Abstract
In our previous investigation of dietary intake of chlordane (CHL), it was found that foods prepared in the houses which had undergone termite treatment were contaminated with CHL at levels 2 to 20 times higher than foods cooked in non-treated houses. Moreover, the pattern of 6 CHL components detected in foods from treated houses was very specific, indicating fresh contamination with technical CHL. Focusing on these results, further investigations were carried out in order to clarify the route of human exposure in the treated houses.
Polished rice was left exposed to the air for 7 days under the sink in the kitchen of 3 treated houses. A high concentration of CHL (0.34ppm) was detected in the sample from the house which had been treated about one year before. In this house, the major route of dietary intake of CHL was inferred to be polished rice.
The clearance rate of CHL from polished rice during cooking was found to be 64 percent overall. Fifty-two percent of the decrease was due to washing and 12 percent was due to boiling of the rice.
Levels of atmospheric CHL in the treated houses varied over a wide range even at the same duration after termite control. In the house which gave the polished rice with 0.34ppm of CHL, however, atmospheric CHL under the sink was also very high compared to 4 other treated houses examined. CHL was not detected in air samples from non-treated houses.
In the non-treated houses, fishes were the main source of human exposure to chlordane, as in the cases of PCB and DDT complex. On the other hand, rice and the inhalation of atmospheric CHL are the two major sources of human exposure in treated houses, and the exposure level through the former route is inferred to be almost the same as that of the latter or even a little higher, when the rice was stored under the sink in the kitchen or under the floor.
Daily intakes of CHL in the treated houses were evaluated in comparison with the value of acceptable daily intake (ADI) proposed by FAO/WHO. Measures for the prevention of CHL exposure of humans in treated houses have also been suggested.
