Octachlorodipropylether residue in polished rice stored in houses during termite treatment and its fate during the cooking process

Abstract

Exposure to a organochlorine synergist, 2,3,3,3,2',3',3',3'- octachlorodipropylether (S-421) in inhabitants of two houses (A and B) treated for termite control was evaluated by examining the residue levels in rice. Polished rice left exposed to air for a week under the sink in the kitchen adsorbed S-421 to the extent of 0.0009 to 0.0091 mg/kg (house A), or 0.22 to 0.58 mg/kg (house B). The level of S-421 in polished rice depended on the season, being high in summer and lower in winter. The clearance rate of S-421 from polished rice during the cooking process was found to be 71 percent overall. Sixty three percent was due to washing of the rice grains with water and 8 percent was due to subsequent heating of the washed rice in an electric rice cooker. Daily intake of S-421 from rice was estimated approximately to be 0.2 μg (house A) or 45 μg (house B). S-421 concentration in the ambient air of the dining room (1F) of house B was around 0.25 μg/m3 throughout the year.