Dieldrin Residue in the Soil and Cucumber from Agricultural Field in Tokyo

Abstract

Soil samples were obtained from 814 farms in Tokyo in 2002. Dieldrin residue was detected in 85 soil samples at concentrations ranging from 0.01 ppm to 2.6 ppm. The residual amount in 70% of dieldrin-positive samples was 0.1 ppm or less. Concentrations of dieldrin residue in cucumbers cultivated in Tokyo exceeded the tolerable level (0.02 ppm) and ranged from 0.02 ppm to 0.1 ppm in 12 of 330 samples. The horizontal distribution of dieldrin in fields was not uniform and the range varied from the quantitative limit (0.01 ppm) to 0.73 ppm. The vertical distribution of dieldrin was also inconsistent. With deeply plowed fields, the vertical distribution was from the surface to a depth of 70 cm, although dieldrin was detected at 30 cm in fields that had not been plowed. As the cucumber roots grew about 1 m in the horizontal and vertical directions, we need to analyze soil samples to a depth of 1 m to prevent dieldrin residue from contaminating cucumbers.

Relationship between dieldrin uptake in cucumber fruits and methanol–water extractable residue in soil

“…2) Although the registration of these insecticides lapsed in 1973, dieldrin is still detected in arable soils, as well as in cucumber fruits, at concentrations exceeding the residue limit (0.02 ppm) set by the Japanese Food Sanitation Law. 3,4) In general, POPs absorbed by plant roots are not usually translocated to above-ground tissue because they have a high n-octanol/water partition coe cient (K ow ) value. 5) Dettenmaier et al 6) found that the transpiration stream concentration factor, which is the ratio of the contaminant concentration in the xylem sap to that in the hydroponic or soil solution surrounding the roots, showed a signi cant negative correlation with K ow .…”

Reduction of dieldrin concentration in cucumber fruits using Cucurbita rootstocks and activated carbon

“…Thus, at present, dieldrin but not aldrin could be found ranging from 0.01 to 2.6 mg/g dw (dry weight) in Tokyo in 2002. 1) Dieldrin is particularly absorbed by cucumber, with concentrations in cucumbers cultivated in Tokyo sometimes exceeding the tolerance level (0.02 ppm) of the Japanese Food Sanitation Law. Understanding the actual residual concentration in cucumber fruits and establishing a method to avoid dieldrin uptake are therefore necessary.…”

Comparative effects of rootstock and scion on dieldrin and endrin uptake by grafted cucumber (Cucumis sativus)

“…Organochlorine pesticides such as DDT, chlordane, mirex, heptachlor, hexachlorobenzene, toxaphene, and the drins categorized as POPs were banned for use on crops in most developed countries by 1990 3) ; however, because of their long persistence, these compounds are still found in soils. [4][5][6][7] The halflives of dieldrin and endrin in soils are relatively long (5-12 years). 8) Therefore, the risk of drin residues being present in crops cultivated in polluted soils might continue for years or decades.…”

“…7,9) In Japan, perhaps because of the high cucumber intake (mean, 11.2 g/day per person), 10) the residue limits in cucumbers are lower than those set by the Codex Alimentarius Commission (aldrin and dieldrin: Ͻ0.1 ppm, endrin: Ͻ0.05 ppm).…”