All the figures shown on the chart are parts per
million. WARF Institute's procedures for determining chlorinated hydrocarbon
residues are in the "FDA Pesticide Analytical Manual," Volume 1, Jan.
1968, sections 212 and 311. The mercury analysis follows "The Analyst,"
Volume 86, page 608, 1961, modified by Atomic Absorption Spectrophotometry with
Note: DDT residues are a combination of DDT, DDE and
DDD. The U.S. Food and Drug Administration has set no tolerance standards for
BHC or PCB residues in human food.