Estimation of Contaminant Loads from the Sacramento-San Joaquin River Delta to San Francisco Bay.

Contaminant concentrations from the Sacramento-San Joaquin River watershed were determined in water samples mainly during flood flows in an ongoing effort to describe contaminant loads entering San Francisco Bay, CA, USA. Calculated PCB and total mercury loads during the 6-year observation period ranged between 3.9 and 19 kg/yr and 61 and 410 kg/yr, respectively. Long-term average PCB loads were estimated at 7.7 kg/yr and total mercury loads were estimated at 200 kg/yr. Also monitored were PAHs, PBDEs (two years of data), and dioxins/furans (one year of data) with average loads of 392, 11, and 0.15/0.014 (OCDD/OCDF) kg/yr, respectively. Organochlorine pesticide loads were estimated at 9.9 kg/yr (DDT), 1.6 kg/yr (chlordane), and 2.2 kg/yr (dieldrin). Selenium loads were estimated at 16 300 kg/yr. With the exception of selenium, all average contaminant loads described in the present study were close to or below regulatory load allocations established for North San Francisco Bay.

Reducing methylmercury accumulation in the food webs of San Francisco Bay and its local watersheds.

San Francisco Bay (California, USA) and its local watersheds present an interesting case study in estuarine mercury (Hg) contamination. This review focuses on the most promising avenues for attempting to reduce methylmercury (MeHg) contamination in Bay Area aquatic food webs and identifying the scientific information that is most urgently needed to support these efforts. Concern for human exposure to MeHg in the region has led to advisories for consumption of sport fish. Striped bass from the Bay have the highest average Hg concentration measured for this species in USA estuaries, and this degree of contamination has been constant for the past 40 years. Similarly, largemouth bass in some Bay Area reservoirs have some of the highest Hg concentrations observed in the entire US. Bay Area wildlife, particularly birds, face potential impacts to reproduction based on Hg concentrations in the tissues of several Bay species. Source control of Hg is one of the primary possible approaches for reducing MeHg accumulation in Bay Area aquatic food webs. Recent findings (particularly Hg isotope measurements) indicate that the decades-long residence time of particle-associated Hg in the Bay is sufficient to allow significant conversion of even the insoluble forms of Hg into MeHg. Past inputs have been thoroughly mixed throughout this shallow and dynamic estuary. The large pool of Hg already present in the ecosystem dominates the fraction converted to MeHg and accumulating in the food web. Consequently, decreasing external Hg inputs can be expected to reduce MeHg in the food web, but it will likely take many decades to centuries before those reductions are achieved. Extensive efforts to reduce loads from the largest Hg mining source (the historic New Almaden mining district) are underway. Hg is spread widely across the urban landscape, but there are a number of key sources, source areas, and pathways that provide opportunities to capture larger quantities of Hg and reduce loads from urban runoff. Atmospheric deposition is a lower priority for source control in the Bay Area due to a combination of a lack of major local sources. Internal net production of MeHg is the dominant source of MeHg that enters the food web. Controlling internal net production is the second primary management approach, and has the potential to reduce food web MeHg in some habitats more effectively and within a much shorter time-frame. Controlling net MeHg production and accumulation in the food web of upstream reservoirs and ponds is very promising due to the many features of these ecosystems that can be manipulated. The most feasible control options in tidal marshes relate to the design of flow patterns and subhabitats in restoration projects. Options for controlling MeHg production in open Bay habitat are limited due primarily to the highly dispersed distribution of Hg throughout the ecosystem. Other changes in these habitats may also have a large influence on food web MeHg, including temperature changes due to global warming, sea level rise, food web alterations due to introduced species and other causes, and changes in sediment supply. Other options for reducing or mitigating exposure and risk include controlling bioaccumulation, cleanup of contaminated sites, and reducing other factors (e.g., habitat availability) that limit at-risk wildlife populations.

Polychlorinated biphenyls (PCBs) in San Francisco Bay.

San Francisco Bay is facing a legacy of polychlorinated biphenyls (PCBs) spread widely across the land surface of the watershed, mixed deep into the sediment of the Bay, and contaminating the Bay food web to a degree that poses health risks to humans and wildlife. In response to this persistent problem, water quality managers are establishing a PCB total maximum daily load (TMDL) and implementation plan to accelerate the recovery of the Bay from decades of PCB contamination. This article provides a review of progress made over the past 15 years in managing PCBs and understanding their sources, pathways, fate, and effects in the Bay, and highlights remaining information needs that should be addressed in the next 10 years. The phaseout of PCBs during the 1970s and the 1979 federal ban on sale and production led to gradual declines from the 1970s to the present. However, 25 years after the ban, PCB concentrations in some Bay sport fish today are still more than ten times higher than the threshold of concern for human health. Without further management action it appears that the general recovery of the Bay from PCB contamination will take many more decades. PCB concentrations in sport fish were, along with mercury, a primary cause of a consumption advisory for the Bay and the consequent classification of the Bay as an impaired water body. Several sources of information indicate that PCB concentrations in the Bay may also be high enough to adversely affect wildlife, including rare and endangered species. The greater than 90% reduction in food web contamination needed to meet the targets for protection of human health would likely also generally eliminate risks to wildlife. PCB contamination in the Bay is primarily associated with industrial areas along the shoreline and in local watersheds. Strong spatial gradients in PCB concentrations persist decades after the release of these chemicals to Bay Area waterways. Through the TMDL process, attention is being more sharply focused on the PCB sources that are controllable and contributing most to PCB impairment in the Bay. Urban runoff from local watersheds is a particularly significant pathway for PCB entry into the Bay. Significant loads also enter the Bay through Delta outflow (riverine input). Recent studies have shown that erosion of buried sediment is occurring in large regions of the Bay, posing a significant problem with respect to recovery of the Bay from PCB contamination because the sediments being eroded and remobilized are from relatively contaminated buried sediment deposits. In-Bay contaminated sites are likely also a major contributor of PCBs to the Bay food web. Dredged material disposal, wastewater effluent, and atmospheric deposition are relatively minor pathways for PCB loading to the Bay. Priority information needs at present relate to understanding the sources, magnitude of loads, and effectiveness of management options for urban runoff; the regional influence of in-Bay contaminated sites; remobilization of PCBs from buried sediment; historic and present trends; in situ degradation rates of PCBs; reliable recovery forecasts under different management scenarios; the spatial distribution of PCBs in soils and sediments; and the biological effects of PCBs in interaction with other stressors. The slow release of pollutants from the watershed and the slow response of the Bay to changes in inputs combine to make this ecosystem very slow to recover from pollution of the watershed. The history of PCB contamination in the Bay underscores the importance of preventing persistent, particle-associated pollutants from entering this sensitive ecosystem.

The relationship of clinic experience with advanced HIV and survival of women with AIDS.

OBJECTIVE: Hospital and physician experience have been linked to improved outcomes for persons with HIV. Because many HIV-infected patients receive care in clinics, we studied clinic HIV experience and survival for women with AIDS. DESIGN: Retrospective cohort study of women with AIDS whose dominant sources of care were clinics. Clinic HIV experience was estimated as the cumulative number of Medicaid enrollees with advanced HIV who used a particular clinic as their dominant provider up to the year of the patient's AIDS diagnosis: low experience (< 20 patients), medium (20-99 patients), high (> or = 100 patients). Proportional hazards models examined relationships between experience and survival. SETTING: A total of 117 New York State clinics. PATIENTS: A total of 887 New York State Medicaid-enrolled women diagnosed with AIDS in 1989-1992. MAIN OUTCOME MEASURE: Survival after AIDS diagnosis. RESULTS: In later study years (1991-1992), patients in high experience clinics had an approximately 50% reduction in the relative hazard of death (0.53; 95% confidence interval, 0.35-0.82) compared with patients in low experience clinics. Adjusting for demographic and clinical variables, 71% of patients in high experience clinics were alive 21 months after diagnosis compared with 53% in low experience clinics. Experience and survival were not significantly associated in the early study years (1989-1990). CONCLUSIONS: In more recent years, women with AIDS receiving care in high experience clinics survived longer after AIDS diagnosis than those in low experience clinics, providing further evidence of a relationship between provider HIV experience and outcomes.

Two-part survival models applied to administrative data for determining rate of and predictors for maternal-child transmission of HIV.

In analysing maternal-child HIV transmission from Medicaid claims data, we must deal with follow-up that is sometimes so short that we cannot claim that an apparently uninfected infant is actually uninfected as opposed to not yet exhibiting HIV-associated symptoms. To overcome this, we have been using analyses of 'time-to-diagnosis' of HIV infection to estimate transmission rates and predictors of transmission. Such analyses mix the event of transmission with that of our ability to diagnose HIV infection from coded claims data. We would like to separate these two pieces. Also, due to incomplete follow-up, Kaplan-Meier analyses will underestimate transmission rates. In econometrics and biostatistics there are two-part (mixture) models that can serve the goal of separating transmission from the process of diagnosing HIV infection in the newborn. Farewell describes a model that combines a logistic regression for the yes/no event (in our case, HIV transmission) and a Weibull regression model for the survival analysis portion (in our case, time-to-diagnosis). We use this approach to fit models that have potentially separate covariates for transmission and for time-to-diagnosis. The results allow us to identify predictors of transmission and estimate transmission rates with reduced concern for adequacy of follow-up.

Prenatal care and birth outcomes of a cohort of HIV-infected women.

Adequate prenatal care has been linked to improved birth outcomes in general populations but has not been assessed in HIV-infected women. We examined longitudinal claims files and vital statistics records for women in the New York State Medicaid HIV/AIDS data base delivering a singleton from 1985 through 1990. Adequacy of the self-reported number of prenatal visits was assessed by the Kessner index. In logistics models, we estimated the association of prenatal care, illicit drug use, and other maternal characteristics with three outcomes; low birth weight, preterm birth, and small-for-gestational-age. Of 2,254 singletons delivered by this HIV-infected cohort, 28% were low birth weight, 23% were preterm birth, and 20% were small for gestational age. Two-thirds had inadequate prenatal care. Non-drug users had 57 and 26% lower adjusted odds of low birth weight and preterm delivery than drug users. The adjusted odds of low birth weight and preterm birth for women with an adequate number of prenatal visits were, respectively, 48 and 21% lower than for women with inadequate care. Adequate prenatal care was also associated with a 43% reduction in the odds of small-for-gestational-age. An adequate number of prenatal visits by women in this HIV cohort was associated with a significant reduction in all three adverse birth outcomes, but most had inadequate prenatal care. These data support strengthening efforts to bring pregnant, HIV-infected women into care.

Health care of children and adults with acquired immunodeficiency syndrome. A population-based analysis.

OBJECTIVES: To compare the use of medical services by pediatric and adult patients with acquired immunodeficiency syndrome (AIDS) in the 6 months before and after the diagnosis of AIDS when demand for care is often high and to study the influence of human immunodeficiency virus specialty care on survival of pediatric patients. DESIGN: Retrospective analysis of Medicaid files. SETTING: New York State Medicaid Program. PATIENTS: A cohort identified as having AIDS from 1985 through 1990 and enrolled on Medicaid from birth or 1 year or more before diagnosis. Because of differing prognoses, 3 groups were studied by age at the time that AIDS was diagnosed: infants younger than 6 months, children aged 6 months to 12 years, and adults aged 13 to 60 years. MAIN OUTCOME MEASURES: Frequencies of any service use and, among users, monthly rates of services. From Cox proportional hazards models, the adjusted hazard of death for human immunodeficiency virus specialty ambulatory care. RESULTS: Nearly all infants (n = 122) were hospitalized before and after the diagnosis of AIDS was made--the most of all groups. After diagnosis, only 81% of older children (n = 612) were hospitalized vs 93% of infants and 90% of adults (n = 5602). Hospitalized children had a median of only 3.3 inpatient days per month vs 12.3 and 7.8 inpatient days for infants and adults, respectively. Of older children, 45% used the emergency department vs 33% of adults. Human immunodeficiency virus specialty care for infants and children was associated with a 40% lower risk of death after the diagnosis of AIDS. CONCLUSIONS: In this AIDS cohort, infants had the greatest use of inpatient care, and older children used the emergency department more than adults. The finding of improved survival for infants and children with human immunodeficiency virus specialty care warrants further study in more recent years.

Serum immunoreactive-leptin concentrations in normal-weight and obese humans.

BACKGROUND: Leptin, the product of the ob gene, is a hormone secreted by adipocytes. Animals with mutations in the ob gene are obese and lose weight when given leptin, but little is known about the physiologic actions of leptin in humans. METHODS: Using a newly developed radioimmunoassay, wer measured serum concentrations of leptin in 136 normal-weight subjects and 139 obese subjects (body-mass index, > or = 27.3 for men and > or = 27.8 for women; the body-mass index was defined as the weight in kilograms divided by the square of the height in meters). The measurements were repeated in seven obese subjects after weight loss and during maintenance of the lower weight. The ob messenger RNA (mRNA) content of adipocytes was determined in 27 normal-weight and 27 obese subjects. RESULTS: The mean (+/- SD) serum leptin concentrations were 31.3 +/- 24.1 ng per milliliter in the obese subjects and 7.5 +/- 9.3 ng per milliliter in the normal-weight subjects (P < 0.001). There was a strong positive correlation between serum leptin concentrations and the percentage of body fat (r = 0.85, P < 0.001). The ob mRNA content of adipocytes was about twice as high in the obese subjects as in the normal-weight subjects (P < 0.001) and was correlated with the percentage of body fat (r = 0.68, P < 0.001) in the 54 subjects in whom it was measured. In the seven obese subjects studied after weight loss, both serum leptin concentrations and ob mRNA content of adipocytes declined, but these measures increased again during the maintenance of the lower weight. CONCLUSIONS: Serum leptin concentrations are correlated with the percentage of body fat, suggesting that most obese persons are insensitive to endogenous leptin production.

Selected nutritional and quality analyses of tomatillos (Physalis ixocarpa).

Proximate composition, total dietary fiber and pH of tomatillos (Physalis ixocarpa) grown in Baja, California were analyzed. Moisture content averaged 92%. On a dry matter basis (DMB), tomatillos contained 11% protein, 18% fat, 13% ash and 5% total dietary fiber. On an as consumed basis (ACB), tomatillos contained 1% protein, 1.5% fat, 1% ash and 0.4% dietary fiber. Carbohydrate (CHO) content was calculated by difference resulting in an average adjusted CHO (excluding dietary fiber) of 53% on a DMB and 4% on an ACB; total CHO (including dietary fiber) was 58 and 4.8%, respectively. Average kcalorie content was calculated to be about 31 kcals/100 g. The average pH of tomatillos was 3.76.

A population-based comparison of the clinical course of children and adults with AIDS.

OBJECTIVE: To examine the association of clinical complications and age at diagnosis with survival for a cohort of children and adults with AIDS. DESIGN: A population-based analysis of 734 children and 5584 adults diagnosed with AIDS from 1985 to 1990 in New York State. RESULTS: The initial AIDS-defining diagnoses for 68% of children were lymphoid interstitial pneumonitis or infections specified in the Centers for Disease Control and Prevention's (CDC) pediatric AIDS case definition but not the CDC's 1987 adult AIDS case definition. Of opportunistic infections in both case definitions, Pneumocystis carinii pneumonia (PCP) was the most common initial AIDS diagnosis, occurring in 53% of adults, 47% of children aged < 6 months at diagnosis (n = 122) and 14% aged > or = 6 months at diagnosis (n = 612). Median survival after AIDS diagnosis was 62 months for all children compared with 11 months for adults. For children initially diagnosed with conditions only in the pediatric case definition, median survival ranged from 27 to 62 months compared with less than 12 months for children and adults with PCP. Compared with children aged 6-54 months, the estimated hazards of death for younger and older children were 2.06 [95% confidence interval (CI), 1.48-2.86] and 1.54 (95% CI, 1.10-2.16), respectively. CONCLUSION: Children survived significantly longer than adults after AIDS diagnosis, but their survival varied by age at diagnosis. Differences in the types of common initial AIDS-defining diagnoses appear to contribute to the observed differences in survival.

Health care delivery, zidovudine use, and survival of women and men with AIDS.

The aim of this study was to define predictors of survival for women and men after AIDS diagnosis. We examined health care delivery and drug therapy in the year before AIDS diagnosis for continuously enrolled New York State Medicaid beneficiaries with AIDS in 1988-1990. We examined the association of these factors with survival after AIDS diagnosis. Of 1,077 women and 1,871 men, 60% of both gender groups were drug users. In both risk groups, women had more outpatient visits than men but were equally likely to visit an AIDS specialist. In those who were not drug users, men were twice as likely as women to receive either zidovudine or Pneumocystis carinii pneumonia prophylaxis. No difference appeared among drug users. Survival after AIDS diagnosis was similar by gender for those who were not drug users (RR = 1.09; 95% CI = 0.90-1.33). In drug users, women had a slightly lower risk of death than men (RR = 0.84; 95% CI = 0.72-0.98). Risk of death after AIDS diagnosis was higher for persons starting zidovudine earlier in both risk groups. Among drug users, women received more ambulatory care and survived slightly longer than men. Among those who were not drug users, survival was similar by gender even after adjusting for differences in care.

Risk factors for bronchopulmonary dysplasia after extracorporeal membrane oxygenation.

OBJECTIVE: To determine risk factors for the development of bronchopulmonary dysplasia (BPD) after treatment with extracorporeal membrane oxygenation (ECMO). DESIGN: Retrospective case-control study. SETTING: Tertiary care level 3 neonatal intensive care unit. PARTICIPANTS: Seventy-three newborns treated with ECMO for severe respiratory failure during a 5-year period, who survived until day of life 28, and who did not have pulmonary hypoplasia as the initial cause for respiratory failure. INTERVENTIONS: None. MAIN OUTCOME MEASURE: The presence of BPD after treatment with ECMO, which was defined as oxygen and/or ventilatory requirements at day of life 28, with characteristic abnormalities seen on chest x-ray film. RESULTS: The age at ECMO initiation was significantly greater for patients with BPD compared with patients without BPD (mean +/- SD, 135 +/- 68 hours vs 50 +/- 37 hours; P < .001). There was an 11.5-fold increased risk for the development of BPD if ECMO was initiated at greater than 96 hours of age. The primary diagnosis of respiratory distress syndrome imparted a 5.2-fold increased risk for the development of BPD. Patients with BPD required ECMO significantly longer than patients without BPD (203 +/- 73 hours vs 122 +/- 51 hours; P < .001). CONCLUSION: These results demonstrate that delayed use of ECMO in treating neonatal respiratory failure is associated with an increased risk for the development of BPD and a longer duration of ECMO therapy.

Body conformation, diet, and risk of breast cancer in pet dogs: a case-control study.

Canine and human breast cancer share several important clinical and histologic features. A case-control study of nutritional factors and canine breast cancer was conducted at the Veterinary Hospital of the University of Pennsylvania in 1984-1987 by interviewing owners of 150 pet dogs diagnosed with breast cancer, owners of 147 cancer control dogs, and owners of 131 noncancer control dogs. The risk of breast cancer was significantly reduced in dogs spayed at or before 2.5 years of age. Neither a high-fat diet nor obesity 1 year before diagnosis increased the risk of breast cancer according to multiple logistic regression analysis. However, the risk of breast cancer among spayed dogs was significantly reduced in dogs that had been thin at 9-12 months of age (odds ratio (OR) = 0.04 (95% confidence interval (CI) 0.004-0.4) and OR = 0.04 (95% CI 0.004-0.5) for cases vs. cancer controls and cases vs. noncancer controls, respectively, after adjustment for age at spay). Among intact dogs, the risk associated with being thin at 9-12 months of age was reduced, but not significantly so (OR = 0.60 (95% CI 0.2-1.9) and OR = 0.51 (95% CI 0.2-1.4) for the two comparisons, respectively). Results of this study suggest that nutritional factors operating early in life may be of etiologic importance in canine breast cancer.

Prognostic factors and survival after radiotherapy for intranasal neoplasms in dogs: 70 cases (1974-1985).

Survival time and 31 prognostic factors were analyzed for 70 dogs undergoing radiotherapy for intranasal tumors at the Veterinary Hospital of the University of Pennsylvania between 1974 and 1985. At the time of analysis (January 1987), 14.3% (10 of 70) of the dogs were alive. Of the remaining dogs, 34 died because of tumor recurrence, 14 died because of intercurrent disease, and 12 were lost to follow-up evaluation. Pretreatment prognostic factors that were significantly correlated with disease-free interval or long-term survival could not be identified. Notably, presence of a facial mass was not prognostically significant, suggesting that extensive disease should not preclude treatment. Median survival time of dogs with all tumor types was 16.5 months, with a 1-, 2-, and 3-year survival of 54%, 43%, and 35%, respectively. Median survival time of dogs with carcinoma was 13.5 months, with 1-year survival of 51%, 2-year survival of 37%, and 3-year survival of 31%. Orthovoltage radiation was efficacious in the treatment of canine intranasal tumors.

Epidemiologic study of insecticide exposures, obesity, and risk of bladder cancer in household dogs.

A case-control study of household dogs was conducted to determine if exposure to sidestream cigarette smoke and chemicals in the home, use of topical insecticides, and obesity are associated with the occurrence of bladder cancer. Information was obtained by interview from owners of 59 dogs with transitional-cell carcinoma of the bladder and 71 age- and breed size-matched control dogs with other chronic diseases or neoplasms. Bladder cancer risk was unrelated to sidestream cigarette smoke and household chemical exposures. Risk was significantly increased by topical insecticide use (OR = 1.6 for 1-2 applications per year and OR = 3.5 for greater than 2 applications per year; chi 2 trend; p = .008). This risk was enhanced in overweight or obese dogs. Further studies of this canine model may facilitate identification of specific carcinogens present in insecticides commonly used on pet animals and in the environment.

Epidemiologic, clinical, pathologic, and prognostic characteristics of splenic hemangiosarcoma and splenic hematoma in dogs: 217 cases (1985).

Data on age, sex, and breed were obtained from surgical pathologic records of 92 dogs with splenic hemangiosarcoma (SHS) and for 125 dogs with splenic hematoma (SHA) diagnosed in 1985 at the University of Pennsylvania School of Veterinary Medicine. Further information on body weight, clinical and surgical findings, and survival time was obtained for 59 dogs (64.1%) with SHS and 91 dogs (72.8%) with SHA. Splenic hemangiosarcoma was markedly more common in dogs 8 to 13 years old, and SHA was appreciably more common in dogs greater than or equal to 8 years old, compared with dogs 1 to 7 years old. Compared with sexually intact females, only spayed females were at significantly (odds ratio [or], 2.2; 95% confidence interval [CI], 1.2 to 4.1) increased risk for developing SHS; sex predisposition was not found for dogs with SHA. The German Shepherd Dog was the only breed with increased risk for development of either SHS (OR, 4.7; 95% CI, 2.7 to 7.8) or SHA (OR, 2.8; 95% CI, 1.7 to 4.9), compared with all other purebred dogs. Association of tumor type for 7 commonly reported clinical signs with observance of hemoperitoneum at surgery was determined; anorexia (P = 0.01), collapse (P = 0.01), and hemoperitoneum (P less than 0.001) were significantly more common in dogs with SHS. The median survival time for dogs with SHS was 19 days, compared with 338 days for dogs with SHA (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)