Are Disadvantaged Populations Exposed to Toxic Chemicals?

Methods

Summary

A measured sample of water taken from a body of water may be referred to as a “Grab Sample,” which suggests that a container was used to collect the water sample from the subject body of water, usually for analysis. By this method the investigator assumes that the chemical or microbial entity to be detected or evaluated (the analyte) will be captured in the random Grab Sample collected. In the case where the microbes or chemicals are anticipated to be present at evaluable concentrations, that can be a useful method. In other cases, especially where the targeted analyte may be at low concentration, even at a concentration below the limits of detection, it is more useful to sample a greater volume of water to determine if the subject analyte is there at all, most especially in the case where an infectious agent of toxic substance has high activity at a low concentration. There are certain materials, including adsorption matrices or filter devices whereby the sought analyte can be expected to be captured or accumulated, thereby providing a greater opportunity for analysis and quantitation of the analyte.

In the case of analytes specifically sought for the purposes of this project, Low Density Polyethylene (LDPE) materials are specific adsorbers (adsorb = to collect or accumulate on the surface) of our targeted analytes (compounds), such as brominated flame retardants, organochlorine pesticides and other compounds that have similar structures, including dioxins, furans, Polychlorinated Biphenyls, and more. Our targeted compounds include, among others:

·         polybrominated diphenyl ethers (PBDEs)

·         2-ethylhexyl-2,3,4,5-tetrabromobenzoate (TBB or EH-TBB)

·         bis(2-ethylhexyl) 3,4,5,6-tetrabromophthalate (TBPH)

·         1,2-bis(2,4,6,-tribromophenoxy)ethane (BTBPE)

·         decabromodiphenylethane (DBDPE)

·         hexabromocyclododecane (HBCD or HBCDD)

·         tetrabromobisphenol A (TBBPA)

·         three chlorinated organophosphate flame retardants (ClOPFRs)

·         tris(1,3-dichloro-2-propyl)phosphate (TDCPP or TDCIPP)

·         tris(1-chloro-2-propyl)phosphate (TCPP or TCIPP)

·         tris(2-chloroethyl)phosphate (TCEP).

The analytical methods are based on ultraperformance liquid chromatography (UPLC)-atmospheric pressure photoionization (APPI) tandem mass spectrometry (MS/MS), for example, as performed by the Department of Environmental & Aquatic Animal Health, Virginia Institute of Marine Science, College of William & Mary, Gloucester Point, Virginia 23062.

The Passive Sampling Devices (PSDs) were constructed of LDPE flat tubing (1” flat tubing; 0.2 mil X 8’ length, 4 per PSD). The PSDs were washed three time in Hexane prior to use. The PSDs were submerged in the river or canal environment by attachment to a substrate base in the water environment by polypropylene twine. The PSDs remained in the water environment for 30 days.

Challenges

The primary challenge to this project is our assumption that the analytes of interest are in the subject waters and that they accumulated on the PSDs during the 30 day period of exposure. Considering that we traced the flows of surface waters to the test areas from local WWTPs, farm fields and land-disposed sewage sludges, the likelihood that the sought analytes are in the subject waters is very high.

We successfully deployed similar PSDs in forest waters that were also exposed to leachates and runoff from sewage sludges from the same and from other WWTPs. The target analytes were recovered successfully and evaluated, which provides added encouragement that the targeted analytes will be discovered in the subject test waters.

Pre Analysis Plan

The expected outcome of this experiment will be a report on the kinds and concentrations of the subject analytes. The point is to discover if the analytes are present in the subject waters, with an ancillary benefit being a determination of the concentration of analytes detected. Considering that the target analytes are known to be toxic at very low concentrations, any detection at all will signal that the subject waters are contaminated and should be the subject of additional analysis.

This project is an exploratory mission to determine if the subject analytes are present in the subject waters. The resulting data will be critical to the design and scope of subsequent investigations. The detection of any of the targeted analytes will demonstrate that disadvantaged populations are in fact exposed to toxic chemicals by their work and lifestyle in the Yakima Valley agricultural environment. This first experiment seeks only to determine if human exposure is likely, as a function of the presence of the analytes investigated.