Impact/Purpose:

The goal of this research effort is development of analytical methods for the determination of compounds selected for the 1998 Contaminant Candidate List (CCL) [Note: chemicals on the CCL are denoted below with a single asterisk, *. Chemicals with a double asterisk, **, are used as Internal Standards (Recovery and Quantitative).]. These may include selected non-pesticidal* , pesticidal, and other types of organotin compounds: monomethyltin trichloride*, dimethlytin dichloride*, trimethyltin trichloride, monobutyltin trichloride*, dibutyltin dichloride*, tributyltin chloride, phenyltin trichloride, diphenyltin dichloride, triphenyltin chloride, tricyclohexyltin, tripropyltin chloride**, tetrapentyltin**, tetrabutyltin**, etc.. The method(s) should be adequate for gathering occurrence data under the Unregulated Contaminant Monitoring Rule (UCMR) and should be applicable to / for compliance monitoring in the event selected non-pesticidal and / or pesticidal organotins become regulated contaminants under the Safe Drinking Water Act (SDWA).

Description:

Organotin compounds, due to their versatility, have been exploited for use in a plethora of diverse applications with the intent to benefit human society. And, as a consequence, they have exerted a profound effect on the environment and the economy. For example, organotin compounds have been used as insecticides, fungicides (e.g., fungicidal wood preservatives), herbicides, acaricides, disinfectants (e.g., textiles), antifoulant coatings/biocides (e.g., applied to ship and boat hulls, docks, fishnets, buoys, etc., to discourage the growth of marine organisms), and preservatives for many other different types of materials. As a result, they are widely used in certain industries, such as paper and pulp mills, cooling towers (electric power generation), breweries, textile mills, leather processing plants and other facilities. Furthermore, the use of organotin compounds in pesticidal applications has raised many issues and concerns. Because of their non-specificity and their extreme toxicity to non-target animal and plant species, the causative effect has been major pollution problems in areas with restricted water circulation, including some recreational waters. However, this task has as its primary focus, a closely related, but different aspect of organotin usage. Non-pesticidal applications of organotin compounds, particularly in the plastics industry, may have far reaching ramifications and consequences for human beings. Because health and safety requirements have become necessarily restrictive in the plastics industry mandating a removal of toxic heavy metals (e.g., lead [neurotoxin], cadmium [renal toxin]), organotin compounds (non-pesticidal) have been substituted. In some studies, organotins have been shown to: 1) be mutagenic in bacterial assays, 2) cause development effects, 3) interfere with normal embryonic development, 4) cause atrophy of the thymus, 5) induce pancreatis, in rats, 6) induce hepatotoxicity in mice, 7) disrupt the function of critical human immune cells, and etc. Thus, there are many concerns about the toxicological significance and occurrence of various organotin species, especially in drinking water. Reports in the chemical literature indicate that organotin compounds from polyvinyl chloride (PVC) and chlorinated PVC systems have the potential to contaminate drinking water. As a consequence, selected organotin compounds (non-pesticidal) are at present listed as contaminants on the 1998 Contaminant Candidate List. As part of the assessment process to determine whether these contaminants should ultimately be regulated, national occurrence data must be collected by the Office of Ground Water and Drinking Water (OGWDW) under the Unregulated Contaminant Monitoring Rule. Thus, analytical methodology suitable for gathering occurrence data for organotins (non-pesticidal and pesticidal) in drinking water is needed and will be developed in this task and delivered to OGWDW. In addition, the methodology may also be used to understand or gain insight into the leaching mechanisms occurring in the PVC systems, and allow the assessment of the effect of chemical and physical variables on leachability.

Record Details:

Record Type:PROJECT

Start Date:07/01/2001

Projected Completion Date:09/01/2006

OMB Category:Other

Record ID: 18406

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Project Information:

Progress :The interface between the gas chromatograph (GC) and the inductively coupled plasma mass spectrometer (ICP/MS) has been installed and training has been completed on the use of the interface. The interface can be used in two different analysis modes (shielded and unshielded). Preliminary evaluation indicates that the shielded mode of operation is about a factor of 10 more sensitive. The shielded mode provides extremely good sensitivity with 1-2 %RSDs on 5 replicate injections of 400 parts per trillion (ppt) standard containing monobutyltin (MBT) and dibutyltin (DBT). The analysis of a 100 ppt standard containing MBT and DBT indicates that a 20 ppt standard could easily be quantified. These results were presented at the Winter Conference in Feb. 2003 (see TIMS Report).

An enriched isotope has been purchased and a synthesis route to a purified enriched standard has been tested. This standard would allow for isotope dilution analysis using GC-ICP/MS.

The plastic pipes to be used in a stability study have been manufactured. This will allow a preliminary evaluation of the stability of organotin compounds.

Parameter optimization for the liquid-liquid extraction of organotin compounds to meet the desired or target detection limit has been finalized.

Parameter optimization for the gas chromatographic - pulsed flame photometric detection (GC-[P]FPD) conditions have been finalized.

Axial inductively coupled plasma-atomic emission detection was evaluated as a potential screening tool for "total" tin determinations. Due to lack of sensitivity and high background, this approach was not feasible.

The splitless injection mode is being studied for sample introduction in GC-[P]FPD.

The minimum reaction time, for organotin alkylation, has been determined to be 5-10 minutes vs. 30 min. cited in Organotin Environmental Programme Association (ORTEPA) standard methodology and various other scientific literature documents.

The issue of mass discrimination effects on the lowered chromatographic response of the high molecular weight organotin compounds has been resolved. The results were presented at the ACS Regional Meeting in June, 2004 (see TIMS Report).

Comparative data has been generated for the method detection limits of the non-pesticidal and pesticidal organotins: EPA single concentration procedure vs. a calibration based detection limit estimator. The results were presented at theACS Regional Meeting in June, 2004 (see TIMS Report).

Relevance :

The Safe Drinking Water Act (SDWA), as amended in 1996, required the EPA to publish a list of contaminants that were not subject to any proposed or promulgated national primary drinking water regulations. This list, the Contaminant Candidate List (CCL) , was promulgated in 1998 and chemicals on the list were selected because of the probability of their occurrence in public water systems and their potential health risk to the public. Selected organotin compounds: monomethyltin trichloride*, dimethlytin dichloride*, monobutyltin trichloride*, and dibutyltin dichloride* are listed on the Occurrence and Research Priorities lists of the CCL because more data are needed for these potential contaminants before the Agency can determine whether to regulate them. In addition to the occurrence data; health, treatment, and /or analytical methods data are also needed to satisfy the research requirements listing and have become a priority under the Agency's research and occurrence programs. The CCL Occurrence Priority listing for organotins makes them prime candidates for an unregulated contaminant monitoring listing. Therefore, analytical methods for determining these compounds have become priority. The analytical method(s) developed under this task will ultimately be used to collect nationwide occurrence data for organotins under a future UCMR. It is also likely that this method(s) may be promulgated for compliance monitoring for organotins in the event that organotins become[a] regulated contaminant(s) under the SDWA.

Contact with OGWDW will be on-going to keep all parties aware of methods progress and potential future (methods) requirements. Additionally, CCL Research Implementation Workgroup Meetings have been held to address issues of health effects, treatment, and risk assessment (in addition to occurrence and analytical methods). Therefore, NERL has liaisons with NHEERL, and the National Toxicology Program (NTP) in regard to developmental neurotoxicity studies of organotins in PVC leachates, neurotoxicity testing, and other endpoints, and pharmacokinetics, etc., in order to share the results of planned research. NERL has participated in workshops / meetings / teleconferences involving government and industry -- manufacturers of organotin intermediates and stabilizers represented by Organotin Environmental Programme Association (ORTEPA). The consensus was to share research results and establish Euclid Dossiers for the dissemination of that information, via the internet, to all parties interested in organotin chemistry as relates to PVC stabilizers. The Plastic Additives Research group of ATOFINA Chemicals has expressed an interest in the NERL research effort and wishes to share information about organotin chemistry and analytical methods. NERL scientists will also be involved in joint collaborative research with NRMRL scientists and engineers on bench- and pilot-scale studies to evaluate the applicability of the analytical methodology to stabilizer determinations and to assess the impact of physical and chemical variables on the leachability of organotins into the drinking water distribution system.

The outcome of this effort should provide the OGWDW, and other entities, with reliable analytical methodology for acquiring occurrence and other data and ensuring applicability for compliance monitoring for organotins, in the event they should become regulated, under the SDWA. In addition, the public can be assured that the drinking water supples are safe from potentially toxic organotin stabilizer materials.

Clients :Office of Ground Water and Drinking Water (Dave Munch, Hiba Shukairy, Valerie Blank, Kesha Forrest)

Research Component :CCL (CHEMICAL)

Risk Paradigm :EXPOSURE

Project IDs:

ID Code :none

Project type :ORD-DW Plan

ID Code :10911

Project type :OMIS