Reported health conditions in animals residing near natural gas wells in southwestern Pennsylvania.

Natural gas extraction activities, including the use of horizontal drilling and hydraulic fracturing, may pose potential health risks to both human and animal populations in close proximity to sites of extraction activity. Because animals may have increased exposure to contaminated water and air as well as increased susceptibility to contaminant exposures compared to nearby humans, animal disease events in communities living near natural gas extraction may provide "sentinel" information useful for human health risk assessment. Community health evaluations as well as health impact assessments (HIAs) of natural gas exploration should therefore consider the inclusion of animal health metrics in their assessment process. We report on a community environmental health survey conducted in an area of active natural gas drilling, which included the collection of health data on 2452 companion and backyard animals residing in 157 randomly-selected households of Washington County, Pennsylvania (USA). There were a total of 127 reported health conditions, most commonly among dogs. When reports from all animals were considered, there were no significant associations between reported health condition and household proximity to natural gas wells. When dogs were analyzed separately, we found an elevated risk of 'any' reported health condition in households less than 1km from the nearest gas well (OR = 3.2, 95% CI 1.07-9.7), with dermal conditions being the most common of canine disorders. While these results should be considered hypothesis generating and preliminary, they suggest value in ongoing assessments of pet dogs as well as other animals to better elucidate the health impacts of natural gas extraction on nearby communities.

Maternal exposure to water disinfection by-products during gestation and risk of hypospadias.

BACKGROUND: The use of chlorine for water disinfection results in the formation of numerous contaminants called disinfection by-products (DBPs), which may be associated with birth defects, including urinary tract defects. METHODS: We used Arkansas birth records (1998-2002) to conduct a population-based case-control study investigating the relationship between hypospadias and two classes of DBPs, trihalomethanes (THM) and haloacetic acids (HAA). We utilised monitoring data, spline regression and geographical information systems (GIS) to link daily concentrations of these DBPs from 263 water utilities to 320 cases and 614 controls. We calculated ORs for hypospadias and exposure to DBPs between 6 and 16 weeks' gestation, and conducted subset analyses for exposure from ingestion, and metrics incorporating consumption, showering and bathing. RESULTS: We found no increase in risk when women in the highest tertiles of exposure were compared to those in the lowest for any DBP. When ingestion alone was used to assess exposure among a subset of 40 cases and 243 controls, the intermediate tertiles of exposure to total THM and the five most common HAA had ORs of 2.11 (95% CI 0.89 to 5.00) and 2.45 (95% CI 1.06 to 5.67), respectively, compared to women with no exposure. When exposure to total THM from consumption, showering and bathing exposures was evaluated, we found an OR of 1.96 (95% CI 0.65 to 6.42) for the highest tertile of exposure and weak evidence of a dose-response relationship. CONCLUSIONS: Our results provide little evidence for a positive relationship between DBP exposure during gestation and an increased risk of hypospadias but emphasise the necessity of including individual-level data when assessing exposure to DBPs.

Identifying public water facilities with low spatial variability of disinfection by-products for epidemiological investigations.

BACKGROUND AND AIMS: Epidemiological studies of disinfection by-products (DBPs) and reproductive outcomes have been hampered by misclassification of exposure. In most epidemiological studies conducted to date, all persons living within the boundaries of a water distribution system have been assigned a common exposure value based on facility-wide averages of trihalomethane (THM) concentrations. Since THMs do not develop uniformly throughout a distribution system, assignment of facility-wide averages may be inappropriate. One approach to mitigate this potential for misclassification is to select communities for epidemiological investigations that are served by distribution systems with consistently low spatial variability of THMs. METHODS AND RESULTS: A feasibility study was conducted to develop methods for community selection using the Information Collection Rule (ICR) database, assembled by the US Environmental Protection Agency. The ICR database contains quarterly DBP concentrations collected between 1997 and 1998 from the distribution systems of 198 public water facilities with minimum service populations of 100,000 persons. Facilities with low spatial variation of THMs were identified using two methods; 33 facilities were found with low spatial variability based on one or both methods. Because brominated THMs may be important predictors of risk for adverse reproductive outcomes, sites were categorised into three exposure profiles according to proportion of brominated THM species and average TTHM concentration. The correlation between THMs and haloacetic acids (HAAs) in these facilities was evaluated to see whether selection by total trihalomethanes (TTHMs) corresponds to low spatial variability for HAAs. TTHMs were only moderately correlated with HAAs (r = 0.623). CONCLUSIONS: Results provide a simple method for a priori selection of sites with low spatial variability from state or national public water facility datasets as a means to reduce exposure misclassification in epidemiological studies of DBPs.

Canine exposure to herbicide-treated lawns and urinary excretion of 2,4-dichlorophenoxyacetic acid.

A recent study by Hayes et al. (J. Natl. Cancer. Inst., 83: 1226-1231, 1991) found an increased risk of malignant lymphoma associated with exposure to 2,4-dichlorophenoxyacetic acid (2,4-D) in pet dogs. We conducted a study to determine the extent to which dogs absorb and excrete 2,4-D in urine after contact with treated lawns under natural conditions. Among 44 dogs potentially exposed to 2,4-D-treated lawns an average of 10.9 days after application, 2,4-D concentrations greater than or equal to 10.0 micrograms/l were found in 33 dogs (75%) and concentrations of > or = 50 micrograms/l were found in 17 (39%). Among 15 dogs with no known exposure to a 2,4-D-treated lawn in the previous 42 days, 4 (27%) had evidence of 2,4-D in urine, 1 at a concentration of > or = 50 micrograms/l. The odds ratio for the association between exposure to a 2,4-D-treated lawn and the detection of > or = 50 micrograms/l 2,4-D in urine was 8.8 (95% confidence interval, 1.4-56.2). Dogs exposed to lawns treated within 7 days before urine collection were more than 50 times as likely to have 2,4-D at concentrations > or = 50 micrograms/l than dogs with exposure to a lawn treated more than 1 week previously (odds ratio = 56.0; 95% confidence interval, 10.0-312.2). The highest mean concentration of 2,4-D in urine (21.3 mg/l) was found in dogs sampled within 2 days after application of the herbicide.(ABSTRACT TRUNCATED AT 250 WORDS)

Reproductive and developmental effects of disinfection by-products in drinking water.

Recent epidemiologic studies have reported associations between the consumption of chlorinated drinking water and reproductive and developmental effects. Here we review the available epidemiologic data, assess the hazard potential posed by exposure to disinfection by-products, identify critical data gaps, and offer recommendations for further research. The epidemiologic evidence supporting associations between exposure to water disinfection by-products (DBPs) and adverse pregnancy outcomes is sparse, and positive findings should be interpreted cautiously. The methods used during the early stages of research in this area have been diverse. Variability in exposure assessment and endpoints makes it difficult to synthesize or combine the available data. Exposure misclassification and unmeasured confounding may have lead to bias in risk estimation. Future studies of reproductive outcome and exposure to chlorinated water should use improved methods for exposure assessment to 1) assure selection of appropriate exposure markers, 2) assess seasonal and annual fluctuations in DBPs, 3) assess variability within the distribution system, and 4) assess exposure through multiple routes such as bathing and showering, as well as consumption. Population-based studies should be conducted to evaluate male and female fertility, conception delay, growth retardation, and specific birth defects. The reproductive and developmental effects of exposure to DBPs could be efficiently explored in ongoing investigations by incorporating valid exposure markers and relevant questionnaire information. Future studies should make use of naturally occurring variability in the concentrations of DBPs and may incorporate biomarkers of exposure and effect in their design. Epidemiologic investigations should be conducted in parallel with laboratory-based and animal studies in a coordinated, multidisciplinary approach.

Animals as sentinels of human health hazards of environmental chemicals.

A workshop titled "Using Sentinel Species Data to Address the Potential Human Health Effects of Chemicals in the Environment," sponsored by the U.S. Army Center for Environmental Health Research, the National Center for Environmental Assessment of the EPA, and the Agency for Toxic Substances and Disease Registry, was held to consider the use of sentinel and surrogate animal species data for evaluating the potential human health effects of chemicals in the environment. The workshop took a broad view of the sentinel species concept, and included mammalian and nonmammalian species, companion animals, food animals, fish, amphibians, and other wildlife. Sentinel species data included observations of wild animals in field situations as well as experimental animal data. Workshop participants identified potential applications for sentinel species data derived from monitoring programs or serendipitous observations and explored the potential use of such information in human health hazard and risk assessments and for evaluating causes or mechanisms of effect. Although it is unlikely that sentinel species data will be used as the sole determinative factor in evaluating human health concerns, such data can be useful as for additional weight of evidence in a risk assessment, for providing early warning of situations requiring further study, or for monitoring the course of remedial activities. Attention was given to the factors impeding the application of sentinel species approaches and their acceptance in the scientific and regulatory communities. Workshop participants identified a number of critical research needs and opportunities for interagency collaboration that could help advance the use of sentinel species approaches.

A cancer registry-based study of occupational risk for lymphoma, multiple myeloma and leukaemia.

Mortality and incidence studies have suggested that agricultural workers may be at increased risk for some cancers. Case-control methods were used to investigate the relationship between farming, other occupations, and lymphoma, multiple myeloma, and leukaemia. A total of 475 male cases, aged 20 years or more, and 1425 age-matched controls were identified through the Missouri Cancer Registry for the years 1984-1985. People with smoking-related cancers were excluded as controls to minimize bias associated with farmers' reported smoking patterns. Farmers had slightly elevated risks for non-Hodgkin's lymphoma (odds ratio (OR) = 1.11) and Hodgkin's disease (OR = 1.30). The risk for leukaemia (all types) was not elevated (OR = 0.91); however, for acute lymphatic leukaemia an OR of 2.84 was detected. An OR of 2.78 (95% confidence interval = 1.09-7.07) for reticulosarcoma was observed among farmers 65 years and older. Several other occupational associations were noted which have been reported previously. Carpenters (OR = 3.10) and machinists (OR = 4.85) were at increased risk for Hodgkin's disease. An elevated risk of leukaemia was observed for mechanics (OR = 4.79). Since most previous studies of the associations between lymphatic and haematopoietic cancers and agriculture have been based on mortality data, additional studies of incident cases are suggested.

Epizootic vesicular stomatitis in Colorado, 1982: infection in occupational risk groups.

In 1982-1983, an epizootic of vesicular stomatitis occurred in the western United States. Veterinarians, research workers, and regulatory personnel who were exposed to vesicular stomatitis virus were examined for patterns of human infection and prevalence of vesicular stomatitis New Jersey serotype neutralizing antibody. Insight into the mechanism of transmission was sought by comparing activities of antibody-positive and antibody-negative persons. A statistically significant risk factor was a history of infected animals sneezing in the face of serosurvey participants. Elevated odds ratios were also calculated for those who usually examined the oral cavity of affected animals, had open wounds on hands or arms, and had exposure to saliva through the eye or skin. Relatively intimate direct contact was required; a higher risk was associated with examining horses than cattle. Neutralizing antibody prevalence was significantly higher among exposed persons with illness (23%) than in exposed persons without a history of clinical illness (7%). Overall, however, infectivity of VSNJ for humans during the epizootic was low.

Epizootic vesicular stomatitis in Colorado, 1982: epidemiologic studies along the northern Colorado front range.

Epidemiologic evaluations were made of farm personnel on vesicular stomatitis-affected premises along the front range of the Rocky Mountains in Colorado during the 1982 epizootic. A similar antibody prevalence was noted to that of veterinarians and research and regulatory personnel who were involved with the same epizootic. Risk of infection resulted from intimate physical contact with infected horses or cows. Incidence and infection rates in horses were 45%; rates in cows were much lower, only 5%. Some epidemiologic clues were gained by a detailed study of an equine ranch. The pasture was incriminated as the area of highest risk, where 100% infection rates were noted. Horses in open pens and barns were at lower risk. Severe clinical disease in horses resulted in higher neutralizing antibody titers than inapparent or mild infection. Maternal antibody was detected in foals up to 4 months of age, and the level of antibody in the foal was a reflection of the dam's antibody level.

Geomagnetic disturbances are associated with reduced nocturnal excretion of a melatonin metabolite in humans.

The effects of geomagnetic disturbances on urinary excretion of the melatonin metabolite, 6-hydroxymelatonin sulfate (6-OHMS), were studied in conjunction with 60 Hz magnetic field (MF) and ambient light exposure in 132 electric utility workers. Geomagnetic activity was assessed using a local (equivalent amplitude or A(K), Boulder, CO) and global (average antipodal or aa) index. Personal exposures to 60 Hz MFs and light were obtained using data-logging meters. The relationship between geomagnetic activity and 6-OHMS was assessed with adjustment for age, light exposure, and month of participation. Mean overnight 6-OHMS excretion was lower on days when the 36-h A(K) or aa values exceeded 30 nT. A greater reduction in 6-OHMS excretion was observed when increased geomagnetic activity was combined with elevated 60 Hz MF or reduced ambient light exposures.

Melatonin metabolite excretion among cellular telephone users.

PURPOSE: The relationship between cellular telephone use and excretion of the melatonin metabolite 6-hydroxymelatonin sulfate (6-OHMS) was evaluated in two populations of male electric utility workers (Study 1, n=149; Study 2, n=77). MATERIALS AND METHODS: Participants collected urine samples and recorded cellular telephone use over 3 consecutive workdays. Personal 60-Hz magnetic field (MF) and ambient light exposures were characterized on the same days using EMDEX II meters. A repeated measures analysis was used to assess the effects of cellular telephone use, alone and combined with MF exposures, after adjustment for age, participation month and light exposure. RESULTS: No change in 6-OHMS excretion was observed among those with daily cellular telephone use >25 min in Study 1 (5 worker-days). Study 2 workers with >25 min cellular telephone use per day (13 worker-days) had lower creatinine-adjusted mean nocturnal 6-OHMS concentrations (p=0.05) and overnight 6-OHMS excretion (p=0.03) compared with those without cellular telephone use. There was also a linear trend of decreasing mean nocturnal 6-OHMS/creatinine concentrations (p=0.02) and overnight 6-OHMS excretion (p=0.08) across categories of increasing cellular telephone use. A combined effect of cellular telephone use and occupational 60-Hz MF exposure in reducing 6-OHMS excretion was also observed in Study 2. CONCLUSIONS: Exposure-related reductions in 6-OHMS excretion were observed in Study 2, where daily cellular telephone use of >25 min was more prevalent. Prolonged use of cellular telephones may lead to reduced melatonin production, and elevated 60-Hz MF exposures may potentiate the effect.

Elevated interleukin 6 activity in aqueous humor of cats with uveitis.

The purpose of this study was to assess the role of interleukin 6 (IL-6) in feline uveitis by measuring IL-6 activity in the serum and aqueous humor of cats. Serum and aqueous humor was collected from clinically normal, random source cats (n = 10); clinically normal, specific-pathogen free cats experimentally inoculated with Toxoplasma gondii strain ME49 and sampled sequentially for 20 months (n = 4); and client-owned cats with uveitis (n = 27). Interleukin 6 activity was measured in each sample. Client-owned cats with uveitis were also evaluated for evidence of present or prior exposure to T. gondii, feline leukemia virus, feline immunodeficiency virus, and feline coronaviruses. Interleukin 6 activity was non-detectable or low in serum from cats of each group. Interleukin 6 activity was not detected in aqueous humor of clinically normal cats. Interleukin 6 activity was detected in 22/27 (81.5%) aqueous humor samples from cats with uveitis, with a range of 28.9 U ml(-1)-15702.9 U ml(-1) (mean = 1911.9 U ml[-1], SD = 3946.7 U ml[-1]). Serologic evidence of exposure to T gondii, feline immunodeficiency virus, feline leukemia virus, or a coronavirus was present in 21/27 (77.8%) cats with uveitis. Interleukin 6 was detected in the aqueous humor of 18/21 (85.7%) and 3/6 (50%) of the cats with and without serologic evidence of exposure to one to the infectious diseases, respectively. Statistically significant increases in mean IL-6 activity in aqueous humor were found for cats with any evidence of infection with T. gondii, for cats with T. gondii antigen in aqueous humor and for cats with coronavirus antibody titers > or = 1:100. Aqueous humor IL-6 activity was greater than corresponding serum IL-6 activity in 21/27 cats. These results show that IL-6 is produced intraocularly in some cats with uveitis and that IL-6 may be a mediator of uveitis in cats.

Exposure to tap water during pregnancy.

Studies of disinfection byproducts (DBPs) in drinking water and risk of adverse reproductive outcome have usually relied on approximate measures of exposure. Individual differences in consumption of bottled or filtered water, variability in tap water consumption at home and at work, dermal and inhalation exposure to volatile contaminants, and changes in residency during pregnancy may lead to exposure misclassification. We characterized exposures to tap water and other risk factors among 71 pregnant and 43 non-pregnant women attending public health clinics. Nearly all residences had a municipal water source, but 25% of women drank filtered or bottled water. Fifty percent of the women in our sample reported working outside the home where, on average, one third of their daily water intake took place. Pregnant women consumed more water than non-pregnant women (3.4 vs. 3.0 total l/day), especially cold tap water at home (1.8 vs. 1.3 l/day, 95% CI for the difference=0.1, 0.9). Patterns of showering were similar for both groups of women, but pregnant women were more likely to bathe and to bathe more frequently. The prevalence of smoking was lower among pregnant women (22.5% vs. 32.6%), as was the consumption of alcohol (4.2% vs. 53.5%, 95% CI for the difference=-64.9, -33.7). Thirty-two percent of women had moved during their current pregnancy. The data reaffirm the importance of collecting individual-level data for water consumption and exposure to potential confounders to avoid misclassification bias. This study is the first to target women of low socio-economic status (SES) and therefore of particular interest in studies of adverse reproductive outcomes for which this group is at increased risk.

Risk factors for exposure to arsenic at a hazardous waste site.

Communities surrounding the Rocky Mountain Arsenal (RMA), a Superfund site in Colorado, were studied in order to determine whether exposures to arsenic were greater among persons who resided there than among residents of a comparison area. A census was conducted in areas adjacent to the RMA and in a comparison area 12-15 miles distant. From a stratified random sample, 469 persons were interviewed and urine samples obtained. Arsenic was detected in urine from 43 (9.2%) of the 469 persons sampled at a detection limit of 10 ppb. Trace levels of arsenic (detectable, but non-quantifiable) were found in 184 (39.2%) of those persons sampled. Neither the frequency of detection, the arithmetic mean nor the geometric mean values for urine arsenic was found to be statistically different when persons living near the site were compared to persons from the more distant comparison area. Therefore, the data were pooled across the study areas to evaluate risk factors for exposure to arsenic in this population-based sample. Multivariate logistic regression analyses were conducted to evaluate the risk of arsenic exposure associated with variables included in the interviews while controlling for confounding. Pathways for exposure to arsenic were evaluated through analysis of residence history, occupation, hobbies, dietary habits, water supply, housing and activity patterns. Children of Hispanic origin or non-white race, children who drank less than three glasses of water daily, and children who spent more time outdoors had an increased risk of having > or = 10 ppb of arsenic in their urine. Among adults, younger persons, especially those less than 40 years of age, persons of Hispanic origin or nonwhite race, and those employed in occupations where arsenic is likely to be found had an increased risk of having > or = 10 ppb of urine arsenic. Consumption of red wine or fish during the week prior to sampling was associated with trace levels of arsenic in urine.

Melatonin metabolite levels in workers exposed to 60-Hz magnetic fields: work in substations and with 3-phase conductors.

Melatonin suppression by 50/60-Hz magnetic fields represents a plausible biological mechanism for explaining increased health risks in workers. Personal exposure to magnetic fields and ambient light, and excretion of the melatonin metabolite 6-hydroxymelatonin sulfate (6-OHMS), were measured over 3 consecutive workdays in electric utility workers. There was a magnetic field-dependent reduction in adjusted mean nocturnal and post-work 6-OHMS levels among men working more than 2 hours per day in substation and 3-phase environments and no effect among those working 2 hours or less. No changes were observed among men working in 1-phase environments. The results suggest that circular or elliptical magnetic field polarization, or another factor linked to substations and 3-phase electricity, is associated with magnetic field induced melatonin suppression in humans.

Cancer risks among New Zealand meat workers.

The study reports a series of case-referent studies based on the New Zealand Cancer Register and involving 19,904 male cancer patients aged 20 years or more at the time of registration during the period 1980-1984. For each cancer site, the registrations for the remaining sites formed the reference group. An increased risk for lung (OR 1.30, 95% CI 1.06-1.58) and laryngeal (OR 2.01, 95% CI 1.19-3.39) cancer was found among meatworkers. It was confined to men aged less than 65 years at registration. The risk for soft-tissue sarcoma was elevated (OR 1.90, 95% CI 0.90-4.02). The risk estimate for all types of leukemia was elevated moderately (OR 1.45, 95% CI 0.90-2.31), but cell type-specific analyses revealed a greater effect for acute myeloid leukemia (OR 2.12, 95% CI 1.09-4.12). This study adds to the evidence that employment as a meatworker is associated with increased risk for several forms of cancer.

Nocturnal excretion of a urinary melatonin metabolite among electric utility workers.

OBJECTIVES: The effects of 60-Hz magnetic field and ambient light exposures on the pineal hormone melatonin were studied among electric utility workers. METHODS: Personal exposure was measured at 15-second intervals over 3 consecutive 24-hour periods. Exposure metrics based on magnetic field intensity, intermittence, or temporal stability were calculated for periods of work, home, and sleep. A rate-of-change metric (RCM) was used to estimate intermittence, and the standardized RCM (RCMS = RCM/standard deviation) was used to evaluate temporal stability. The effects of magnetic field exposure on total overnight 6-hydroxymelatonin sulfate (6-OHMS) excretion and creatinine-adjusted nocturnal 6-OHMS (6-OHMS/cr) concentration were analyzed with adjustment for age, month, and light exposure. RESULTS: Magnetic field intensity, intermittence, or cumulative exposure had little influence on nocturnal 6-OHMS excretion. Residential RCMS magnetic field exposures were associated with lower nocturnal 6-OHMS/cr concentrations. In multivariate statistical analyses, the interaction term for geometric mean and RCMS magnetic field exposures at home was associated with lower nocturnal 6-OHMS/cr and overnight 6-OHMS levels. Modest reductions in the mean 6-OHMS levels occurred after RCMS exposures during work. The greatest reductions occurred when RCMS exposures both at work and at home were combined; therefore the effects of temporally stable magnetic fields may be integrated over a large portion of the day. CONCLUSIONS: Results from this study provide evidence that temporally stable magnetic field exposures are associated with reduced nocturnal 6-OHMS excretion in humans.

Regional seroprevalence of Cryptosporidium parvum-specific IgG of cats in the United States.

The objective of this study was to determine the regional prevalence of Cryptosporidium parvum-specific IgG in the sera of cats in the United States. The continental United States was partitioned into eight regional areas. Serum samples from 75 cats from each region were assayed for C. parvum-specific IgG using an indirect enzyme-linked immunosorbent assay (ELISA). Age, sex, breed, and indoor/outdoor status were examined as possible risk factors for developing a positive C. parvum-specific IgG antibody titer. The presence of gastro-intestinal signs and Toxoplasma gondii-specific IgG in the serum were also evaluated for association with C. parvum seropositivity. Of the 600 samples assayed, 50 (8.3%) were positive for C. parvum-specific IgG. Regional seroprevalence ranged from 1.3% in the mid-Atlantic states to 14.7% in the south-eastern states. The oldest group of cats (>10 years) had the highest seroprevalence (15.3%). The prevalence of C. parvum-specific IgG was higher among male (10.1%) than among female cats (6.9%), although, the difference was not statistically significant (p = 0.17). Seropositivity was not associated with pure-bred status. C. parvum-specific IgG antibodies was detected most frequently in T. gondii-specific IgG seropositive cats, outdoor cats, and cats with gastro-intestinal signs. These results suggest that cats in the United States are commonly exposed to C. parvum.

Opportunities for using Navy marine mammals to explore associations between organochlorine contaminants and unfavorable effects on reproduction.

The Department of Defense (DoD) has a unique marine mammal program maintained by the US Navy that includes the largest force of bottlenose dolphins, Tursiops truncatus, worldwide. In recent years, this population of cetaceans that lives in netted open water enclosures in San Diego Bay has been monitored for levels of organochlorine (OC) contaminants in blubber, blood and milk. Data generated from these studies have afforded insight into the fate and possible effects of OC contaminants in marine mammals. We now report preliminary findings on the effects of maternal OC exposure on pregnancy outcome. Blubber OC levels were compared between females whose calves survived beyond 6 months and females whose calves were stillborn or died within 12 days of birth. The mean concentration of SigmaDDT was more than 3 times as high among dolphins whose calves died as that among dolphins whose calves survived beyond 6 months (P = 0.002). Mean SigmaPCB was more than 2.5 times higher in females whose calves did not survive (P= 0.076). This population is a logical sentinel for the assessment of environmentally mediated disease. Biological tissues and fluids can be sampled on a regular basis from the dolphins for accumulation of tissue residues, facilitated by conditioned husbandry behaviors. These trained behaviors help preclude possible alterations in health measures resulting from capture stress. Animals' diets can be monitored for contaminant levels. With these data, the expertise and facilities available at the Navy laboratory and in collaboration with other experts in the field, controlled studies can be designed to monitor and assess dietary exposure, measurable immune and neurologic responses and assess reproductive and transgenerational effects of contaminants. Biomarkers can be developed to relate the health of individual animals relative to contaminant exposures. Such investigations of natural exposure and response scenarios are a logical adjunct to traditional laboratory toxicity studies.

Effect of feline immunodeficiency virus infection on Toxoplasma gondii-specific humoral and cell-mediated immune responses of cats with serologic evidence of toxoplasmosis.

Serum samples from 89 cats with serologic evidence of toxoplasmosis were identified by using an enzyme-linked immunosorbent assay (ELISA) that detected Toxoplasma gondii-specific immunoglobulin M (IgM) or T. gondii-specific immunoglobulin G (IgG). Concurrent feline immunodeficiency virus (FIV) infection was detected in 36 cats using an ELISA for detection of FIV-specific IgG. The majority of the cats in both the FIV-seropositive and FIV-seronegative groups were male and > 5 years of age. FIV-seropositive cats were more likely to have T. gondii IgM titers without IgG (P < 0.05) or any T. gondii IgM titer (P < 0.05) than were FIV-seronegative cats. FIV-seronegative cats (1328) had a higher T. gondii IgG geometric mean titer than did FIV-seropositive cats (724) and were more likely to have T. gondii IgG titers > 1:2048 than were FIV-seropositive cats (P < 0.05). Cats with serologic evidence of both T. gondii and FIV infections had persistent T. gondii IgM titers for > 12 weeks. Lymphoblast transformation in response to concanavalin A, T. gondii-specific intracellular antigens, and T. gondii-specific secretory antigens was compared in T. gondii seropositive and FIV-seronegative cats, cats with serologic evidence of T. gondii infection alone, and cats with serologic evidence of concurrent FIV and T. gondii infections. Lymphocytes from all but one cat in the FIV-seropositive group responded to concanavalin A. Whereas lymphocytes from FIV-seronegative cats with serologic evidence of toxoplasmosis responded to T. gondii-specific antigens, four of five of the FIV-seropositive cats with concurrent serologic evidence of toxoplasmosis did not.