posted on 2005-06-15, 00:00authored byXinghua Qiu, Tong Zhu, Bo Yao, Jianxin Hu, Shaowen Hu
High DDT concentrations and o,p‘-DDT/p,p‘-DDT ratios
observed in the air over Taihu Lake, a lake near Shanghai,
China, led us to suggest that current use of dicofol in
the area north of the lake was the main source of the
measured DDTs. To examine this hypothesis, samples of
commercially available formulated dicofol in China
were collected in 2003 to measure the impurities of DDT
related compounds (DDTs). The o,p‘-DDT/p,p‘-DDT ratio in
the samples was 7.0, close to the observed value in the
air over Taihu Lake. Average contents of o,p‘-DDT, p,p‘-Cl-DDT, o,p‘-DDE, and p,p‘-DDT in the samples were 114,
69, 44, and 17 g per kg dicofol, respectively. On the basis
of a production and distribution survey, total input of
DDTs to the environment from the dicofol use in China
was estimated to be 8770 t between 1988 and 2002. “Dicofol
type DDT pollution”, defined as DDT pollution caused by
dicofol use and characterized with high o,p‘-DDT/p,p‘-DDT
ratio, might be serious in China, especially in southern
and eastern China. The conversion of p,p‘-Cl-DDT to p,p‘-DDE can lead to high p,p‘-DDE/p,p‘-DDT ratio and could
mislead the evaluation of p,p‘-DDT resident time in
the environment. Therefore, more studies on p,p‘-Cl-DDT
in the environment are needed.