Update: Although this article was published three years ago, very little cleaning has occurred, and
many houses in the Vernon/Boyle Heights/East Los Angeles area have soil lead concentrations
greater than 300ppm that haven't been cleaned. The maximum level was changed to 300ppm, but
that's still much higher than the state maximum of 80ppm. In addition, houses that have soil lead
concentrations between 80ppm and 300ppm are still at dangerous levels, but are not scheduled to be
cleaned. -Williams
Figure 1: Lead effect on IQ and Socioeconomic Status.
Change in full-scale IQ by childhood blood lead levels
6
Change in socioeconomic status by childhood blood lead levels
1.0-
Change in Full-Scale IQ
Score Between Childhood
and Age 38 y
3
0
3
Change in Socioeconomic
Status Between Childhood
and Age 38 y
-0.5-
0.5
-6
-1.0
$5
6-10
11-15
>15
≤5
6-10
Blood Lead Level at Age 11 y, pg/dL
11-15
Blood Lead Level at Age 11 y, ug/dL
>15
No. of participants 31
260
168
74
No. of participants 31
262
170
78
I

3. According to figure 1, if the blood concentration of lead of a child is more than 15 micrograms per
deciliter, what is the average effect on IQ as an adult?