In addition, it is easy to assume that the child has experienced no additional deleterious exposures, especially with longitudinal studies involving the initial study cohort. Other studies take an analytical epidemiological approach, investigating health changes over a period of time. This avoids single agent paradigms, instead substituting environmental change as the causative factor. Also, each population under study incorporates a host of varied biological, social, and technological factors that influence the environment. An Expanded Approach for evaluating Preschool Children Exposed to Multiple Pesticides Much of our knowledge about the physiological mechanisms of pesticides that lead to detrimental effects is the result of wildlife and laboratory studies.
Additional exposure can continue after birth.
Although blood levels of pesticides indicate their presence in the body, there is no readily available means to identify when an individual was first exposed to a single compound or mixture of chemicals or the degree of exposure occurring during critical periods of embryonic or neonatal development. Additionally, it is difficult to establish reliable temporal exposure patterns for most individuals. Therefore, it is important to select a study population in which all mothers and their children experience relative equality in their contact with pesticides. Only then can it be assumed that the children under study have a similar probability in their timing of exposure and levels of exposure to similar mixtures of pesticides-both in utero and following birth. In turn, the reference population must meet the requirement of sharing minimal exposure to the ambient contamination.