The aim of this study was to examine the effects of perinatal lead exposure on locomotor responding following acute and repeated cocaine challenges (sensitization).Lead poisoning continues to present major health concerns nationwide, and this situation is especially problematic among children. Recent sociodemographic data indicate the threat of lead toxicity is especially great among economically disadvantaged, nonwhite, and inner-city children (Goldman and Carra 1994;Pirkle et al. 1994). Along these lines, a 1999 report alarmingly places the "at risk" figure for children suffering from excessive lead exposure at around 70% in major metropolitan areas of the United States (cf., Mielke 1999).The sizable literature on developmental lead poisoning understandably has focused on global disturbances produced by early contaminant exposure that may have an enduring impact on the quality of life. In this sense, the data are compelling with respect to showing that even low-level lead exposure during development can occasion long-lasting neurobehavioral disturbances that compromise adult adaptive abilities and threaten stability. In this regard, functional deficits in cognitive and intellectual processing have been shown to persist well into the adult cycle of humans, rodents, and nonhuman primates (e.g., Bellinger et al. 1987). In addition, it seems that even emotional expression and attendant psychosocial phenomena may be influenced by lead ex- N EUROPSYCHOPHARMACOLOGY 2000 -VOL . 23 , NO . 4 Developmental Lead Exposure and Cocaine 445 posure during early development (Needleman et al. 1996).In the present report, our objective was to investigate interactive relations between developmental lead exposure and drug sensitivity later in the life cycle. This is an especially pertinent issue given that lead uniquely threatens sub-populations where drug abuse is more common, i.e., urban minorities . Clearly, experiential elements, availability, drug history, poverty, etc., must be considered in the list of dispositional factors that determine drug habits in humans. But it also must be considered that other types of environmental events may contribute to the abuse potential of selective drugs. That is, to the extent that lead or any other xenobiotic chemical alters the impact of a set delivery of a drug, motivational features related to drug seeking and taking may be redefined and therein influence maintenance responding and/or the effectiveness of certain pharmacotherapies for drug abuse (Mello et al. 1995).The development of behavioral sensitization during repeated administration of psychomotor stimulants is a well-characterized phenomenon which has received considerable attention because of its proposed relevance to drug addiction (Robinson and Berridge 1993;Wise and Bozarth 1987;Wolf et al. 1995) and psychosis (Post et al. 1992;Segal and Schuckit 1983). Therefore, the procedure was employed here in an effort to determine the effects of lead exposure during lactation and gestation on cocaine-induced changes in locomotor re...