James R. Sanborn

The fate of dieldrin in a model ecosystem

The current interest in environmental quality has stimulated research into the nature and persistence of agricultural chemicals and their metabolites. The widespread occurrence of undesirable residues from the ubiquitous use of the chlorinated hydrocarbons as pest control agents, particularly DDT, has resulted in the gradual termination of these materials as environmentally unsuitable insecticides in the United States. To insure that future pest control agents or their degradation products are not persistent and therefore undesirable, an initial screening must take place before they are put into large-scale use. The development of a model ecosystem (Metcalfet al. 1971) clearly establishes a means for evaluation of the environmental suitability of currently employed pesticides as well as those in developmental stages. As a part of a continuous program to investigate the effects of pesticides on the environment, the fate of dieldrin has been examined in a model ecosystem.

The fate of parathion in a model ecosystem.

ConclusionFrom the data presented in this paper, it is concluded that parathion does not accumulate to any appreciable extent in any of the organisms of this data to environmental situations is reasonable, as there has not been any indication of accumulation of organophosphate insecticides by upper food chain organisms such as fish. The chemical properties of parathion, such as the susceptibility to degradation by physical, chemical, or biological means to polar products, readily account for the low accumulation of parathion by the aquatic organisms of this ecosystem. It appears that the continued use of parathion for insect control will not result in the ubiquitous environmental contamination which has occurred with the use of chlorinated hydrocarbons, such as DDT.

Plasticizers in the environment: The fate of di-n-octyl phthalate (DOP) in two model ecosystems and uptake and metabolism of DOP by aquatic organisms

The fate of the plasticizer, di-n-octyl phthalate (DOP) has been examined in 33-day terrestrial-aquatic and three-day aquatic model ecosystems. The five organisms of the two systems contained residues of DOP, demonstrating the propensity of this lipoid soluble organic molecule to be concentrated from the water. The residues in the organisms in the three-day system were higher than in the 33-day system with the exception of the fish, indicating perhaps, that DOP can undergo some degradation before the fish is placed in the system on the 30th day. A half-life of five days for DOP disappearance from the water was calculated from water samples taken periodically. Further, effects of mixed function oxidase and esterase inhibitors were investigated on the metabolism of DOP by various selected organisms and tissues of the two ecosystems.

Composition of fatty acids in Culex pipiens quinquefasciatus: a developmental study

Abstract In anticipation of antioxidants affecting the lipid content, uptake, or metabolic biosynthesis within the mosquito Culex pipiens quinquefasciatus , a preliminary study was conducted to determine the background quantities of total fatty acids found in the 4th instar larvae, 1-day and 2-day ‘pupae’ (pharate adults) reared on two different diets. It was found that the preponderant fatty acid detected was palmitoleic acid (16:1), which accounted for 40% of all fatty acids present. The greatest amount of saturated fatty acid was palmitic acid (16:0) which constituted 82% of the saturated fatty acids and 21% of the total fatty acids. About 16% of the total percentage of fatty acids was myristoleic acid (14:1). It was 21% of the unsaturated fatty acids. The approximate ratio in all categories of unsaturated-saturated fatty acids was 3:1. There were no abrupt fluctuations in percentage composition of fatty acids over the developmental period studied, nor did the ratio of unsaturated-saturated change appreciably.