Human papillomavirus DNA detection, p16INK4a, and oral cavity cancer in a U.S. population.

OBJECTIVES: The role of HPV in oral cavity cancers was investigated using two markers of viral exposure. MATERIALS AND METHODS: HPV DNA and p16INK4a expression were evaluated in tumor tissue from a U.S. population-based sample of 122 invasive oral cavity cancer cases. RESULTS: HPV DNA was detected in 38 of 122 (31%) oral cavity tumors. Seven genotypes were detected including HPV 16, which was found in 22% of tumors. p16INK4a was expressed in 30% of tumors and was poorly correlated with HPV DNA detection (Kappa <0.1). Joint positivity for HPV 16 and/or 18 and p16INK4a was observed in only 7% of cases. When comparing cases diagnosed in 1993-1999 and in 2000-2004, positivity for HPV DNA 16/18 increased from 19% to 39% (p = 0.02) and joint HPV 16/18 - p16INK4a positivity increased from 0% to 12% (p = 0.01). For gingival tumors, HPV 16 and/or 18 positivity was 67% compared to 11-38% for other sites (p = 0.02); joint HPV 16/18 - p16INK4a positivity was 33% compared to 0-8% for other sites (p = 0.01). The association of HPV with gingival tumors and more recent diagnosis period remained after adjustment for age and stage (p < 0.05). Neither HPV DNA nor p16INK4a were associated with overall survival. CONCLUSIONS: Based on both HPV DNA and p16INK4a, HPV is etiologically linked to a limited subset of oral cavity cancers. However, the role of HPV in oral cavity cancer may vary widely by subsite and may have increased over time, similar to trends observed for oropharyngeal cancer.

p16(INK4A) expression in invasive laryngeal cancer.

We examined p16 expression in tumors from a population-based sample of laryngeal cancer cases diagnosed in the U.S. Samples had been previously genotyped for HPV DNA. Overall, p16 expression was observed in laryngeal tissue from 8 of 101 (7.9%) cases. p16 expression was observed in 2 of 16 (12.5%) cases previously determined to be HPV DNA positive. The two cases dually positive for p16 and HPV DNA were non-keratinizing SCC and papillary SCC tumors that were positive for genotypes 18 and 35/89, respectively. Positivity for p16 and/or HPV DNA was not associated with 5-year survival (log-rank p value= 0.55). Our findings support a limited role of HPV in laryngeal carcinogenesis. p16 is not a reliable surrogate for HPV status in laryngeal cancers and is not a predictor of laryngeal cancer survival.

Human papillomavirus genotype and oropharynx cancer survival in the United States of America.

BACKGROUND: The presence of human papillomavirus (HPV) DNA in oropharyngeal squamous cell cancer (OPSCC) tissue appears to be a strong predictor of improved prognosis, but this observation has not been explored in a population-based sample with generalisable findings. METHODS: Follow-up data from a large sample of OPSCC patients identified through six population-based cancer registries in the United States of America (USA) were used to characterise the association of tumour HPV status with survival. RESULTS: HPV DNA was detected in tumour tissue from 71% (378 in 529) of the OPSCC patients. A total of 65% of patients with HPV16-associated tumours survived 5 years compared to 46% of patients with other HPV types and 28% of patients with HPV-negative tumours (p log-rank test <0.0001). The OPSCC patients with detectable HPV16 DNA had a 62% reduced hazard of death at 5 years, and patients with other HPV types had a 42% reduced hazard of death at 5 years compared to HPV-negative patients. Compared to non-Hispanic Whites, Blacks with OPSCC had a 2.6-fold greater risk of death at 5 years after adjustment for HPV status and other prognostic variables. Both surgery and radiation therapy were associated with a reduced 5-year risk of death, but no evidence was found for an interaction between HPV status and radiotherapy or surgery on survival time. CONCLUSIONS: Data from this US study suggest that HPV16-positive OPSCC patients survive longer than HPV-negative patients regardless of treatment, highlighting the prognostic importance of HPV status for this malignancy. Optimal treatment regimens for OPSCC could be tailored to each patient's HPV status and prognostic profile.

US assessment of HPV types in cancers: implications for current and 9-valent HPV vaccines.

BACKGROUND: This study sought to determine the prevaccine type-specific prevalence of human papillomavirus (HPV)-associated cancers in the United States to evaluate the potential impact of the HPV types in the current and newly approved 9-valent HPV vaccines. METHODS: The Centers for Disease Control and Prevention partnered with seven US population-based cancer registries to obtain archival tissue for cancers diagnosed from 1993 to 2005. HPV testing was performed on 2670 case patients that were fairly representative of all participating cancer registry cases by age and sex. Demographic and clinical data were evaluated by anatomic site and HPV status. Current US cancer registry data and the detection of HPV types were used to estimate the number of cancers potentially preventable through vaccination. RESULTS: HPV DNA was detected in 90.6% of cervical, 91.1% of anal, 75.0% of vaginal, 70.1% of oropharyngeal, 68.8% of vulvar, 63.3% of penile, 32.0% of oral cavity, and 20.9% of laryngeal cancers, as well as in 98.8% of cervical cancer in situ (CCIS). A vaccine targeting HPV 16/18 potentially prevents the majority of invasive cervical (66.2%), anal (79.4%), oropharyngeal (60.2%), and vaginal (55.1%) cancers, as well as many penile (47.9%), vulvar (48.6%) cancers: 24 858 cases annually. The 9-valent vaccine also targeting HPV 31/33/45/52/58 may prevent an additional 4.2% to 18.3% of cancers: 3944 cases annually. For most cancers, younger age at diagnosis was associated with higher HPV 16/18 prevalence. With the exception of oropharyngeal cancers and CCIS, HPV 16/18 prevalence was similar across racial/ethnic groups. CONCLUSIONS: In the United States, current vaccines will reduce most HPV-associated cancers; a smaller additional reduction would be contributed by the new 9-valent vaccine.

Human papillomavirus prevalence in invasive laryngeal cancer in the United States.

PURPOSE: Human papillomavirus (HPV) is a major risk factor for specific cancers of the head and neck, particularly malignancies of the tonsil and base of the tongue. However, the role of HPV in the development of laryngeal cancer has not been definitively established. We conducted a population-based, cancer registry study to evaluate and characterize the genotype-specific prevalence of HPV in invasive laryngeal cancer cases diagnosed in the U.S. METHODS: The presence of genotype-specific HPV DNA was evaluated using the Linear Array HPV Genotyping Test and the INNO-LiPA HPV Genotyping Assay in formalin-fixed paraffin embedded tissue from 148 invasive laryngeal cancer cases diagnosed in 1993-2004 within the catchment area of three U.S. SEER cancer registries. RESULTS: HPV DNA was detected in 31 of 148 (21%) invasive laryngeal cancers. Thirteen different genotypes were detected. Overall, HPV 16 and HPV 33 were the most commonly detected types. HPV was detected in 33% (9/27) of women compared with 18% (22/121) of men (p = 0.08). After adjustment for age and year of diagnosis, female patients were more likely to have HPV-positive laryngeal tumors compared to males (adjusted OR 2.84, 95% CI 1.07-7.51). Viral genotype differences were also observed between the sexes. While HPV 16 and 18 constituted half of HPV-positive cases occurring in men, among women, only 1 was HPV 16 positive and none were positive for HPV 18. Overall 5-year survival did not vary by HPV status. CONCLUSIONS: HPV may be involved in the development of a subset of laryngeal cancers and its role may be more predominant in women compared to men.

Human papillomavirus genotype prevalence in invasive vaginal cancer from a registry-based population.

OBJECTIVE: To describe the human papillomavirus (HPV) genotype distribution in invasive vaginal cancers diagnosed before the introduction of the HPV vaccine and evaluate if survival differed by HPV status. METHODS: Four population-based registries and three residual tissue repositories provided formalin-fixed, paraffin-embedded tissue from microscopically confirmed primary vaginal cancer cases diagnosed between 1994 and 2005 that were tested by L1 consensus polymerase chain reaction with type-specific hybridization in a central laboratory. Clinical, demographic, and all-cause survival data were assessed by HPV status. RESULTS: Sixty cases of invasive vaginal cancer were included. Human papillomavirus was detected in 75% (45) and 25% (15) were HPV-negative. HPV 16 was most frequently detected (55% [33/60]) followed by HPV 33 (18.3% [11/60]). Only one case was positive for HPV 18 (1.7%) Multiple types were detected in 15% of the cases. Vaginal cancers in women younger than 60 years were more likely to be HPV 16- or HPV 18-positive (HPV 16 and 18) than older women, 77.3% compared with 44.7% (P=.038). The median age at diagnosis was younger in the HPV 16 and 18 (59 years) group compared with other HPV-positive (68 years) and no HPV (77 years) (P=.003). The HPV distribution did not significantly vary by race or ethnicity or place of residence. The 5-year unadjusted all-cause survival was 57.4% for women with HPV-positive vaginal cancers compared with 35.7% among those with HPV-negative tumors (P=.243). CONCLUSION: Three fourths of all vaginal cancers in the United States had HPV detected, much higher than previously found, and 57% could be prevented by current HPV vaccines.

Human papillomavirus prevalence in oropharyngeal cancer before vaccine introduction, United States.

We conducted a study to determine prevalence of HPV types in oropharyngeal cancers in the United States and establish a prevaccine baseline for monitoring the impact of vaccination. HPV DNA was extracted from tumor tissue samples from patients in whom cancer was diagnosed during 1995-2005. The samples were obtained from cancer registries and Residual Tissue Repository Program sites in the United States. HPV was detected and typed by using PCR reverse line blot assays. Among 557 invasive oropharyngeal squamous cell carcinomas, 72% were positive for HPV and 62% for vaccine types HPV16 or 18. Prevalence of HPV-16/18 was lower in women (53%) than in men (66%), and lower in non-Hispanic Black patients (31%) than in other racial/ethnic groups (68%-80%). Results indicate that vaccines could prevent most oropharyngeal cancers in the United States, but their effect may vary by demographic variables.

Human papillomavirus genotype prevalence in invasive penile cancers from a registry-based United States population.

BACKGROUND: Human papillomavirus (HPV) is estimated to play an etiologic role in 40-50% of penile cancers worldwide. Estimates of HPV prevalence in U.S. penile cancer cases are limited. METHODS: HPV DNA was evaluated in tumor tissue from 79 invasive penile cancer patients diagnosed in 1998-2005 within the catchment areas of seven U.S. cancer registries. HPV was genotyped using PCR-based Linear Array and INNO-LiPA assays and compared by demographic, clinical, and pathologic characteristics and survival. Histological classification was also obtained by independent pathology review. RESULTS: HPV DNA was present in 50 of 79 (63%) of invasive penile cancer cases. Sixteen viral genotypes were detected. HPV 16, found in 46% (36/79) of all cases (72% of HPV-positive cases) was the most prevalent genotype followed equally by HPV 18, 33, and 45, each of which comprised 5% of all cases. Multiple genotypes were detected in 18% of viral positive cases. HPV prevalence did not significantly vary by age, race/ethnicity, population size of geographic region, cancer stage, histology, grade, penile subsite, or prior cancer history. Penile cases diagnosed in more recent years were more likely to be HPV-positive. Overall survival did not significantly vary by HPV status. CONCLUSION: The relatively high prevalence of HPV in our study population provides limited evidence of a more prominent and, possibly, increasing role of infection in penile carcinogenesis in the U.S. compared to other parts of the world.

Prevalence of human papillomavirus types in invasive cervical cancers from 7 US cancer registries before vaccine introduction.

OBJECTIVE: We conducted a baseline study of human papillomavirus (HPV) type prevalence in invasive cervical cancers (ICCs) using data from 7 cancer registries (CRs) in the United States. Cases were diagnosed between 1994 and 2005 before the implementation of the HPV vaccines. MATERIALS AND METHODS: Cancer registries from Florida, Kentucky, Louisiana, Michigan, Hawaii, Iowa, and Los Angeles, California identified eligible ICC cases and obtained sections from representative blocks of archived tumor specimens for DNA extraction. All extracts were assayed by linear array and, if inadequate or HPV negative, retested with INNO-LiPA Genotype test. Clinical and demographic factors were obtained from the CRs and merged with the HPV typing data to analyze factors associated with different types and with HPV negativity. RESULTS: A total of 777 ICCs were included in this analysis, with broad geographic, age, and race distribution. Overall, HPV was detected in 91% of cases, including 51% HPV-16, 16% HPV-18 (HPV-16-negative), and 24% other oncogenic and rare types. After HPV-16 and -18, the most common types were 45, 33, 31, 35, and 52. Older age and nonsquamous histology were associated with HPV-negative typing. CONCLUSIONS: This study provides baseline prevaccine HPV types for postvaccine ICC surveillance in the future. HPV-16 and/or -18 were found in 67% of ICCs, indicating the potential for vaccines to prevent a significant number of cervical cancers.

Human papillomavirus prevalence in invasive anal cancers in the United States before vaccine introduction.

OBJECTIVE: This study aimed to conduct a representative survey of human papillomavirus (HPV) prevalence and its genotype distribution in invasive anal cancer specimens in the United States. MATERIALS AND METHODS: Population-based archival anal cancer specimens were identified from Florida, Kentucky, Louisiana, and Michigan cancer registries and Surveillance, Epidemiology, and End Results (SEER) tissue repositories in Hawaii, Iowa, and Los Angeles. Sections from 1 representative block per case were used for DNA extraction. All extracts were assayed first by linear array and retested with INNO-LiPA if inadequate or HPV negative. RESULTS: Among 146 unique invasive anal cancer cases, 93 (63.7%) were from women, and 53 (36.3%) were from men. Human papillomavirus (any type) was detected in 133 cases (91.1%) and 129 (88.4%) contained at least 1 high risk-type, most (80.1%) as a single genotype. Human papillomavirus type 16 had the highest prevalence (113 cases, 77.4%); HPV types 6, 11, 18, and 33 were also found multiple times. Among HPV-16-positive cases, 37% were identified as prototype variant Ep, and 63% were nonprototypes: 33% Em, 12% E-G131G, 5% Af1, 4% AA/NA-1, 3% E-C109G, 3% E-G131T, 2% As, and 1% Af2. No significant differences in the distributions of HPV (any), high-risk types, or HPV-16/18 were seen between sex, race, or age group. CONCLUSIONS: The establishment of prevaccine HPV prevalence in the United States is critical to the surveillance of vaccine efficacy. Almost 80% of anal cancers were positive for the vaccine types HPV-16 or HPV-18, and in 70%, these were the only types detected, suggesting that a high proportion might be preventable by current vaccines.

Prevalence of human papillomavirus types in invasive vulvar cancers and vulvar intraepithelial neoplasia 3 in the United States before vaccine introduction.

OBJECTIVE: The study aimed to determine the baseline prevalence of human papillomavirus (HPV) types in invasive vulvar cancer (IVC) and vulvar intraepithelial neoplasia 3 (VIN 3) cases using data from 7 US cancer registries. MATERIALS AND METHODS: Registries identified eligible cases diagnosed in 1994 to 2005 and requested pathology laboratories to prepare 1 representative block for HPV testing on those selected. Hematoxylin-eosin-stained sections preceding and following those used for extraction were reviewed to confirm representation. Human papillomavirus was detected using L1 consensus polymerase chain reaction (PCR) with PGMY9/11 primers and type-specific hybridization, with retesting of samples with negative and inadequate results with SPF10 primers. For IVC, the confirmatory hematoxylin-eosin slides were re-evaluated to determine histological type. Descriptive analyses were performed to examine distributions of HPV by histology and other factors. RESULTS: Human papillomavirus was detected in 121/176 (68.8%) cases of IVC and 66/68 (97.1%) cases of VIN 3 (p < .0001). Patients with IVC and VIN 3 differed by median age (70 vs 55 y, p = .003). Human papillomavirus 16 was present in 48.6% of IVC cases and 80.9% of VIN 3 cases; other high-risk HPV was present in 19.2% of IVC cases and 13.2% of VIN 3 cases. Prevalence of HPV differed by squamous cell carcinoma histological subtype (p < .0001) as follows: keratinizing, 49.1% (n = 55); nonkeratinizing, 85.7% (n = 14), basaloid, 92.3% (n = 14), warty 78.2% (n = 55), and mixed warty/basaloid, 100% (n = 7). CONCLUSIONS: Nearly all cases of VIN 3 and two thirds of IVC cases were positive for high-risk HPV. Prevalence of HPV ranged from 49.1% to 100% across squamous cell carcinoma histological subtypes. Given the high prevalence of HPV in IVC and VIN 3 cases, prophylactic vaccines have the potential to decrease the incidence of vulvar neoplasia.

Rate of decline in serum PFOA concentrations after granular activated carbon filtration at two public water systems in Ohio and West Virginia.

BACKGROUND: Drinking water in multiple water districts in the Mid-Ohio Valley has been contaminated with perfluorooctanoic acid (PFOA), which was released by a nearby DuPont chemical plant. Two highly contaminated water districts began granular activated carbon filtration in 2007. OBJECTIVES: To determine the rate of decline in serum PFOA, and its corresponding half-life, during the first year after filtration. METHODS: Up to six blood samples were collected from each of 200 participants from May 2007 until August 2008. The primary source of drinking water varied over time for some participants; our analyses were grouped according to water source at baseline in May-June 2007. RESULTS: For Lubeck Public Service District customers, the average decrease in serum PFOA concentrations between May-June 2007 and May-August 2008 was 32 ng/mL (26%) for those primarily consuming public water at home (n = 130), and 16 ng/mL (28%) for those primarily consuming bottled water at home (n = 17). For Little Hocking Water Association customers, the average decrease in serum PFOA concentrations between November-December 2007 and May-June 2008 was 39 ng/mL (11%) for consumers of public water (n = 39) and 28 ng/mL (20%) for consumers of bottled water (n = 11). The covariate-adjusted average rate of decrease in serum PFOA concentration after water filtration was 26% per year (95% confidence interval, 2528% per year). CONCLUSIONS: The observed data are consistent with first-order elimination and a median serum PFOA half-life of 2.3 years. Ongoing follow-up will lead to improved half-life estimation.

Exogenous and endogenous determinants of blood trihalomethane levels after showering.

BACKGROUND: We previously conducted a study to assess whether household exposures to tap water increased an individual's internal dose of trihalomethanes (THMs). Increases in blood THM levels among subjects who showered or bathed were variable, with increased levels tending to cluster in two groups. OBJECTIVES: Our goal was to assess the importance of personal characteristics, previous exposures, genetic polymorphisms, and environmental exposures in determining THM concentrations in blood after showering. METHODS: One hundred study participants completed a health symptom questionnaire, a 48-hr food and water consumption diary, and took a 10-min shower in a controlled setting. We examined THM levels in blood samples collected at baseline and 10 and 30 min after the shower. We assessed the significance of personal characteristics, previous exposures to THMs, and specific gene polymorphisms in predicting postshower blood THM concentrations. RESULTS: We did not observe the clustering of blood THM concentrations observed in our earlier study. We found that environmental THM concentrations were important predictors of blood THM concentrations immediately after showering. For example, the chloroform concentration in the shower stall air was the most important predictor of blood chloroform levels 10 min after the shower (p < 0.001). Personal characteristics, previous exposures to THMs, and specific polymorphisms in CYP2D6 and GSTT1 genes were significant predictors of both baseline and postshowering blood THM concentrations as well as of changes in THM concentrations associated with showering. CONCLUSION: The inclusion of information about individual physiologic characteristics and environmental measurements would be valuable in future studies to assess human health effects from exposures to THMs in tap water.

Body size, dairy consumption, puberty, and risk of testicular germ cell tumors.

The etiology of testicular germ cell tumors (TGCTs) is poorly understood, with cryptorchidism and family history being the only well-established risk factors. Body size, age at puberty, and dairy consumption, however, have been suggested to be related to TGCTs. To clarify the relation of these variables to TGCT risk and to one another, the authors analyzed data from 767 cases and 928 controls enrolled in the Servicemen's Testicular Tumor Environmental and Endocrine Determinants Study (2002-2005). Overall, increased height was significantly related to risk (odds ratio (OR) = 1.83, 95% confidence interval (CI): 1.36, 2.45), though body mass index was not (OR = 1.06, 95% CI: 0.66, 1.69). There was no association with age at puberty, based on ages at first shaving (OR = 1.29, 95% CI: 0.96, 1.73), voice changing (OR = 0.97, 95% CI: 0.71, 1.32), and nocturnal emissions (OR = 1.00, 95% CI: 0.73, 1.37). Similarly, there was no relation with dairy consumption at any age between birth and 12th grade. These results suggest that height is a risk factor for TGCTs, but the relation is unlikely explained by childhood dairy consumption. As adult height is largely determined in the first 2 years of life, increased attention to events in this interval may help elucidate the etiology of TGCTs.

Changes in breath trihalomethane levels resulting from household water-use activities.

Common household water-use activities such as showering, bathing, drinking, and washing clothes or dishes are potentially important contributors to individual exposure to trihalomethanes (THMs), the major class of disinfection by-products of water treated with chlorine. Previous studies have focused on showering or bathing activities. In this study, we selected 12 common water-use activities and determined which may lead to the greatest THM exposures and result in the greatest increase in the internal dose. Seven subjects performed the various water-use activities in two residences served by water utilities with relatively high and moderate total THM levels. To maintain a consistent exposure environment, the activities, exposure times, air exchange rates, water flows, water temperatures, and extraneous THM emissions to the indoor air were carefully controlled. Water, indoor air, blood, and exhaled-breath samples were collected during each exposure session for each activity, in accordance with a strict, well-defined protocol. Although showering (for 10 min) and bathing (for 14 min), as well as machine washing of clothes and opening mechanical dishwashers at the end of the cycle, resulted in substantial increases in indoor air chloroform concentrations, only showering and bathing caused significant increases in the breath chloroform levels. In the case of bromodichloromethane (BDCM), only bathing yielded a significantly higher air level in relation to the preexposure concentration. For chloroform from showering, strong correlations were observed for indoor air and exhaled breath, blood and exhaled breath, indoor air and blood, and tap water and blood. Only water and breath, and blood and breath were significantly associated for chloroform from bathing. For BDCM, significant correlations were obtained for blood and air, and blood and water from showering. Neither dibromochloromethane nor bromoform gave measurable breath concentrations for any of the activities investigated because of their much lower tap-water concentrations. Future studies will address the effects that changes in these common water-use activities may have on exposure.

Influence of tap water quality and household water use activities on indoor air and internal dose levels of trihalomethanes.

Individual exposure to trihalomethanes (THMs) in tap water can occur through ingestion, inhalation, or dermal exposure. Studies indicate that activities associated with inhaled or dermal exposure routes result in a greater increase in blood THM concentration than does ingestion. We measured blood and exhaled air concentrations of THM as biomarkers of exposure to participants conducting 14 common household water use activities, including ingestion of hot and cold tap water beverages, showering, clothes washing, hand washing, bathing, dish washing, and indirect shower exposure. We conducted our study at a single residence in each of two water utility service areas, one with relatively high and the other low total THM in the residence tap water. To maintain a consistent exposure environment for seven participants, we controlled water use activities, exposure time, air exchange, water flow and temperature, and nonstudy THM sources to the indoor air. We collected reference samples for water supply and air (pre-water use activity), as well as tap water and ambient air samples. We collected blood samples before and after each activity and exhaled breath samples at baseline and post-activity. All hot water use activities yielded a 2-fold increase in blood or breath THM concentrations for at least one individual. The greatest observed increase in blood and exhaled breath THM concentration in any participant was due to showering (direct and indirect), bathing, and hand dishwashing. Average increase in blood THM concentration ranged from 57 to 358 pg/mL due to these activities. More research is needed to determine whether acute and frequent exposures to THM at these concentrations have public health implications. Further research is also needed in designing epidemiologic studies that minimize data collection burden yet maximize accuracy in classification of dermal and inhalation THM exposure during hot water use activities.

Exposures of preschool children to chlorpyrifos and its degradation product 3,5,6-trichloro-2-pyridinol in their everyday environments.

As part of the Children's Total Exposure to Persistent Pesticides and Other Persistent Organic Pollutants (CTEPP) study, we investigated the exposures of preschool children to chlorpyrifos and its degradation product 3,5,6-trichloro-2-pyridinol (TCP) in their everyday environments. During this study, the participants were still able to purchase and apply chlorpyrifos at their homes or day care centers. Participants were recruited randomly from 129 homes and 13 day care centers in six North Carolina counties. Monitoring was performed over a 48-h period at the children's homes and/or day care centers. Samples that were collected included duplicate plate, indoor and outdoor air, urine, indoor floor dust, play area soil, transferable residues (PUF roller), and surface wipes (hand, food preparation, and hard floor). The samples were extracted and analyzed by gas chromatography/mass spectrometry. Chlorpyrifos was detected in 100% of the indoor air and indoor floor dust samples from homes and day care centers. TCP was detected at homes and day care centers in 100% of the indoor floor dust and hard floor surface wipe, in >97% of the solid food, and in >95% of the indoor air samples. Generally, median levels of chlorpyrifos were higher than those of TCP in all media, except for solid food samples. For these samples, the median TCP concentrations were 12 and 29 times higher than the chlorpyrifos concentrations at homes and day care centers, respectively. The median urinary TCP concentration for the preschool children was 5.3 ng/ml and the maximum value was 104 ng/ml. The median potential aggregate absorbed dose (ng/kg/day) of chlorpyrifos for these preschool children was estimated to be 3 ng/kg/day. The primary route of exposure to chlorpyrifos was through dietary intake, followed by inhalation. The median potential aggregate absorbed dose of TCP for these children was estimated to be 38 ng/kg/day, and dietary intake was the primary route of exposure. The median excreted amount of urinary TCP for these children was estimated to be 117 ng/kg/day. A full regression model of the relationships among chlorpyrifos and TCP for the children in the home group explained 23% of the variability of the urinary TCP concentrations by the three routes of exposure (inhalation, ingestion, dermal absorption) to chlorpyrifos and TCP. However, a final reduced model via step-wise regression retained only chlorpyrifos through the inhalation route and explained 22% of the variability of TCP in the children's urine. The estimated potential aggregate absorbed doses of chlorpyrifos through the inhalation route were low (median value, 0.8 ng/kg/day) and could not explain most of the excreted amounts of urinary TCP. This suggested that there were other possible sources and pathways of exposure that contributed to the estimated potential aggregate absorbed doses of these children to chlorpyrifos and TCP. One possible pathway of exposure that was not accounted for fully is through the children's potential contacts with contaminated surfaces at homes and day care centers. In addition, other pesticides such as chlorpyrifos-methyl may have also contributed to the levels of TCP in the urine. Future studies should include additional surface measurements in their estimation of potential absorbed doses of preschool children to environmental pollutants. In conclusion, the results showed that the preschool children were exposed to chlorpyrifos and TCP from several sources, through several pathways and routes. .

Changes in blood trihalomethane concentrations resulting from differences in water quality and water use activities.

Water disinfection is extremely important for the protection of public health; however, it also forms by-products, including trihalomethanes (THMs). Previous studies of health effects from disinfection by-products have lacked accurate methods to quantify exposure over time. As a first step in establishing a better system for exposure assessment, the authors investigated which household water use activities cause a significant increase in internal dose concentrations of THMs. In this study, 7 subjects in 2 different cities carried out 12 common activities that involved water use. In 3 of these activities-bathing, showering, and washing dishes by hand-the blood concentrations of THMs increased substantially. Further analysis of the data suggested that tap water concentrations primarily controlled the blood concentrations from bathing exposure, whereas tap water concentrations and ambient air concentrations resulting from water use affected the blood concentrations from showering exposure. Further studies will focus on variables in these activities that can alter exposure.

Design and sampling methodology for a large study of preschool children's aggregate exposures to persistent organic pollutants in their everyday environments.

Young children, because of their immaturity and their rapid development compared to adults, are considered to be more susceptible to the health effects of environmental pollutants. They are also more likely to be exposed to these pollutants, because of their continual exploration of their environments with all their senses. Although there has been increased emphasis in recent years on exposure research aimed at this specific susceptible population, there are still large gaps in the available data, especially in the area of chronic, low-level exposures of children in their home and school environments. A research program on preschool children's exposures was established in 1996 at the USEPA National Exposure Research Laboratory. The emphasis of this program is on children's aggregate exposures to common contaminants in their everyday environments, from multiple media, through all routes of exposure. The current research project, "Children's Total Exposure to Persistent Pesticides and Other Persistent Organic Pollutants," (CTEPP), is a pilot-scale study of the exposures of 257 children, ages 1(1/2)-5 years, and their primary adult caregivers to contaminants in their everyday surroundings. The contaminants of interest include several pesticides, phenols, polychlorinated biphenyls, polycyclic aromatic hydrocarbons, and phthalate esters. Field recruitment and data collection began in February 2000 in North Carolina and were completed in November 2001 in Ohio. This paper describes the design strategy, survey sampling, recruiting, and field methods for the CTEPP study.

Aggregate exposures of nine preschool children to persistent organic pollutants at day care and at home.

In the summer of 1997, we measured the aggregate exposures of nine preschool children, aged 2-5 years, to a suite of organic pesticides and other persistent organic pollutants that are commonly found in the home and school environment. The children attended either of two child day care centers in the Raleigh-Durham-Chapel Hill area of North Carolina and were in day care at least 25 h/week. Over a 48-h period, we sampled indoor and outdoor air, play area soil and floor dust, as well as duplicate diets, hand surface wipes, and urine for each child at day care and at home. Our target analytes were several polycyclic aromatic hydrocarbons (PAH), organochlorine pesticides, and polychlorinated biphenyls (PCB); two organophosphate pesticides (chlorpyrifos and diazinon), the lawn herbicide 2,4-dichlorophenoxyacetic acid (2,4-D), three phenols (pentachlorophenol (PCP), nonyl phenols, and bisphenol-A), 3,5,6-trichloro-2-pyridinol (TCP), and two phthalate esters (benzylbutyl and dibutyl phthalate). In urine, our target analytes were hydroxy-PAH, TCP, 2,4-D, and PCP. To allow estimation of each child's aggregate exposures over the 48-h sampling period, we also used time-activity diaries, which were filled out by each child's teacher at day care and the parent or other primary caregiver at home. In addition, we collected detailed household information that related to potential sources of exposure, such as pesticide use or smoking habits, through questionnaires and field observation. We found that the indoor exposures were greater than those outdoors, that exposures at day care and at home were of similar magnitudes, and that diet contributed greatly to the exposures. The children's potential aggregate doses, calculated from our data, were generally well below established reference doses (RfDs) for those compounds for which RfDs are available.