Kristine Tollestrup

How clean must our drinking water be: the importance of protective immunity.

BACKGROUND Cryptosporidium parvum is an important cause of epidemic diarrhea. Few studies have assessed whether serological evidence of prior infection in adults is related to a reduced occurrence of enteric illness. METHODS Serum samples and enteric illness event data were obtained in 2000 and 2001 from 326 people served by 1 of 2 unfiltered surface sources or 1 groundwater source. In 2001, filtration was initiated at 1 of the surface sources. Poisson regression related illness episodes with serological responses to the 15/17- and 27-kDa Cryptosporidium antigen groups. RESULTS Subjects with moderately strong responses to the 15/17-kDa antigen had <65% of the risk of all 1-3-day episodes of diarrheal or gastrointestinal illness and <40% of the risk of all >/=4-day episodes, compared with subjects without a moderately strong response. Water source, change in water treatment, and very weak responses were unrelated to illness events. CONCLUSIONS Endemic Cryptosporidium infections are a common cause of diarrheal and gastrointestinal illness in persons without a moderately strong response to the 15/17-kDa antigen group. Users of surface-derived drinking water are more likely to have strong serological responses to this antigen group and may be at a lower risk of endemic gastrointestinal illness caused by Cryptosporidium infection.

Identifying US populations for the study of health effects related to drinking water arsenic.

The US Environmental Protection Agency recently set a new maximum contaminant level (MCL) for arsenic in drinking water of 10 μg/l. In this paper, we review the completeness and accuracy of drinking water arsenic occurrence data in the United States and identify populations exposed to elevated arsenic concentrations that would be suitable for epidemiological studies of arsenic health effects. Using existing data from the Environmental Protection Agency Arsenic Occurrence and Exposure Database and additional data from state health and environment departments and water utilities, we identified 33 counties in 11 states with an estimated mean drinking water arsenic concentration of 10 μg/l or greater. A total of 11 of these ‘confirmed’ counties had an estimated mean arsenic concentration of 20 μg/l or more and two had an estimated mean arsenic concentration 50 μg/l or more. Based on census data, between 1950 and 1999 there were approximately 51.1 million person-years of exposure to drinking water arsenic at levels of 10 μg/l or more, 8.2 million at levels of 20 μg/l or more arsenic and 0.9 million at levels of 50 μg/l or more. Mortality and incidence of diseases known to be associated with arsenic exposure can and should be examined in these counties as part of a comprehensive assessment of arsenic health effects in US populations.

Protective Immunity Associated with a Strong Serological Response to a Cryptosporidium-Specific Antigen Group, in HIV-Infected Individuals

This study assessed whether serological responses to Cryptosporidium antigens are associated with a reduced risk of diarrheal illness in cases of infection with human immunodeficiency virus (HIV). The association between serological responses to the Cryptosporidium 15/17-kDa and 27-kDa antigen groups and reported diarrheal illness was examined by use of data from a previously published study of cases of HIV infection. In immunosuppressed individuals, a strong serological response to the 27-kDa antigen group was associated with a reduced risk of diarrhea without weight loss. This finding suggests that acquired protective immunity to cryptosporidiosis may be important in controlling the burden of cryptosporidiosis in immunosuppressed individuals.

Mortality in a cohort of orchard workers exposed to lead arsenate pesticide spray.

During the period from 1890 to 1940, lead arsenate was the major pesticide used in apple orchards to control the coddling moth. In the Wenatchee area of Washington State, lead arsenate spray was used for longer periods and in larger quantities than in other areas of the United States. In 1938, a cohort of 1,231 people who lived in this area was selected for a study to determine the effects of exposure to lead arsenate spray and residue. This same cohort was re-examined to determine whether there was excess mortality that could be attributed to the lead arsenate exposure. Three levels of exposure (i.e., orchardist, intermediate, consumer) were defined, based upon the use of lead arsenate pesticide spray before and during the 1938 apple growing season. Age-adjusted hazard ratios for all causes of mortality were elevated for both male orchardists and male intermediates. The only significantly increased age-adjusted hazard ratio (1.94) was heart disease in male intermediates. No significantly elevated age-adjusted hazard ratios were observed for women in any exposure group. The lack of evidence that supported an increase in mortality from respiratory cancer in this cohort may have resulted from the lower cumulative concentration of arsenic exposure, the type of arsenical compound, and the small number of study subjects.

Mortality among Children Residing near the American Smelting and Refining Company (ASARCO) Copper Smelter in Ruston, Washington

A retrospective cohort study was undertaken to determine whether childhood exposure to ambient arsenic was associated with increased mortality rates. Cohort members comprised children who had lived within 4.0 km (2.5 mi) of the American Smelting and Refining Company (ASARCO) copper smelter and arsenic refinery in Ruston, Washington, for at least 2 yr during the time period from 1907 to 1932. The cohort included 1,827 boys and 1,305 girls identified from school census records. Exposure intensity was computed as the total number of years a child had lived at a residence less than 1.6 km (1.0 mi) from the smelter stack during the study period. In only one exposure intensity group (i.e., residence ⩾ 10.0 yr less than 1.6 km [1.0 mi] from the smelter) for boys were Cox proportional hazards ratios significantly higher than 1.00: for all causes of death (1.52), ischemic heart disease (1.77), and external causes (1.93). For girls, hazard ratios were not elevated significantly for any cause of death in any exposure intensity group.

The excess costs of breast cancer health care in Hispanic and non-Hispanic female members of a managed care organization

The differences in costs for health care services between women with breast cancer and those without were estimated for Hispanic and non-Hispanic members of a managed care organization. A total of 317 cases of breast cancer and 949 controls were selected using a comprehensive patient database. All health care costs for the 4–12 months prior to the cases diagnosis and for the 12 months following the cases diagnosis were obtained. Costs were defined as charges to the health plan. Mean differences in total health care costs between cases and controls were predicted using Tobit models for 4–12 months prior to diagnosis and the year after diagnosis by age group. Compared to controls, women diagnosed with in situ breast cancers in all age groups had significantly higher health care costs 4–12 months prior to diagnosis. For women under 50 years of age, the difference in costs for cases compared to controls 12 months after diagnosis was almost three times greater for women with regional/distant disease (

A community integration approach to social determinants of health in New Mexico.

 17,093 ± 

Cryptosporidium infection, onsite wastewater systems and private wells in the arid Southwest

 1,559) compared to in situ disease (

Enteric illness risks before and after water treatment improvements.

 5,089 ± 

Influenza and COPD mortality protection as pleiotropic, dose-dependent effects of statins.

 1,050). For women in the two other age groups (50–70 years and over 70 years), the difference was over twice as great for those with regional/distant disease compared to those with in situ disease. Mean differences between cases and controls in health care costs 12 months after diagnosis were similar for Hispanic and non-Hispanic women for all stages of disease.