C. C. Roan

Interaction of pesticides with aquatic microorganisms and plankton

The interactions of pesticides 1 and soil microorganisms are heavily documented from the agricultural view. Many of the same soil particles, microorganisms, and pesticides are found in freshwater and estuarine ecosystems, and similar relationships may exist. It is the purpose of this paper, then, to review the interactions of pesticides and aquatic microorganisms, those microscopic plants and animals found in freshwater, estuarine, and marine environments.

Urinary Excretion of DDA Following Ingestion of DDT and DDT Metabolites in Man

Oral doses of DDT (5, 10, 20 mg/day) DDE, DDD, and DDA (5 mg/day) administered to human volunteers are, in part, excreted as DDA in the following order: DDA>DDD>DDT. Ingestion of DDE failed to produce any increase of DDA excretion. Increased urinary DDA excretion is detectible within 24 hours of DDT, DDD, or DDA ingestion. DDA excretion returns to predose levels within two to three days of dose termination for DDA but continues significantly above predose levels for over four months following termination of DDD or DDT doses.

Liver function in workers having high tissue stores of chlorinated hydrocarbon pesticides.

Five serum enzyme activities and urinary d-glucaric acid excretion were measured in 56 controls and 71 pesticide-exposed subjects to determine whether workers with large tissue stores of DDT and dieldrin show signs of liver cell injury or induction of drug-metabolizing enzymes. Although serum concentrations of these chlorinated hydrocarbons in many workers exceeded by far those found in persons not occupationally exposed to pesticides, only small, equivocal differences in serum enzyme activities were observed. Urinary excretion of d-glucaric acid was unrelated to serum concentrations of either DDT, DDE, or dieldrin.

Safety Evaluation in the Home of Polyvinyl Chloride Resin Strip Containing Dichlorvos (DDVP)

In a period of two years a series of three-home studies involving 26 families in Arizona was conducted to further evaluate the safety of the dichlorvos (DDVP)- containing insecticide strip. Physical examination, hematologic and clinical chemistry measurements, blood cholinesterase assays, and analysis of air and food for dichlorvos were carried out. Exposures were designed to be exaggerated in that strips were used throughout the homes (averaging 7 to 11 per home) and replaced with fresh ones, either every three months for one year or monthly for six months. Throughout the studies, all examinations and measurements revealed no adverse effect on health. The red cell cholinesterase activity also remained unaffected. A slight plasma cholinesterase depression of no toxicological importance was observed in the study where the strips were replaced monthly over six months. In homes containing 8 to 18 strips, maximum air and food concentrations of dichlorvos averaged approximately 0.13 mg/cu m and 0.12 ppm, respe...

Renal function in persons occupationally exposed to pesticides.

Kidney-function tests carried out on 42 pesticideexposed and 23 control subjects failed to identify chronic occupational differences in glomerular function, or in tubular reabsorption of phosphate or total α amino acid nitrogen. In one case of acute organophosphate poisoning, tubular reabsorption of phosphate was initially defective but returned to normal in the course of four months. Certain occupational differences in uric acid excretion are as yet unexplained.

Determinants of serum DDT and DDE concentrations.

Conclusions1)Measurements of serum DDT concentration are capable of relfecting changes in oral DDT intake accurately and promptly.2)Serum DDE level is only slightly increased by a 300–600 fold increase in DDT intake over a period of 5 months. It is therefore an essentially worthless measure of recent change in oral DDT intake. Stable individual differences in serum DDE levels, seemingly much wider than differences in dietary patterns (i.e. DDE intake), suggest the importance of individual metabolic factors in determining this level.3)A high degree of correlation between serum DDT and DDE in day to day samples extracted once by hexane, probably reflects changes in extractability influencing the two measurements similarly.