Acute Responses from Pyraclostrobin Fungicide Exposure - Iowa, 2007
Pyraclostrobin is an agricultural pesticide product used to kill fungi. Hazards to humans from pyraclostrobin exposure include eye injury and skin irritation. In July 2007, the Iowa Department of Public Health (IDPH) received reports of five events involving pyraclostrobin that sickened 33 persons, including 27 workers who were exposed in a single incident during aerial application.
On July 20, an aerial applicator pilot visited an emergency room with first-degree chemical burns after skin and inhalational exposure to pyraclostrobin fungicide that occurred when his plane crashed during takeoff, spilling the liquid fungicide. The pilot was admitted to the hospital for observation for two days, and the case was categorized as being of moderate severity. Although inhalational exposure occurred, the pilot reported no respiratory symptoms.
On July 23, the IDPH received media reports that workers in a field had been inadvertently exposed to pyraclostrobin fungicide by an aerial applicator on July 22. An IDPH investigation identified 27 cases of acute illness among the potentially exposed workers; all illnesses were associated with off-target drift of the pyraclostrobin to an adjacent field, owned by a different grower, where workers were detasseling field corn. The IDPH learned that the pilot had seen the nearby workers yet proceeded to apply the fungicide. All received skin decontamination on-site by a hazardous materials team before being transported to an emergency department for observation until their symptoms resolved. The most common symptom was upper respiratory tract pain or irritation (26 patients), followed by chest pain (20 patients). Three patients had nausea, and one patient had pruritus, skin redness, eye pain, weakness, headache, dizziness, and chest pain. On August 1, the Iowa Department of Agriculture and Land Stewardship suspended the commercial pesticide applicator license of the aerial applicator company that applied the fungicide and an administrative law judge later revoked the license.
Also during July 2007, the IDPH was notified of three additional events involving five cases of acute pesticide poisoning associated with pyraclostrobin exposure that resulted from off-target drift of pyraclostrobin from nearby aerial applications. On July 5, a man experienced headache and eye pain after pyraclostrobin exposure while riding a motorcycle near a field. On July 12, a woman reported eye pain and headache, and a man reported eye pain, headache, and dizziness after pyraclostrobin drifted into the yard of their homes. On July 14, a man and woman reported eye pain and conjunctivitis after pyraclostrobin drifted into the yard of their home. In all five of these cases, symptoms subsided after the exposed persons moved indoors or away from the pyraclostrobin-treated fields.
The cases described in this report are the first published accounts of human illness caused by exposure to pyraclostrobin or any of the strobilurin fungicides used in agriculture. Pyraclostrobin has a toxicity category of II and the product label warns that exposure can cause substantial, although temporary, eye injury and skin irritation and can be fatal if swallowed. Although upper respiratory symptoms are not mentioned on the product label warnings, 26 of the 27 workers exposed in the detasseling event experienced these symptoms, perhaps as a result of irritation of the upper respiratory mucosa by a mechanism similar to that causing skin and eye irritation. Pyraclostrobin was approved for sale in the United States in 2002 for use on a limited number of crops but was not approved for use on corn until December 2004. During 2007, the first year of widespread use on field corn, pyraclostrobin was applied to an estimated 1.5 million acres of corn in Iowa. Increased use of pyraclostrobin on corn likely is attributable to several factors, such as increased planting of corn in the same field in successive seasons and high market demand for corn. No cases of illness related to exposure to trifloxystrobin or azoxystrobin were reported to the IDPH during 2006 or 2007.
In the United States, cases of pesticide-related illness and injury are identified through state-based surveillance systems, several of which are supported by the National Institute for Occupational Safety and Health (NIOSH) through the Sentinel Event Notification System for Occupational Risk (SENSOR)-Pesticides program. Data from SENSOR-Pesticides and the California Department of Pesticide Regulation were reviewed to identify cases associated with pyraclostrobin exposure through 2005. A total of 12 cases were identified; however, only one of these cases was associated with pyraclostrobin application to 
corn. The other cases were associated with applications to grapes (five cases), other fruits (four), almonds (one), and tomatoes (one). One case each occurred in Michigan, Florida, and Washington, and nine cases occurred in California. All cases were work related; six occurred among pesticide handlers, five occurred during routine agricultural work (not involving pesticide application), and one occurred to a mosquito-control worker in a vineyard treated with pyraclostrobin. Patients reported combinations of skin, eye, respiratory, gastrointestinal, nervous system/sensory, and systemic symptoms. Two cases were of moderate severity, and ten were of low severity. None of the patients were hospitalized.
These events reinforce the importance of compliance with existing pesticide regulations and pesticide label requirements. Pesticide applicators must avoid aerial applications of pesticides when workers are in nearby fields, application methods must minimize off-target drift of pesticides, and farmers should consider the potential adverse health effects on humans when weighing the risks and benefits of pesticide use. Greater use by pilots of educational programs offered by the National Agricultural Aviation Association (e.g., Professional Aerial Applicator Support System) also might help reduce the incidence of acute illnesses resulting from exposure to pesticide. (CDC Morbidity and Mortality Weekly Report, 1/4/08).
