Critical and systematic evaluation of data for estimating human exposures to 2,4-dichlorophenoxyacetic acid (2,4-D) – quality and generalizability

Figures & data

Table 1. Elements of the Biomonitoring, Environmental Epidemiology, and Short-Lived Chemicals (BEES-C) Instrument used in this assessment (from, 2015; LaKind et al. 2014, 2015)

Study assessment components	Tier 1	Tier 2	Tier 3
Biomarker Selection and Measurement
Biomarker stability	Samples with a known history and documented stability data or those using real-time measurements.	Samples have known losses during storage but the difference between low and high exposures can be qualitatively assessed.	Samples with either unknown storage history and/or no stability data for target analytes.
Sample contamination	Samples are contamination-free from time of collection to time of measurement (e.g. by use of certified analyte-free collection supplies and reference materials, and appropriate use of blanks both in the field and lab). Research includes documentation of the steps taken to provide the necessary assurance that the study data are reliable.	Incomplete documentation of QC steps taken to avoid contamination.	There are known contamination issues and no documentation that the issues were addressed.
Matrix adjustment	Study provides results either in the main publication or as a supplement for creatinine-adjusted or SG-adjusted and non-adjusted urine concentrations and reasons are given for adjustment approach.	Study only provides results using one method (matrix-adjusted or not).	No established method for adjustment (e.g. adjustment for hair).

Table 2. Summary of publications relevant for human exposure assessment by matrix

Matrix	Reviewed publications*	Publications assessed with BEES-C*
Food	16	7
Soil/Dust	24	16
Air	40	32
Water	78	44
Urine	77	52
Blood/Semen	6	5
Total	241	156

*Some publications evaluated more than one matrix and are included more than once

Figure 1. Temporal decline of LODs in 2,4-D literature on urine biomonitoring.

Figure 2. 2,4-D publications by medium/matrix over time.

LaKind, J. S., J. R. Sobus, M. Goodman, D. B. Barr, P. Fürst, R. J. Albertini, T. E. Arbuckle, G. Schoeters, Y. M. Tan, J. Teeguarden, R. Tornero-Velez, and C. P. Weisel. 2014. A proposal for assessing study quality: Biomonitoring, Environmental Epidemiology, and Short-lived Chemicals (BEES-C) instrument. Environ. Int. 73:195–207. doi:10.1016/j.envint.2014.07.011.

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LaKind, J. S., and D. Q. Naiman. 2015. Temporal trends in bisphenol A exposure in the United States from 2003–2012 and factors associated with BPA exposure: Spot samples and urine dilution complicate data interpretation. Environ. Res. 142:84–95. doi:10.1016/j.envres.2015.06.013.

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