Boucher et al. reinforcement of low rates (DRL) schedules may be sensi- tive to low-level polychlorinated piphenyl, methylmercury, and lead exposure in children. Environ Health Perspect 114:1923–1929. Van Der Meulen BF, Smorkovsky M. 1985. MOS 2 1/2-8 1/2 McCarthy Ontwikkelingsschalen. Lisse, the Netherlands:Swets & Zeitlinger. Van Eldik MCM, Schlichting JEPT, Lutje Spelberg HC, Van Der 2004a. Effects of perinatal exposure to PCBs on neuro- psychological functions in the Rotterdam cohort at 9 years of age. Neuropsychology 18:185–193. Vreugdenhil HJI, Van Zanten GA, Brocaar MP, Mulder PGH, Weisglas-Kuperus N. 2004b. Prenatal exposure to poly- chlorinated biphenyls and breastfeeding: opposing effects on auditory P300 latencies in 9-year-old Dutch children. Dev Med Child Neurol 46:398–405. Meulen BF, Van Der Meulen S. 1995. Reynell test voor Walkowiak J, Wiener JA, Fastabend A, Heinzow B, Krämer U, Taalbegrip. Vol 1. Nijmegen:Berkhout. Vreugdenhil HJI, Lanting CI, Mulder PGH, Boersma ER, Weisglas-Kuperus N. 2002. Effects of prenatal PCB and dioxin background exposure on cognitive and motor abili- ties in Dutch children at school age. J Pediatr 140:48–86. Vreugdenhil HJI, Mulder PGH, Emmen HH, Weisglas-Kuperus N. Schmidt E, et al. 2001. Environmental exposure to poly- chlorinated biphenyls and quality of the home environ- ment: effects on psychodevelopment in early childhood. Lancet 358:1602–1607. Wechsler D. 1949. Manual for the Weschler Intelligence Scale for Children. San Antonio, TX:Psychological Corporation. Wechsler D. 1974. Wechsler Intelligence Scale for Children- Revised. New York:Psychological Corporation. Wechsler D. 1991. Manual for the Wechsler Intelligence Scale for Children. 3rd ed. San Antonio TX:Psychological Corporation. Winneke G, Bucholski A, Heinzow B, Krämer U, Schmidt E, Walkowiak J, et al. 1998. Developmental neurotoxicity of polychlorinated biphenyls (PCBs): Cognitive and psycho- motor functions in 7-month old children. Toxicol Lett 102–103:423–428. Woodcock RW. 1987. Woodcock Reading Mastery Tests- Revised for Form G. Circle Pines, NM:American Guidance Service. 16 ovlume 117 | number 1 | January 2009 • Environmental Health Perspectives