A probabilistic analysis reveals fundamental limitations with the environmental impact quotient and similar systems for rating pesticide risks

Comparing risks among pesticides has substantial utility for decision makers. However, if rating schemes to compare risks are to be used, they must be conceptually and mathematically sound. We address limitations with pesticide risk rating schemes by examining in particular the Environmental Impact Quotient (EIQ) using, for the first time, a probabilistic analytic technique. To demonstrate the consequences of mapping discrete risk ratings to probabilities, adjusted EIQs were calculated for a group of 20 insecticides in four chemical classes. Using Monte Carlo simulation, adjusted EIQs were determined under different hypothetical scenarios by incorporating probability ranges. The analysis revealed that pesticides that have different EIQs, and therefore different putative environmental effects, actually may be no different when incorporating uncertainty. The EIQ equation cannot take into account uncertainty the way that it is structured and provide reliable quotients of pesticide impact. The EIQ also is inconsistent with the accepted notion of risk as a joint probability of toxicity and exposure. Therefore, our results suggest that the EIQ and other similar schemes be discontinued in favor of conceptually sound schemes to estimate risk that rely on proper integration of toxicity and exposure information

Economic Cost Analysis of West Nile Virus Outbreak, Sacramento County, California, USA, 2005

Aerial spraying is cost-effective

A Human-Health Risk Assessment for West Nile Virus and Insecticides Used in Mosquito Management

West Nile virus (WNV) has been a major public health concern in North America since 1999, when the first outbreak in the Western Hemisphere occurred in New York City. As a result of this ongoing disease outbreak, management of mosquitoes that vector WNV throughout the United States and Canada has necessitated using insecticides in areas where they traditionally have not been used or have been used less frequently. This has resulted in concerns by the public about the risks from insecticide use. The objective of this study was to use reasonable worst-case risk assessment methodologies to evaluate human-health risks for WNV and the insecticides most commonly used to control adult mosquitoes. We evaluated documented health effects from WNV infection and determined potential population risks based on reported frequencies. We determined potential acute (1-day) and subchronic (90-day) multiroute residential exposures from each insecticide for several human subgroups during a WNV disease outbreak scenario. We then compared potential insecticide exposures to toxicologic and regulatory effect levels. Risk quotients (RQs, the ratio of exposure to toxicologic effect) were < 1.0 for all subgroups. Acute RQs ranged from 0.0004 to 0.4726, and subchronic RQs ranged from 0.00014 to 0.2074. Results from our risk assessment and the current weight of scientific evidence indicate that human-health risks from residential exposure to mosquito insecticides are low and are not likely to exceed levels of concern. Further, our results indicate that, based on human-health criteria, the risks from WNV exceed the risks from exposure to mosquito insecticides

Bystander Exposure to Ultra-Low-Volume Insecticide Applications Used for Adult Mosquito Management

A popular and effective management option for adult mosquitoes is the use of insecticides applied by ultra-low-volume (ULV) equipment. However, there is a paucity of data on human dermal exposure to insecticides applied by this method. The objective of the current study was to estimate dermal exposures to the insecticide active ingredient permethrin using water- (Aqua-Reslin®) and oil-based (Permanone® 30-30) formulations with passive dosimetry. No significant differences in deposition of permethrin were observed between years, distance from the spray source, front or back of the body, or the placement of the patches on the body. However, exposure to Aqua-Reslin was significantly greater than Permanone 30-30 and average concentrations deposited on the body were 4.2 and 2.1 ng/cm2, respectively. The greater deposition of Aqua-Reslin is most likely due to the higher density of the water-based formulation which causes it to settle out faster than the lighter oil-based formulation of Permanone 30-30. The estimated average absorbed dermal exposure for permethrin from Aqua-Reslin and Permanone 30-30 was 0.00009 and 0.00005 mg/kg body weight, respectively. We also found that ground deposition of ULV insecticides can be used as a surrogate for estimating dermal exposure. The estimated exposures support the findings of previous risk assessments that exposure to ULV applications used for mosquito management are below regulatory levels of concern

G95-1263 When to Sample for Alfalfa Weevil

Dates for initiating alfalfa weevil scouting are provided, based on 30 years of climatic data used to estimate appropriate degree day accumulations for northern and southern Nebraska. Sampling activities for alfalfa weevil need to be timed properly because it is inefficient to sample when the pest is not active or present. Conversely, delayed sampling is financially risky because economic damage can occur before a management practice is implemented. Integrated pest management programs often use degree day accumulations to initiate activities, while producers often use calendar dates. Calendar scheduling is traditionally based on subjective experience rather than research

Invasive Species Management: Ensuring the \u27Cure\u27 Is Not Worse Than the Condition

The challenge in effectively managing invasive species arises out of our subjective response to the problem: 1) these species do not belong in our ecosystems; and 2) their impact on our ecosystems will be negative. These visceral responses typically dove-tail into the fundamental management objective: get rid of it! Society promotes the idea that good management is timely, and the best approach is to catch an invasive species before it reaches exponential population growth and becomes widespread. Although this is a sound approach, multiple examples illustrate that it is not universally applicable. Exotic species that are intentionally introduced either for resource improvement or classical biological control purposes are now themselves targets of management programs. Negative publicity associated with adverse outcomes of invasive species management has resulted in widespread ‘management paralysis’. Risk assessment is presented here as a viable strategy to offset this trend, and can be significantly enhanced through the adoption of best management practices