.2

Control farms Total Field work Livestock work Off-farm time School Job Other

168.0 10.9 4.8 47.3 4.6 9.5 33.2

168.0 3.2 5.7 48.1 5.2 9.8 33.1

168.0 12.5 4.8 47.5 5.2 9.4 32.9

168.0 11.7 4.5 46.8 1.8 8.9 36.1

168.0 16.0 4.4 46.5 6.2 9.8 30.5

Autumn

il Calculated by averaging the monthly responses for each season over the 3-year period, beginning with the first monthly interview following the initial sludge application and the corresponding monthly interview for controls. Winter, Jan.-March; Spring, April-June; Summer, July-Sept.; Autumn, Oct.Dec.

Tuberculin

Testing

A total of 153 and 119 tuberculin tine tests were administered in the sludge and control groups, respectively, prior to the date of sludge application on the sludge farms (Table 8). In the sludge group, seven persons had significant reactions of 5 mm or greater induration at the site of inoculation in the baseline test. Six of these were followed with a Mantoux intradermal skin test. Of these, two persons had significant reactions. Both of these persons then received chest X rays and TABLE 7 COMPARISONOFESTIMATEDAMOUNTOFHOME-PRODUCEDFOODCONSUMEDBY CONTROL POPULATIONSIN ALL COUNTIES BY SEASON" Percentage of total consumption

SLUDGE AND

that was home raised

Group

All seasons

Winter

Spring

Summer

Autumn

Meat

Sludge Control

35.6 27.9

37.6 27.8

32.9 28.4

35.1 26.4

37.0 28.8

Fruits or vegetables

Sludge Control

34.9 33.3

34.8 32.6

29.5 29.7

36.3 35.2

39.1 35.5

Food item

a Winter, Jan.-March;

Spring, April-June:

Summer, July-Sept.;

Autumn, Oct.-Dec.

SLUDGE

SPREADING-HEALTH

347

EFFECTS

TABLE 8 SUMMARY OFTUBERCULIN TESTS FOR SLUDGEANDCONTROLGROUPS BY SLUDGE APPLICATION PERIOD, ALL COUNTIES

Group

Pre-sludge baseline

Years post-sludge” I

2

3

Sludge Tine tests Tine significant reactions” Mantoux tests Mantoux significant reactions’

153 I 6 2

148 I 3 0

131 2 4 0

80 0 I 0

Control Tine tests Tine significant reactions Mantoux tests Mantoux significant reactions’

119 5” 2 0

114 0 2 0

91 0 2 0

51 0 I” 0

(’ Post-sludge period for controls represents the period beginning with the date of interview closest to the date of first sludge application for the corresponding sludge farm. h Tine test significant reaction is defined as any response of induration 5 mm or more. Prior to September 1979 those reporting a reaction to tine test were referred to their family physician for further evaluation. After September 1979 individuals who reported a significant reaction to tine test were given a Mantoux test. In subsequent years, only Mantoux test was given to these individuals. (’ Mantoux significant reaction is an induration of 10 mm or more at the site of intermediate strength PPD injection. d Of the five tine significant reactions, 3 were before 9179 which were not Mantoux tested nor tine tested subsequently. The other two were only Mantoux tested in subsequent years. c Only one participant who was Mantoux tested, was in the project for 3 years post-sludge.

both were negative radiographically. The one tine test-positive person in the first year and the two positives in the second year of the study were all persons who had been positive prior to sludge application. There were no significant Mantoux reactions after sludge application began. In the control group, 5 of 119 persons tested before sludge application had significant tine test reactions (Table 8). Two of these were followed with a Mantoux test and none of these were significant. The Mantoux tests performed in subsequent years were also negative. Human Illnesses

Illness rates. The number of persons ill, number of new acute illnesses, and overall illness rates for each county are presented in Table 9. Chronic illnesses. reported in pre-sludge interviews, were not included. Individuals reporting an illness with similar symptoms in two consecutive interviews were further questioned about the time lapse between the two illnesses. An asymptomatic period of at least 1 week between the illnesses was required to consider them separate episodes. The illness rates were higher on the control farms than on the sludge farms in Medina and Franklin-Pickaway Counties, but in Clark County the sludge farms had higher rates. Illness rates per 100 person-years at risk for specific symptoms were calculated for all three study locations (Table 10). For each symptom category in Medina

348

DORN ET AL. HUMANILLNESSRATESON

TABLE 9 SLUDGEANDCONTROLFARMS,BYCOUNTY Illness rate per

County All counties Sludge Control Medina Sludge Control Franklin and Pickaway Sludge Control Clark Sludge Control

Persons at risk

Persons ill

Reported illnesses

100 persons at risk

100 personyears at risk”

168 130

161 126

874 831

520 639

261 325

31 26

30 25

135 228

435 877

207 378

101 76

98 76

525 481

520 633

246 319

36 28

33 25

214

594 436

384 274

122

a Person-years at risk values were calculated by adding participation periods for all individuals at risk during the post-sludge period. For controls, participation started on the date of interview following the date of sludge application on its corresponding sludge farm.

County and in Franklin-Pickaway Counties the rates were higher on the control farms than on the sludge farms. The opposite relationship existed in Clark County where the sludge farm rates were higher. Illness rates were also calculated for specific age and sex groups. The overall rates for all illnesses are shown in Fig. 4. The rates for both sludge and control farms are highest in the younger ages (~13 years). They then drop in the 13- 19 age group followed by a rise in the 20-59 group. The male- and female-specific rates are similar in the sludge and control groups except for an abnormally high female rate in the 20-29 age group for control respondents. The respiratory illness rates are shown in Fig. 5. Again the rates for sludge and control respondents were very similar except for the higher female rate in the 20-29 age group for controls. The digestive illness rates (Fig. 6) were very similar in the sludge and control groups and did not reveal a higher rate in females on control farms as observed for respiratory illnesses. Statistical analysis. Following descriptive examination of the data, the matched pair logistic regression analysis was performed. The health history information was statistically examined separately for the 3-month period following the first sludge application and for the corresponding period following the second sludge application. There were only a few farms that received a third sludge application, too few for statistical analysis. The corresponding odds ratios and P values for each symptom and for combined symptoms reported on sludge and control farms are shown in Tables 11 and 12, respectively. There were no statistically significant associations between sludge use and the occurrence among farm residents of any single symptom or any of the four combinations of symptoms.

SLUDGE

HUMAN

ILLNESS

R.&ES

SPREADING-HEALTH

FOR SELECTED

TABLE SYMFTOMS

10 IN SLUDGE

Rate All counties All reported Sludge Control

349

EFFECTS

per

Medina County

AND CONTROL

100 person-years

FARMS

BY Cowmes

at risk

Franklin & Pickaway Counties

Clark County ___-

illnesses 261.4 325. I

206.7 377.5

246.0 319.4

Fever Sludge Control

62.2 66.1

64.3 107.6

52.5 52.5

96.9 56. I

Headache Sludge Control

60.7 72.0

56.7 114.2

50.6 61.8

104. I 49.3

GMAP” Sludge Control

48.4 52.4

38.3 86.1

41.2 41.8

8X.0 42.6

Nausea Sludge Control

47.8 53.2

41.3 82.8

43.1 47.1

73.6 33.6

Diarrhea Sludge Control

36.5 53.6

33.7 62.9

30.0 52.5

64.6 44.8

Runny nose Sludge Control

101.4 131.5

82.7 150.7

96.1 131.5

143.6 105.4

Cough Sludge Control

87.6 117.0

78. I 175.5

82.9 107.9

118.5 85.2

Sore throat Sludge Control

76.9 97.4

49.0 l4S.7

70.3 91.0

134.6 53.x

Nasal congestion Sludge Control

93.9 122.8

76.6 168.9

89.0 112.2

132.9 96.4

Chest congestion Sludge Control

40.7 48.9

39.8 67.9

35.6 4x.5

61.0 ‘4.7

Hoarseness Sludge Control

26.0 33.6

32.2 41.4

19.7 32.5

43.1 26.9

Other Sludge Control

81.9 104.5

58.2 81.1

81.5 113.5

III.3 105.4

” Generalized

muscular

aches

and pains.

-

384.2 273.5

-

350

DORN ET AL.

i i E P

‘1 b

I-

0

. o-4

5-12

13-19

20-29

30-59

6Oand

up

AGE GROUP(yeors1

FIG. 4. Age- and sex-specific rates, for all illnesses among persons on sludge (.,A) (0,fI) farms; circles, ma& triangles, females.

13-19

20-29

and control

30.5960andup

Age group (years1

FIG. 5. Age- and sex-specific respiratory illness rates for persons on sludge (.,A) (0,/I) farms; circles, males; triangles, females.

I 04

5-12

and control

13-19 20-29 30-59 60md up PGE GROUP ( yews)

FIG. 6. Age- and sex-specific digestive illness rates for persons on sludge (0.A) farms; circles, males; triangles, females.

and control (0.n)

SLUDGE

SPREADING-HEALTH TABLE

MATCHED PAM

LINEAR

BETWEEN

LOGISTIC SLUDGE

REGRESSION AND CONTROL

II

ANALYSIS FARMS,

Single Fever Headache GMAP’ Nausea Diarrhea Runny nose Sore throat Nasal congestion Hoarseness Chest congestion Cough Any of above Combined General Digestive

Upper respiratory Lower respiratory

OF SINGLE FIRST

SLUDGE

ANU COMBINED

SYYWTOMS

APPLICATION

Matched pa?’ adjusting for additional confounde&

Matched pa+ Symptoms

351

EFFECTS

Odds ratio

P

Odds ratio

P

1.00 0.76 0.86 0.92 0.91 1.20 1.11 I .oo 0.75 1.39 1.05 1.16

0.99 0.46 0.70 0.84 0.83 0.55 0.75 0.99 0.51 0.29 0.88 0.53

0.85 I.50 0.34 1.12 0.26 0.90 0.83 2.00 0.45 I.35 0.96 I .05

0.83 0.50 0.15 0.88 0.10 0.79 0.66 0.46 0.34 0.52 0.92 0.88

1.09 0.76 1.32 1.10

0.76 0.47 0.33 0.76

0.82 0.38 I.05 0.99

0.64 O.OY 0.90 0.99

” Matched for county and period of observation. ’ Age (5 categories) and weeks of observation. ’ Generalized muscular aches and pains.

Anzourzt qf sllndgr exposure. By determining the number of hours of sludge exposure per week and the illness rates for various levels of exposure, an examination for a dose-response relationship was possible (Table 13). Contrary to the hypothesis of more illness with greater sludge exposure (dose), the illness rate was highest (314.5/100 person-years at risk) for persons with no sludge exposure. The rate was lowest (230.21100 person-years at risk) for the highest weekly sludge exposure, i.e., > 1 ‘/z hr. A multiple regression analysis was conducted on the proportion of persons with any symptom in sludge farm families as a function of exposure dose (number of tons per acre multiplied by number of hours spent in sludge-treated fields per week), proportion of school age children per family, number of interviews, and number of people per family. As apparent from the descriptive data in Table 13, the multiple regression analysis confirmed a negative relationship between exposure dose and illness; however, this was not significant at the 5% level. The proportion of school age children and number of people per family were also nonsignificant independent variables. As one would expect, the more interviews conducted, the larger the proportion ill in a family. This relationship approached significance, P = 0.07. The tendency of lower risk of illness in those farm members who work in the fields compared to the illness risk in persons not working on the fields, such as the housewives and children, was not observed on the control farms.

352

DORN ET AL.

MATCHED

PAIR

TABLE 12 LINEAR LOGISTIC REGRESSIONANALYSIS

BETWEEN

SLUDGE

AND CONTROL

FARMS,

OF SINGLE

SECOND

AND COMBINED

SLUDGE

SYMPTOMS

APPLICATION

Matched pair” adjusting for additional confoundersb

Matched pa? Symptoms

Odds ratio

P

Odds ratio

P

Single Fever Headache GMAP’ Nausea Diarrhea Runny nose Sore throat Nasal congestion Hoarseness Chest congestion Cough Any of above

1.50 1.80 2.00 2.25 2.00 1.10 1.00 1.60 0.83 2.14 1.08 1.37

0.53 0.29 0.33 0.18 0.33 0.83 1.00 0.41 0.76 0.10 0.84 0.33

1.39 1.37 d 6.04 4.42 0.69 1.05 12.11 0.98 1.98 0.23 1.13

0.66 0.71 0.83 0.16 0.43 0.62 0.26 0.94 0.89 0.75 0.28 0.80

Combined General Digestive Upper respiratory Lower respiratory

1.75 1.80 0.81 1.42

0.21 0.29 0.59 0.36

1.55 2.69 1.21 0.72

0.56 0.41 0.72 0.60

a Matched for county and period of observation. b Age (5 categories) and weeks of observation. c Generalized muscular aches and pains. d Value not reported due to high standard error.

Relationship between illness and seroconversion. The seroconversions that could have been due to sludge exposure were identified for the sludge and control farms as explained under Methods. There were 15 seroconversions on sludge farms and 14 seroconversions on control farms (Table 14). The distributions of Coxsackie A, Coxsackie B, and Echo virus infections on the sludge and control farms were similar. The distributions of respiratory symptoms and digestive symptoms associated TABLE HUMAN

Mean Sludge Exposure Total 0 l- 10 min/week 1I-45 mm/week 46 min-1’/2 hr/week > 1t/z hriweek

ILLNESS

RATES

Participants 168 30 34 36 32 36

13

AND SLUDGE

EXPOSURE

Illnesses

Illness rate per 100 person-years at risk

874 172 170 176 166 190

261.4 314.5 247.3 275.8 257.1 230.2

SLUDGE

SPREADING-HEALTH TABLE

With digestive symptoms

EC 3 EC6 EC 7 EC9 EC I I EC 20 EC21 EC 25

IS 3 I I 0 I I I 0 I 0 I I 5

IO 1 I I 0 I 0 0 0 I 0 0 0

3 0 I 0 0 I 0 I 0 0 0 0 0

4

EC 26

0

0

Virus All CA3 CA7 CB1 CB3 cl34

Total

14

on sludge farms

With respiratory symptoms

353

COXSACKIE B (CB) AND ECHO AMONG SLUDGE AND CONTROL

SEROCONVERSIONS” TO COXSACKIE A (CA), ASSOCIATED SYMPTOMS AND PHYSICIAN VIWTS

Seroconversions

EFFECTS

Seroconversions

Visited physician

Total

With respiratory symptoms

(EC) VIWSES. FARM RESID~NIS

on control farms With digestive symptoms

Visited phyGcian

14

6

6

0

I I 0 3 0 0 0 I 7 I I I

0 I 0 I 0 0 0 0 I 0 I 0

0 I 0 0 0 0 0 I 0 I 0 0

0 0 0 0 0 0 0 0 0 0 0 0

0

5 2 0 I 0 0 0 0 0 I 0 0 0 I

3

2

3

0

0

0

I

0

0

0

(i Persons with a fourfold rise in antibody titer between sequential serum samples collected during the sludge application period.

with the seroconversions on sludge and control farms were similar (Table 14). The seroconversions on the sludge farms were associated with five visits to the physician while on the control farms none of the persons with seroconversions visited the physician. However, the worst illness status experienced by the ill persons were similar in the two groups (Table 1.5). Most of the infections resulted in person feeling ill and either continuing to work or staying at home. Only a few persons responded that they were confined to a bed or to the hospital. A relatively large number of the seroconversions did not result in self-perceived illness and none were associated with death.

The numbers of animal units of various species and types of operations on sludge and control farms are shown in Table 16. Cattle raising was the most common type of livestock enterprise followed by swine, equine, avian. porcine and ovine production. The distribution of various species was similar in sludge and control groups. Illness rates were usually higher on the control farms than on the sludge farms: however, there were no statistically significant differences (Table 17). The canine illness rates for sludge and control groups are presented in Table 17. Again there is a pattern of higher unit and animal illness rates in the control group than in the sludge group. The most common symptoms were off feed, fever. and weakness. None of the observed differences were statistically significant. The feline illness rates for sludge and control groups are presented in Table 17.

354

DORN ET AL.

SEVERITY

A (CA),

OF COXSACKIE

SLUDGE

AND CONTROL

COXSACKIE

FARM

TABLE 15 B (CB) AND

RESIDENTS

DURING

Sludge farm residents illness status

Virus

All CA3 CA7 CB 2 CB 3 CB 4 EC 3 EC 6 EC 7 EC 9 EC 11 EC 20 EC 21 EC 25 EC 26

(EC)

VIRUS

INFECTIONS“

APPLICATION

AMONG

PERIOD

Control farm residents illness status

Ill

Not

ECHO

THE SLUDGE

ill

Worked

At home

Bed

4

5

5 2

1

Not ill 5 1

1 1

Ill Worked

At home

Bed

3

3

3

1 1

1

1 1 1 1 1

1 1

1 1 1

1 3

1 1 1

1

2

1

u Infections were persons with fourfold rise in antibody titer between sequential serum samples; severity was defined as worst illness status recorded during period of fourfold rise.

The overall illness rate weakness, statistically

unit illness rate was higher in the control group but the overall animal was higher in the sludge group. The most common symptoms were fever, and difficult breathing. None of the observed differences was significant. DISCUSSION

The sex and age characteristics of the persons on sludge and control farms were similar to those of the total rural farm population in Ohio with the exception that both the sludge and control groups had a slightly older age profile than the total population. Only farms with over 20 acres were eligible to participate. This study criterion excluded smaller farms which may have younger families than larger, better established farms. In the study design this age disparity was taken into account by the random assignment of farms into sludge and control groups. This procedure resulted in balanced sex and age distributions in the two groups (Table 3). Approximately one-third of the meat consumed and one-third of the fruits and vegetables consumed by farm residents in this study were home raised. Since both infectious agents and chemical substances such as heavy metals reach human beings via ingestion, the amount of home-raised food products consumed is an obvious factor in evaluating possible health effects due to sludge application on farmland. By randomly assigning participating farms to sludge and control groups, the amount of exposure to home-raised food products did not differ significantly between the sludge and control groups. Thus the study design appeared to be

SLUDGE

SPREADING-HEALTH TABLE

COMPARISON

OF THE NUMBER

SLUDGE

AND CONTROL

OF ANIMALS FARMS

16

AND ANIMAL

UNITS

AND THEIR

BY SPECIES AND TYPE OF OPERATIONS, -

Sludge Species and type of operation

Units”

Unit-years at riskh

All bovine Beef breeding Calves Yearlings Feedlot cattle Dairy cattle

72 I7 22 I3 I7 3

89.83 26.65 31.77 15.79 13.69 I .92

All porcine Breeding pigs Baby pigs Fattening pigs

36 9 II 16

All ovine Breeding Fattening

355

EFFECTS

RISK

PERIODS

ALL

BETWEEN

COUNTIES

Control Animalyears at risk’

Unit-years at risk”

Animalyears at risk’

108.77 36.04 36.96 20.92 13.98 0.87

1772.Y8 640. I2 4Y2.3 I 246.31 418.38 0.87

59.88 22.42 16.06 2 I .40

3266.3 I

18.46 10.87 7.60

630. I2 409.YX 120. I3 57.79 0.00 2.90

I5

27.58 0.00 2.19 0.60 24.70

Units“

1492.85 514.27 412.33 185.08 379.25 1.92

79 20 23 20

43.27 13.27 9.85 20.15

3397. IO 377.56 836.90 2182.63

42 I3

17 Y 8

19.50 10.50 9.00

411.71 229.27 182.44

II

26 3 4 2 I7

25.50 2.48 2.38 1.73 18.90

All avian Chickens Layers Broiler Misc. poultry

22

37.96

947.33

23

25.33

643.81

IO 4 8

22.33 3.40 12.23

725.7s 99.17 122.40

IO 4 8

14.13 2.54 8.46

443.17

Dogs

(Canine)

45

78.27

165.81

40

67.37

127.00

Cats

(Feline)

32

57 73 --.-

270.46

All equine Breeding Foals Yearlings Pleasure

sheep sheep horses

horses

29

47.77

88.62 1 I .08 3.44 5.37 68.73

138.42

IS I

I2 I7

6 5 20 0 4 I

381.52

1001.10 1783.69

l.IY 53.69

70.19 I30.44

I’ Unit was defined as a group of animals of the same species and type of operation under the management of a single individual. h Number of unit-years at risk was calculated by adding of the number of weeks of data contribution by each unit for each interview and dividing by 52. ’ Number of animal years at risk was calculated by adding the total number of weeks of data contribution by all animals within each unit at the time of each interview and dividing by 52.

adequate in controlling for a possible bias due to more or less exposure to homeraised food products among sludge farm residents than among controls. Based upon this study, the concern about tuberculosis or tuberculin conversions occurring in human beings as a result of sludge exposure on farms seems to be unwarranted. Under the conditions of this study, there were no tuberculosis cases nor conversions on the sludge-receiving farms. The main objective of this study was to determine if sludge application was associated with higher illness rates in exposed persons. Both the examination of descriptive data and the statistical analysis were negative. Since this is the only

356

DORN ET AL. TABLE 17 ILLNESSRATES FOR SPECIFICANIMAL SPECIESON SLUDCEANDCONTROLFARMS Sludge

Control

Species

Rate per 100 unit-years at risk

Rate per 100 animal-years at risk

Rate per 100 unit-years at risk

Rate per 100 animal-years at risk

Bovine Porcine Ovine Equine Avian Canine Feline

69.0 168.7 164.1 19.6 79.0 17.9 50.2

13.9 28.5 12.9 5.6 12.7 10.3 31.9

75.4 230.4 287.1 21.8 115.4 44.5 82.3

20.0 56.1 14.8 10.4 19.3 25.2 25.1

study of a human population exposed to municipal sewage sludge that has been conducted to date, it is not possible to directly compare these results with those of other studies of health effects of sludge application on farmland. These negative findings are, however, consistent with results of several epidemiologic studies of a similar type of exposure, i.e., persons living near sewage treatment facilities (Fannin et al., 1980; Camann et al., 1980; Northrup et al., 1980). In the Illinois study of a new activated sludge wastewater treatment plant, a higher incidence of skin disease and severe gastrointestinal symptoms was observed after the plant became operational (Johnson et al., 1980). Skin disease was not one of the disease categories included in this Ohio study of farm families exposed to sludge nor was it reported when either the sludge or control farm participants were asked about other symptoms. Also, diarrhea symptoms were not reported more frequently from sludge farm than from control farm participants. Furthermore, the frequency of serological conversions of a fourfold or greater rise in antibody to a series of 23 test viruses and the frequency of associated illnesses were similar among persons on sludge and control farms. Most of the previous studies of animal health effects of exposure to sewage sludge have been concerned with laboratory confirmed infections, e.g., Safmonellu and T. suginatu infections, and heavy metal uptake. Results of similar research in the Ohio study are presented in the accompanying articles (Reddy et al., 1985; Reddy and Dorn, 1985). The present report includes results of the animal health questions that accompanied the hu’man health questions in the monthly health interviews. The animal health analysis was somewhat restricted by the small numbers of animal units and animals for specific species and types of operations due to the large number of farms without domestic animals. When the numbers of units or animals permitted statistical analysis there was no observed differences between the animal illness rates for the sludge and for the control farms. It should be pointed out, however, the small sample size and large variances would hinder obtaining a statistically significant result if, in fact, there is an association between sludge exposure and illness among farm animals. The sludge application rates used in this study (average of 2-10 dry metric

SLUDGE

SPREADING-HEALTH

EFFECTS

357

tons/ha/year) resulted from applying the Ohio and U.S.EPA guidelines (Miller et al., 1979; U.S.EPA, 1979) to the specific conditions on each farm. Therefore these results can be used to evaluate the suitability of these guidelines at least on these Ohio farms. Since no adverse health effects were observed in either people or animals, there is no reason, based on this study, to consider modification of the guidelines related to health effects at this time. Caution should be exercised, however, in using these data to predict health risks associated with sludges containing higher levels of disease agents and with higher sludge application rates and larger acreages treated per farm than used in this study. ACKNOWLEDGMENTS The authors thank all the study participants who willingly provided health information, received tuberculin tests, and provided samples for laboratory testing. Dr. Vincent Hamparian and Dr. Abram0 Ottolenghi, Department of Medical Microbiology and Immunology, The Ohio State University, provided the serum neutralization test results. Mrs. Veronica Dickey provided nursing services and Mrs. Sandy Lantz conducted the questionnaire interviews. The statistical services of Dr. P. K. Tandon. programming services of Mr. Mitch Dysart, and word processing services of Mrs. Dolores Fischer are gratefully acknowledged.

REFERENCES Ayanwale, L. F., Kaneene. J. M.. Sherman, D. M.. and Robinson, R. A. (1980). Investigation of Srcimonella infection in goats fed corn silage grown on land fertilized with sewage sludge. Appl. EnGwn.

Microbial.

40, 285-286.

Babyayeva. R. 1. (1966). Survival of beef tapeworm oncospheres on the surface of the soil in Samarkand. Med. Para;iiiol. Pm&. Bolezn. 35, 557-560. Beaudouin. J., Shirley, R. L.. and Hammell. D. L. (1980). Effect of sewage sludge diets fed swine on nutrient digestibility, reproduction, growth and minerals in tissues. J. Anim Sci. 50, 572-580. Bertrand. J. E., Lutrick. M. C.. Breland. H. L.. and West, R. L. (1980). Effects of dried digested sludge and corn grown on soil treated with liquid digested sludge on performance, carcass quality and tissue residues in beef steers. J. Anim. Sci. 50, 35-40. Boyer. K. W., Jones. J. W., Linscott, D., Wright, S. K., Stroube. W.. and Cunningham. W. (1981). Trace element levels in tissues from cattle fed a sewage sludge-amended diet. J. Tosic~ol. Environ. Health

8, 281-295.

Breslow. N. E., and Day, N. E. (1980). “Statistical Methods in Cancer Research.” Vol. I. “The Analysis of Case-Control Studies.” International Agency for Research on Cancer, Lyon, France. Burge. W. D.. and Marsh. P. B. (1978). Infectious disease hazards of landspreading sewage wastes. J. Etlviron.

QIIU/.

7, I-9.

Camann. D. E., Harding, H. J.. and Johnson, D. E. (1980). Wastewater aerosol and school attendance monitoring at an advanced wastewater treatment facility: Durham Plant. Tigard, Oregon. /rt “Wastewater Aerosols and Disease: Proceedings of a Symposium Held at Cincinnati, Ohio. September 19-21. 1979” tH. R. Pahren and W. Jakubowski. Eds.), EPA-60019-80-028, pp. 160-170. Health Effects Research Laboratory, U.S. Environmental Protection Agency. Cincinnati. Clark, C. S.. Cleary. E. J., Schiff, Cl. M., Linnemann, C. C., Jr.. Phair, J. P.. and Briggs, T. M. (1976). Disease risks of occupational exposure to sewage. J. Enr~iron. Eng. Div. (Amer-. SW. Cir. Eng, 1 102, 375-388. Clark. C. S.. Schiff. G. M.. Linnemann, C. C.. VanMeer, G. L.. Bjornson. A. B.. Gartside, P. S.. Buncher. C. R.. Phair, J. P., and Cleary, E. J. (1978). A seroepidemiologic study of workers engaged in wastewater collection and treatment. In “State of Knowledge in Land Treatment of Wastewater.” Vol. 2. U.S. Army Corps of Engineers. Hanover. N.H. Clark, C. S.. Van Meer, G. L., Linnemann, C. C., Jr., Bjornson. A. B.. Gartside. P. S., Schiff. G. M.. Trimble. S. E., Alexander, D., and Cleary, E. J. (1980). Health effects of occupational exposure to wastewater. In “Wastewater Aerosols and Disease: Proceedings of a Symposium Held at Cincinnati. Ohio. September 19-21. 1979“ tH. R. Pdhren and W. Jakubowski. Eds.). EPA-600;

358

DORN ET AL.

9-80-028, pp. 239-264. Health Effects Research Laboratory, U.S. Environmental Protection Agency, Cincinnati. Doby, J. M., Duval, J. M., and Beaucoumu, J. C. (1980). Amibiase maladie professionnelle des egoutiers. Nouv. Presse Med. 9, 532-533. Epstein, E., and Chaney, R. L. (1978). Land disposal of toxic substances and water-related problems. J. Water Polk. Control Fed. 50, 2037-2042. Fannin, K. F., Cochran, K. W.. Lamphiear, D. E., and Monto, A. S. (1980). Acute illness differences with regard to distance from the Tecumseh, Michigan, Wastewater Treatment Plant. In “Wastewater Aerosols and Disease: Proceedings of a Symposium Held at Cincinnati, Ohio, September 19-21, 1979” (H. R. Pahren and W. Jakubowski, Eds.), EPA-60019-80-028, pp. 117-135. Health Effects Research Laboratory, U.S. Environmental Protection Agency, Cincinnati. Fertig, D. L. (1982). “Epidemiologic Investigation of Taenia saginata Cysticercosis in an Ohio Cattle Feeding Operation.” MS. thesis, The Ohio State University, Columbus. Fertig, D. L. and Dom, C. R. (1985). Taenia saginata cysticercosis in an Ohio cattle feeding operation. J. Amer. Vet. Med. Assoc. 186, 1281-1285. Fitzgerald, P. R. (1980). An evaluation of the health of livestock exposed to anaerobically digested sludge from a large community. In “Proceedings, National Conference on Municipal and Industrial Sludge Utilization and Disposal,” Library of Congress Catalog 80-83238. Silver Springs, Md. Galen, G. R. (1980). Federal regulations for municipal sludge: Impact of EPA rules and regulations and land application. In “Proceedings, National Conference on Municipal and Industrial Sludge Utilization and Disposal,” Library of Congress Catalog 80-83238. Silver Spring, Md. Geldreich, E. E., and Bordner, R. H. (1971). Fecal contamination of fruits and vegetables during cultivation and processing for market: A review. J. Milk Food Technol. 34, 184-185. Hammell, D. L., Beaudouin, J.. and Shirley, R. L. (1977). “Effect of Sewage Sludge Diets Fed to Breeding Swine on Reproduction and Tissue Mineral Accumulation,” Research Report SW-19771. Agricultural Res. Center, Live Oak, Fla. Hammerberg, B., Mac Innis, G. A.. and Hyler, T. (1978). Taenia saginata cysticerci in grazing steers in Virginia. J. Amer. Vet. Med. Assoc. 173, 1462-1464. Hanson, L. G., and Hinesly, T. D. (1979). Cadmium from soil amended with sewage sludge: Effects and residues in swine. Environ. Health Perspect. 28, 51-57. Hoadley, A. W., and Goyal, S. M. (1976). Public health implications of the application of wastewaters to land. In “Land Treatment and Disposal of Municipal and Industrial Wastewater” (R. L. Sanks and T. Asano, eds.), pp. 101-132. Ann Arbor Science Pub., Ann Arbor, Mich. Holford, T. R.. White, C., and Kelsey, J. L. (1978). Multivariate analysis for matched case-control studies. Amer. J. Epidemiol. 107, 245-256. Johnson, D. E., Camann, D. E., Kimball, K. T., Prevost, R. J.. and Thomas, R. E. (1980). Health effects from wastewater aerosols at a new activated sludge plant: John Egar Plant. Schaumburg, Ill. In “Wastewater Aerosols and Disease: Proceedings of a Symposium Held at Cincinnati, Ohio. September 19-21, 1979” (H. R. Pahren and W. Jakubowski, Eds.), EPA-600/9-80-028, pp. 136159. Health Effects Research Laboratory, U.S. Environmental Protection Agency, Cincinnati. Jones, P. W., Rennison, L. M., Matthews, P. R. J., Collins, P., and Brown, A. (1981). The occurrence and significance to animal health of Leptospira, Mycobacterium, Escherichia coli, Brucella abortus and Bacillus anthracis in sewage and sewage sludges. J. Hyg. 86, 129-137. Jones, W. P. (1980). Disease hazards associated with slurry disposal. Brit. Vet. J. 136, 529-542. Kienholz, E., Ward, G. M., Johnson, D. E., and Baxter, J. C. (1977). Health considerations relating to ingestion of sludge by farm animals. In “Proceedings, Third National Conference on Sludge Management Disposal and Utilization, Miami Beach, Fla.. Dec. 14-16, 1976,” pp. 128-134. Information Transfer Inc., Rockville, Md. Kienholz, E. W., Ward, G. M., Johnson, D. E., Baxter, J., Braude, G.. and Stern, G. (1979). Metropolitan sewage sludge fed to feedlot steers. J. Anim. Sci. 48, 735-741. Kleinbaum, D. G., Kupper, L. L., and Morgenstern, H. (1982). “Epidemiologic Research: Principles and Quantitative Methods.” Lifetime Learning Pub., Belmont, Calif. Kowal, N. E., and Pahren, H. R. (1980). Health effects associated with wastewater treatment and disposal. J. Water Poll&. Control Fed. 52, 1312-1325. Macpherson, R., Mitchell, G. B. B., and McCance, C. B. (1978). Bovine cysticercosis storm following the application of human slurry. Vet. Rec. 101, 156-157.

SLUDGE

SPREADING-HEALTH

EFFECTS

359

Miller, R. H., White, R. K.. Logan, T. J., Forster. D. L., and Stitzlein, J. N. (1979). “Ohio Guide for Land Application of Sewage Sludge,” Bulletin 598 (revised). Cooperative Extension Service. The Ohio State University, Columbus. Northrup, R., Carnow, B., Wadden, R., Rosenberg, S., Neal, A., Sheaff, L., Holden. J.. Meyer, S.. and Scheff, P. (1980). Health effects of aerosols emitted from an activated sludge plant. In “Wastewater Aerosols and Disease: Proceedings of a Symposium Held at Cincinnati, Ohio, September 19-21. 1979” (H. R. Pahren and W. Jakubowski, Eds.), EPA-60019-80-028. pp. 180-227. Health Effects Research Laboratory, U.S. Environmental Protection Agency, Cincinnati. Pahren. H. R.. Lucas, J. B., Ryan, J. A., and Dotson. G. K. (1979). Health risks associated with land application of municipal sludge. J. Water Polhf. Control Fed. 51, 2588-2601. Reddy, C. S., Dorn, C. R.. Lamphere. D. N., and Powers, J. D. (1985). Municipal sewage sludge application on Ohio farms: Tissue metal residues and infections. Environ. Res. 38, 360-376. Reddy, C. S., and Dorn, C. R. (1985). Municipal sewage sludge application on Ohio farms: Estimation of cadmium intake. Environ. Res. 38, 377-388. Rickard, M. D., and Adolph, A. J. (1977). The prevalence of cysticerci of 7’uenia suginafu in cattle research on sewage-irrigated pasture. Med. 1. Ausr. 1, 525-527. Rothman, K. J., and Boice. J. D., Jr. (1979). “Epidemiologic Analysis with a Programmable Calculator,” N.I.H. Pub. 79-1649, U.S. Dept. Health, Education and Welfare. Sepp, E. (1971). “The Use of Sewage for Irrigation: A Literature Review,” revised ed. Bureau ot Sanitary Engineering, Dept. of Public Health, State of California. Shink, J. P., Hollinser, F. B., Hovind-Housen, K., and Lous, P. (1981). Infectious liver diseases in three groups of Copenhagen workers: Correlation of hepatitis A infection to sewage exposure. Arch. Environ. Heulth 36, 139- 143. Shuval, H. I.. and Fattal. B. (1980). Epidemiological study of wastewater irrigation in kibbutzim in Israel. In “Wastewater Aerosols and Disease: Proceedings of a Symposium Held at Cincinnati. Ohio. September 19-21, 1979” (H. R. Pahren and W. Jakubowski. Eds.). EPA-60019-80-02X. Health Effects Research Laboratory, U.S. Environmental Protection Agency, Cincinnati. Shuvai, H. L.. Fattal. B.. and Wax. Y. (1983). “Retrospective Epidemiological Study of Disease Associated with Wastewater Utilization,” Draft Final Report, Grant 805174. U.S. Environmental Protection Agency, Cincinnati. Smith, G. S., Kiesling. H. E.. Cadle, J. M.. Staples, C.. and Bruce. L. B. (1977). Recycling sewage solids as feedstuffs for livestock. “Proceedings, Third National Conference on Sludge Management Disposal and Utilization. Miami Beach, Fla.. Dec. 14-16. 1976.” pp. 119-127. Information Transfer Inc. Rockville, Md. Taylor, R. J. (1973). A further assessment of the potential hazard for calves allowed to graze pasture contaminated with Su/tnone//u duhh in slurry. Brit. Vet. /. 129, 354-358. Taylor, T. J.. and Burrows, M. R. (1971). The survival of Esclrerichiu co/i und Sultnonellu dub/in in slurry in pasture and the infectivity of S. dub/in for grazing calves. Brir. Vet. J. 127, 536-543. U.S. Environmental Protection Agency (1979). Criteria for classification of solid waste disposal facilities and practices: Final. interim final, and proposed regulations. Fed. Regist. 44( 179). 53,43853,468. World Health Organization (1981). “The Risk to Health of Microbes in Sewage Sludge Applied to Land: Report on a WHO Working Group, Stevenage, 6-9 January 1981.” EURO Reports and Studies 54. World Health Organization, Copenhagen.