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PubMed2004

Fluxes and reservoirs of trichloroacetic acid at a forest and moorland catchment.

The concentrations and input/output fluxes of trichloroacetic acid (TCA) were measured in all relevant media for one year at a 0.86 km2 upland conifer plantation and moorland catchment in SW Scotland (n > 380 separate samples analyzed). Annual wet precipitation to the catchment was 2.5 and 0.4 m for rain and cloud, respectively. TCA input to the catchment for the year was 2100 g, predominantly in rainwater (86%), with additional input via cloudwater (13%) and gas plus particle dry deposition (1%). There were no seasonal trends in TCA deposition, and cloudwater concentration was not enhanced over rainwater. TCA in precipitation exceeded concentrations estimated using currently accepted routes of gas-phase oxidation from anthropogenic chlorinated hydrocarbon precursors, in agreement with previous studies. Export of TCA from the catchment in streamwater totalled 1970 g for the year of study. The TCA concentration in streamwater at outflow (median 1.2 microg L(-1)) was significantly greater than that before the stream had passed through the conifer plantation. To well-within measurement uncertainties, the catchment is currently at steady-state with respect to TCA input/output. The catchment reservoir of TCA was dominated by soils (approximately 90%), with the remainder distributed in forest litter (approximately 9%), forest branchwood and stemwood (approximately 0.7%), forest foliage (approximately 0.5%), and moorland foliage (approximately 0.1%). Although TCA is clearly taken up into foliage, which consequently may be important for the vegetation, this was a relatively minor process for TCA at the catchment scale. If it is assumed, on the basis of laboratory extraction experiments, that only approximately 20% of "whole soil" TCA measured in this work was water extractable, then total mass of TCA in the catchment is reduced from approximately 13 to approximately 3.5 kg. Comparing the latter value with the annual flux yields an average steady-state residence time for TCA in the catchment of approximately 1-2 y, if all TCA is involved in catchment turnover. Considering that other evidence indicates the lifetime of TCA in soil and biota is considerably shorter than this (weeks rather than years), the magnitude of the TCA reservoir is suggested to be strong evidence for net natural TCA production in soils and/or that the majority of TCA in the reservoir is not involved with external fluxes.

Caustics↗

PubMed1983

Interference by hemolysis with various methods for total calcium and its correction by trichloroacetic acid precipitation.

We evaluated the influence of hemolysis on total serum calcium as determined with the Du Pont aca, SMA 12/60, Ektachem 400, Corning 940 EGTA titrator, and the Beckman Astra 8, comparing results with those obtained by atomic absorption spectroscopy. We find that hemoglobin does not influence calcium measurements with the SMA 12/60, Ektachem 400, or Beckman Astra 8. The presence of hemoglobin exceeding 2 to 3 g/L caused falsely high results with the aca and falsely low results with the Corning 940 titrator. Similar interferences may be observed with other titrating or colorimetric procedures that involve direct reaction of the sample with o-cresolphthalein complexone or calcein. Upon removal of the hemoglobin by precipitation with trichloroacetic acid, the values obtained with the aca and the Corning 940 EGTA titrator were similar to those measured by atomic absorption. With nonhemolyzed serum samples the acid treatment had little or no effect on the aca procedure but resulted in a positive bias of approximately 10% with the EGTA procedure. Thus we recommend this trichloroacetic acid procedure for measuring calcium in hemolyzed samples with the aca and, with certain reservations, with the EGTA titrator.

Autoanalysis↗

PubMed2002

Trichloroacetic acid fate and toxicity to the macrophytes Myriophyllum spicatum and Myriophyllum sibiricum under field conditions.

Trichloroacetic acid (TCA) has been detected in rain, snow, and river samples throughout the world. It may enter into natural water systems via herbicide use, as a by-product of water disinfection, from emissions of spent bleach liquor of kraft pulp mills, and as a natural fungal product. This compound is phytotoxic and likely to accumulate in aquatic environments. A study to assess the fate of TCA in semi-natural aquatic environments and the toxicity of TCA to rooted aquatic macrophytes was conducted. The experiment involved exposing three replicate 12000 l aquatic microcosms at the University of Guelph Microcosm Facility to 0.05, 0.5, 3, and 10 mg/l of TCA for 35 days in a one-way analysis of variance design. Each microcosm was stocked with 14 individual 5 cm apical shoots of Myriophyllum spicatum and M. sibiricum. The plants were sampled at regular intervals and assessed for the somatic endpoints of plant length, root growth, number of nodes and wet and dry mass and the biochemical endpoints of chlorophyll-a and chlorophyll-b, carotenoid content, and citric acid levels. TCA half-lives in the microcosms ranged from 190 to 296 h depending on the initial concentration of TCA. Myriophyllum spp. results indicate that while there were some statistically significant differences from controls, there were no biologically significant effects of TCA for any of the endpoints examined. These data suggest that TCA does not pose a significant risk to these macrophytes up to 10 mg/l, which typically exceeds environmentally relevant concentrations by several orders of magnitude.

Biomass↗

PubMed1976

Identification of Propionibacterium acnes and related organisms by precipitin tests with trichloroacetic acid extracts.

The serological identification of Propionibacterium acnes, P. granulosum, and P. avidum, using trichloroacetic acid extracts, is described. With antisera prepared against reference strains, the method has been tested on 142 strains recently isolated from human skin. All except two of the strains could be identified serologically, and there was excellent agreement between the serological results and the fermentation pattern of the strains. Two serological types of P. acnes and two of P. avidum were identified, but only one of P. granulosum.

Antigens, Bacterial↗

PubMed1995

Administration of subtoxic doses of t-butyl alcohol and trichloroacetic acid to male Wistar rats to study the interactive toxicity.

Tertiary butyl alcohol and trichloroacetic acid (TCA) are known to be contaminants in drinking water. In order to evaluate the interactive toxicity of t-butyl alcohol (TBA) with TCA, young male Wistar rats were dosed through water at a dose level of TBA (0.5% v/v), 25 ppm TCA and a combined dose of TBA+TCA (0.5% v/v TBA, 25 ppm TCA) for a period of 10 weeks ad libitum and were maintained on normal diet. The control animals received plain water and normal diet. There was remarkable loss of body weight and significantly decreased liver triglycerides in the treatment groups in the order of TBA+TCA, TCA, TBA and increased liver weights were observed. Serum succinate dehydrogenase (SDH) levels were significantly increased in TCA- and TBA+TCA-treated groups. There was no significant change in serum alanine (GPT), aspartate (GOT) aminotransferase, serum alkaline (ALP) and acid (ACP) phosphatase levels as well as liver glutathione (GSH) and liver and serum cholesterol levels in the treated groups. But serum triglycerides, liver glycogen, serum glucose (only in TBA- and TCA-treated animals) were significantly high in the treated groups. Lipid peroxidation measured by diene conjugation was significant in TBA+TCA-treated group and kidney GSH levels were significantly low in the treated groups. These results show that interaction of TBA+TCA does bring about alteration in biochemical parameters which may play a pivotal role in toxic responses on long-term exposure.

Alanine Transaminase↗

PubMed1991

Trichloroacetic acid: studies on uptake and effects on hepatic DNA and liver growth in mouse.

Trichloroacetic acid (TCA) was tested in mice for its ability to cause single-strand breaks (SSBs) in hepatic DNA in the presence and absence of liver growth induction. Male B6C3F1 mice were given 1, 2 or 3 daily doses of TCA (500 mg/kg p.o.) as a neutralized solution (sodium salt) and killed 1 h after the final dose. Some mice were given a single dose of TCA (500 mg/kg p.o.) as the acid or as a neutralized solution and killed 24 h after. Liver nuclei were prepared and the induction of DNA SSBs assayed. TCA gave no significant response. Absorption and distribution studies were conducted with radiolabelled trichloro[2-14C]acetic acid, which was administered by gavage (500 mg/kg) as aqueous free acid, neutral aqueous solution (sodium salt) or free acid in corn oil. The absorption and distribution of TCA was similar in all cases: the chemical was absorbed rapidly after dosing, maximum plasma and liver concentrations of free radiolabel being achieved in less than 1 h. Within the first 4 h following dosing there was no evidence of binding to DNA or other macromolecules in plasma and very little 'covalent' binding was detected in liver, indicating that at times when maximum DNA single-strand breakage has been reported there was no significant binding to liver cells. Studies on liver growth parameters (hyperplasia and peroxisome proliferation) with TCA revealed that the chemical induced small but significant increases in both parameters. No SSB induction was detected in association with either liver growth phenomenon elicited by TCA. We have thus found no evidence that TCA causes SSBs in the hepatic DNA of treated mice, in contrast to previous observations by other investigators.

Animals↗

PubMed2002

Simulation of trichloroacetic acid kinetics in the isolated perfused rat liver using a biologically based kinetic model.

Trichloroacetic acid (TCA) is a contaminant of drinking water. It induces peroxisome proliferation in livers of rats and mice and is hepatocarcinogenic in the latter species. Previous experimental studies of the kinetics of TCA in the isolated perfused rat liver (IPRL) at two doses have been reported. To gain more insight into the mechanistic processes controlling TCA kinetics in the liver a biologically based kinetic (BBK) model for the IPRL was used to analyze the experimental data. The IPRL was exposed to 25, 250, or 1000 microM TCA for 2 h in a recirculating perfusion system. These doses were not cytotoxic. The BBK model simulated the TCA concentration in perfusion medium and liver, and the biliary excretion of TCA. Separate protein binding studies showed that over 90% of TCA was bound to albumin in the perfusion medium whereas binding in liver homogenate was much lower. Integrating the information on protein binding into the BBK model, the hepatic uptake of TCA and its biliary excretion could be fitted assuming asymmetrical saturable transport at the sinusoidal membrane and linear transport at the bile canalicular membrane. To validate the BBK model, additional washout experiments were conducted in which the perfusion medium was replaced with TCA-free medium after 30 min of exposure of the liver to 1000 microM TCA. This approach illustrates the usefulness of BBK modeling for analyzing experimental kinetic data and gaining insight in kinetic mechanisms controlling the behavior of a chemical in the liver.

Animals↗

PubMed2006

Cardiogenic effects of trichloroethylene and trichloroacetic acid following exposure during heart specification of avian development.

Trichloroethylene (TCE) and its metabolite trichloroacetic acid (TCA) are common drinking water contaminants in the United States. Both chemicals have been implicated in causing congenital heart defects (CHD) in human epidemiological and animal model studies. However, the latter studies have primarily focused on assessment of cardiac morphology at late embryonic stages. Here, we tested whether treating avian embryos with TCE or TCA during an exposure window encompassing cardiac specification (Hamburger-Hamilton [HH] 3+) until the onset of chambering (HH 17) informs the etiology of CHD at later stages of development. Embryos were exposed to TCE or TCA via direct injection into the yolk, over a range of doses that included each compound's maximum contaminant level as established by the U.S. Environmental Protection Agency. A modified TUNEL (Terminal deoxynucleotide transferase mediated dUTP-biotin Nick-End Labeling) assay indicated that neither compound induced apoptotic cell death in ventricular myocytes or endocardiocytes at HH 18. However, mid-range dosages of TCE increased myocyte and endocardiocyte proliferation by this time, as determined by monitoring BrdU incorporation; in contrast, an intermediate dose of TCA inhibited proliferation in endocardiocytes. These cellular changes had no apparent functional consequences because all measured hemodynamic parameters were normal for TCE- and TCA-exposed embryos at HH 18, HH 21, and HH 23. In summary, TCE or TCA exposure during the cardiac specification window has only minimal effects on the developing avian heart. These results sharply contrast with our previously reported observations following administration of equivalent doses during a window of valvuloseptal morphogenesis. Taken together, these findings indicate that, as for other teratogens, sensitivity is dictated by the embryo's stage of development.

Animals↗

PubMed1972

A simple lipase assay using trichloroacetic acid.

An extremely rapid and sensitive assay for lipoprotein lipase activity, suitable for routine determinations, is described. The substrate for the assay is emulsified [2-(3)H]glyceryl trioleate, activated by serum. The method is based on trichloroacetic acid precipitation of unreacted substrate and measurement of (3)H-labeled glycerol.

Adipose Tissue↗

PubMed2002

Trichloroacetic acid (TCA) and trifluoroacetic acid (TFA) mixture toxicity to the macrophytes Myriophyllum spicatum and Myriophyllum sibiricum in aquatic microcosms.

Trichloroacetic acid (TCA) and trifluoroacetic acid (TFA) have been detected together in environmental water samples throughout the world. TCA may enter into aquatic systems via rainout as the degradation product of chlorinated solvents, herbicide use, as a by-product of water disinfection and from emissions of spent bleach liquor of kraft pulp mills. Sources of TFA include degradation of hydrofluorocarbons (HFCs) refrigerants and pesticides. These substances are phytotoxic and widely distributed in aquatic environments. A study to assess the risk of a binary mixture of TCA and TFA to macrophytes in aquatic microcosms was conducted as part of a larger study on haloacetic acids. M. spicatum and M. sibiricum were exposed to 0.1, 1, 3 and 10 mg/l of both TCA and TFA (neutralized with sodium hydroxide) in replicate (n = 3) 12000 l aquatic microcosms for 49 days in an one-way analysis of variance design. Each microcosm was stocked with 14 individual apical shoots per species. The plants were sampled at regular intervals and assessed for the somatic endpoints of plant length, root growth, number of nodes and wet and dry mass and the biochemical endpoints of chlorophyll-a, chlorophyll-b, carotenoid content and citric acid levels. Results indicate that there were statistically significant effects of the TCA/TFA mixture on certain pigment concentrations immediately after the start of exposure (2-7 days), but the plants showed no signs of stress thereafter. These data suggest that TCA/TFA mixtures at environmentally relevant concentrations do not pose a significant risk to these aquatic macrophytes.

Biomass↗

PubMed2004

Trichloroacetic acid in Norway spruce/soil-system. II. Distribution and degradation in the plant.

Independently from its origin, trichloroacetic acid (TCA) as a phytotoxic substance affects coniferous trees. Its uptake, distribution and degradation were thus investigated in the Norway spruce/soil-system using 14C labeling. TCA is distributed in the tree mainly by the transpiration stream. As in soil, TCA seems to be degraded microbially, presumably by phyllosphere microorganisms in spruce needles. Indication of TCA biodegradation in trees is shown using both antibiotics and axenic plants.

Anti-Bacterial Agents↗

PubMed2004

Chemical ablation of endometrium with trichloroacetic acid.

OBJECTIVES: The aim of this study was to assess the efficacy of topically applied trichloroacetic acid (TCA) for endometrial ablation in patients with dysfunctional uterine bleeding (DUB). This trial has also compared the advantages of prethinning the endometrium with danazol and goserelin acetate before ablation with TCA. METHODS: This prospective trial was conducted on 90 volunteer cases. Patients were allocated into three treatment groups comprised of 30 patients. In group I cases underwent dilatation and curettage before endometrial ablation. In group II cases were administered danazol before ablation. Cases in group III received goserelin acetate on the same day and 28 days after ablation. Endometrium was evaluated by biopsy, transvaginal ultrasonography and hysteroscopy. Endometrial ablation was performed with 95% TCA. All of the patients were evaluated 3 and 6 months after TCA application. RESULTS: After 6 months of treatment, the success rate was recorded as 83% in the first group, 92.3% in the second group and 96.6% in the third group. The mean length of uterine cavity was reduced in all groups, being only significant in Goserelin group (P<0.5). Endometrial thickness was decreased significantly in all treatment groups (P<0.001). CONCLUSIONS: This study concluded that endometrial ablation by TCA may readily be performed as an alternative treatment method in the management of DUB. Moreover, suppression of endometrium with danazol or especially with goserelin acetate before ablation, resulted in significant success rate.

Administration, Oral↗

PubMed2003

Urinary levels of trichloroacetic acid, a disinfection by-product in chlorinated drinking water, in a human reference population.

Trichloroacetic acid (TCAA), a known mouse liver carcinogen and a possible human carcinogen, is found in chlorinated drinking water. We measured TCAA in archived urine samples from a reference population of 402 adults using isotope-dilution high-performance liquid chromatography-tandem mass spectrometry. TCAA was detected in 76% of the samples examined at concentrations ranging from < 0.5 micro g TCAA/L to more than 25 micro g/L; the 90th percentile concentration was 23 micro g/L (22 micro g TCAA/g creatinine); and the geometric mean and median concentrations were 2.9 micro g/L (2.6 micro g/g creatinine) and 3.3 micro g/L (3.2 micro g/g creatinine), respectively. The frequency of detection of TCAA in urban areas was higher than in rural areas (p = 0.00007), and sex and place of residence (i.e., urban vs. rural) were found to have a significant interaction in modulating the levels of TCAA (p = 0.012). Urban residents had higher mean levels of TCAA (men, 5.3 micro g/L, 3.8 micro g/g creatinine; women, 2.9 micro g/L, 2.8 micro g/g creatinine) than did rural residents (men, 2.2 micro g/L, 1.7 micro g/g creatinine; women, 2.6 micro g/L, 2.7 micro g/g creatinine). The higher frequency of detection of TCAA in urban than in rural areas and higher levels of TCAA among urban than among rural residents may reflect the fact that urban residents use primarily chlorinated water from public water supplies, whereas those in rural areas are more likely to obtain water from private wells, which typically are not chlorinated.

Adult↗

PubMed2004

Trichloroacetic acid cycling in Sitka spruce saplings and effects on sapling health following long term exposure.

Trichloroacetic acid (TCA, CCl(3)COOH) has been associated with forest damage but the source of TCA to trees is poorly characterised. To investigate the routes and effects of TCA uptake in conifers, 120 Sitka spruce (Picea sitchensis (Bong.) Carr) saplings were exposed to control, 10 or 100 microg l(-1) solutions of TCA applied twice weekly to foliage only or soil only over two consecutive 5-month growing seasons. At the end of each growing season similar elevated TCA concentrations (approximate range 200-300 ng g(-1) dwt) were detected in both foliage and soil-dosed saplings exposed to 100 microg l(-1) TCA solutions showing that TCA uptake can occur from both exposure routes. Higher TCA concentrations in branchwood of foliage-dosed saplings suggest that atmospheric TCA in solution is taken up indirectly into conifer needles via branch and stemwood. TCA concentrations in needles declined slowly by only 25-30% over 6 months of winter without dosing. No effect of TCA exposure on sapling growth was measured during the experiment. However at the end of the first growing season needles of saplings exposed to 10 or 100 microg l(-1) foliage-applied TCA showed significantly more visible damage, higher activities of some detoxifying enzymes, lower protein contents and poorer water control than needles of saplings dosed with the same TCA concentrations to the soil. At the end of each growing season the combined TCA storage in needles, stemwood, branchwood and soil of each sapling was <6% of TCA applied. Even with an estimated half-life of tens of days for within-sapling elimination of TCA during the growing season, this indicates that TCA is eliminated rapidly before uptake or accumulates in another compartment. Although TCA stored in sapling needles accounted for only a small proportion of TCA stored in the sapling/soil system it appears to significantly affect some measures of sapling health.

Air Pollutants↗

PubMed2005

Intrauterine instillation of trichloroacetic acid is effective for the treatment of dysfunctional uterine bleeding.

OBJECTIVE: To evaluate the effectiveness of trichloroacetic acid (TCA) instillation into uterine cavity for the treatment of dysfunctional uterine bleeding (DUB). DESIGN: Prospective clinical study. SETTING: A university research hospital. PATIENT(S): Ninety women participated who had dysfunctional uterine bleeding. INTERVENTION(S): Ninety-five percent of TCA was instilled into uterine cavity for endometrial ablation in women with dysfunctional uterine bleeding who want conservative treatment. Participants in group 1 received only TCA; participants in group 2 received a single dose of gonadotropin-releasing hormone analogue 1 month before the procedure. MAIN OUTCOME MEASURE(S): All participants underwent an evaluation that included cycle history, body mass index measurement, and transvaginal ultrasonography of pelvis, diagnostic hysteroscopy and endometrial biopsy. RESULT(S): At the end of 12 months of the treatment, amenorrhea rates in group 1 and group 2 were 26.7% vs. 31.1%, with pooled amenorrhea, hypomenorrhea, and eumenorrhea rates of 95.6% vs. 97.8%, respectively. There was no significant difference between the groups vis-a-vis postprocedure results. More than 90% of women who have this procedure are satisfied with the results. There were no observed negative effects or related complications with this treatment. CONCLUSION(S): An instillation of TCA into uterine cavity produces acceptable results and provides conservative management of DUB.

Adult↗

PubMedDate not supplied

Changes of epidermal Langerhans cells in skin treated with trichloroacetic acid.

The changes in Langerhans cells (LCs) from normal human skin peeled with 40 and 60% trichloroacetic acid (TCA) or liquid nitrogen , which is known in cryosurgery as a control, were examined using monoclonal antibodies against the CD1a, HLA-DR and Lag in order to examine the immune surveillance system. In the 40% TCA group, the number of CD1a-positive cells decreased gradually until day 7, whereas both HLA-DR- and Lag-positive cells decreased for 12 hours, increased until day 2 and decreased thereafter. In the 60% TCA group, the number of CD1a-, HLA-DR- and Lag-positive cells decreased gradually until day1, increased temporarily until day 2, and decreased again until day 7. There were no significant differences in the decrease of the LCs between the 40% and 60% TCA groups. In both cases the number of LCs on day 7 was statistically lower than before treatment. In the liquid nitrogen group, which served as a control, the LCs decreased gradually and slightly until day 2, and then increased. Taken together, the number of epidermal LCs from TCA-treated skin was reduced more significantly than LCs from liquid nitrogen-treated skin, suggesting a temporary impairment of the skin defense system. Therefore, long-term and frequent TCA peeling will require special attention for potential carcinogenesis.

Adult↗

PubMed2005

Therapeutic effect of topical applications of trichloroacetic acid for vaginal intraepithelial neoplasia after hysterectomy.

OBJECTIVE: We attempted to evaluate the therapeutic effect of trichloroacetic acid (TCA) for vaginal intraepithelial neoplasia (VaIN) after hysterectomy and to identify factors affecting persistence/recurrence. METHODS: Twenty-eight post-hysterectomy patients with various grades of VaIN were enrolled in this study between January 2001 and December 2003. They were managed with intravaginal 50% TCA once weekly for 1-4 weeks, and all patients were followed up every 3 months for at least 1 year. Assessments by Papanicolaou smear and colposcopy were performed, as was biopsy when indicated during the follow-up period. Cox regression analysis was used to identify independent factors predicting persistence/recurrence. RESULTS: In 20 of 28 patients (71.4%) VaIN went into remission. Treatment success was observed in all 11 patients with VaIN I, whereas only 9 out of 17 patients (53%) with VaIN II/III went into remission (P = 0.009). Severity of VaIN was the only significant independent predictor of persistence/recurrence (odds ratio = 3.5; 95% confidence interval = 1.1, 11.6; P = 0.038). The treatment was well tolerated with no major side effects. CONCLUSIONS: Based on our findings, 50% TCA was a potential agent with minimal side effects for low-grade VaIN. Further prospective controlled study is warranted to verify our statements. However, as for high-grade lesions, further investigation with different TCA concentration is compelling.

Administration, Topical↗

PubMed2003

Atmospheric concentrations and deposition of trichloroacetic acid in Scotland: results from a 2-year sampling campaign.

The first long-term concurrent measurements of trichloroacetic acid (TCA) in rainwater, in cloudwater, and in air (both gas and particle phase) are reported. Measurements were made weekly between June 1998 and April 2000 at a rural forested upland site in SE Scotland. Rainwater TCA concentration did not differ significantly between two elevations (602 and 275 m asl), with precipitation-weighted mean values of 0.77 and 0.70 microg L(-1), respectively (n > 75). The precipitation-weighted mean concentration of TCA in cloudwater at the highest elevation was 0.92 microg L(-1), yielding an average cloudwater enrichment factor of 1.2, considerably lower than for other inorganic ions measured. Rainwater and cloudwater TCA concentrations did not vary systematically with season. Since wet precipitation depth also did not vary systematically with season, the wet deposition fluxes of TCA were likewise invariant (annual fluxes at the highest elevation of 880 and 130 microg m(-2), respectively, for rain and cloud interception to spruce forest). Weekly integrated concentrations of TCA in air (gas and particle) were very low (median 25 pg m(-3), range < LOD-110 pg m(-3)). The estimated upper limit for annual dry deposition of TCA at this site was approximately 20 microg m(-2), assuming a deposition velocity of 2 cm s(-1). Concentrations of TCA in air correlated reasonably strongly with concentrations in rainwater, with a partition ratio approximately equal to the Henry's law coefficient. On average, only about 23% of TCA measured in Edinburgh air was associated with the particle phase. These measurements are consistent with the observed high scavenging ratio of TCA (ratio of concentration in air to concentration in rainwater). Overall, these data confirm that the atmosphere is an important source of TCA to the environment and that precipitation is the dominant transfer mechanism. In line with previous work, the atmospheric deposition flux is greater than expected from the current understanding of atmospheric production of TCA from anthropogenic precursors. It is suggested that aqueous-phase processes could lead to greater atmospheric conversion of chlorinated solvent precursors to TCA than is currently accepted.

Acid Rain↗