Carcinogens limiting exposure

Tubal ligation is another procedure that has shown potential for risk reduction. However, it is not recommended as a sole procedure in prophylaxis. Protective effect may be due to limiting exposure of the ovary to environmental carcinogens. A case-control study conducted by Narod and colleagues found that a history of tubal ligation in /f RCA-positive women was associated with a statistically significant 63% reduction in risk.22... 

The lARC has determined that there is inadequate evidence in humans but sufficient evidence in experimental animals for the carcinogenicity of ethylene dibromide. An overall evaluation of probably carcinogenic to humans is given. A threshold limit exposure limit has not been assigned by ACGIH. 

There is no threshold limit value (TLV) for PNB. It is classified as a confirmed human carcinogen and exposure by any route— respiratory, oral, or skin—should be avoided. 

Action level for dioxin and dioxin-like compounds in soil. Action levels are concentrations of chemicals at which consideration of action to interdict exposure occurs 1 ppb TCDD in residential soil was identified by Kimbrough et al. (1984) as a "level of concern" and recommended as "a reasonable level to begin consideration of action to limit exposure." The conclusions of Kimbrough et al. (1984) were derived in part from an evaluation of the carcinogenic potential of TCDD, based on a 2-year oral chronic toxicity and oncogenicity study in rats (Kociba et al. 1978). With the advancement of knowledge about dioxin-like chemicals and their assumed common mechanism of toxicity, the TEQs were introduced into the risk assessment process. Since then, 1 ppb of total dioxins (expressed as TEQs) in soil has been used as an action level by ATSDR. 

This was a policy, or risk management, choice on the part of FDA, pursued to seek a method for limiting exposure to carcinogens that would rest upon the degree of risk posed, not the irrelevant capabilities of analytical chemists. The same, one in one million insignificant risk... 

Many national standards for consumer products other than food have been based on limiting exposure to carcinogens. However, product standards have rarely utilized a specific cancer risk level, and thus there appear to be few scientific issues unique to development of product standards based on cancer. The major consideration would be the difficulty in arriving at accurate population-based exposure estimates for cancer risk from products but since specific cancer risks are not generally utilized, this point may be moot. 

Potential occupational carcinogen occupational exposure should be limited to the lowest feasible concentration. 

NIOSH carcinogen occupational exposures to carcinogens should be limited to the lowest feasible concentration. (see discussion above about proposed NIOSH policy change )... 

The adverse health effects of cyclopiazonic acid manifest at higher concentrations. It is a specific inhibitor of calcium-ATPase, which transfers calcium after a muscle has contracted. In animals it causes necrosis of the liver and necrotic changes in the gastrointestinal tract and muscles. It is considered a potential carcinogen, but exposure limits are not yet defined. 

The monomer is now almost exclusively obtained from ethylene, which has displaced the older acetylene-based process. There is some evidence that vinyl chloride is carcinogenic and there are legal requirements limiting exposure to the monomer. 

Toluenediamine is classed as toxic. The oral LD q for animals is between 270—350 mg /kg body weight (45). TDA is readily absorbed through the skin and this is the major route of human exposure. Several studies have shown the 2,4 isomer of TDA to be carcinogenic for rats and mice, but tests on the 2,5 and 2,6 isomers were not positive. AH three of the isomers have been shown to be mutagenic (45). Results of limited studies on the reproductive ha2ards for male workers are equivocal, but animal experiments have shown TDA to cause adverse reproductive effects (45). 

Styrene is Hsted in the U.S. Toxic Substance Control Act (TSCA) Inventory of Chemicals. It is not confirmed as a carcinogen but is considered a suspect carcinogen. The recommended exposure limits are OSHA PEL 50 ppm, ACGIH TLV 50 ppm. For higher concentrations,... 

Succinic anhydride is extremely irritating to the eyes. It causes skin, mucous membranes, and respiratory tract irritation. It may be a sensiti2er. There is no evidence of carcinogenic activity in male or female tats given 50 or 100 mg/kg succinic anhydride (186) the Ames test is negative (187). LD q in rat 1510 mg/kg. There ate no estabflshed exposure limits for ACGIH TLV or TWA. 

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