Crawl space, chlordane residues

Chlordane and heptachlor residues from clay soils from houses constructed with crawl spaces are shown in Table I. Concentrations varied widely. The average level of chlordane in the first 10 cm of soil was 1405-ppm (15 samples) and the average concentration in soil from the 10 to 20 cm depth was 806 ppm (7 samples). In many instances) it was impossible to obtain a 10 to 20 cm depth sample, because of the hardness of the soil, interfering foundation footings, or construction debris which had been buried under many of the dwellings. The amount of heptachlor found in the soil samples averaged 386 ppm from the 0 to 10 cm (11 samples) and 261 ppm from the 10 to 20 cm depth (3 samples). 

Residues of chlordane and heptachlor in air from houses with crawl spaces constructed on clay soils are shown in Table II. The highest chlordane residues found were in the crawl space (8.7 pg/nP) compared to the kitchen (2.3 pg/m ) and bedroom (2.5 pg/m3), Heptachlor residues in air averaged 1.7 pg/m in crawl spaces compared to 0.6 pg/m3 in kitchens and bedrooms. 

Tables III and IV show residue levels of chlordane and heptachlor in soils and air, respectively, from crawl-slab constructed houses built on clay soils. Soil residues of chlordane averaged 1545 ppm (15 samples) from the 0 to 10-cm depth and 861 ppm (five samples) from the 10 to 20 cm depth. Heptachlor levels for the upper and lower soil layers were, respectively 441 ppm (11 samples) and 314 ppm (two samples). As was seen in crawl-space dwelling on clay soils, residues of chlordane were highest in air of the crawl space...

Slab-constructed dwellings were treated prior to the foundation being poured, and soil samples could not be taken. The data for airborne concentrations of termiticides are shown in Table VI. No residues were detected in five of the houses sampled and although the average amount of termitlcide applied was greater than that applied to the crawl-space houses (613 L vs 574 L), average residues in air in the kitchen and bedroom were lower. Residues of chlordane and heptachlor in the kitchens averaged 2.3 and 0.7 pg/m and those for bedrooms were 2.6 and 0.5 pg/m, respectively. 

Air of eight of the rooms sampled during the study contained chlordane residues above the recommended 5.0 pg/m limit. Five of these rooms were from houses treated in 1983, two were from houses treated in 1980, and one was from a 1979-treated house. Both the kitchen and bedroom in a 1983-treated home (crawl-space construction on sandy soil) were higher than the recommended level, while the other six rooms were in six different dwellings. The air concentrations iti these rooms ranged from 5.3 to 9.9 pg/m3. 

Table II. Chlordane and Heptachlor Residues in Air from Houses with Crawl Spaces ...

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