Message from charlie.cray@green2.greenpeace.org

[charlie.cray@green2.greenpeace.org]

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Original-TO:      dioxin-l@essential.org
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The Chemical Gamble in Las Vegas
 
The U.S. Department of the Interior's U.S. Geological Survey (with help from
the US Fish and Wildlife Service's Reno office and the University of Florida,
Gainesville) recently released a new study conducted on chemical contamination
in Lake Mead entitled "Synthetic Organic Compounds And Carp Endocrinology and
Histology in Las Vegas Wash and Las Vegas and Callville Bays of Lake Mead,
Nevada, 1992 and 1995," (Water-Resources Investigations Report 96-4266, Nevada
Basin and  Range Study Unit, National Water-Quality Assessment Program (By Hugh
E. Bevans, et al).   
 
The report is available from the U.S.G.S.'s Branch of Information Services Box
25286, MS 517, Denver, CO 80225-0046.  The USGS Survey programs can be found by
accessing the NAWQA "homepage" on the Web at
<http:/wwwrvares.er.usgs.gov/nawqa/nawqa_home.html>
 
The investigators found organochlorines and semivolatile industrial compounds
in the water column, bottom sediment, and carp tissue at five sites in Lake
Mead.  
 
The investigators wrote:
 
"The most compelling evidence of endocrine disruption is the presence of
vitellogenin in blood-plasma samples of male carp from Las Vegas Wash and Bay
and elevated concentrations in female carp from Las Vegas Bay."  
 
Semi-permeable membrane devices (SPMDs) used to sample the water column also
found that concentrations of combined dioxins, furans, total PCBs, HCBs and
other organochlorines were greatest in Las Vegas Wash than in other areas.
 
Combined concentrations of organochlorines, DDT residues and Arochlors (PCBs
and PC'd Terthenyls) in Carp tissue were also analyzed, with levels between 0
and over 800 mg/kg.  Overall, twenty different organochlorines were detected in
carp-tissue samples.  Again, more were detected in Las Vegas Wash and Las Vegas
Bay than other areas.
 
"The median concentrations of the mixture of compounds resembling Arochlor 1254
detected in cross-sectional carp-tissue samples from Las Vegas Wash and Las
Vegas Bay exceeded risk based consumption limits for chronic systemic health
effects for the general population." 
 
The report did not trace the contaminants found to any particular source,
though it does state that "Las Vegas Wash transports urban runoff and treated
sewage effluent to Las Vegas Bay from the Las Vegas Area."  
 
According to a chart on page 7 of the report, in 5 out of 6 sites they found a
higher concentration of phthalates in sediment than any of the other groups of
contaminants. "Combined concentrations of phthalates were about an order of
magnitude higher in bottom-sediment samples from Las Vegas Wash and Bay than in
the sample from Callville Bay.  The  phthalates di-n-butylphthalate and
diethylphthalate were detected in bottom-sediment samples from all Las Vegas
Bay sites."
 
The apparent contribution that phthalates are making to sediment pollution and
possibly endocrine disruption in Lake Mead Carp adds to what the Danish EPA
said in its report, "Male Reproductive Health and Environmental Chemicals with
Estrogenic Effects." (For a summary, Rachel's Hazardous Waste News, #438, which
quotes the Danish EPA: "Phthalates are the most abundant man-made environmental
pollutants..." 
 

Phthalates are principally used as a plasticizer to make PVC items flexible.
Some PVC products ("soft" or flexible "vinyl" products) which are stuffed with
phthalates and probably used in Las Vegas more than most places include
packaging, artificial leather, shower curtains, wallpaper, flooring, auto seat
covers, pool bottoms, etc.).
 
-End-
 

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