| 9/23/08 |
Download the four-page summary of the results and recommendations (PDF). |
| 9/23/08 | Download the full technical report, "Air Monitoring in Hastings, Florida, October 1–December 6, 2007: Technical Report" (76-page PDF). |
| 9/23/08 |
Go to the media advisory announcing the new results. |
| 4/16/07 | Go to PANNA's webpage on results of our 2006 Drift Catcher results from Hastings, FL. |
Executive Summary of the Technical Report on 2007 data
This report presents the results of a second air monitoring experiment area near South Woods Elementary School in Hastings, Florida. The school is located in an agricultural area adjacent to fields of Chinese cabbage. Thirty-nine samples were collected over the monitoring period, which started October 1 and ended December 6, 2007. Four pesticides were identified in the samples: the insecticides endosulfan and diazinon, the herbicide trifluralin, and the fungicide chlorothalonil. Of the samples collected, 56% contained three of the four pesticides, and 18% contained all four pesticides.
The fact that all of the pesticides were detected as long as several days to a week after an application indicates that volatilization of the pesticides (entry of contaminants into the atmosphere by evaporation) is the primary source of the drift, although application-related drift may have also contributed on the days on which applications took place. Three "spikes" in the concentrations of endosulfan were observed, coinciding with three applications during the 9.5-week sampling period.
Results from the air monitoring in Hastings are summarized below and in Table 1 on page 16 of the full technical report. Exposures calculated from the measured air concentrations should be viewed as estimates that may or may not represent worst-case exposure scenarios, and do not necessarily represent the precise exposure individuals may experience. Variability in actual exposures and the effects that may be experienced by individuals are governed by breathing rates and activity levels, time spent in areas where pesticide exposure can occur, and individuals' ability to detoxify chemicals. Inhalation may not be the sole exposure source, and total exposures from all routes (air, skin, diet) may be higher.
The pesticide levels observed in Hastings were compared to Reference Exposure Levels (RELs) derived from U.S. EPA toxicology data. Exceedances of the RELs are not necessarily anticipated to cause the symptoms of acute poisoning described below; however, the REL does represent a level of concern for inhalation exposure analogous to U.S. EPA's Reference Dose for dietary exposure. It is unknown what exposure levels would produce the chronic effects noted below. In contrast, concentrations below the REL do not necessarily indicate that the air is "safe" to breathe. A number of recent studies evaluating the capacity of different people to metabolize toxic substances show that the variability among different people can be substantially greater than the variability assumed by U.S. EPA in its toxicological analysis. No "acceptable" levels have been established for exposures to multiple pesticides simultaneously. It is possible that additive or synergistic effects may increase the toxicity of one pesticide in the presence of others.
Endosulfan: Of the 39 samples collected (spikes and blanks excluded) between October 1 and December 6, 87% were found to be above the limit of quantitation (LOQ) of 51 nanograms (ng) of α-endosulfan per sample. The LOQ is equivalent to an air concentration of 18 ng/m3 for the sampling method used. Sixty-nine percent of samples were found to be above the LOQ of 25 ng of β-endosulfan per sample (equivalent to an air concentration of 8.7 ng/m3). None of the samples contained endosulfan sulfate above the LOQ of 124 ng per sample (equivalent to an air concentration of 43 ng/m3); however, 38% did have concentrations above the MDL of 25 ng/sample (equivalent to an air concentration of 9 ng/m3).
Nine endosulfan samples (23%) were above the 24-hour acute and sub-chronic one-year-old child REL of 340 ng/m3, calculated from U.S. EPA's inhalation No Observed Adverse Effect Level (NOAEL), as shown in the Calculations section of this report. Twenty-one percent of the samples were above the seven-year-old REL of 500 ng/m3. The highest concentration of total endosulfan observed for a 24-hour period was 1,376 ng/m3 (4.0 times the 24-hour acute one-year-old REL and 2.8 times the seven-year-old REL) on October 13, 2007. The average concentration for the 39 days sampled was 248 ng/m3. Results are summarized in Figure 3.
Endosulfan is acutely neurotoxic to both insects and mammals and a suspected endocrine disruptor. Symptoms of acute poisoning include hyperactivity, tremors, convulsions, lack of coordination, staggering, difficulty breathing, nausea/vomiting, and diarrhea. Studies have found associations between chronic exposure and delayed sexual maturity (in males) and increased incidence of birth defects of the male reproductive system. Maternal endosulfan exposure during pregnancy has been associated with an increased incidence of autism in the children born to these mothers. Brain damage and skin irritation have been noted among adults exposed to endosulfan occupationally.
Endosulfan is an organochlorine insecticide that is applied in the US in greatest quantities to cotton, potatoes, and apples, and used in lesser amounts on a variety of vegetable and fruit crops. Residential uses of endosulfan were terminated in 2000. Nationwide from 1987–1997, U.S. EPA estimated that average annual use of endosulfan was 1.38 million pounds.
Diazinon: For the insecticide diazinon, 21% of the 39 samples were found to be above the LOQ of 94 ng per sample (equivalent to an air concentration of 33 ng/m3). Eight percent of the samples were above the 24-hour acute and sub-chronic one-year-old child REL of 145 ng/m3, and 5% were above the seven-year-old REL of 220 ng/m3, calculated from the U.S. EPA's inhalation NOAEL, as shown in the Calculations section of this report. The highest concentration of diazinon observed for a 24-hour period was 575 ng/m3 (4.0 times the 24-hour acute one-year-old REL and 2.6 times the seven-year-old REL) on November 6-8, 2007 (this sample was collected over two days and represents the average concentration for that 2-day period). The average concentration for the 39 days sampled was 42 ng/m3. The diazinon-oxon degradation product was not detected in any of the samples. Results are summarized in Figure 4.
Diazinon is neurotoxic to both insects and mammals, inhibiting cholinesterase, an enzyme essential for the proper transmission of nerve impulses. Citing unacceptable risks to children and the environment, the U.S. EPA banned all residential uses of diazinon effective in 2004; however, agricultural use continues. Symptoms of acute poisoning range from headache, nausea and vomiting, dizziness, weakness, drowsiness, and agitation to difficulty breathing, twitching, excessive salvation and sweating, watery eyes, pinpoint pupils, confusion, inability to concentrate, and memory loss. Asthma, gestational diabetes, and certain types of cancer have been linked to chronic exposure to diazinon.
Diazinon is an organophosphorus insecticide applied in the United States to a wide variety of fruits, nuts, and vegetables. Nationwide in 2001, U.S. EPA estimated that 4–7 million pounds of diazinon were used, third behind malathion and chlorpyrifos for US organophosphorus insecticide use.
Trifluralin: For the herbicide trifluralin, 72% of the 39 samples were found to be above the LOQ of 31 ng per sample (equivalent to an air concentration of 11 ng/m3). Another 21% of samples were found to contain trifluralin below the LOQ, but above the MDL of 6.1 ng/sample (equivalent to an air concentration of 2.1 ng/m3). The highest concentration of trifluralin observed for a 24-hour period was 136 ng/m3 on October 17, 2007, and the average concentration for the 39 days sampled was 29 ng/m3. Results are summarized in Figure 5. Because this herbicide has relatively low acute toxicity to mammals, the U.S. EPA has not determined an acute or sub-chronic NOAEL, and therefore an REL could not be calculated.
Trifluralin is not acutely toxic, but epidemiological studies of farm workers and pesticide applicators have linked trifluralin exposure to increased incidence of stomach cancer and birth defects, and animals studies show increases in urinary bladder tumors, renal pelvis carcinomas, and thyroid gland tumors. It is therefore ranked by the U.S. EPA as a "possible" carcinogen, and concerns with exposure center around the carcinogenicity of the compound, not its acute or sub-chronic toxicity. For trifluralin, a potential lifetime cancer risk estimate was developed for a hypothetical exposure scenario based on the trifluralin levels observed in this and our previous study. Lifetime cancer risk is defined as the estimated number of cancer cases for a given population size per mg/kg-day. U.S. EPA defines lifetime cancer risks exceeding one additional cancer per one million people as "of concern." Table 2 on page 20 shows the cancer risk estimate for trifluralin, which does not exceed the one in one million level of concern. See the Calculations section for full details.
Trifluralin is a dinitroaniline herbicide used as a preemergent weed control agent to control annual grasses and broadleaf weeds on cotton, soybeans, peanuts, leafy greens, cole crops, peppers, tomatoes and fruit trees. It is also currently permitted for residential use on lawns and golf courses. Nationwide in 2001, U.S. EPA estimated that 12–16 million pounds of trifluralin were used.
Chlorothalonil: For the fungicide chlorothalonil, 77% of the 39 samples were found to be above the LOQ of 36 ng per sample (equivalent to an air concentration of 12 ng/m3), and eight percent were below the LOQ but above the MDL of 7.1 ng per sample (equivalent to an air concentration of 2.5 ng/m3). In all, chlorothalonil was detected in 85% of the samples. U.S. EPA has not identified an acute or sub-chronic inhalation NOAEL; however, the California Department of Pesticide Regulation (CDPR) did identify an acute inhalation screening level of 560 ng/m3 for chlorothalonil. Screening levels are essentially equivalent to RELs, and also apply to specific populations-in this case, one-year-old children. None of the samples exceeded CDPR's acute screening level, although the highest observed concentration (555 ng/m3 on October 24, 2007) was very close. The average concentration for the 39 days sampled was 107 ng/m3. Results are summarized in Figure 6.
The acute toxicity of chlorothalonil is dependent on the route of exposure. It is not acutely toxic when ingested, but when inhaled, U.S. EPA classifies it as "moderately toxic." Chlorothalonil exposure has also been associated with asthma and allergic reactions; in one case, a severe reaction to chlorothalonil led to the death of a man who had been exposed while playing golf on a course that had been treated with chlorothalonil. The toxicity of some contaminants and metabolites of chlorothalonil is known to be higher than that of the parent compound.
U.S. EPA has listed chlorothalonil as a "probable" carcinogen, based on studies in rats that show increased incidence of tumors of the kidney and forestomach in chronically exposed animals. A potential lifetime cancer risk estimate was developed for a hypothetical exposure scenario based on the levels observed in this study. Since chlorothalonil was not observed in the previous air monitoring study from this site, it was assumed that exposures are limited to the period from October 1 to December 6. The lifetime cancer risk was therefore calculated assuming an exposure scenario of 106 ng/m3 per day for 67 days each year. Table 2 on page 20 shows the cancer risk estimate for chlorothalonil, which does not exceed the one in one million level of concern. See the Calculations section for full details.
Chlorothalonil is a broad-spectrum pesticide, used primarily as a fungicide to combat a variety of mildews, blights, rusts, molds, and scab as well as some mites and insects. In Florida, chlorothalonil is used extensively on fresh tomatoes, watermelons, and fresh cabbage, with 94%, 88%, and 82% respectively of the acreage of these crops treated in 2006. It is also used on residential lawns and golf courses and in paints. Nationwide from 1987–1997, U.S. EPA estimated that average annual use of chlorothalonil was 15.5 million pounds.