Stochastic Estimates of Exposure and Cancer Risk from Carbon Tetrachloride Released to the Air from the Rocky Flats Plant

Abstract

Carbon tetrachloride is a degreasing agent that was used at the Rocky Flats Plant (RFP) in Colorado to clean product components and equipment. The chemical is considered a volatile organic compound and a probable human carcinogen. During the time the plant operated (1953-1989), most of the carbon tetrachloride was released to the atmosphere through building exhaust ducts. A smaller amount was released to the air via evaporation from open-air burn pits and ground-surface discharge points. Airborne releases from the plant were conservatively estimated to be equivalent to the amount of carbon tetrachloride consumed annually by the plant, which was estimated to be between 3.6 and 180 Mg per year. This assumption was supported by calculations that showed that most of the carbon tetrachloride discharged to the ground surface would subsequently be released to the atmosphere. Atmospheric transport of carbon tetrachloride from the plant to the surrounding community was estimated using a Gaussian Puff dispersion model (RATCHET). Time-integrated concentrations were estimated for nine hypothetical but realistic exposure scenarios that considered variation in lifestyle, location, age, and gender. Uncertainty distributions were developed for cancer slope factors and atmospheric dispersion factors. These uncertainties were propagated through to the final risk estimate using Monte Carlo techniques. The geometric mean risk estimates varied from 5.2 x 10(-6) for a hypothetical rancher or laborer working near the RFP to 3.4 x 10(-9) for an infant scenario. The distribution of incremental lifetime cancer incidence risk for the hypothetical rancher was between 1.3 x 10(-6) (5% value) and 2.1 x 10(-5) (95% value). These estimates are similar to or exceed estimated cancer risks posed by releases of radionuclides from the site.

Protective Role of <i>Commiphora molmol</i> Extract against Liver and Kidney Toxicity Induced by Carbon Tetrachloride in Mice

“…On the other side, it was discovered that not just the liver is affected by CCl 4 intoxication, but also the kidneys are damaged and this could lead to cancer [5]. The kidney is sensitive to CCl 4 [2,5].Therefore, less urine may be formed, leading to a buildup of water and waste products in the body and blood, respectively.…”

“…The kidney is sensitive to CCl 4 [2,5].Therefore, less urine may be formed, leading to a buildup of water and waste products in the body and blood, respectively. Recently, it was reported that there is an increase in the reactive oxygen species production, oxidative stress and a significant decrease in the antioxidant enzymes after CCl 4 injection [4,6].…”

“…The toxicity of CCl 4 resulted from the bio-activation of CCl 4 into trichloromethyl free radical by cytochrome P450 system in the liver microsomes and consequently this causes lipid peroxidation of membranes that leads to liver injury [4]. Exposure to CCl 4 also causes kidney damage that may finally lead to cancer [5]. Several approaches have shown how CCl 4 could cause this damage.…”

Quantity-based and toxicity-based evaluation of the U.S. Toxics Release Inventory

“…Carbon tetrachloride is used as cleaning and degreasing solvents; extraction, paint, and coating solvents; and as a feedstock to produce other chemicals [29]. Carbon tetrachloride can cause liver cancer and is classified as a probable human carcinogen [30,31].…”

Proposal of a model for chemical risk preliminary assessment

“…This method consists of three steps: (i) analysis of the chemical product life cycle, (ii) definition of the exposure scenarios and (iii) calculation of the potential risk. Many assessments on very large systems are based on this approach, like territorial chemical risk assessment (Rood et al, [3]). …”