Memorandum DRAFT Date: June 19, 1995 To: Melissa Valentin From: Don Cortes Re: Trichlorobenzenes I wish to point out some important chemicals associated with PCBs, which are perhaps being overlooked in the assessment and monitoring of the PCB contamination in and around Bloomington. Chlorinated benzenes, especially trichlorobenzenes and tetrachlorobenzenes, have historically been an essential component of dielectric fluids used in transformers and capacitors. Askarels, which contain 35:65 trichlorobenzenes to PCBs (mainly as Aroclor 1242 and 1254), was one of the most common formulations used on large scale in electrical equipment. Furthermore, a common way to synthesize PCBs was by phenylation of trichlorobenzenes, so even the starting PCB material may be contaminated with a substantial amount of trichlorobenzenes. Trichloro and tetrachlorobenzenes are of concern because: 1. They have been shown to cause adverse hepatic, renal, and nervous system effects in animals. At least one epidemiological study has indicated chromosomal aberrations in humans who work with tetrachlorobenzenes. Toxicity has been demonstrated in aquatic species. Environment Canada has set the chronic lowest effect threshold at 4.3 ppb for trichlorobenzenes (Daphnia pulex) and 9.0 ppb for tetrachlorobenzenes (Daphnia magna)1,2,3 2. Although they are removed from aerobic environments (air and surface water) by volatilization and degredation more rapidly than PCBs, they persist and accumulate under anaerobic conditions in buried sediments and soils, and biomagnify up the food chain.4,5,6 3. Their presence enhances the solubility of PCBs in water. 4. They are much more water soluble than PCBs (see Table 1). They will therefore migrate further in soil affected by stormwater runoff and landfill leachate. In situations where groundwater and private drinking water wells are found to contain ppb levels of PCBs, trichlorobenzenes may be present at ppm levels. 5. They are much more volatile than PCBs (see Table 1). Thus, they will migrate further in soil regardless of the presence of water. Their rapid removal by volatilization from top soil means increased short term concentrations in the atmosphere. 6. Due to their mobility relative to PCBs, their presence in the abscence of PCBs may indicate nearby "PCB hotspots". Unfortunately, laboratories have historically not included trichloro and tetrachlorobenzenes as target analytes when analyzing for PCBs by EPA 8080, nor when analyzing for volatile or semivolatile compounds by EPA 8240 or 8270. Currently, only one of the 3 trichlorobenzene isomers is included as a semivolatile target compound, and none of the tetrachlorobenzenes is included. Neither the trichlorobenzenes nor the tetrachlorobenzenes are included as volatile target compounds in soil or groundwater. Although two of the trichlorobenzenes are now part of EPA 524.2 for drinking water, many laboratories do not include these compounds as target analytes. It is a simple matter to have the trichlorobenzenes and tetrachlorbenezenes included as target analytes in any of the aforementioned methods. 1. When performing EPA 8080, ask the laboratory to analyze trichlorobenzene and tetrachlorobenezne standards. This may require an adjustment of temperature program in order to include all of the isomers. When running samples, include them as target analytes. Depending on the temperature program used for 8080, this may or may not significantly increase the cost of analysis. 2. When analyzing for volatile target compounds, ask the laboratory to scan for the three trichlorobenzene isomers if they are not already included on the target list. Tetrachlorobenzenes cannot be detected by this method. This should not cost more than $20 additional per sample. 3. When analyzing for semivolatile target compounds, ask the laboratory to scan for the three trichlorobenzene and tetrachlorobenzene isomers. This should not cost more than $20 additional per sample. If GC/MS chromatograms from past analyses are available, they should be examined for the presence of extraneous peaks in appropriate time windows. If extraneous peaks are found, their mass spectra should be obtained from the laboratory and examined by a trained mass spectroscopist. Unless it can be determined that trichlorobenzenes and tetrachlorobenzenes were never present in any capacitor fluids used by Westinghouse, I recommend that past chromatograms be examined for the presence of extraneous peaks and that future analyses include trichloro and tetrachlorobenzenes, until it can be demonstrated that they are not of concern. If these compounds are found to be present, they should be included as part of drinking water analyses performed to determine the extent of PCB contamination in and around Bloomington. TABLE 1: Comparison of Solubilities and Vapor Pressures Water Solubility Vapor Pressure (mg/L @ 25ż C) (Pa @ 25ż C) Arochlor 1016 0.2-0.9 0.05-0.12 Arochlor 1221 3.5-15. 0.8-2.0 Arochlor 1232 1.45 0.54 Arochlor 1242 0.1-0.7 0.03-0.09 Arochlor 1248 0.05-0.10 0.01-0.06 Arochlor 1254 0.01-0.10 0.004-0.02 Arochlor 1260 0.002-0.01 0.0004-0.005 1,2,3-Trichlorobenzene 20-40 18-67 1,2,4-Trichlorobenzene 30-50 39-67 1,3,5-Trichlorobenzene 5-25 20-77 1,2,3,4-Tetrachlorobenzene 3-7 3.4-5.6 1,2,3,5-Tetrachlorobenzene 2-6 9.8-18.6 1,2,4,5-Tetrachlorobenzene 0.5-5 0.3-6 Measurements vary according to methodology and testing conditions. Data was compiled from 7,8,9. ENDNOTES 1 Canadian Environmental Protection Act. Tetrachlorobenzenes. Page 13-17. 2 Canadian Environmental Protection Act. Trichlorobenzenes. Page 12-15. 3 Cockerham and Shane. Basic Environmental Toxicology. Page 205. 4 Canadian Environmental Protection Act. Tetrachlorobenzenes. Page 13-17. 5 Canadian Environmental Protection Act. Trichlorobenzenes. Page 12-15. 6 Mackay, Shiu, Ma. Illustrated Handbook of Physical-Chemical Properties and Environmental Fate for Organic Chemicals, Vol 1. 7 Kimbrough, Jensen. Halogenated biphenyls, terphenyls, naphthalenes, dibenzodioxins and related products. Elsevier, New York 1989. 8 Mackay, Shiu, Ma. Illustrated Handbook of Physical-Chemical Properties and Environmental Fate for Organic Chemicals, Vol 1. Lewis Publishers, 1992. REFERENCES Canadian Environmental Protection Act. Tetrachlorobenzenes. Priority Substances List Assessment Report, Canada Communication Group, Ottawa 1993. Canadian Environmental Protection Act. Trichlorobenzenes. Priority Substances List Assessment Report, Canada Communication Group, Ottawa 1993. Cockerham and Shane. Basic Environmental Toxicology. CRC Press, Boca Raton, Florida, 1994. Kimbrough, Jensen. Halogenated biphenyls, terphenyls, naphthalenes, dibenzodioxins and related products. Elsevier, New York 1989. Mackay, Shiu, Ma. Illustrated Handbook of Physical-Chemical Properties and Environmental Fate for Organic Chemicals, Vol 1. Lewis Publishers, 1992.