Correspondence Comment on “Bioaccumulation of Pharmaceuticals and Other Anthropogenic Waste Indicators in Earthworms from Agricultural Soil Amended With Biosolid or Swine Manure” The environmental behavior of microconstituents (e.g., pharmaceuticals and personal care products (PPCPs), hormones) is attracting much media attention and public concern. One topic of interest is microconstituent bioaccumulation in earthworms following land application of biosolids, the topic of a recent paper by Kinney et al. (1). My reading of the paper raised several concerns. First, standard EPA protocols (2) to document data quality were not followed. The results as shown in Table 1 in the Kinney et al. paper, particularly for earthworms, are inaccurate and/ or incorrect based on both data validation protocols as well as a review of the data patterns. Second, the data presentation and interpretation appears to overstate and/or misinterpret the findings. Data Quality/Validity. Rigorous protocols to validate data require more information than Kinney et al. provide, and the authors should have used the standard protocols to validate the results. Based on the information provided, I conclude that many of the results shown in Table 2 should be rejected, listed as undetected, and/or labeled as estimated concentrations. Confidence is greater for results much higher than the detection limit (DL). Concentrations below the samplespecific DL should be flagged as uncertain. The method DLs shown in Table S2 are not relevant for earthworm samples. Because of the lower dry weight used in the analysis, earthworm detection limits will be many times higher than reported. Earthworm results are likely estimated values, and even large numbers falsely convey confidence in microconstituent presence or concentration. EPA guidelines state “Qualify data as undetected (U) if concentration in sample is less than five or ten times the blank concentration.” This comparison is to be made on the raw data, rather than after adjustments for factors like sample volume. Using the EPA-proscribed protocols, earthworm Galaxolide concentrations, in many cases, are likely more accurately designated as undetected. Presentations of results using emerging methodologies require authors to fully disclose the relevant information. Thus, compounds tested for, but not detected, should be identified. The range of sample-specific detection limits for biosolids, manure, soil, and earthworms should be stated and the samples below the limits should be appropriately flagged. The method to calculate averages of (three) composited samples when the chemical was not detected in each sample should be stated. A review of the data patterns and potential for artifacts also raises issues. Earthworms were collected in the spring and the fall. Samples were collected from “reference”, biosolids-amended and manure-amended sites as much as 160 km apart. The sites differed in crop type grown, soil properties, tilling practices, etc. One would expect clear differences among microconstituent concentrations at the sites if amendments of differing microconstituent composition had a significant impact on earthworm accumulation. Many chemicals were reported at nearly identical, low concentrations in the reference and amended sites. For 544
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example, tributylphosphate and benzophenone were not detected in the manure or biosolids. The same chemicals were detected at similar concentrations in earthworms from the reference site and amended sites, and all concentrations are likely below the sample specific DLs. These results may be artifacts of the analysis, and certainly do not support the contention that the chemical concentrations are related to soil amendments. Similar comments pertain to a range of other chemicals, including PAHs, d-limonene, camphor, and others. The authors’ suggestion that further investigation at the reference site is needed to identify a “source” misses the point that near identical low concentrations at the three sites is an analytical issue, not a contamination issue. Data Interpretation. The paper’s title implies that anthropogenic waste indicators (AWIs) at sites amended with biosolids or manures are bioaccumulating in earthworms. We regard the title misleading and inaccurate. Identifying biogenic sterols as AWIs is inappropriate for agricultural sites where the highest concentrations were frequently at the reference site. Moreover, presenting relative concentrations (Figure 1) infers lower levels of other chemicals of interest at Site 1, rather than just higher sterol concentrations. Phenol was detected in earthworms from all three sites only in the fall. This “disinfectant AWI” is also found naturally in decomposing organic material and has a relatively short half-life in soil. If actually present, it is likely not an AWI. The calculated bioaccumulation factors (BAFs) (Table 2) and the conclusion that bioaccumulation results from the use of soil amendments are not supported by the data. For example, there are 15 BAFs >0 for chemicals at the reference site, more than the 13 at the manure-amended site. Calculating a BAF for “AWIs” like cholesterol is inappropriate. Cholesterol is a lipid in cell membranes, synthesized by all animals including earthworms. In this context it is not appropriate to infer it is anthropogenic, waste, or is present in earthworms because it is bioaccumulating. Models exist to estimate bioaccumulation of organic compounds by earthworms based on chemical properties like Log Kow (3) Kinney et al. acknowledge the lack of correlation of compound Kow with BAFs values shown in Table 2. Indeed, the BAFs for chemicals like Galaxolide and indole show the reverse of expected patterns. Models for BAFs are based on empirical data with much higher confidence in the concentrations of earthworms and the associated soils than the data obtained by Kinney et al., and should be carefully considered in further evaluation of data.
Literature Cited (1) Kinney, C. A.; Furlong, E. T.; Kolpin, D. W.; Burkhardt, M. R.; Zaugg, S. D.; Werner, S. L.; Bossio, J. P.; Benotti, M. J. Bioaccumulation of pharmaceuticals and other anthropogenic waste indicators in earthworms from agricultural soil amended with biosolid or swine manure. Environ. Sci. Technol. 2008, 42, 1863–1870. (2) U.S. Environmental Protection Agency. Contract Laboratory Program National Functional Guidelines for Organic Data Review; Washington, DC, February1994. (3) U.S. Environmental Protection Agency. Attachment 4-1. Guidance for Developing Ecological Soil Screening Levels (EcoSSLs); OSWER Directive 9285.7-55; Washington, DC, April 2007.
Patricia V. Cline Strategic Environmental Analysis, Inc. ES8020759 10.1021/es8020759 CCC: $40.75
2009 American Chemical Society
Published on Web 12/12/2008
