Anne Anastasi
Different types of toxic substances that are present during pregnancy or early post pregnancy environments can have damaging effects on a child's intelligence scores.  A study completed by Michel (1989), Neisser (1996), Streussguth (1994), Vogel (1997), and Vorhess (1987) showed that alcohol, drugs, radiations, lead based paint dust affected the neurological development which contributed to the lower scores of children's intelligence scores.