Advantage
Confirms absorption into the human body
Measures integrated exposure
Very low level exposures detectable
Helps to test and validate exposure models
Helps to follow exposure trends
Helps to evaluate public health interventions
Limitation
Does not define sources, pathways or duration of exposure
Cannot define toxic dose
Susceptible to inferior or unscrupulous analytical laboratories
Lack of meaningful reference levels
Lack of toxicological and epidemiological information about the vast majority of environmental chemicals
Silicosis
Respiratory exposure
Fibrotic pulmonary disease
Chronic inflammation: accumulation of inflammatory mediators
Silicosis Diagnosis
ILO film: 12 scales
>1/0: abnormality
X-ray film result with exposure history
Long term change in anatomy
Lung function is not specific to silicosis
Treatment/health care is not effective in severe case
Sensitive marker
Heme Oxygenase 1(HO-I)
Rate-limiting enzyme in heme catabolism, antioxidation and antiinflammation
Lung inflammation marker
Lung epithelial cells, smooth muscle cells, macrophage
HO-I induction was found in lung tissue of silica exposed rat (Nagamoto et al., 2006)
How about human?