Low Level Pesticide Poisonings

The toxicological properties of individual pesticides are well known. I41l The effects of poisoning by low levels of pesticides and pesticide mixtures have not been as well documented. These effects are the subject of this section. The octanokwater partition coefficients (7T w) are given for each of the chemicals in this section, so as to demonstrate the effects of exposures to mixtures of lipophiles and hydrophiles. 

Exposures to low levels of pesticides are those that occur when toxic effects are observed following inhalation, ingestion, or dermal absorption of concentrations not known to be toxic. An example is the exposure to a commercial formulation of a bifenthrin-containing (8.15) insecticide that was shown to be neurotoxic at levels 3-4 orders of magnitude lower than the NOEL for bifenthrin alone J34l Other chemicals contained in the commercial formula include a surfactant, heavy petroleum naphtha (5.0-6.5) and aromatic petroleum distillate (5.0-7.0). 

Chronic low level exposures to pesticides can lead to permanent neurological impairment. A study of banana workers illustrates this point. The psychomotor and visuomotor skills of 81 banana workers who had previously received nonhospitalization medical attention for mild exposures to organophosphate or carbamate pesticides were diminished relative to a control group of 130 banana workers who had never sought medical attention for pesticide exposure. The diminished effects were observed on an average of 27 months after the reported exposures.  

The toxic effects of low level pesticide exposure can follow single or chronic exposures. The following examples illustrate this. 

A mystery illness that affected 17 casino workers following fumigation of the premises with a pesticide mixture that contained the carbamate propoxur (1.52), the organophosphate coumaphos (4.13), 1,1,1-trichloro-ethane (2.49), methylene chloride (1.25), xylene (3.15), and acetone 

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