Crops and soils from field trials in 1967-1970 in several countries have been analysed for residues of the triazine herbicide cyanazine ('BLADEX'" or 'FORTROL'"' 2-chloro-4-(l-cyano-1-methylethylamino)-6-ethylamino-l,3,5-triazine) and for its degradation products 2-chloro-4-( l-carbamoyl-l-methylethylamino)-6ethylamino-1,3,5-triazine (11), 2-chloro-4-( 1-cyano-1 -methylethylamino) -6-amino-l,3,5-triazine (V) and 2-chloro-4-(1-carbonyl-l-methylethylamino)-6amino-l,3,5-triazine (VI).The time for the concentration of cyanazine in soils to fall to half the initial value was in the range 1.3 to 5 weeks with a mean value of 2.4 weeks. The rate of loss was not affected by sparse crop cover and there was some indication that the rate was greater under moist soil conditions.Residues of up to 0.5 part/million of (11) and up to 0.08 part/million of (VI) were detected in soils at 4 weeks from cyanazine application at 2 kg/ha. The residues of cyanazine and the degradation products declined rapidly and were 0.07 part/million or less at 16 weeks from treatment. Repeated annual applications did not lead to a detectable build up of residues in soil.Neither residues of cyanazine nor those of (11), (V) or (VI) could be detected in a wide range of crops harvested from soil treated in accordance with the likely recommendations and the limits of detectability were 0.01 to 0.04 part/million.

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Methods have been developed for the analysis of residues of a new soil insecticide, diethyl 1-(2,4-dichlorophenyl)-2-chlorovinyI phosphate (SD 7859, Birlane*) in a range of crops and soils. Enzyme inhibition procedures using plasma and fly-head cholinesterases and gas-liquid chromatography (GLC) can be used for the measurement of Birlane in crop and soil extracts down to a level of 0.01 pg/ml which corresponds to 0.02 ppm in the original sample at the normal sample/solvent ratios that are used.Treated soils may be stored for at least one month at -10" without decomposition of the Birlane residues and Birlane in solvent extracts is stable for at least one month at 0". Extraction procedures have been investigated using chloroform and acetone-hexane mixtures with different extraction times.Recoveries of Birlane average 95 "/, from soils at the 0.2-1 .O ppm level and average 100% from a range of crops at the 0.05-0.10 ppm level. Without clean-up, blank values of soil extracts can approach 0 . 2 ppm (using GLC) but are generally 0.05 ppm or less in crops apart from carrots. The interference, however, can readily be removed using column chromatography.

Crops and soils from a large number of field trials have been analysed for residues of 2,6dichlorothiobenzamide (chlorthiamid) and for residues of 2,6‐dichlorobenzonitrile (dichlobenil). The thiobenzamide is converted to the benzonitrile after application to the soil and only a small percentage of the material applied initially remains unchanged after 4 weeks. However, both the benzonitrile and the thiobenzamide are of similar low mammalian toxicity. The initial half‐life of the ‘total nitrile’ residues (the thiobenzarnide + the benzonitrile) is, on average, near 4 weeks but varies from 1 to 12 weeks depending on the locality, soil type, climate, dosage level and formulation. The penetration of the herbicide into soils of different types is considered and it is shown that in sand, loam, and clay, residues in the 4–12 in. layer are less than 10% of the residue at the same time in the 0–4 in. layer. Residues of the thiobenzamide and the benzonitrile could not be detected in a very wide range of crops (other than rice) harvested at 2–6 months after soil applications of the thiobenzamide at 1–16 lb/acre. In rice grains, where the plants can be in intimate contact with the herbicide, the ‘total nitrile’ residues did not exceed 0·05 ppm.

Samples were obtained from Dutch mothers and their babies throughout the perinatal period and analyzed by gas-liquid chromatography with electron-capture detection for a range of organochlorine pesticides. Organochlorine concentrations in the blood of breast or bottle-fed babies were not significantly different. Differences in organochlorine concentrations in blood between mothers who had "slimmed" and those who had not were small, but it must be noted that there were few slimming mothers in our sample. Twelve to 21% and 36-61% of the estimated daily intake of dieldrin and DDT, respectively, by mothers may be eliminated by lactation. The placenta restricts the transmission of organochlorine pesticides to the fetus to some extent. The very low concentrations of organochlorine in fetal blood prevented a study of the comparative metabolism in mothers and babies.