Organotin in PVC and CPVC Water Piping 

Organotin Environmental Programme 29may01

Note: The Organotin Environmental Programme (ORTEP) Association is an industry association dealing with the scientific and technical information on the environmental effects of organotin compounds.

29 May 2001

Ms. Kelly O'Grady, R.N.
Lead Environmental Awareness and Detection (L.E.A.D.)
219 Welland St. 
Pembroke, Ontario Canada K8A 5X5

Dear Ms. O'Grady:

The questions you posted recently on the CEHN listserver concerning trace levels of organotins in drinking water and the use of triethyltin in PVC were forwarded to the Organotin Environmental Programme (ORTEP) Association for response.

In response to your first question, I believe the study you are referring to is the Draft Environmental Impact Report (EIR) for Chlorinated Polyvinyl Chloride (CPVC) Pipe Use for Potable Water Piping in Residential Buildings. The State of California, Department of Housing and Community Development (HCD) published the report in June 1988. The intent of the EIR was to examine the use of CPVC for interior potable water plumbing in residential buildings in California. As part of the EIR, leachates from CPVC pipe into water were reviewed, including organotins. Organotin compounds are added to CPVC as stabilizers, and there are established standards for organotin leachates from CPVC. The National Sanitation Foundations (NSF's) testing of CPVC pipe and fittings includes tests for organotins. Only CPVC pipe and fittings which meet the ANSI/NSF standards may be certified and sold in California. The Lead Agency, HCD, concluded that pipe leachates would not cause adverse health effects or significant environmental contamination. Consequently, CPVC pipe was approved for use in residential structures in California.

Several studies by Health Canada have been published documenting measured concentrations of butyltins in drinking water. In both PVC and CPVC pipe, levels of monobutyltin (MBT) and dibutyltin (DBT) in potable water have been noted in the parts per trillion (ppt) range (Forsyth and Jay, 1997). However, the occurrence of organotin compounds at low concentrations does not suggest any potential risk from drinking water.

Sadiki and Williams (1996) studied 45 municipalities and found butyltins in six. The values at most municipalities were below detectable levels (i.e., c0.5 ppt), Sadiki et al. (1996) further studied the organotins measured in tap water of five municipalities and found butyltins in only 1 of 22 homes sampled. In a comprehensive study, Sadiki and Williams (1999) monitored Canadian drinking water distributed through recently installed PVC pipe and found a few positive detections of butyltins (DBT maximum of 53 ppt, MBT maximum of 28.5 ppt), though in most cases the concentrations were not detectable (r0.5 ppt). If one considers drinking water consumption to be two liters per day for an adult and a standard adult body weight to be 60 kg (WHO 1993; USEPA 1989), a "safe" long-term intake for DBT in water is at least 300 µg/day (as tin) for an individual. On a concentration basis, this translates to 150 µg/L (as tin) as a "safe" long-term concentration in water. Considering the recent monitoring data reported for butyltins in drinking water (Sadiki and Williams 1999), this predicted safe drinking water level is more than 2,800 times higher than the highest concentration of DBT (53 ppt as Sn) recently measured from drinking water in PVC piping.

Concerning your second question about whether triethyltin (TET) is used in PVC pipes. The mono- and di-methyltins and octyltins are used mainly in rigid PVC water pipes and fittings in countries where lead stabilizers are not permitted by regulation. Tri-substituted organotin compounds are not used as stabilizers, but some are used primarily as biocide in antifouling paints for ocean going vessels as fungicides for industrial wood protection or as miticides in the agricultural area. There are no industrial uses of triethyltin, and there never have been. Without information concerning the analytical method and quality control measures undertaken, there is no way to determine whether triethyltin was actually present in the sample analyzed or was a laboratory contaminant, or misidentified compound. Because organotin compounds vary considerably with the nature and number of organic groups bonded to the tin atom, the most appropriate methods of organotin analysis are those that are species-specific.

The Organotin Environmental Programme (ORTEP) Association is an industry association dealing with the scientific and technical information on the environmental effects of organotin compounds. One of the ways we accomplish this effort is by providing information on our website (www.ortepa.org). We, too, are concerned over allegations of human health issues which is why we are constantly studying our products and support third party certification by organizations like NSF to assure that the use of organotins does not present a threat to human health. You are encouraged to periodically check the ORTEPA website for new updates.

Sincerely,

Terry Phipps
ORTEPA Website Administrator

Forsyth, D.S. and B. Jay. 1997. Organotin leachates in drinking water from chlorinated poly(vinyl chloride) (CPVC) pipe. Applied Organometallic Chemistry. 11:551-558.

Sadiki, A and D. Williams- 1999. A study on organotin levels in Canadian drinking water distributed through PVC pipes. Chemosphere. 38(7): 1541-1548.

Sadiki, A. and D. Williams. 1996. Speciation of organotin and organolead compounds in drinking water by gas chromatography-atomic emission spectrometry. Chemosphere, 32(10):1983-1992.

Sadiki, A., D. Williams, R. Carrier and B Thomas. 1996. Pilot study on the contamination of drinking water by organotin compounds from PVC materials. Chemosphere. 32(12):2389-2398.

State of California. Department of Housing and Community Development. Draft Environmental Impact Report for Chlorinated Polyvinyl Chloride (CPVC) Pipe Use for Potable Water Piping in Residential Buildings. June 29, 1988. State Clearinghouse Number: 970820040.

USEPA (United States Environmental Protection Agency). 1989. Risk Assessment Guidance for Superfund, Volume 1: Human Health Evaluation Manual (Part A). Interim Final. EPA/540-1-89/002. December 1989.

WHO (World Health Organization). 1993. Guidelines for Drinking Water Quality. Second Edition. Volume 1: Recommendations. World Health Organization, Geneva.

Submission I.D.: 100009836
Job Number: 8200978

September 29. 2000

Kelly O'Grady
219 Welland Sreet
Pembroke. On
K8A 5Y5

Sample: One plastic water jug received September 05. 2000
Analysis: Organotins (grignard reagent derivatization).
Result: