A fear has been implanted in uninformed America–Chemophobia-the irrational fear of chemicals.
“Trike” was a normal degreaser used for various metal parts. Many panicked over the thought of getting cancer from a common degreaser used in thousands of locations. Trichloroethylene (C2HCl3) was used so frequently, that typical names such as Trichlor, Trike, Tri, or Tricky were commonplace.
The big stick was the ominous label CARCINOGEN. Of course, the documented TLV (Threshold Limit Value) is 200ppmillion. But the ACGIH classified it as cancer “not suspected for humans”. To date, there has been no change to the exposure limit because the EPA cannot prove TCE exposure to cause cancers.
But 1 mile away, in sight of the writer’s house, lies a Superfund Site in Skyland (Asheville, NC). CTS of Asheville manufactured hearing aids and automotive parts. Before plating, parts were cleaned using TCE. CTS, vacant since the 1990’s, still worries about TCE contamination exacerbating the cancer scare.
The site was assessed by the EPA in 1985, 2001, and 2006. In each instance, they concluded the site did not warrant qualification as Superfund. Finally, in soils under the building, the EPA found the highest TCE concentration (830ppm).
As a result, in 2008, EPA sampled 72 private wells. Continued samples of these wells revealed no TCE results. Today, over 105 private wells are being monitored. Seven of those are considered to have TCE. However, the acceptable lower limit for TCE is 5 pp[billion], and is significantly lower than 20 years ago (200pp[million]). But there still has been no cancer.
Back in 1930, Wikipedia reports that for 20 years, TCE was used as an inhaler (tradenames: Trilene & Trimar), and an analgesic for millions. The maximum dose was ~1000ppm. This was extensively used in obstetrics, and especially during pregnancy. Taking these dosages relieved pain, but never resulted in cancer in any of the millions inhaling it. TCE was substituted for earlier anesthetics such as chloroform and ether.
Bioassays by the National Cancer Institute showed kidney cancer in some mice and rats. It was therefore reported TCE was “reasonably anticipated to be a human carcinogen”, based on animals. One review of kidney cancer rated obesity and cigarette smoking as higher risk factors for kidney cancer.
“Reasonably anticipated” doesn’t square with “cancer not found”. To date, ACGIH has carcinogenicity “not suspected for humans”; mutagenic—not available; teratogenic–not available; developmental—not available.
US Superfund Sites (2010). Red: National Priority List, yellow: proposed, green: deleted (usually cleaned up).
The health risks of TCE have been studied to excess.
Here is a classic example of the EPA spending almost $50 million to cleanup the Skyland, NC, Superfund Site–unnecessarily. Multiply that by ~100x for all the TCE Superfund Sites that have been, or will be, cleaned up. Could a transparent case of chemophobia be worth that to allay misguided fears?
Looking at chemicals we see daily can be eye-opening:
Ethanol (grain alcohol) is manufactured, and has an LD50 (50% rats given 7060 mg ethanol/Kg weight–was lethal dosage).
Marijuana (Delta 1-3,4 trans-tetrahydrocannabinol) has an LD50 for rats at 42 mg/Kg.
Caffeine in coffee (3,7-dihydro-1,3,7-trimethyl-1-H-purine-2,6-dione), and has an LD50 at 355 mg/Kg.
Horse radish (allylisothiocyanate)has an LD50 at 339. Ibuprofen [2-(4-(2-methylpropyl)phenyl)propionic acid]has an LD50 of 1050, and is manufactured.
Saxitoxin (a red tide toxin, sometimes found in contaminated clams, mussels and scallops) has an LD50 of 0.01.
What makes trichloroethylene so dangerous? Certainly not rational thinking.