Academic journal article Environmental Health Perspectives

Effects of Environmental Agents on the Attainment of Puberty: Considerations When Assessing Exposure to Environmental Chemicals in the National Children's Study

Academic journal article Environmental Health Perspectives

Effects of Environmental Agents on the Attainment of Puberty: Considerations When Assessing Exposure to Environmental Chemicals in the National Children's Study

Article excerpt

The apparent decline in the age at puberty in the United States raises a general level of concern because of the potential clinical and social consequences of such an event. Nutritional status, genetic predisposition (race/ethnicity), and environmental chemicals are associated with altered age at puberty. The Exposure to Chemical Agents Working Group of the National Children's Study (NCS) presents an approach to assess exposure for chemicals that may affect the age of maturity in children. The process involves conducting the assessment by life stages (i.e., in utero, postnatal, peripubertal), adopting a general categorization of the environmental chemicals by biologic persistence, and collecting and storing biologic specimens that are most likely to yield meaningful information. The analysis of environmental samples and use of questionnaire data are essential in the assessment of chemicals that cannot be measured in biologic specimens, and they can assist in the evaluation of exposure to nonpersistent chemicals. Food and dietary data may be used to determine the extent to which nutrients and chemicals from this pathway contribute to the variance in the timing of puberty. Additional research is necessary in several of these areas and is ongoing. The NCS is uniquely poised to evaluate the effects of environmental chemicals on the age at puberty, and the above approach will allow the NCS to accomplish this task. Key words: children, environmental chemicals, exposure assessment, hormonally active agents, National Children's Study, puberty. doi:10.1289/ehp.7615 available via http://dx.doi.org/[Online 12 May 2005]

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The purpose of the National Children's Study (NCS) is to evaluate the health risks to children in this country from environmental exposures by using a longitudinal cohort design (Children's Health Act of 2000). This effort is expected to improve our children's health by mitigating these health risks in our society. The approach of the NCS is to centralize its activities around hypotheses that evaluate the relationship between a wide array of environmental exposures (i.e., chemical, biologic, physical, and psychosocial factors) and priority health outcomes. The list of priority outcomes includes pregnancy, neurodevelopmental injury, asthma, and obesity and physical development. One of several NCS hypotheses addressing these concerns seeks to evaluate the effects of environmental agents on the age at puberty, which was discussed at an inter-work group meeting co-chaired by the Nutrition, Growth, and Pubertal Development Working Group and the Exposure to Chemical Agents Working Group (Baltimore, Maryland, 17-18 December 2002). This article presents a brief background on the factors associated with the age of maturity and discusses the assessment for exposure to environmental chemical agents in the developing child by using a life-stage approach. The articles in this mini-monograph describe the roles and efforts of the Exposure to Chemical Agents Working Group in the NCS. Portions of this discussion may refer the reader to these other articles for additional information.

Recent evidence suggests that puberty in U.S. children is starting at an earlier age compared with previous years (Anderson et al. 2003; Freedman et al. 2003; Herman-Giddens et al. 1997, 2001). This is of general interest because the extent to which this is occurring in this population has not been well characterized and because such findings have potential influences within our society. In cross-sectional studies of populations in the United States from 1988 through 1994, it is reported that the mean age of onset for breast development for girls was 9.5-9.7 years, which is approximately 1-2 years earlier than the observations of previous investigators (Lee et al. 2001). This approximates to 14% of the population achieving Tanner stage 2 or greater for breast development at the age of 8 years (Lee et al. 2001). In U. …

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