Postnatal damage

The most reasonable explanation of the results is that among poor children genetic differences contribute almost nothing to the measured IQ variance because environmental damage, both fetal and postnatal, overwhelms all other variables in accounting for IQ variation. In contrast, in the middle and upper classes, in which fetal and postnatal damage to the nervous system is much reduced and hardly variable from one family to the next, genetic differences account for most of the variation in IQ. 

Miller TJ, Hanson RD, Yancey PH (2000) Developmental changes in organic osmolytes in prenatal and postnatal rat tissues. Comp Biochem Physiol A Mol Integr Physiol 125(l) 45-56 Naqvi NH, Rudrauf D, Damasio H, Bechara A (2007) Damage to the insula disrupts addiction to cigarette smoking. Science 315(5811) 531-534... 

The aims of testing for genotoxicity are, therefore, to assess the potential of a substance to be a genotoxic carcinogen, or to cause heritable damage in humans, which can be manifested as impaired male and/or female fertility, or adverse effects on fetal or postnatal development. 

Prenatal and early postnatal diazepam exposure was shown to induce gliosis and perivascular cuffing in the brains of 45- to 64-day-old rats suggesting inflammatory processes and direct cell damage. These changes were possibly a consequence of effects of diazepam on the immune system or blood-brain barrier (ref. 67). 

Biomarkers do not measure exposure directly, but are an indicator of absorbed dose. A biomarker of exposure is defined as a xenobiotic substance or its metabolite(s) or the product of an interaction between a xenobiotic agent and some target molecules(s) or cell(s) that is measured within a compartment of an organism and can be related to exposure. Urine, blood, nail, saliva, hair, and faeces are common media collected for biomarker measurements. Maternal biomarkers of exposure can also be measured in amniotic fluid and breast milk. These matrices can also provide a measure of exposure for children, both prenatally and postnatally. Biomarkers in first teeth have also been used to assess early childhood exposure, whereas biomarkers in meconium and cord blood have been used to assess in utero exposures. Biomarkers of genetic damage (e.g. DNA adducts) have been extensively used to assess exposure to genotoxic agents (Neri et al., 2006). 

Fertility and early embryonic development rats Developmental rats, rabbits Prenatal and postnatal development rats Genetic toxicology Ames test, gene mutations in mammalian cells grown in vitro (mouse L5178Y cells), and chromosomal damage in intact animals (bone marrow cells in rats)... 

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