***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Cross-sectional studies have reported an association between lead ( Pb ) levels in bone and delinquent behavior in later childhood and adolescence . This is the first prospect i ve longitudinal study of Pb and child development to address this question with comprehensive assessment s of toxicant exposure and other developmental cofactors . A prospect i ve longitudinal birth cohort of 195 urban , inner-city adolescents recruited between 1979 and 1985 was examined . Relationships between prenatal and postnatal exposure to Pb ( serial blood Pb determinations ) and antisocial and delinquent behaviors ( self- and parental reports ) were examined . Prenatal exposure to Pb was significantly associated with a covariate-adjusted increase in the frequency of parent-reported delinquent and antisocial behaviors , while prenatal and postnatal exposure to Pb was significantly associated with a covariate-adjusted increase in frequency of self-reported delinquent and antisocial behaviors , including marijuana use . Use of marijuana itself by Cincinnati Lead Study ( CLS ) teens was strongly associated with all measures of delinquent and antisocial behavior . This prospect i ve longitudinal study confirmed earlier clinical observations and recent retrospective studies that have linked Pb exposure with antisocial behavior in children and adolescents . Both prenatal and postnatal exposure to Pb were associated with reported antisocial acts and may play a measurable role in the epigenesis of behavioral problems independent of the other social and biomedical cofactors assessed in this study OBJECTIVE To evaluate the direct effects of prenatal cocaine exposure and prenatal opiate exposure on infant  mental , motor , and behavioral outcomes  longitudinally between 1 and 3 years old . METHODS As part of a prospect i ve , longitudinal , multisite study , the Bayley Scales of Infant Development II were administered to 1227 infants who were exposed to cocaine ( n = 474 ) , opiates ( n = 50 ) , cocaine and opiates ( n = 48 ) , and neither substance ( n = 655 ) at 1 , 2 , and 3 years of corrected age by certified , masked examiners . Hierarchic linear modeling of the 1- , 2- , and 3-year scores was conducted using cocaine and opiate exposure as predictors with and without controlling for covariates . RESULTS Overall retention was 88.4 % and did not differ by cocaine or opiate exposure . Overall ( at 1 , 2 , and 3 years ) , cocaine-exposed infants scored 1.6 Mental Development Index points below infants who were not exposed to cocaine . Opiate-exposed infants scored 3.8 Psychomotor Development Index points below infants who were not exposed to opiates . Neither the cocaine nor the opiate effect remained significant after controlling for covariates . Neither cocaine nor opiate exposure was associated with the Behavioral Record Score during the examination . Low birth weight and indices of nonoptimal caregiving were associated with lower Mental Development Index , Psychomotor Development Index , and Behavioral Record Score scores for all groups of infants . CONCLUSIONS In the largest at-risk sample observed longitudinally to date , infant prenatal exposure to cocaine and to opiates was not associated with mental , motor , or behavioral deficits after controlling for birth weight and environmental risks Abstract .This paper reports on a prospect i ve , longitudinal study of children prenatally exposed to poly-substances , who were reared under minimal postnatal risk conditions . The aim of the study was to examine whether the substance-exposed group exhibited a higher level of attention-related problems than a group of age-matched , nonexposed children . The substance-exposed children ( n = 42 ) evinced significant elevated levels of impulsivity and attention problems on the CBCL and on the ADHD rating scale at ages 2 and 4 1/2 as compared to the non-exposed peers ( n = 50 ) . The severity of the attention problems in the substance-exposed group was related to dysfunction in the area of perceptual performance and motor abilities assessed on the McCarthy scales . This finding lends support to the hypothesis of a neurological basis of the behavioral problems . The combination of attention problems and specific cognitive deficits indicates that the children exposed to poly-substances in utero had symptoms associated with ADHD/DAMP . The study suggests that even if children experience adequate care after birth , the accumulation of risk factors associated with prenatal substance exposure is still a potential contributor to impulsivity and attention-related problems in preschool children A cohort of 1022 consecutive singleton births was generated during 1986 - 1987 in the Faroe Isl and s. Increased methylmercury exposure from maternal consumption of  pilot whale meat was indicated by mercury concentrations in cord blood and maternal hair . At approximately 7 years of age , 917 of the children underwent detailed neurobehavioral examination . Neuropsychological tests included Finger Tapping ; H and -Eye Coordination ; reaction time on a Continuous Performance Test ; Wechsler Intelligence Scale for Children-Revised Digit Spans , Similarities , and Block Design s ; Bender Visual Motor Gestalt Test ; Boston Naming Test ; and California Verbal Learning Test ( Children ) . Clinical examination and neurophysiological testing did not reveal any clear-cut mercury-related abnormalities . However , mercury-related neuropsychological dysfunctions were most pronounced in the domains of language , attention , and memory , and to a lesser extent in visuospatial and motor functions . These associations remained after adjustment for covariates and after exclusion of children with maternal hair mercury concentrations above 10 microgram(s ) ( 50 nmol/g ) . The effects on brain function associated with prenatal methylmercury exposure therefore appear widespread , and early dysfunction is detectable at exposure levels currently considered safe In Amsterdam a longitudinal , prospect i ve and multidisciplinary study on the development of infants of drug‐dependent mothers ( IDDM ) was started in 1983 : 35 IDDM and 35 reference infants were originally enrolled . The drug‐dependent women had used combinations of methadone , heroin , cocaine and other drugs during pregnancy . Of the IDDM , 80 % had to be treated pharmaceutically for neonatal abstinence symptoms ( NAS ) . Physical , neurological , cognitive and the socio – emotional development of the children were studied regularly from birth until 5.5 years of age . Differences between the reference group and the IDDM were found most clearly in cognitive development . The IDDM also had more behavioural problems at some of the ages studied . No group differences were seen in motor development . So far the results of the study show that IDDM and their caregivers need extra support in order to improve early communication and the children 's cognitive development OBJECTIVE To examine the relation of prenatal  polychlorinated biphenyl ( PCB )  exposure to child performance on neuropsychological tests of attention and information processing . Study design In this prospect i ve , longitudinal study , assessment of prenatal PCB exposure was based on umbilical cord serum and maternal serum and milk concentrations . The children were tested in their homes at age 11 years . Multiple regression was used to examine the relation of this exposure to performance on 15 neuropsychological tests after controlling for a broad range of potential confounding variables . RESULTS Adverse effects were seen primarily in children who had not been breast fed . Among these children , prenatal PCB exposure was associated with greater impulsivity , poorer concentration , and poorer verbal , pictorial , and auditory working memory . There was no evidence of visual-spatial deficit or increased hyperactivity . CONCLUSIONS These findings are consistent with earlier reports of greater vulnerability to prenatal PCB exposure in children who were not breast fed . It is not clear whether the protection offered by breast-feeding is caused by nutrients in breast milk or better quality of intellectual stimulation often provided by breast-feeding mothers ABSTRACT . This article presents a Norwegian prospect i ve , longitudinal study of children prenatally exposed to opiates and other substances under conditions of minimal postnatal social risk . Outcome at 4½ years of age is presented . The study reports on the prediction of later intellectual performance , on the basis of the children ’s prenatal , perinatal , and early developmental status , as well as the foster or adoptive parents ’ socioeconomic level . Significant differences were found between the substance-exposed group and the comparison group on the Bayley Scales at age 1 year and on the McCarthy Scales at age 4½ years . The findings showed that although the mean cognitive scores were within normal limits at age 4½ years , a special weakness in the area of visual-motor and perceptual abilities was detected among the substance-exposed children . It is indicated that these areas of performance are especially sensitive to the effect of prenatal adversity . A special vulnerability among the substance-exposed boys , detected at an earlier age , persisted at 4½ years . The study indicates that even if children experience adequate caregiving , the accumulation of biomedical risk factors associated with prenatal substance exposure is still a potential determinant of developmental problems , especially in the area of perceptual-performance functions . The study also hints at differential influences of biomedical and environmental variables on outcome at age 4½ years The association between early lead exposure and later problem behaviors was evaluated prospect ively in a cohort of 8-year-old children born during a 12-month period at one hospital .  Lead levels in umbilical cord blood  ( means = 6.8 micrograms/dl , SD = 3.1 ) and the dentin of a shed deciduous tooth ( means = 3.4 micrograms/g , SD = 2.4 ) provided measures of prenatal and postnatal exposure , respectively . Ratings on the Teacher Report Form of the Child Behavior Profile provided information about children 's problem behaviors . Cord blood lead level was not associated with the overall prevalence or nature of problem behaviors . In both crude and adjusted analyses , tooth lead level was significantly associated with total problem behavior scores ( approximately 2 points in T score per log unit increase in tooth lead ) . Significant tooth lead-associated increases in both internalizing and externalizing scores were also observed ( approximately 1.5 points in T score per log unit increase ) . Weaker associations were noted between tooth lead level and the prevalence of " extreme " problem behavior scores . The extent to which these associations reflect residual confounding is uncertain . These data suggest , however , that social and emotional dysfunctions are correlates and may be expressions of increased lead exposure OBJECTIVE This study was undertaken to determine the effects of repeated courses of antenatal corticosteroids on  childhood behavior and disabilities , including cognitive delay and cerebral palsy . STUDY DESIGN Nonr and omized regional cohort of 541 very preterm infants born in Western Australia from singleton pregnancies and alive at 3 years were included in the study . MAIN OUTCOME MEASURES Physical , cognitive , and psychological assessment s up to 6 years . RESULTS Increasing numbers of antenatal corticosteroid courses were associated with a reduction in the rate of cerebral palsy . Three or more courses were also associated with increased rates of aggressive/destructive , distractible , and hyperkinetic behavior and these effects were present at both ages 3 and 6 years . Measures of internalizing behavior and intelligence quotient were unaffected by antenatal corticosteroid use . CONCLUSION Repeated antenatal courses of corticosteroids may protect against cerebral palsy but are associated with hyperactivity later in childhood Prenatally  irradiated children ( n = 544 ) , who were born between 26 April 1986 and 26 February 1987 , in regions of the Ukraine which were radioactively contaminated as a result of the Chernobyl disaster , their mothers and teachers have been examined with psychometric tests .  The control group of relevant children ( n = 759 ) , their mothers and teachers , were living at the radioecological ' clear ' regions ( Kharkov and Kharkov Region ) . Further , we r and omly selected 50 prenatally irradiated children whose mothers were evacuated from the Chernobyl exclusion zone and 50 age- and -gender-matched non-exposed children . At this phase clinical examinations ,  psychometric tests , computerized EEG , thyroid function assessment and dosimetric reconstruction  were used . We found a significant increase in mental retardation ( IQ < 70 ) and of borderline and low range IQ , as well as emotional and behavioral disorders and a decrease in high IQ ( IQ > 110 ) in children irradiated in utero as a result of the Chernobyl disaster , in comparison with the controls . One important biological mechanism in the genesis of mental disorders in prenatally irradiated children is the radiation-induced malfunction of the thyroid-pituitary system with the effect threshold of 0.30 Sv of thyroid exposure dose . We hypothesize that the cerebral basis of mental disorders in the prenatally irradiated children is the malfunction of the left hemisphere limbic-reticular structures , particularly in those exposed at the most critical period of cerebrogenesis ( 8 - 25 weeks of gestation ) . The data obtained reveal mental disorders in prenatally irradiated children and obviously reflect developmental abnormalities of brain structure and function as a result of the interaction of prenatal and post-natal factors where it is possible to assume radiation effects on the developing brain . A follow-up study of the children irradiated in utero , who may be at risk for schizophrenia , is proposed because of its particular importance to clinical medicine and neuroscience Abstract Objective : To examine the association between environmental exposure to lead and children 's intelligence at age 11 - 13 years , and to assess the implication s of exposure in the first seven years of life for later childhood development . Design : Prospect i ve cohort study . Subjects : 375 children born in or around the lead smel 
    Output:
    
However , some findings are consistent .
Lead and PCB ’s have a general effect on brain development , whilst marijuana and alcohol appear to have long-term effects specifically on attentional skills .
The effects of alcohol increase with maternal age and binge drinking is more important than average intake .
The effects of cocaine diminish with age and are largely mediated through psychosocial factors , whilst the relation between smoking and later delinquency is largely mediated by genetically inherited factors .
Exposure to toxins during pregnancy may constitute an important but relatively unacknowledged cause of child psychiatric morbidity