The most heavily exposed groups included occupants of buildings, passersby, residents of lower Manhattan, and early responding rescue/recovery workers.
This translated roughly into a nine-point drop in Verbal IQ from the least to the most highly exposed groups.
Currently, the mean doses to the most heavily exposed groups are 1/10,000 or less of the mean overall effective dose from all sources.
A recent human health risk assessment (U.S. EPA 2004) found that land application of sewage sludge would lead to a negligible increase in cancer cases even among the most highly exposed groups.
The most highly exposed groups may share common trajectory patterns, for example those with commuter/work patterns that have the highest health risk (e.g., professional drivers, traffic police and construction workers, etc).
The highest mean doses to the most heavily exposed groups living in the vicinity of Finnish NPPs were estimated in the 1980s, and they were about 1/1,000 of the annual effective dose received from other sources [ 27, 28].
Concentrations of cadmium in urine (mean 2.0 nmole/mmole creatinine) and blood (mean 21.8 nmole/L) observed in the smelter workers confirmed that this group had absorbed more cadmium than the general population, but less than most other occupationally exposed groups studied.
The relative rates of developing OAD for the most highly exposed group compared with the least exposed group were 3.96 (95% confidence interval (CI): 2.51, 6.26) during the first 15 months after September 11 , 2001 and 1.76 (95% CI: 1.26, 2.46) after 15 months (Table 2).
Within the exposure ranges of this study, this translated roughly into a six- to seven-point decline in Full Scale IQ from the least exposed group (average of 0.75 ng/g) to the most highly exposed group (average of 3.15 ng/g PCB).
