Reduction of pesticide exposure with protective clothing for applicators and mixers.

Systemic pesticide illness in agricultural workers may result from excessive dermal exposure to pesticides. Workers who apply and mix pesticides (applicators and mixers) are not at special risk. Both acute and chronic exposures can occur from spillage or by environmental contamination of clothing. Two exposure assessment studies were conducted of Central Florida citrus grove workers who applied ethion daily. Measuring the percentage of penetration of ethion through clothing and measuring the daily urinary excretion of diethyl phosphate (DEP) were the techniques used to assess the protection afforded by changing daily to freshly laundered 100% cotton coveralls. Coveralls provided significantly greater protection than did regular clothing and the use of respirators.

A physical concept of soil-water equilibria for nonionic organic compounds.

Soil-water equilibrium data suggest that the transfer of nonionic chemicals from water to soil may be described in terms of a hypothesis of solute partitioning in the soil organic matter. This concept allows estimation of soil-water distribution coefficients either from solvent-water partition coefficients or aqueous solubilities.

Some physical factors in toxicological assessment tests.

Many thousand organic compounds are in common use and new ones introduced daily. With many of these materials, little is known about their toxic hazard. For years scientists have been investigating the relation of structure and properties to biological activity. Among the factors relating to toxicity are bioaccumulation and persistence in the organism. In this study, the relation of partition coefficient and solubility to bioaccumulation of some organochlorine compounds was investigated as was also the reactivity of several organophosphates. The work adds confirmation to the relation of molecular parameters to penetration, accumulation, and persistence in toxic action.

Chemodynamics: transport and behavior of chemicals in the environment--a problem in environmental health.

In the manufacture and use of the several thousand chemicals employed by technological societies, portions of these chemicals escape or are intentionally introduced into the environment. The behavior, fate, and to some extent the effects produced by these chemicals are a result of a complex interaction of the properties of the chemical with the various processes governing transport, degradation, sequestration, and uptake by organisms. In addition, such processes as adsorption, evaporation, partitioning, and degradation are influenced by ambient conditions of temperature, air movement, moisture, presence of other chemicals, and the concentration and properties of the subject chemicals. These influence the level and extent of exposure to these chemicals that man might receive. Study of the physiochemical properties and extent of exposure to these chem;cals that man might receive. Study of the physiochemical properties of compounds in relation to these various processes has provided a basis for better understanding of the quantitative behavior. Such information is useful in development of predictive models on behavior and fate of the chemicals in relation to human exposure. Beyond this, it provides information that could be used to devise procedures of manufacture, use, and disposal that would minimize environmental contamination. Some of the physical principles involved in chemodynamics are presented in this review.

Chemical structure and properties of selected benzene compounds in relation to biological activity.

Four fundamental physical parameters of series of benzene derivatives were studied to ascertain correlations with biological activity. These included octanol/water coefficient, vapor pressure, infrared absorption (out-of-plane C-H vibration), and the pi values. Each physicochemical constant exhibited a partial correlation with biological activity suggesting that each played a role. It was presumed that more precise and specific data on the biological activity would have permitted a better correlation. It is postulated that the biological activity of a compound is due to the sum of such physicochemical factors as: partition coefficient, molecular geometry and spatial orientation, electronic characteristics of the molecular orbitals, and vibrational-rotational frequencies of constituent groups.

Physicochemical properties of some organophosphates in relation to their chronic toxicity.

Organophosphates in increasing amounts and wider varieties of molecular structure are being used to replace the organochlorine pesticides. It has been assumed that the organophosphates as a class would have a minimal chronic toxicity due to rapid hydrolysis and an unfavorable partitioning as regards to lipids. The physicochemical properties of a number of representative organophosphates were determined, including the octanol/water partition coeffecient, hydrolysis, and binding to proteins. Those having a halogenated aryl substitution were found to have partition coefficients not largely different from the organochlorines, suggesting the possibility of fat deposition. Certain of these compounds are sufficiently stable toward hydrolysis to allow bioaccumulation to occur. These preliminary findings appear to indicate a correlation between readily determined physical properties and the potential for chronic effects in this class of compounds.

Role of striatal dopamine in delayed neurotoxic effects of organophosphorus compounds.

Mipafox administered to rats daily for 35 days produced ataxia and a reduction in the level of dopamine in the corpus striatum. Treatment with Leptophos for the same period produced slight motor dysfunction and a small but significant reduction in the level of striatal dopamine. Fenitrothion neither produced motor dysfunction nor changed the level of striatal dopamine. The cholinesterase activity of corpus striatum was inhibited by all the compounds. The results suggest the possible involvement of striatal dopamine in the delayed neurotoxic effects of certain organophosphorus compounds.

Human pesticide poisonings by a fat-soluble organophosphate insecticide.

In five cases of dichlofenthion poisoning due to suicidal ingestions, unusual toxicologic features were encountered. Initial symptoms were mild or delayed and severe cholinergic crises did not appear until 40 to 48 hours after ingestion. Two patients died, and in the three survivors, cholinesterase symptoms persisted for five to 48 days. An almost total inhibiton of both cholinesterase enzymes continued in one patient for 66 days, and prolonged antidotal therapy was required. Residues of the intact pesticide were detected in fat after 54 days in one patient, and in the blood for 75 days in another patient. The partition coefficient of dichlofenthion in fat was 20 times greater than parathion, and exceeded only by leptophos. Considering the chemical and toxicologic properties of this compound, we postulated that the mechanism of protracted intoxication is a slow release from adipose reservoirs.

Hypertension in Oregon pesticide-formulating workers.

In a statewide survey of hypertension prevalence among pesticideformulating workers and controls in Oregon, we found no difference in mean systolic and diastolic blood pressure values but a modest excess of hypertension prevalence among chlorophenoxy herbicide workers which was largely explained by a greater constitutional predisposition to hypertension as estimated by positive family histories. Neither our study nor other published to date are adequate to allay the suspicion that chronic pesticide exposure may increase the risk of hypertension manifestation.