Equine Risk Assessment for Insecticides Used in Adult Mosquito Management

Stoch Environ Res Risk Assess

Macedo

Davis

et al. 2008

Self Cite

Ultra-low-volume (ULV) aerosol applications of insecticides are used to manage high densities of adult mosquitoes. We used two-dimensional probabilistic risk assessment methodologies to evaluate three pyrethroid insecticides (phenothrin, resmethrin, and permethrin), pyrethrins, and two organophosphate insecticides (malathion and naled), applied by truck-mounted ULV sprayer. Piperonyl butoxide, a synergist commonly used in pyrethroid and pyrethrins formulations, was also assessed. The objective of our study was to evaluate probabilistically if a deterministic human-health risk assessment of mosquito insecticides was sufficiently conservative to protect human-health. Toddlers and infants were the highest risk groups while adult males were the lowest risk group assessed in this study. Total acute exposure ranged from 0.00003 to 0.0003 mg/kg day -1 for the chemicals and subgroups assessed examining inhalation, dermal, oral, and hand-to-mouth exposure. We used the risk quotient (RQ) method for our risk assessment, which is calculated by dividing the total potential exposure for each subgroup and chemical by its ingestion toxic endpoint value (RfD). Mean RQs ranged from 0.000004 to 0.034 for all subgroups and chemicals, with none exceeding the RQ level of concern. Naled had the highest RQs of any chemical assessed while PBO had the lowest. Sensitivity analysis demonstrated that the exposure from inhalation and deposition contributed the largest variance to the model output. Results support the findings of previous studies that the risks from adult mosquito management are most likely negligible, and that the human-health deterministic risk assessment is most likely sufficiently conservative.

Section: Introductionsupporting

confidence: 67%

A two-dimensional probabilistic acute human-health risk assessment of insecticide exposure after adult mosquito management

Stoch Environ Res Risk Assess

Macedo

Davis

et al. 2008

Self Cite

“…Those researchers demonstrated that the risks to humans most likely are negligible. Davis et al [5] and Schleier et al [6] examined pyrethrins and PBO as well and found similar results, demonstrating that ecological and equine risks from truck-mounted ULV applications most likely are negligible. Carr et al [7] showed that the use of aerially applied ULV resmethrin above agricultural fields as a result of a public health emergency would result in negligible human dietary risk.…”

Section: Introductionsupporting

confidence: 52%

“…The amount of PBO deposited on the ground was 47-to 76-fold less than that estimated by Peterson et al [4] and by Davis et al [5] using a tier I model, ISCST3 (http:// www.epa.gov/scram001/tt22.htm#screen). Amounts of PBO were two-to threefold less than what Schleier et al [6] estimated using the model AgDrift (Stewart Agricultural Research Services, Macon, MO, USA) [23]. This indicates that exposures and concomitant human and ecological risks from aerial applications most likely are much lower than those from ground applications of pyrethrins and PBO.…”

Section: Discussionmentioning

confidence: 79%

“…If PBO is used as a surrogate for potential concentrations of pyrethrins, we would have seen 0.002 and 0.001 g/cm 2 at 1 h after application in Princeton and Colusa, respectively. These values are 103-and 205.8-fold less, respectively, than the concentrations modeled in ISCST3 and 6-and 12-fold smaller, respectively, than the concentrations modeled in AgDrift [4][5][6].…”

Section: Discussionmentioning

confidence: 93%

See 1 more Smart Citation

Environmental concentrations, fate, and risk assessment of pyrethrins and piperonyl butoxide after aerial ultralow‐volume applications for adult mosquito management

Enviro Toxic and Chemistry

Peterson

Macedo

et al. 2008

Self Cite

Abstract-One of the most effective ways of managing adult mosquitoes that vector human and animals diseases is the use of ultralow-volume insecticides. Because of concerns about the safety of the insecticides used for the management of adult mosquitoes, we conducted an environmental fate and efficacy study in Princeton and Colusa (both CA, USA) after aerial applications of pyrethrins and piperonyl butoxide (PBO). One hour before application, PBO concentrations in water were 0.008 and 0.2175 g/L for Princeton and Colusa, respectively. One hour after the spray event in Princeton, the average PBO concentrations were 0.0125 g/cm 2 on ground-deposition pads and 0.1723 g/L in water samples, with concentrations decreasing significantly over time. One hour after the spray event in Colusa, the average PBO concentrations were 0.0199 g/cm 2 on deposition pads and 1.274 g/L in water samples, with concentrations decreasing significantly over time. A significant time and location effect for both deposition pads and water samples in Princeton and Colusa was observed ( p Ͻ 0.001 and p ϭ 0.014, respectively). Pyrethrins were not detected in nearly all ground and water samples. One hour after application, mortality of Culex tarsalis and Culex pipiens in sentinel cages was significantly higher than at the control site for both locations ( p Ͻ 0.001). Risk quotients for aquatic surrogate species in Princeton and Colusa were 0.002 or less at 1 h after application, which did not exceed the U.S. Environmental Protection Agency risk quotient level of concern for endangered aquatic organisms of 0.05. Our results suggest that the amounts of pyrethrins and PBO deposited on the ground and in water after aerial ULV insecticide applications are lower than those estimated by previous exposure and risk assessments.

“…Therefore, the concentration incorporating dilution without incorporating the effect of DOC at the 95th percentile from our data would be between 0.003 and 0.0005 mg/L, which would result in less than 0.1 and 0.009% of the potentially affected fraction of species reaching their LC50, respectively. Our results are protective of aerial ULV applications because the concentrations deposited on surfaces and water are lower than those observed after ground-based ULV applications [52][53][54].…”

Section: Resultsmentioning

confidence: 64%

A refined aquatic ecological risk assessment for a pyrethroid insecticide used for adult mosquito management

Enviro Toxic and Chemistry

Peterson

2013

Self Cite

Abstract-The use of pyrethroid insecticides has increased substantially throughout the world over the past few decades as the use of organophorous, carbamate, and organochlorine insecticides is being phased out. Pyrethroids are the most common class of insecticides for ultralow-volume (ULV) aerosol applications used to manage high densities of adult mosquitoes. Pyrethroids are highly toxic to nontarget organisms such as certain aquatic organisms, and there have been concerns about the effect of applications of ULV insecticides on these organisms. To address the uncertainties associated with the risks of ULV applications and the contradictory findings of other ecological risk assessments, the authors performed a probabilistic aquatic ecological risk assessment for permethrin using actual environmental deposition on surfaces to estimate permethrin concentrations in water. The present study is the first ecological risk assessment for pyrethroids to quantitatively integrate the reduction in bioavailability resulting from the presence of dissolved organic matter. As part of the risk assessment, the authors incorporated a species sensitivity distribution to take into account the differences in toxicity for different species. The 95th percentile estimated concentration would result in less than 0.0001% of the potentially affected fraction of species reaching the lethal concentration that kills 50% of a population. The results of the present study are supported by the weight of evidence that pyrethroids applied by ground-based ULV equipment will not result in deleterious effects on aquatic organisms. Environ. Toxicol. Chem. 2013;32:948-953. # 2013 SETAC