Executive Summary
Fumigant Sampling and Analysis Plan

Back to Lompoc Air Monitoring Project

What is the purpose of the air sampling that the Department of Pesticide Regulation (DPR) plans to conduct in Lompoc, California?

The Department of Pesticide Regulation (DPR) plans to measure air concentrations of several pesticides (fumigants) that are applied to agricultural soils before planting. The fumigants include 1,3-dichloropropene (Telone®), chloropicrin, metam-sodium, and methyl bromide. The sampling and analysis plan is designed to measure the highest concentrations of these pesticides over a short period of time. DPR will then use these data to determine if the measured air concentrations of these fumigants, as used in the Lompoc area (Santa Barbara County), exceed the acute (24-hour) human health screening levels for each of these four pesticides. The study is part of a two-phase comprehensive monitoring program to measure pesticide air concentrations in the Lompoc area.

The primary objective of the two-phase pesticide air monitoring program is to gather information to provide answers to two main questions: (1) Are Lompoc residents exposed to pesticides in air? (2) If so, which pesticides, and in what amounts?

Why is DPR conducting this air sampling?

In 1997, DPR formed the Lompoc Interagency Work Group (LIWG) to help investigate residents' concerns first voiced in 1992 about pesticide use as it relates to community health. The LIWG is composed of staff from federal, state, and county agencies as well as community representatives. The LIWG formed several subgroups to develop recommendations to address health concerns, to conduct a pesticide air monitoring strategy, and to consider potential exposures from environmental factors, such as crystalline silica, radon, meteorological conditions, and pollen and mold. Other agencies plan or have done monitoring to measure levels of crystalline silica and radon.

The pesticide exposure subgroup (now called the Technical Advisory Group) developed a work plan that recommended comprehensive air monitoring in Lompoc during the growing season to determine whether pesticides applied to agricultural fields migrate by air to adjacent residential areas.

In May 1999, DPR received a grant from the U.S. Environmental Protection Agency to monitor fumigant applications in the Lompoc area during fall and winter months, part of the Phase Two air monitoring study for pesticides. DPR conducted Phase One pesticide air monitoring last fall.

Fumigants are a unique class of pesticides. They are highly volatile, applied infrequently but at higher rates than other pesticides, and used to control a wide variety of pests and diseases. Since fumigants are applied before planting, many applications occur during the fall and winter. Because of their high volatility, high application rates, and season when most applications occur, fumigants are the focus of the monitoring described here.

DPR plans to monitor for the remainder of the pesticides in Phase Two next spring during their months of highest use.

How many fumigant applications will be monitored?

We decided how many fumigant applications to monitor based on the number of applications made for each fumigant in the past (1996-1998). We will monitor a maximum of 13 fumigations: one to two for 1,3-dichloropropene, one to two for chloropicrin/methyl bromide (since these two chemicals are applied together, we will monitor for both during an application), and five to eight for metam sodium.

How many sites will DPR monitor and where will the sites be located?

Air monitoring will be conducted at five sites within the city limits of Lompoc. Three of the five air sampling sites were selected to represent areas where the highest fumigant concentrations will probably occur, based on proximity to fumigant application sites and predominant wind patterns at that time of year. The fourth site, near the center of Lompoc, was selected to be representative of fumigant concentrations that might be found closer to the center of the city. The fifth site is located in the northeast region of Lompoc to capture applications that might occur in the smaller agricultural areas to the north and east of the city.

What is the sample collection plan?

Air samplers will be located on rooftops for sample security. Each fumigant will be monitored individually due to the limited supply of air sampling equipment. Air monitoring will begin within 24 hours of notification of field-sampling personnel. The Santa Barbara County Agricultural Commissioner's Office will notify field-sampling personnel about 24 hours before every fumigant application. Once an application begins, field personnel will collect samples for three days. Air sampling will be conducted for about 8 hours during daylight and 16 hours at nighttime (for a total of 72 hours).

What air sampling methods will be used?

Sorbent tubes (chloropicrin and metam sodium) and canisters (1.3-dichloropropene and methyl bromide) will be used to collect air samples. Samples will be stored on ice, and then delivered to the analyzing laboratory. The Department of Health Services will analyze the samples to measure pesticide concentrations, using standard analytical methods.

What quality assurance and quality control procedures will be used?

To ensure sample validity and quality, appropriate quality control and quality assurance procedures will be used along the entire sampling process: in the field, during sample storage, and in laboratory analysis. In addition, an independent, multi-agency quality assurance team will audit the laboratories participating in this study.

What actions will DPR take based on the results?

DPR has developed screening levels for the fumigants to place results in a health-based context. Although not regulatory standards, DPR will use these screening levels to evaluate the results and take actions as follows. (1) If the maximum air concentration is an order of magnitude (1/10) below the screening level, no action will be taken. However, more evaluation may still be done. (2) If the maximum air concentration is between the screening level and an order of magnitude (1/10) less than the screening level, a more refined analysis will be undertaken. (3) Maximum air concentrations exceeding the screening level will prompt DPR to respond immediately. The response would depend on the specific circumstances, but may involve determining the extent of use and compliance. The results may lead to the imposition of interim regulatory measures (e.g., modifying permit conditions, reevaluation, regulations).

What the sampling and analysis plan can and cannot do.

This sampling and analysis plan can provide data to answer questions about the highest concentrations of these fumigants that occur over a short period of time, as under worst-case conditions. Toxicologists use these values to determine potential exposures and to characterize the risk from these exposures. These data will be used to assess the risk to human health due to acute exposure. This sampling and analysis plan has not been designed to answer questions about low-level exposures over a long period to any of these fumigants.

At this time, insufficient toxicological information exists to determine the possible health hazard from exposure to multiple chemicals. The plan will provide information to estimate inhalation exposure; however, community exposure to pesticides by ingestion, dermal absorption, or other potential routes will not be measured. Some concentrations of fumigants may be too low to quantify given the current state of technology for chemical analysis.