Oh no! Here come the rats again
There are two kinds of rats in this world.
One kind includes a variety of long-tailed rodents, known on
the one hand as detriments to human health and the environment
and on the other for their usefulness in scientific experiments
that attempt to benefit human health and the environment. The
other kind of rat is the tailless, two-legged sort that
exaggerates and misuses data from the scientific experiments to
malign certain products and people.
Drycleaners have been plagued for years by
both types of rats — the rodents that developed cancerous
tumors after long and elevated exposure to perc and the humans
who have used that information to taint the industry as an
environmental hazard. Now it’s happening again, this time
concerning silicone drycleaning solvent, known most commonly in
the industry as GreenEarth.
Here’s what has happened.
Dow-Corning recently reported to EPA on results of a two-year
test in which 192 rats were exposed to
decamethylcycopentasiloxane, also known as D5, which is also
the silicone used in the GreenEarth cleaning process. Male and
female rats were exposed to varying levels of D5 for six hours
a day, five days a week, some for one year, some for two. The
findings showed no adverse health effects except for one group
of rats. Of 60 female rats exposed to the highest concentration
of D5 — 160 ppm over two years — five developed
uterine tumors.
No other adverse effects from D5 exposure
were revealed in the study. And it should be noted that one of
the female rats in the control group which had no exposure also
developed a uterine tumor. That’s news in itself —
rats can develop tumor even when they’re not exposed to
suspect chemicals.
Toxicologists say they are puzzled by the
findings of this study. Dow-Corning says it “does not
believe the results of this study represent a risk to health or
the environment,” noting that the 160 ppm exposure far
exceeds any workplace or human exposure in the many
applications in which D5 is used.
Dow-Corning advised EPA of its findings
and that it is considering further studies “to determine
the potential relevance of these findings.” Since then
“word” has spread through the drycleaning industry.
Cleaners are naturally wary of another rat-based cancer scare
involving a drycleaning solvent. The motivations of some in
spreading the “word” simply exhibit the caution of
the once-bitten, twice shy. We won’t be surprised,
however, to see some “rats” using this study to
cast a shadow over GreenEarth.
GreenEarth has moved to counter
misinformation and rumors about the study through a letter from
GreenEarth chairman Jim Barry to the drycleaning industry.
Barry noted that exposure to GreenEarth in
the drycleaning industry is way below the 160 ppm level —
an average of only 3 ppm in plants using GreenEarth and
dry-to-dry equipment. He also notes that exposure test
notwithstanding, the chance of GreenEarth causing soil or
groundwater pollution problems are nil since the solvent
quickly breaks town into sand, water and CO2 if it is spilled
on the ground.
And, he adds, “Other than this one
unexpected results, there were no other unfavorable results
seen in this study. Further, the extensive database, based on
numerous studies, strongly supports the safety of D5 for
drycleaning and other applications.”
Barry makes another point in his letter
that bears repeating: “It is important to note that other
solvents, except perc, have not done bioassay studies.” A
full evaluation of the complete safety profile of these
chemicals should be undertaken, he wrote.
He adds: “To make proper, educated
decisions on alternative solvents, the industry needs complete
and comparative facts for all.” We agree, and would add
that after all these years, the industry should be skeptical of
rats, both the four- and two-legged variety.
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