Cancer assessment

CAG Cancer Assessment Group of the U.S. Environmental Protection Agency... 

Verified inhalation and oral slope factors were unavailable from U.S. EPA for dimethylhydrazine. A cancer assessment based upon the carcinogenic potential (withdrawn cancer slope factors) of dimethylhydrazine revealed that AEGL values for a theoretical excess lifetime 10 4 carcinogenic risk exceeded the AEGL-2 values that were based on noncancer endpoints. Because the risk for dimethylhydrazine exposure was estimated from nonverified sources and because AEGLs are applicable to rare events or single once-in-a-lifetime expo... 

Page, N. P., D. V Singh, W. Farland, J. I. Goodman, R. B. Conolly, M. E Andersen, H. J. Clewell, C. B. Frederick, H. Yamasaki, G. Lucier. Implementation of EPA Revised Cancer Assessment Guidelines Incorporation of Mechanistic and Pharmacokinetic Data. Fundam. Appl. Toxicol. 37 16-36, 1997. 

USEPA (2000). Cancer Assessment Review Committee, Atrazine Evaluation of Carcinogenic Potential. December 13, 2000. HED Doc. No. 014431. 

The EPA s cancer assessment procedures have been used by several federal and state agencies. The Agency for Toxic Substances and Disease Registry (ATSDR) relies on EPA s carcinogen assessments. A substance is assigned to one of six categories as shown in Table 9.9. 

Other models that have been used for cancer assessments include ... 

Slattery, M.L. Sorenson, A.W. Mahoney, A.W. French, T.K. Kritchevsky, D. Street, J.C. 1988. Diet and colon cancer—assessment of risk by fibre type and food source. J. Natl. Caneer Inst. 80 1474-1480. 

S.3 Summary of Cancer-Assessment Methodology Used by the NAC/ AEGL Committee... 

Buckley, D.L., Drew, P.J., Mussurakis, S., etal. (1997) Microvessel density of invasive breast cancer assessed by dynamic Gd-DTPA enhanced MRI. Journal of Magnetic Resonance Imaging, 1, 461-464. 

Hair may also be an important tool for the diagnosis and monitoring of various disease states. For example, the concentrations of polyamines (e.g., putrescine, spermidine, and spermine) in the hair may be helpful in diagnosing and assessing disease activity in women with cervical or ovarian cancer. Assessing the level of polyamines in the hair shaft is preferred to measuring them in plasma and urine because the polyamine levels can vary during the day in plasma and urine. Increased levels of porphyrins in hair have been detected in patients with porphyria... 

Minimal Risk Levels, Critical Effects, and Cancer Assessments for Fractions of TPH... 

Inhalation MRLs, Critical Effects, and EPA Cancer Assessments for Aromatic EC>5-EC9 Fraction... 

The focus of this section is the selection, when possible, of appropriate MRLs for the assessment of health effects of the aromatic and aliphatic fractions of TPH. Approaches to cancer assessment are also discussed. The TPH fractions are environmental transport fractions, as suggested by the TPHCWG (1997c), with a slight modification to include all the BTEXs in a redefined aromatic EC5-EC9 fraction. 

Tables 6-1 and 6-2 summarize the suggested fraction-specific MRLs for inhalation and oral exposure. These fraction-specific MRLs are provisional values, reflecting the uncertainty inherent in this approach (see Section 6.6.2 for a more complete discussion). As with any ATSDR MRL, the MRLs in Tables 6-1 and 6-2 are intended to serve as health guidance values and are not to be used to define clean-up or action levels. Information listed in brackets in Table 6-2 is from sources other than ATSDR toxicological profiles. This information indicates potentially sensitive end points but does not have the same level of confidence as information from the ATSDR toxicological profiles. Additional details and tables listing all the candidate MRLs and relevant cancer assessments are presented in Section 6.6.2. Chapter 7 also...

Inhalation Exposure. The available inhalation MRLs for each of the BTEXs, and the EPA cancer risk for benzene, can be used to assess the potential for health effects for each of these indicator compounds individually. This is consistent with current practice. These MRLs and their associated effects, as well as the EPA cancer assessments, are summarized in Table 6-3. Health effects that are common to the BTEXs are neurological effects. Developmental effects appear to be a sensitive effect of inhalation exposure to ethylbenzene and xylene. Benzene has hematological and immunological/ lymphoreticular effects and is classified in EPA Group A (human carcinogen). 

---