Department of Health Seal

TGM for the Implementation of the Hawai'i State Contingency Plan
Section 9.1
PESTICIDE CONTAMINATION AT FORMER AGRICULTURAL FACILITIES AND SITES

9.1 PESTICIDE CONTAMINATION AT FORMER AGRICULTURAL FACILITIES AND SITES

The Hazard Evaluation and Emergency Response (HEER) Office recommends that sites with known pesticide-related contamination and also those where pesticides were regularly applied be evaluated for residual contamination prior to re-development. "Pesticides" is a general term that includes any type of chemical mixture specifically formulated to kill "pests." Pesticides commonly used in Hawai`i include herbicides, fungicides and insecticides, the latter including termiticides and nematocides.

This section presents specific guidance regarding former sugarcane and pineapple operations because these were Hawai`i's most significant commercial agricultural crops during the 19th and 20th centuries. HDOH has created maps of former sugarcane lands in the Hawaiian islands in the early 20th century that can be accessed on the HEER Office soil arsenic information webpage. Between sugarcane and pineapple operations, these two industries cultivated as much as 250,000 acres of Hawai`i's farmlands (at the peak of production in the 1920s). However, it may be necessary to evaluate additional pesticides that could pose an unacceptable risk to human health and the environment. Large areas of former agricultural land are currently under consideration for residential and commercial development. Strategies for investigating former agricultural operations are discussed in Sections 3 and Section 4.

The criteria for selecting a target pesticide for a soil investigation is the potential for the pesticide to be present in soil at concentrations that pose potential direct-exposure hazards and/or leaching hazards. Factors that should be taken into account in selecting target pesticides for analysis include:

  1. Known or suspected use
  2. Application rate and duration of application
  3. Environmental persistence (e.g., resistance to chemical and biological breakdown)
  4. Nature of potential environmental hazards
  5. Availability of toxicity and physiochemical data
  6. Availability of commercial laboratory test methods

Investigations of former field areas should focus on pesticides and related contaminants that are persistent, toxic, and pose potential direct-exposure hazards for future residents and workers (e.g., dioxins, arsenic, organochlorine pesticides, etc.). Conditions in pesticide mixing and storage areas are much more uncertain, however. In addition to direct-exposure hazards, contamination could also pose leaching hazards and subsequent contamination of underlying groundwater resources (e.g., triazine pesticides and fumigants). This generally requires that the full range of pesticides be screened in these areas, and that all potential environmental hazards be fully evaluated in an Environmental Hazard Evaluation report (refer to Sections 3 and Section 13).

Although specifically directed to former sugarcane and pineapple operations, the approaches described in this section can be modified for investigation of lands that may have been impacted by cultivation of other agricultural crops, including macadamia nuts, coffee, and vegetables, as well as commercial pest control operations.

In 2011 the HEER Office prepared a summary of pesticide data for environmental investigations carried out for fields, mixing areas, seed dipping vats and various other sugarcane operations across Hawai‘i (HDOH 2011d). An overview of the report is provided in Section 9.1.4.

9.1.1 Targeted Operations

Table 9-1 identifies specific areas of sugarcane and pineapple operations to target for investigation. Operations are divided into field areas and various non-field areas. Pesticide mixing and other areas that could contain localized but heavy contamination should be investigated separately from field areas (refer to Section 3). In this way, field areas may be quickly screened and, ideally, cleared of contamination concern while closer investigation of smaller areas is carried out. Bagasse pile and cane wash discharge areas should be tested for the same suite of target pesticides as field areas.

Table 9-1 Example Target Areas for Investigation of Potential Pesticide Contamination
Areas of Concern 1Target Pesticide Groups
Sugarcane Operations
2Fields Heavy metals (arsenic only), organochlorine pesticides
Pesticide mixing areas Carbamates, chlorinated herbicides, dioxins/furans, heavy metals (arsenic, lead, and total mercury), organochlorine pesticides, organophosphorus pesticides (known spill areas only), semivolatile organic compound (SVOCs), triazine pesticides, Total Petroleum Hydrocarbons (TPH) (middle distillates)
Seed dipping areas Fungicides (benomyl and propiconizole [carbamates], total mercury)
3Settling ponds Heavy metals (arsenic only), organochlorine pesticides
3Bagasse piles Heavy metals (arsenic only), organochlorine pesticides
Pesticide container disposal areas Carbamates, chlorinated herbicides, dioxins/furans, heavy metals (arsenic, lead, and total mercury), organochlorine pesticides, organophosphorus pesticides (known spill areas only), SVOCs, triazine pesticides, TPH (middle distillates)
Pineapple Operations
2Fields Heavy metals (arsenic only), organochlorine pesticides
Pesticide mixing areas Carbamates, chlorinated herbicides, dioxins/furans, heavy metals (arsenic and lead), organochlorine pesticides, organophosphorus pesticides (known spill areas only), SVOCs, triazine pesticides, volatile organic compound (VOCs), TPH (middle distillates)
Seed dipping areas Fungicides (benomyl and propiconizole [carbamates])
Pesticide container disposal areas Carbamates, chlorinated herbicides, dioxins/furans, heavy metals (arsenic and lead), organochlorine pesticides, organophosphorus pesticides (known spill areas only), SVOCs, triazine pesticides, VOCs, TPH (middle distillates)
3Other Potential Areas of Concern
Air Strip mixing and storage areas Same as for pesticide mixing areas
Drainage ditches Site specific depending on areas drained (e.g., pesticide mixing areas, seed dipping vats, cane wash, etc.)
Plantation camp Site-specific
Maintenance facilities Site-specific
Transformer pads Polychlorinated biphenyls (PCBs); total petroleum hydrocarbons (TPH) as mineral oil
Rail lines Same as fields
Notes
1.    Categorized by laboratory method used for analysis. Refer to Appendix 9-B and Appendix 9-C for specific pesticides.
2.    Dioxins removed as potential contaminant of concern for former sugarcane field areas based on 2011 HEER Office review (see Section 9.1.4).
3.    See Tables 9-2 and 9-3. Testing for full suite of pesticides listed recommended for any areas that may have been impacted by runoff or discharges from a pesticide mixing area (e.g., mill ditches, settling ponds, areas of canewash discharges, bagasse piles, etc.).

9.1.2 Target Pesticides and Related Contaminants

Categories of pesticides and related contaminants associated with sugarcane and pineapple cultivation in Hawai`i are shown in Tables 9-2 and 9-3, respectively. These typically are grouped based on laboratory analytical methods, as follows, rather than by type of application:

  • Organochlorine pesticides
  • Organophosphorus pesticides
  • Triazine pesticides
  • Chlorinated herbicides
  • Carbamates
  • Fumigants
  • Dioxins/furans
  • Heavy metals (primarily arsenic, lead & mercury)
  • Petroleum (e.g., Total Petroleum Hydrocarbons (TPH) (middle distillates), often used as a vehicle, or carrier oil, for application of pentachlorophenol, EDB, DBCP and other pesticides)
  • Other (pentachlorophenol, etc.)

Appendix 9-A identifies pesticides (and related contaminants) known or suspected to have been used for agricultural purposes, and presents criteria for evaluating specific pesticides for further consideration. The list is based primarily on review of historical documents related to sugarcane and pineapple cultivation (e.g., Hanson 1959, 1962; HDOA 1969, 1977, 1987, 1989, USDA 2000). Few records exist prior to the late 1960s; therefore pesticide use prior to that time is uncertain. Rapid growth in the synthetic organic chemical industry began during the 1930s and 1940s. Prior to World War II, most pesticides were inorganic chemicals and naturally occurring plant extracts (Newman 1978), with the most common being arsenical compounds (Sheets 1980) and sulfur and mercury compounds (Newman 1978). In particular, arsenical compounds are known to have been used in sugarcane cultivation in Hawai`i in the 1920s through the 1940s, when up to 200,000 acres of land in Hawai`i was being used for sugarcane cultivation.

Several pesticides were banned or discontinued after the 1960s (e.g., dichloro-diphenyl-trichloroethane [DDT] in 1972). For the purposes of the target pesticide tables, it is assumed that use of these pesticides in Hawai`i ended at that time. However, it is possible that these pesticides may have continued to be used at a given site (e.g., use of existing supplies, etc.). Additional pesticides may have been used in some areas, but the appended list is considered to capture pesticides that would drive the need for remedial actions. Petroleum products, such as diesel fuel (middle distillates), were used to prepare some pesticide mixtures as carrier oils and may need to be included in the site investigation. See also Section 9.2 for a discussion of petroleum contaminated sites.

Herbicides are the primary pesticide of potential concern for former sugarcane lands in Hawai`i (i.e., weed killers). Insect control (i.e., insecticides) on sugarcane fields historically has been primarily through biological control methods (i.e., predator species). The overall use of insecticides by the Hawai`i sugar industry historically has been very low (less than one half of one percent of total crop protection chemical usage), and it is unlikely that residues from past applications or handling/storage of insecticides would be of concern at a site used only to cultivate sugarcane. In many cases, the use of insecticides would have been counterproductive, since they could impact the desirable predator species as well as the target species.

Pesticides that are contaminants of potential concern in field and non-field areas are presented in Appendix 9-B and Appendix 9-C. For former field areas, the emphasis is on pesticides and related compounds that are persistent and primarily pose direct-exposure hazards (e.g., vs. leaching hazards).

The assumed persistence of other pesticides is based on published half lives in soil (refer to Appendix 9-A). A pesticide is considered to be highly persistent if the published half life exceeds one year or if the half-life exceeds 100 days and sorption coefficient is greater than 3,000 cubic centimeters per gram (cm3/g) (default cutoff for "mobile" vs. "nonmobile" contaminants; HDOH, 2016). All metals, as well as organochlorine pesticides and dioxins/furans fall into this category.

A pesticide is considered to be moderately persistent if the published half-life is between 30 and 100 days. A pesticide is considered to have low persistence if the expected half-life in soil is less than 30 days. Existing field data support this breakdown of anticipated pesticide persistence. The half-lives noted in Appendix 9-A are considered to be gross estimates only, but suitable for purposes of this guidance.

Information regarding pesticide application rates for field areas was not available for most pesticides at the time this guidance was prepared. Estimating long-term buildup of pesticides in soil was therefore not practical. Assumptions regarding likely application rates, likely persistence, and the time needed to exceed target action levels were used to screen out a small number of pesticides with relatively low toxicity from further consideration (refer to Appendix 9-B and Appendix 9-C).

Toxicity factors, physiochemical constants, and standard commercial laboratory test methods were not available for several pesticides at the time this guidance was published (refer to Appendix 9-A). These pesticides were excluded from further consideration. The majority of these pesticides were developed after the 1960s, when stricter regulations on pesticide formulations were put into effect. These pesticides are assumed to be less persistent and toxic than the broader list of pesticides selected for inclusion in site investigations and noted in the appendices.

Tables 9-2 and 9-3 summarize categories of pesticides that should be tested at former sugarcane and pineapple cultivation operations. The investigation of former field areas should focus on pesticides and associated contaminants that are highly persistent, as indicated, with an emphasis on arsenic and organochlorine pesticides (see Section 9.1.4). For non-field areas (mixing areas, storage areas, etc.), the investigation should focus on all pesticides with moderate to high persistence that may have been used or released at the site. Testing for the full suite of pesticides listed is recommended for any areas that may have been impacted by runoff or discharges from a pesticide mixing area (e.g., mill ditches, settling ponds, areas of canewash discharges, bagasse piles, etc.). Contaminants identified in initial, screening level investigations above laboratory reporting limits (e.g., neighborhood-size decision units) should be carried forward in more detailed investigations (e.g., lot-size decision units). Refer to Section 3 and Section 4 for additional information on sampling decision units and sampling strategies.

Table 9-2 Summary of Target Pesticide Categories for Investigation of Former Sugarcane Operations
Laboratory Analytical Group1 Laboratory
Analytical Method
Field Areas Non-Field Areas2 Notes
Carbamates 8321 No Yes Test for benomyl and propiconazole at seed dipping operations (fungicides).
Chlorinated Herbicides 8151 or 8321 No Yes  
Dioxins/furans 8280 or 8290 No Yes See footnotes.
Heavy Metals
(Arsenic, Lead)
6010B/ 6020 Yes Yes Arsenic only in field areas.
Mercury (elemental) 7471 No Yes Test for total mercury at seed dipping operations (fungicides).
Organochlorine Pesticides 8081 or 8270 Yes Yes Field areas: heptachlor
Non-Field areas: heptachlor and trifluralin.
Organo- phosphorus Pesticides 8141 or 8270 No No Limited use. Include as contaminant of concern in known spill areas only.
Triazine Pesticides 8141 or
619M/ 8270
No Yes  
Volatile Organic Compounds 8260 No No  
Semi-Volatile Organic Compounds 8270 No Yes  
Total Petroleum Hydrocarbons 8015M No Yes Petroleum (e.g., diesel fuel) used as a base for applying some pesticides.
Notes:        
1. May differ from actual family of individual pesticides tested under noted laboratory method.
2. Testing for full suite of pesticides listed recommended for any areas that may have been impacted by runoff or discharges from a pesticide mixing area (e.g., mill ditches, settling ponds, areas of canewash discharges, bagasse piles, etc.).


Table 9-3 Summary of Target Pesticide Categories for Investigation of Former Pineapple Operations
Laboratory Analytical Group1 Laboratory
Analytical Method
Field Areas Non-Field Areas2 Notes
Carbamates 8321 No Yes Test for benomyl and propiconazole at seed dipping operations (fungicides).
Chlorinated Herbicides 8151 or 8321 No Yes  
Dioxins/furans 8280 or 8290 No Yes See footnotes. PCP used to lesser extent in pineapple operations than sugarcane operations
Heavy Metals
(Arsenic, Lead)
6010B/ 6020 Yes Yes Arsenic only in field areas.
Organochlorine Pesticides 8081 or 8270 Yes Yes  
Organo- phosphorus Pesticides 8141 or 8270 No No Limited use. Include as contaminant of concern in known spill areas only.
Triazine Pesticides 8141 or 619M/ 8270 No Yes  
Semi-Volatile Organic Compounds 8270 No Yes  
Fumigants (Volatile Organic Compounds) 8260 No Yes  
Total Petroleum Hydrocarbons 8015M No Yes Petroleum (e.g., diesel fuel) used as a base for applying some pesticides.
Notes:        
1. May differ from actual family of individual pesticides tested under noted laboratory method.
2. Testing for full suite of pesticides listed recommended for any areas that may have been impacted by runoff or discharges from a pesticide mixing area (e.g., drainage ditches, settling ponds, etc.).

Soil action levels are provided in the EHE guidance for the majority of the pesticides listed in Appendix 9-C (HDOH 2016). Follow the methodology presented in the HDOH EHE guidance to compile action levels for pesticides not currently listed in that guidance. At a minimum, site data should be compared to action levels for both direct exposure and leaching hazards. Soil action levels for a number of additional pesticides are included in the United States Environmental Protection Agency Regional Screening Level guidance (USEPA 2012b).

An evaluation of potential contaminant mobility in terms of vapor-phase or dissolved-phase (i.e., leachate) mobility in soil is important (refer to Appendix 9-B). Detailed discussions of contaminant mobility are provided in Volume 1 and Appendix 1 of the HDOH EHE guidance (HDOH 2016); refer also to HDOH technical memorandum Use of laboratory batch tests to evaluate potential leaching of contaminants from soil (HDOH 2007).

Pesticides classified as "volatile" in the HDOH EHE guidance are considered to be highly mobile in the vapor phase [Henry's number >0.00001 atmosphere cubic meters per mole (m3/mol)] and molecular weight <200 (see HDOH 2016). Pesticides with organic carbon sorption coefficients (Koc) values less than 100 cm3/g are considered highly mobile in leachate. Pesticides with Koc values >100 cm3/g but <3,000 cm3/g are considered to be moderately mobile. Pesticides with Koc values greater than 3,000 cm3/g are considered to be essentially immobile. Metals are given a default mobility ranking of low, although the need to evaluate potential leaching hazards posed by metals should be considered on a site-by-site basis (refer to Sections 3 and 13; see also Section 9.1.4).

9.1.3 Discussion of Select Pesticides

A summary of historical pesticide use for sugarcane and pineapple in Hawai‘i is provided in the appendices to this section, including primary references for more detailed information. A brief discussion of select pesticides and pesticide groups is provided below. Additional information on arsenic, dioxins, and technical chlordane is provided in the HDOH EHE guidance document (HDOH 2016, Volume 1, Chapters 2 and 4).

9.1.3.1 Fumigants

Fumigants used in pineapple cultivation to control nematodes began in the 1940s (HDOH 1985b; see Appendices 9-A and 9-B). Soil fumigants commonly used in Hawai`i include:

  • 1,2-dibromo-3-chloropropane (DBCP);
  • 1,2-dibromoethane (EDB);
  • 1,3-dichloropropene (Telone);
  • D-D (a mixture of 1,2-dichloropropane; 1,3-dichloropropene; and 2,3-dichloropropene);
  • 1,2,3-trichloropropene (TCP; an impurity associated with D-D).

Fumigants were typically injected from four to fourteen inches below ground surface. DBCP and EDB have been detected in groundwater wells on Oahu and Maui and have not been used since the mid-1980s (HDOH 1985, 1985c). 1,2,3-Trichloropropene (TCP) is an impurity associated with D-D and has also been detected in groundwater wells in the state (see HDOH 1985)

Fumigants are not likely to be persistent in field areas more than one year after use due to a propensity to volatilize into the atmosphere and degrade or be carried downward in leachate. Fumigants could, however, be a contaminant of concern in former pesticide mixing, storage or disposal areas. Soil vapor data collection is strongly recommended when investigating for these areas.

9.1.3.2 Arsenic

Appendix 9-E, Update to Soil Action Levels for Inorganic Arsenic and Recommended Soil Management Practices, contains detailed information on updated soil action levels for total inorganic arsenic, bioaccessible arsenic , and recommended soil management practices. Contact the HEER Office for further assistance if needed.

Historical Use

Arsenic-based pesticides are largely associated with sugarcane cultivation in Hawai`i during the 1910s through the 1940s. Various arsenic-based compounds were used as herbicides, insecticides and rodenticides in agricultural operations. The primary use was for weed control with respect to the overall volume stored, mixed and applied. The HEER Office has a dedicated webpage, Soil Arsenic Guidance and Information, which houses fact sheets, arsenic assessments throughout Hawai`i, maps and technical guidance for arsenic. Monosodium methane arsenate (MSMA) and sodium arsenite were used as herbicides during various stages of sugarcane cultivation (HDOA 1969). Arsenic was typically applied to surface soils by "poison gangs" using backpack sprayers. In addition, Canec, a building material made from sugarcane waste (i.e., bagasse) and used extensively in Hawai`i, was treated with calcium arsenate and arsenic acid as an anti-termite agent (NOAA 1990). The HEER Office fact sheet, Arsenic in Canec Ceilings and Wallboard in Hawai’i, provides an overview of the potential public health concerns associates with Canec (HDOH 2010b). Other arsenic-based pesticides include lead arsenite and lead arsenate, but it is unknown if these were used in Hawai`i.

Significantly elevated levels of total arsenic have been identified in a small number of former sugarcane fields in Hawai`i. Based on a review of pesticide data for former sugarcane operations, arsenic drives human health risk posed by residual pesticides in these fields (HDOH 2011d, see Section 9.1.4). A brief discussion on public health concerns associated with arsenic is provided in HDOH’s Arsenic in Hawaiian Soils: Questions and Answers on Health Concerns (HDOH 2013).

Arsenic Bioaccessibility Tests

Because of extensive, historic use of arsenic-based pesticides in Hawai`i, soil samples collected at former agricultural sites should always be analyzed for total arsenic. The HEER Office recommends that a laboratory bioaccessibility test be carried out when the total arsenic concentration in the <2mm fraction of soil exceeds 24 mg/kg, the default, upper limit assumed for background arsenic in soil (see Appendix 9-E and HDOH 2016). Soil action levels and categories specific to bioaccessible arsenic are included in Appendix 9-E. The bioaccessibility test and the associated action levels apply to the <250µm, fines fraction of soil.

Bioaccessible tests are used to estimate the fraction of total arsenic that could be stripped or "desorbed" from the soil following ingestion and thus made available for uptake. Arsenic that remains sorbed to the soil sample is considered to be unavailable for uptake and essentially non-toxic. Bioaccessibility should be tested and evaluated based on the gastric-phase, in vitro Solubility Bioaccessibility Research Consortium method ("SBRC" or "Drexler method"; Ruby 1996, 2001; Kelly 2002; Juhasz et al 2007). Studies have demonstrated that the SBRC assay method provides the best predictive capability to swine in vitro bioavailability testing in comparison to other in vitro methods, such as the Physiologically Based Extract Test (PBET) method or the In-Vitro Gastrointestinal Method (IVG).(Juhasz et al 2009; Juhasz et al 2011). These studies concluded that a 1:1 relationship between swine arsenic bioavailability and bioaccessibility using the SBRC gastric-phase method could be estimated, without the need for a correction factor. A direct correlation between SBRC data and in vivo data was also observed in soil from Hawai‘i that was included in a cynomolgus monkey study overseen by the University of Florida (Roberts et al 2007). In this study an average of 5.4% bioavailability was determined in the in vivo tests compared with an average SBRC-gastric phase bioaccessibility of arsenic in the same soil of 6.5%.

A higher confidence in the SBRC-gastric method over other approaches was also observed in suite of twenty arsenic contaminated soil samples from Hawai‘i that were submitted to a Canadian laboratory (RMC 2007). Three different bioaccessibility in vitro tests were evaluated, including SBRC, PBET and In Vitro Gastro-Intestinal (IVG) methods. The results demonstrated that the SBRC assay provided the highest estimate of bioaccessible arsenic of the gastric phase testing results, and consequently provides the most "protective" estimate of bioaccessibility of the three in vitro methods.

The SBRC bioaccessibility test is carried out on the <250μm fraction of dried soil separated from the original bulk sample by the laboratory. Under this method, one gram of the <250μm soil fraction is placed in 100ml of extraction solution intended to mimic human gastro-intestinal fluids and agitated for one hour. The concentration of bioaccessible arsenic in the soil sample is calculated by dividing the mass of arsenic that moves into the batch test solution by the mass of the sample. The percent bioaccessibility is calculated as the concentration of bioaccessible arsenic divided by the concentration of total arsenic reported for the same sample.

Both the total and bioaccessible concentrations of arsenic (mg/kg) in the <250μm fraction of the soil should be reported, even though the former may not be required as part of the bioaccessibility test. The percent bioaccessible arsenic, calculated as the concentration of bioaccessible arsenic divided by the concentration of total arsenic in the <250μm fraction, should also be reported. This will help confirm the test results and provide insight on possible enrichment of arsenic in the fine-grained fraction of contaminated soil.

The USEPA recommends a default bioavailability of 60% for arsenic in soil, based on a review of data for samples collected primarily on the mainland (USEPA 2012c). This default can be applied to the concentration of total arsenic reported for the <250μm soil fraction in lieu of a laboratory-based test if desired, provided that the total concentration of arsenic in this fraction does not exceed 160 mg/kg. This reflects the concentration of total arsenic in soil that would equate to the commercial/industrial action level for bioaccessible arsenic of 95 mg/kg and a bioaccessibility of sixty-percent. Laboratory-based bioaccessibility tests are recommended when the concentration of total arsenic in the <250μm soil fraction exceeds a concentration of 160 mg/kg.

Data compiled for Hawai‘i suggest that bioaccessibility as well as bioavailability is unlikely to exceed this threshold for soils with low to moderate concentrations of total arsenic, regardless of iron content and other factors (e.g., Cutler 2011, HDOH 2011c, Cutler et al 2013). Note that this default value is highly conservative for iron-rich, volcanic soils, where bioaccessibility is more typically less than 30% and as low as 5%. The default factor should not be applied to total arsenic in the <2mm fraction of soil due to the potential for enrichment of metal concentrations in the fines.

9.1.3.3 Technical Chlordane and Other Organochlorine Pesticides

Technical chlordane is a mixture of chlordane isomers (50-75%) and over 100 related compounds, including heptachlor and heptachlor epoxide (ATSDR 1994). Technical chlordane was used in Hawai`i in large quantities by pest control operators, lawn and garden services, and homeowners for the control of termites, armyworms, and other pests. The use of technical chlordane was discontinued in the 1980s. Soil contaminated with technical chlordane is highly likely to be present around and under the foundations of buildings constructed before this time. Technical chlordane was also used as an insecticide during pineapple cultivation (HDOA 1969).

The HEER Office recommends that soil samples be analyzed for technical chlordane rather than individual chlordane isomers and related compounds generally found in technical chlordane. The concentrations of chlordane isomers, heptachlor, and heptachlor epoxide do not need to be reported unless applied as a separate chemical. Laboratories should be directed to test for technical chlordane using USEPA Method 8081A or an equivalent method (USEPA 1996). This must be specifically requested prior to submitting the samples for analysis and noted on the chain of custody form. Laboratories also should be instructed to report any additional organochlorine pesticides that are not typically found in technical chlordane (e.g., DDT, dieldrin, endrin, etc.). Additional information on technical chlordane is presented in HDOH 2011g, 2011h.

In addition to the approach noted for technical chlordane, concentrations of the following chemicals should be summed as indicated for comparison to HDOH EALs in a screening level EHE:

  • Hexachlorocyclohexane ("BHC" as Lindane) = Alpha-BHC + Beta-BHC + Gamma-BHC (Lindane) + Delta-BHC;
  • Endosulfan = Endosulfan I + Endosulfan II + Endosulfan sulfate;
  • Endrin = Endrin + Endrin aldehyde + Endrin ketone.

These chemicals can be evaluated individually in a site-specific risk assessment as necessary.

9.1.3.4 Dioxins and Furans

Appendix 9-F, Update to Soil Action Levels for TEQ Dioxins and Recommended Soil Management Practices, contains detailed information on updated soil action levels for TEQ dioxins and recommended soil management practices. Contact the HEER Office for further assistance if needed.

Dioxins and furans ("dioxins") should be included as chemicals of potential concern at former pesticide mixing areas associated with both sugarcane and pineapple operations. Although significant data are not currently available for the latter, dioxin contamination in soil well above HDOH action levels have been documented at numerous former pesticide mixing and storage areas associated with past, sugarcane operations (see following section).

Dioxins were created as a manufacturing byproduct in older formulations of several commonly used pesticides, especially pentachlorophenol (PCP), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), and 2,4,5-trichlorophenoxypropionic acid (2,4,5-TP or Silvex; NTP 2005). Soils in former pesticide mixing areas should be analyzed for dioxins if any the above-noted pesticides are known or suspected to have been stored, mixed or otherwise released in the area under investigation. These chemicals are not known to have been widely used in pineapple fields and dioxins are no longer considered a potential chemical of concern for these areas (see Table 9-3). Organochlorine pesticides such as heptachlor, used for ant control, are instead considered to drive the need for investigation of former pineapple field areas.

Dioxins and furans are evaluated in terms of Toxicity Equivalent calculations or "TEQ "dioxins. Quantification of dioxins in soil for use in human health risk assessments requires conversion of congener-specific gas chromatography/mass spectrometry (GC/MS) data to TEQ dioxin concentrations by use of Toxicity Equivalence Factors (TEFs) (WHO 2005). A summary of World Health Organization (WHO) TEFs is provided in Table 9-4. The TEQ concentrations for individual congeners are then added together to calculate a total TEQ dioxin concentration for the sample. Unless otherwise approved by HDOH, one-half of the Method Detection Limit (not the Reporting Limit) should be used for calculation of TEQ concentrations when the specific congener is reported as "Non Detect."

The HEER Office currently accepts the use of bioassay methods such as CALUX for testing of TEQ dioxins in soil provided that splits of 10% of the samples are tested using GC/MS methods such as Method 8280 or 8290, generally samples with the highest-reported concentration of TEQ dioxins (see Appendix 9-F). Bioassay data in studies carried out by the HEER Office consistently overestimated TEQ dioxin concentrations in soil in comparison with split samples that were tested using laboratory GC/MS methods (HDOH 2007e). This suggests that the bioassay tests provide a conservative estimate of TEQ dioxin concentrations. Paired GC/MS and bioassay data for split samples can be used to develop a correction factor and adjust the bioassay data for actual comparison to HEER Office EALs.

Other investigations, however, suggest that bioassay tests may underestimate TEQ dioxin concentrations for very-low concentrations of dioxins in soil (e.g., <100 ng/kg; e.g., see TTEMI 2012). While this will not affect development of a correction factor based on paired, GC/MS data, it is important to be aware of for initial screening of sites, and emphasizes the need for Method 8280 or 8290 data.

Table 9-4 Summary of Toxicity Equivalence Factors for Dioxin
Compound WHO 2005 TEF
chlorinated dibenzo-p-dioxins
2,3,7,8-TCDD 1
1,2,3,7,8-PeCDD 1
1,2,3,4,7,8-HxCDD 0.1
1,2,3,6,7,8-HxCDD 0.1
1,2,3,7,8,9-HxCDD 0.1
1,2,3,4,6,7,8-HpCDD 0.01
OCDD 0.0003
chlorinated dibenzofurans
2,3,7,8-TCDF 0.1
1,2,3,7,8-PeCDF 0.03
op2,3,4,7,8-PeCDF 0.3
1,2,3,4,7,8-HxCDF 0.1
1,2,3,6,7,8-HxCDF 0.1
1,2,3,7,8,9-HxCDF 0.1
2,3,4,6,7,8-HxCDF 0.1
1,2,3,4,6,7,8-HpCDF 0.01
1,2,3,4,7,8,9-HpCDF 0.01
OCDF 0.0003
WHO World Health Organization
TEF Toxicity Equivalence Factor

9.1.4 Review of Pesticide Contamination at Former Sugarcane Operations

In 2011 the HEER Office prepared a summary of pesticides identified in fields, mixing areas, seed dipping vats and various other sugarcane operations across Hawai‘i (HDOH 2011d). An overview is provided below. Refer to references in the 2011 report, for examples associated with different operations.

9.1.4.1 Pesticide Mixing Areas

Data reviewed for the pesticide and dioxin summary report (HDOH 2011d) confirm that pesticide mixing areas have the highest potential for significant contamination and maintain a high priority for identification and investigation. Identification of these areas through historical records, interviews with past employees and field reconnaissance is especially important as urban growth expands into former agricultural areas.

In order of potential risk to human health and the environment and presence at former mixing sites, the pesticide categories and pesticide-related chemicals can be generally prioritized as follows (see HDOH 2011d):

  • Arsenic and dioxins (chronic direct exposure),
  • Ametryn and atrazine (leaching),
  • Petroleum (vapor intrusion, gross contamination, leaching),
  • Lead (chronic direct exposure),
  • DDT (chronic direct exposure),
  • Chlorinated herbicides (leaching),
  • Carbamates (leaching),
  • Organophosphates (acute direct exposure).

Arsenic, dioxins, ametryn, atrazine, and petroleum in particular drive the need for remediation at former mixing areas. Significant lead contamination is also identified at many mixing area sites, although this may in part be due to the use of lead-based paint, since lead-based pesticides are not known to have been widely used.

Although the remaining chemicals can also be present in the same soil at elevated levels, addressing potential environmental hazards posed by the former will almost always coincidentally address potential concerns posed by the latter. Organophosphates primarily pose a short-term, direct exposure risk during and immediately after application. These chemicals are not normally identified in abandoned, former mixing areas above levels of potential concern. Full testing of Decision Units within a former pesticide mixing area most suspected of heavy contamination is recommended. These observations, however, can be used to limit testing for these chemicals to areas suspected of the highest contamination in order to reduce investigation costs, if needed.

Heavy arsenic contamination due to the past use of water-based, arsenical herbicides has been identified to depths of greater than ten feet at former pesticide mixing areas. In some cases contamination can be so significant that soils will fail Toxicity Characteristic Leaching Procedure (TCLP) tests and require management as hazardous waste. It is important to determine this as part of the site investigation in order to help design future remedial actions. Fortunately, the strong binding capacity of iron-rich, volcanic soils in Hawai‘i limits this potential problem to sites with arsenic concentrations in excess of several thousand ppm or at sites where the soil is relatively iron-poor. Arsenic can expected to be much more mobile (and bioaccessible) at sites in coastal areas that are situated on low-iron, calcareous soils rather than volcanic soils.

Petroleum contamination is also present at many former pesticide mixing areas. This can be associated with the use of diesel for preparation of pesticide emulsions. Examples include the use of Concentrated Activated Diesel Emulsion or "CADE" that is "activated" with pentachlorophenol (PCP) for application as an herbicide. Long-term release of petroleum-based emulsions at mixing sites can lead to heavy contamination of underlying soils with dioxins to a depth of ten or more feet. The identification of diesel-contaminated soil at a mixing site should raise concerns about potential dioxin contamination.

Trace levels of PCP are typically identified at pesticide mixing areas operated prior to 1970, when the use of PCP for agricultural operations was banned (HDOA 1969, 1977). Most non-wood preservative uses of PCP were banned in 1987 and use of PCP for wood treatment was significantly restricted by the Federal government (USEPA 2008e; see also ATSDR 2001). The reported concentration of PCP in soil is often below or only marginally above the Tier 1 soil action level of 0.82 mg/kg (HDOH 2016). Pentachlorophenol degrades relatively rapidly in the environmental and is only moderately persistent (see Appendix 9-A). The reported level of PCP in the soil is not a reliable indicator of the presence or absence of significant dioxin contamination. Heavy dioxin contamination, well over 10,000 to 100,000+ ng/kg, associated with the past use of PCP has been identified at sites where little to no PCP remains.

This highlights that the presence or absence of PCP in soil cannot be used as a stand-alone tool to screen for potentially significant dioxin contamination. Soils that could have been significantly impacted by past releases of PCP or similar, dioxin containing chemicals (e.g., 2,4,5 TP) should always be independently tested for dioxins in addition to the suspected parent chemical.

Soils in some, but not all, pesticide mixing areas are also heavily contaminated with ametryn and atrazine. While reported levels often do not exceed action levels for potential direct-exposure concern, these chemicals can still pose leaching threats to underlying groundwater. Comparison to screening levels that do not consider leaching is therefore not appropriate (e.g., USEPA Regional Screening Levels, USEPA 2012b). Reference to the more comprehensive HDOH EALs or equivalent is required. It is important to indentify and remediate soils contaminated with these chemicals in order to prevent and/or cease long-term contamination of drinking water aquifers.

9.1.4.2 Former Field Areas

With the local exception of arsenic, residual pesticides in former sugarcane fields are rarely detected above levels of potential concern (see Appendix 9-E). Arsenic has been identified in some fields at concentrations that are marginally above HDOH action levels for residential exposure. The distribution of former field areas with elevated arsenic is not uniform, but appears to be associated with specific sugarcane companies that operated from the 1910s through the 1940s and relied on arsenic-based herbicides for weed control in high-rainfall areas (see Section 9.1.3.2). Continued testing for arsenic in former sugarcane fields is recommended (see Table 9-2).

Data compiled over the past ten (and especially five) years indicate that dioxins in former sugarcane fields do not pose significant health risk should these areas be redeveloped for residential use in the future. Dioxins have subsequently been removed as a recommended contaminant of concern for former field areas (see Table 9-2). Trace levels of dioxins, reported in terms of Toxicity Equivalent or TEQ dioxins, are often below or slightly above expected, ambient background in many fields (<20 ng/kg; refer to Appendix 9-F). In other fields the concentration of TEQ dioxins typically ranges between 50ng/kg and 100 ng/kg, below the HDOH residential action level of 240 ng/kg (e.g., see HDOH 2007e). In relatively rare cases, the concentration of TEQ dioxins in soil at the scale of an individual, hypothetical, residential lot (e.g., 5,000 ft2; see Section 3), may slightly exceed the current action level but are still at or below past, residential action levels (e.g., 390 to 1,000 ng/kg; see Appendix 9-F; see also USEPA 1998g). This does not pose a significant risk to future residents when more site-specific exposure factors such as soil ingestion rates for urban areas are taken into consideration (see HDOH 2016).

9.1.4.3 Seed Dipping Vats

Heavy mercury contamination has been identified at the outfalls of seed dipping vats that operated before the mid 1970s (see HDOH 2011d). Contaminated sediment has also been identified in mill ditches that drain these areas, however contamination to date is primarily associated with arsenic and dioxins (see HDOH 2011d). Earlier reports of mercury contamination in mill ditches that drained former seed dipping vats were not verified in followup sampling. This may have been due to misreporting of units in laboratory reports or investigation summaries. Laboratories in general report metal concentrations in soil or sediment in units of mg/kg. In the case of mercury, however, laboratories sometime report concentrations in units of μg/kg (1 mg/kg = 1000 μg/kg). Background levels of mercury in soil are typically less than 1.0 mg/kg (HDOH 2012b). It is important to review and confirm units for mercury at sites where apparent contamination is identified.

9.1.4.4 Other Areas and Target Pesticides

The review of data for former sugarcane operations did not identify a need to revise guidance for testing in other areas where pesticides may have been used or stored. Significant contamination with organochlorine pesticides (e.g., DDT, Technical Chlordane, aldrin-dieldrin) has not been identified at the majority of pesticide mixing areas or field areas (see HDOH 2011d). Given their high toxicity and persistence in the environment, however, and past use for mosquito, termite and other pest control around former agricultural areas (e.g., around field margins), continued testing for these chemicals in both former mixing areas and in former field areas is still recommended.

Testing for thallium and barium in an area where rat poison was formerly stored and potentially mixed is currently underway (used in cakes, versus sprayed as a liquid), and data are anticipated in the future. Elevated levels of thallium have not been reported in mixing areas or fields. Due to its potential toxicity, anticipated background levels in soil are likely to be close to risk-based action levels for direct exposure (see HDOH 2016, 2011d). Toxicity factors employed in the action levels assume that the thallium is highly soluble and bioavailable, however. Like arsenic, the actual bioavailability of both natural and pesticide-related thallium in soil is expected to be low.