The legislation governing usage of pesticdes is complex and considerable. Here we will only briefly mention a few examples which have been of historical significance to nematicides.
RPAR or the Rebuttal Presumption Against Reregistration was utilized in the reviews which resulted in the withdrawal of registration or usage of the fumigant nematicides EDB, DBCP and the 1,2-D component of D-D Mixture.
Several nematicides including Temik (aldicarb) and Telone II (1,3-Dichloropropene) have undergone Special Review by the US EPA for their potential for groundwater contamination, and carcinogenicity, respectively. During this process, the product is still allowed to be sold and used. Passage of nematicides into Special Review has typically been heralded by intensive negative publicity. When the process, which can take several years, is completed without major changes in use of the product this has occurred very quietly.
Periodically, all pesticide products are required to go through a process called Reregistration during which time a variety of tests may be required to meet current safety standards. This can be very expensive and has resulted in the withdrawal of registration of at least one nematicide, Dasanit, because the company deemed that projected sales would not offset the cost of Reregistration.
The Endangered Species Act has caused some differences of opinion with respect to nematicides among government agencies. At the same time that Telone II was in Special Review by US EPA and the subject of a discussion section at a meeting of the Society of Nematologists, a representative of another agency declared it to be the safest nematicide from the standpoint of endangered species because of its low acute toxicity and rapid degradation in soil.
The US EPA ADI or Average Daily Intake levels which specify the allowable pesticie residues in food have severely limited the number of crops on which several nematicides can be registered.
Within California, Proposition 65 requires all products for which there is some published evidence of carcinogenicity be placed on a list and posted as such wherever it is used. It also requires a 100,000 fold safety factor for pesticides. Several nematicides including carbon disulfide and Telone II are on the Prop 65 list. The safety factor required by Prop 65 combined with the level indicated to be carcinogenic in the NTP Technical Report which caused Telone II to be placed into Special Review by US EPA resulted in a safety factor for Telone II at the parts per billion level. AB 1807 required the state to test for the presence of pesticides in air. In terms of pounds of active ingredient used on a yearly basis, Telone II ranked third among pesticides used in California, although relatively few acres were treated annually compared to other pesticides which are active at lower rates. In any event, based on pesticide use reports, air samples were taken in areas which historically had high use rates and unallowable levels were found to be present resulting in immediate suspension of use of the most widely used nematicide in California.
Other legislation requires the state to sample for pesticides which might have moved below the zone of microbial degradation in soil. Although this legislation is difficult if not impossible to enforce because the depth at which the zone of microbial degradation ends is not defined, such sampling resulted in removal of the labeled usage of Nemacur (fenamiphos) for Easter lilies.
Growers can request Section 18 Emergency or Crises Exemptions for short term usage of pesticides on particular crops. Special Local Need 24C Registrations can be requested for longer term usages. Extensive written documentation must be submitted to a County Agricultural Commissioner, who submits it to California EPA for processing, and then passes it on to the US EPA for approval. Within California, Section 18 registrations have been issued in recent years for use of methyl bromide on carrots, sweet potatoes, and potatoes, and for use of Nemacur (fenamiphos) on prunes, walnuts, broccoli and cauliflower.
The IR-4 program is designed to help speed the registration of minor use pesticides. Research trials conducted under this program must be done utilizing Good Laboratory Practice (GLP).