Determination of benchmark levels could be proposed as one of the first step in procedure of noncarcinogen risk assessment.
In order to determine benchmark levels, examined children (n = 233, average age, 8.6 ± 0.6 years) with chronic upper respiratory diseases living in areas with relatively low-level formaldehyde air pollution. The maximum formaldehyde air concentration was 0.0264 mg/m3, the minimum concentration was 0.0002 mg/m3 and the average annual concentration was 0.0062 ± 0.0032 mg/m3. Blood formaldehyde concentrations were determined using high performance liquid chromatography. The concentrations ranged from 0.001 to 0.181 mg/dm3. Data concerning the diseases of children were obtained from individual medical records containing all the cases when they were provided with medical care. The study analyzed recorded respiratory diseases, ie, rhinitis (J30.3, J30.4), asthma (J45.0), and other upper respiratory diseases (J35.0, J35.1, J35.2, and J35.3).
A number of hypotheses concerning BMC values of formaldehyde in blood were evaluated. It was proposed that a BMC value that was used to divide the examined children into groups, ie, with no effects (blood concentration is lower than the suggested BMC value) and with effects (blood concentration is higher than the suggested BMC value). For each hypothesis, the study calculated odds ratio (OR) characterizing the link between the exposure and health disorders (ORmax = 1.42 DI = 2.46÷0.82). Using these calculations, they were built a mathematical models “blood concentration—odds ratio.” Formaldehyde blood concentration corresponding to model upper 95% confidence limit at the OR = 1 level was considered as a benchmark level.
According to minimal, this criterion (for rhinitis incidence OR) was suggested the formaldehyde concentration of 0.023 mg/dm3 as the benchmark level.