In this study, the value of (DDE + DDD)/DDTs in seafoods
of Shengsi, Putuo, Daishan, and Dinghai ranged from 0.28–0.70
(mean 0.46), 0.37–0.63 (mean 0.49), 0.57–0.83 (mean 0.71), and
0.57–0.89 (mean 0.72), respectively (Table 3). These results
indicate that DDT of seafoods in Dinghai and Daishan mainly
originated from historical usage and degradation had occurred.
However, ratios of (DDE + DDD)/DDTs < 0.5 were found in some
seafoods of Shengsi and Putuo (see Table 3 for details). This reveals
that there are possible fresh inputs of DDTs in these two areas. DDT
is still used as an additive for the production of antifouling paints
used in fishing ships in China