Kimmel et al. these collaborations and interactions have implications for children’s environmental health and the National Children’s Study. For example, studies have shown that blood and urine specimens from pregnant women show measurable levels of pesticides, suggesting that the fetus is exposed to these chemicals during early development (Bradman et al. 2003; Whyatt et al. 2003); children in urban and rural environments are exposed to a complex mix of agricultural and household pesticides, environmental tobacco smoke, and polycyclic aromatic hydrocarbons and negative social fac- tors that can affect their early growth and devel- opment (Berkowitz et al. 2004; Eskenazi et al. 2004; Perera et al. 2004; Rauh et al. 2004); and exposures to lead in the urban environment can have lifelong effects such as behavioral problems and criminal behavior in early adult life (Ris et al. 2004). Research on air pollution and asthma has broadened our understanding of the inﬂammatory process in the lung (Walters et al. 2002) such that the effects of air pollution can be seen in school-age children as increased exac- erbation of asthma symptoms and increased days absent from school (Gilliland et al. 2003; McConnell et al. 2003). Intervention studies have been conducted to show that the house- hold environment can be cleaned up in a way to significantly reduce allergens from dust mites and cockroaches that should reduce the incidence of asthma symptoms in children (Eggleston et al. 2004). Community-based participatory research. A requirement for every Children’s Center is the inclusion of one project that uses commu- nity-based participatory research methods. This type of methodology encourages full par- ticipation of the community in the design, implementation, evaluation, and translation of the research. Research ideas may begin with the concerns of the community. Community partners, scientists, and clinicians share knowl- edge of exposure, health effects, and preven- tion strategies. Many studies train and employ community members as study coordinators, interviewers, or environmental technicians. Community participation ensures the rele- vance of the research questions and appropri- ateness of the research strategies. Research results are disseminated back to the commu- nity on an ongoing basis through community advisory boards, newsletters, health fairs, and other educational activities. Cohorts and study designs. Most of the centers have established cohorts of children in which to study the dynamic relationship between exposures to environmental agents and health outcomes. In general, two distinct age groups are targeted: birth cohorts where preg- nant women were enrolled and their offspring become study participants, and cohorts of school-age children enrolled either in school settings or in a medical care environment. 1416 The birth cohort studies seek to understand exposures during fetal development and health risks related to respiratory illness progression and neurodevelopmental effects, including motor, sensory, and cognitive deﬁcits. Because asthma cannot be deﬁnitively diagnosed until ages 3–4, prospective follow-up of a group of young children provides for new opportunities as they age. The school-age cohort studies focus on asthma, and children are recruited through school classrooms, neighborhood health clinics, and other medical care settings. One large cohort study of school children in Los Angeles, California, that was started 10 years ago continues to follow the children and compare genetic factors from recently col- lected specimens with historical air pollution and medical data. Case-only or case–control designs are used in two other studies of chil- dren that focus on understanding the possible environmental causes of autism, a relatively rare disorder. Intervention/prevention studies include cohorts of children with disease or unique exposures that can be found in urban and rural settings. These studies are unique with regard to community participation, recruitment and retention, and dissemination of study results; Table 2 lists the types of studies and centers. Government/Children’s Centers partner- ships. The NIEHS and U.S. EPA, as federal funding partners, continue to align their priorities and working relationships to man- age and support this $140 million program. The agencies’ commitment to overcoming differences in their regulatory and research mandates is reflected in the broad success of the Centers Program’s impact on public pol- icy and influence in several fields of public health. The federal partners share responsibility in both supporting the national network of researchers and sponsoring annual center meet- ings. Bringing center scientists and community members together on a consistent basis has been instrumental in the success of these pro- grams. This created a stronger working rela- tionship across the Children’s Centers than would have been fostered with individual pro- grams working alone. At the inception of the program, many meetings were held to discuss definitions of health outcomes and ways to measure them, methodologies for exposure assessment, questionnaire items, and follow-up strategies with special attention to retention of study participants, cultural sensitivities, and engagement of community. Information was shared and protocols were designed for individ- ual studies that strove for commonality. The goal was not to have standardized methods employed, but rather to see where collabora- tions could be built and methodologies shared. The NIEHS/U.S. EPA Children’s Centers Program is now in its seventh year. The pro- gram has generated important scientiﬁc results and expanded our knowledge of exposures to young children and how they affect their health status. There is a wealth of knowledge about issues that pertain to conducting future studies in this field, especially the National Children’s Study. This mini-monograph is an attempt to describe in detail the lessons learned from these important groundbreaking studies. Major Lessons Considered Important for Planning the National Children’s Study Several major lessons from the Children’s Centers are important for consideration in planning the National Children’s Study. These and a number of others are discussed in detail in the articles in this mini-monograph (Dietrich et al. 2005; Eggleston et al. 2005; Eskenazi et al. 2005; Fenske et al. 2005; Gilliland et al. 2005; Israel et al. 2005). First, long-term studies that follow partici- pants into adolescence and early adulthood are considered essential to assess the full range of developmental consequences of exposure to environmental chemicals. It is also important to identify a popula- tion with a wide range of exposure concentra- tions for those key pollutants hypothesized a priori to be of interest in order to evaluate the relationships between the distributions of multiple exposures and observed effects. It is necessary to allow for population differences in literacy, language, and culture when establishing study procedures for recruitment and retention and in determining the type of information collected and the methods of collection. Assessment tools need to balance meas- ures both broad and narrow in scope. Questionnaires, neurodevelopmental instru- ments, and the like employed in these studies should include a core set to evaluate the entire cohort and additional segments for selected populations that may be unique based on their exposure or other attributes. Exposure assessment should include a combination of environmental and personal measurements as well as data derived from questionnaires and from observational and ecologic data. The exposure assessment effort should take advantage of modeling approaches to provide estimates for the entire cohort. Targeted exposure studies in a selected sub- sample of study subjects may be useful for improving exposure assessment. The depth of assessments that can be realistically imple- mented will be restricted in populations that are widely dispersed geographically, have limited transportation, or lack trained personnel in the community. Procedures for monitoring the quality and accuracy of data collection must be established and maintained not only for the collection and VOLUME 113 | NUMBER 10 | October 2005 • Environmental Health Perspectives