Organochlorine pesticide concentrations in perinatal samples from mothers and babies.

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.

Absence of residues from crops irrigated with water treated with trifenmorph for schistosomiasis control.

The fate of the molluscicide trifenmorph (N-tritylmorpholine) following its use in irrigation systems to control the intermediate hosts of schistosomes was studied by laboratory and field experiments. Laboratory studies with (14)C-trifenmorph indicated that bean plants did not take up detectable residues when the soil in which they were grown was irrigated with water containing trifenmorph in concentrations likely to occur in the field. These laboratory studies have been complemented by field irrigation studies of growing crops in southern Africa and the Sudan. Residues of trifenmorph and its breakdown product triphenylmethanol could not be detected in the crops and the limit of detectability was 0.01-0.02 ppm. These results indicate that residues are not likely to be present in irrigated crops following the treatment of the irrigation water systems with trifenmorph.

Analytical methods for the determination of the molluscicide N-tritylmorpholine in water.

A colorimetric method has been developed for the determination of the molluscicide N-tritylmorpholine (Frescon, WL 8008) in water. The method is based on the production, from N-tritylmorpholine in strong acid, of the typical yellow colour of the tritylcarbonium ion.Two procedures are recommended for field use, neither of which distinguishes between N-tritylmorpholine and its hydrolysis product triphenylcarbinol (triphenylmethanol). A more precise laboratory procedure is described, by means of which both N-tritylmorpholine and triphenylcarbinol can be determined separately.

The rate of hydrolysis of the molluscicide N-tritylmorpholine.

N-Tritylmorpholine (Frescon, WL 8008) shows promise for the control of the snails that are intermediate hosts of trematodes. A knowledge of the rate of hydrolysis of the compound is important in connexion with its field use, and the rate of hydrolysis of (14)C-N-tritylmorpholine has been found to be dependent on the pH of the water and on the initial concentration of the compound. This rate is relatively high at low pH values (< 7.0), but decreases logarithmically as the pH increases.A prolonged low-dosage technique has been developed for the application of N-tritylmorpholine to irrigation systems. The present results indicate that, under these conditions, effective control of the snails is likely to be achieved in water of pH > 7.5, whereas in water of pH < 7.0 the compound is unlikely to penetrate very far downstream before losing its molluscicidal activity. In waters in the pH range 7.0-7.5 the use of higher concentrations and shorter application times may be desirable.

Break-down of the molluscicide N-tritylmorpholine in soil and in rice.

The molluscicide N-tritylmorpholine (Frescon, WL 8008) is likely to be applied to flowing water systems in bilharziasis control programmes. The treated water in irrigation systems will sometimes be applied to growing crops, such as rice, and the nature of the terminal residues of N-tritylmorpholine in rice has therefore been investigated.Crops were grown under greenhouse conditions in soil treated with water containing (14)C-and(3)H-N-tritylmorpholine, using dosage levels very much greater than those that will generally be used in the field. The major radiocomponent in the rice plants was triphenylcarbinol (triphenylmethanol), together with smaller amounts of unchanged N-tritylmorpholine and o-, m-, and p-hydroxytriphenylcarbinol. The hydroxytriphenylcarbinols were present as the free hydroxy compounds and as plant conjugates.Residues of the parent molluscicide and its break-down products are not considered likely to present a toxic hazard to animals or men that eat the crops.