Pesticides, market data

Figure 8.1 Worldwide pesticide markets in the final two decades of the 20th century. Data compiled from annual reviews of the Crop Protection Association...

Pubhc concerns about pesticides in the diet of infants and children resulted in an expert committee convened by the U.S. National Academy of Sciences which devoted four years to the review of all available data. A consensus report was issued in 1993 (80). A number of recommendations for further work to more precisely define what constitutes the diet of infants and children were made. No risk could be estimated. The residue data reviewed by the panel were mainly from monitoring studies conducted by the PDA using multiresidue methods to analyze fresh produce and market basket samples collected from various geographic areas (81,82). These and other rehable scientific studies have demonstrated that relatively few food samples contain detectable residues. Most residues are far below estabhshed tolerances which are set above the maximum residue found in treated raw agricultural... 

The need to develop and use chiral chromatographic techniques to resolve racemates in pesticide residues will be driven by new hazard and risk assessments undertaken using data from differential metabolism studies. The molecular structures of many pesticides incorporate chiral centers and, in some cases, the activity differs between enantiomers. Consequently, in recent years manufacturers have introduced resolved enantiomers to provide pesticides of higher activity per unit mass applied. For example, the fungicide metalaxyl is a racemic mix of R- and 5-enantiomers, both having the same mode of action but differing considerably in effectiveness. The -enantiomer is the most effective and is marketed as a separate product metalaxyl-M. In future, it will not be satisfactory to rely on hazard/risk assessments based on data from metabolism studies of racemic mixes. The metabolism studies will need to be undertaken on one, or more, of the resolved enantiomers. 

The US Congress funded the Pesticide Data Program (PDP) in order to improve the accuracy of pesticide dietary risk assessments carried out by the US EPA. The USDA s Agricultural Marketing Service carries out the program. As recommended in the 1993 NAS/NRC report, the PDP focuses on the foods consumed most heavily by children and food is tested, to the extent possible, as eaten (Agricultural Market Service, 2004 National Research Council, 1987). For example, banana and orange samples are tested without the peel processed foods are tested as they come out of a can, jar or freezer bag. 

Table 14.4 Number of pesticide residues found by market claim and average number of residues in selected fruits and vegetables tested by the USDA s Pesticide Data Program PDP 2004... 

Agricultural Market Service (2002). Pesticide Data Program Annual Summary Calendar year 2000. US Department of Agriculture, Washington, DC. 

To produce QSAR models, a data set containing chemicals within a specified well-defined end-point is necessary. Since our knowledge about the properties of the natural compounds that surround us is very poor, especially for allelochemicals and toxicological evaluation of synthetic pesticides is well documented (regulators oblige the chemical industry to produce experimental data for synthetic chemicals, before they can be marketed), when allelochemicals toxicity values are not available, pesticides with similar structure can be used in the analysis. Therefore suitable data sets can be defined with pesticides and their activities, to predict the toxicity (activity) of the allelochemicals. 

For protection of public health, there must be some control of the experimental use of pesticide chemicals in obtaining data necessary for registration of a marketable product. Experimental use permits are issued under provisions, at 40 USC 136c, of the Federal Insecticide, Fungicide, and Rodenticide Act. Either temporary tolerance or an exemption can be granted with a permit. When the EPA takes such action, a notice is published in the Federal Register (Schultz, 1981). 

The pesticide materials now available meet most of the requirements for good control of the prevalent diseases and pests in the tropics. Most urgently needed are accurate data to provide reliable guidance to commercial firms having pesticides for the market in tropical countries. In the tropics, as elsewhere, the more progressive farmers are always interested in improvements and better methods. Too often, unfortunately, they are disillusioned by control failures which are due to lack of information or to ineffective or inappropriate materials. 

Analysis of PDP data from 1994 to 1999 showed that 73% of approximately 27,000 food samples that had no market claim (conventional or organic) showed detectable residues, while 23% of 127 fresh food samples designated as organic had detectable residue levels (Baker et al., 2002). Unavoidable contamination of some of the organic samples was due to the presence of persistent chlorinated hydrocarbon insecticides, which had been banned several years earlier, but 13% of the organic samples showed residues of pesticides other than the chlorinated hydrocarbon insecticides. 

These data tell us that to be a successful player in the pesticide industry you must be a large organisation with the ability to invest a great deal of support into the discovery (in most cases), development, manufacture and marketing of your products. There are some organisations that have built their successful position on their ability to manufacture and formulate commodity products, those products that were discovered some years ago and whose patents have lapsed, thereby allowing organisations, other than the inventor to make, formulate and sell the product internationally. 

Considerations for the acceptability of the are similar to those for the uncertainty factor used to calculate the RfD, RfC or other reference values from the NOAEL or BMD. The has been calculated from reproductive toxicity data for several chemicals. Examples include dinoseb (US EPA, 1986), lithium (Moore, 1995) and boric acid and borax (Moore, 1997). In the case of dinoseb, the MOEs were very low, in some cases less than one, indicating toxicity in the animal studies at levels to which people are exposed. This information on dinoseb led to an emergency suspension of use of this pesticide in the USA in 1986 and ultimately led to its removal from the market (Kimmel Kimmel, 1994,1996). 

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