Attention, activity level, and lead exposure at 18 months

The relation of low-level prenatal lead exposure to behavioral indicators of attention in Inuit infants in Arctic Quebec

“…Other studies have also found observed behavioral outcomes from video recordings to be highly sensitive in detecting subtle effects of low-level Pb exposure [15,19,35,55]. In the structured settings of the BSID-II administration, our visual inattention measures appeared to provide a natural assessment of the inability to maintain focus and alertness over time, an aspect of behaviour often referred to as sustained attention [48].…”

“…By contrast, a large literature has documented adverse effects of low-level postnatal Pb exposure on various aspects of preschoolers and school-age behavior including activity, attention, anxiety, sleep disturbances, and conduct disorders [11,15,19,31,35,55,66,74,75]. In most studies, the postnatal exposures are substantially higher than the prenatal exposures [55] which may make it more difficult to detect the possibly subtler effects of the lower level prenatal exposure. Examining the effects of prenatal exposure on behaviors that occur very early in development using highly sensitive direct behavioural observation measures may make it possible to detect these subtler effects.…”

“…Moreover, when children with cord blood Pb levels higher than 10 μg/dL were removed from the analysis, observed attention continued to be associated with Pb exposure (F = 2.94, r 2 = .10, p = .03, n = 69; std β for Pb = .22, p= .06). One limitation is that only prenatal level of exposure was available in our cohort, whereas most of the behavioral effects found in the literature originate from postnatal exposure [4,15,19,25,35,47,53,55,66,74,75]. Blood Pb isotope studies indicate that sources of Pb in the southern population of Quebec include a mixture of atmospheric Pb coming from southern Ontario and the USA and urban Pb found in paint, dust, tires, etc [58].…”

“…Based on previous studies on the influence of Pb exposure on child behavior [35,36,55], two summary measures of visual attention were constructed: off task duration, which was defined as the proportion time the child looked away from the test material and tester during the task and off task latency, which was derived by summing the time (in sec.) that lapsed between the initial presentation of each object and the child's initial look away from the object and tester divided by the total number of objects presented.…”

“…In the relatively few studies that have examined effects on behaviour in childhood, low-level prenatal Pb exposures have not been associated with detectable adverse effects [4,55,75]. By contrast, a large literature has documented adverse effects of low-level postnatal Pb exposure on various aspects of preschoolers and school-age behavior including activity, attention, anxiety, sleep disturbances, and conduct disorders [11,15,19,31,35,55,66,74,75]. In most studies, the postnatal exposures are substantially higher than the prenatal exposures [55] which may make it more difficult to detect the possibly subtler effects of the lower level prenatal exposure.…”