BACKGROUND To estimate a threshold limit value for a compound known to have harmful health effects, an 'elbow' threshold model is usually applied. We are interested on non-parametric flexible alternatives. METHODS We describe how a step function model fitted by isotonic regression can be used to estimate threshold limit values. This method returns a set of candidate locations, and we discuss ...

OBJECTIVE To investigate the relationship between several physiological variables that can be easily obtained during cycle ergometer gradual testing (for example, peak power output (W(peak)), Vo(2max), or ventilatory threshold (VT)) and actual (>50 km) time trials (TT) time performance during the Tour de France. METHODS We collected data in professional cyclists from the first TT of the 1998 ...

BEIs: Threshold limit values for chemical substances and physical agents biological exposure indices. Cincinnati, OH: American Conference of Governmental Industrial Hygienists. *ACGIH. 1999b. Strontium chromate. 1999 TLVs and BEIs: Threshold limit values for chemical substances and physical agents biological exposure indices. Cincinnati, OH: American Conference of Governmental Industrial Hygien...

background:  controversy exists as to the potential of asphalt fumes to induce respiratory symptoms and lung functional impairments. objective: to examine the respiratory effects, if any, of occupational inhalation exposure to asphalt fumes. methods:  in this cross-sectional study, 74 asphalt workers and 110 unexposed employees were investigated. the prevalence of respiratory symptoms among sub...

Acceptable occupational exposure levels for hundreds of airborne concentrations of dusts, vapors, fumes, and gases have been set by consensus organizations and regulatory bodies for decades. These levels have established tremendous precedent and are tempting reference values in the relatively new field of indoor air quality evaluations where validated criteria are greatly needed. The American C...