Formaldehyde estimating exposures

Indoor (mean) concentrations for benzene range from 8.2 to 17 pgm. Typical values for indoor as well as for outdoor environments were up to 5 pg m For formaldehyde mean indoor concentrations reach values up to 92pgm, while typical values for outdoor air concentrations of 4pgm are reported. Indoor/outdoor (I/O) ratios, based on typical air concentration levels, of 2 and of 50 for benzene and formaldehyde, respectively, are calculated. Daily exposure estimates are based on the assumption that people spend 90% of its time in indoor environments and 10% outdoors. For benzene daily personal exposures vary between 108 and 177pgm for 24h periods, 20% lower than the mean exposures estimated for European citizens. For formaldehyde personal exposures range from 1080 to 2000 pgm over 24 h, rather similar to European exposure estimates. 

A major route of formaldehyde exposure for the general population is inhalation of indoor air releases of formaldehyde from new or recently installed building materials and furnishings may account for most of the exposure. Environmental tobacco smoke may contribute 10-25% of the exposure. Since formaldehyde in food is not available in free form, it is not included in estimated exposures (Fishbein... 

Stewart (USA) 1986 Comparison of historical exposures, current exposures, and job titles to develop a final exposure estimate Formaldehyde Cumulative exposure (ppm)... 

Hawthorne, A., et al. (1987) Models for estimating organic emissions from building materials formaldehyde example. Atmos. Environ. 21, No. 2. Lewis, R. G., et al. (1986) Monitoring for non-occupational exposure to pesticides in indoor and personal respiratory air. Presented at the 79th Annual Meeting of the Air Pollution Control Association, Minneapolis, MN. 

Formaldehyde exposure raises a marginal concern for cancer risk to professional painters (risk estimates of 10 4 to 10 6). 

Indoor/Outdoor Air Concentrations and Exposure Estimates for Benzene and Formaldehyde in Europe... 

Institute for Occupational Safety and Health (NIOSH) estimates that 1,329,332 individuals in the United States have had the potential for occupational exposure to formaldehyde. 

Levels of exposure associated with carcinogenic effects (Cancer Effect Levels, CELs) of formaldehyde are indicated in Tables 2-1, 2-4, and 2-5 and Figures 2-1 and 2-2. Because cancer effects could occur at lower exposure levels, Figure 2-1 also shows a range for the upper bound of estimated excess risks, ranging from a risk of 1 in 10,000 to 1 in 10,000,000 (10 to lO ), as developed by EPA. 

Estimates of exposure levels posing minimal risk to humans (Minimal Risk Levels or MRLs) have been made for formaldehyde. An MRL is defined as an estimate of daily human exposure to a substance that is likely to be without an appreciable risk of adverse effects (noncarcinogenic) over a specified duration of exposure. MRLs are derived when reliable and sufficient data exist to identify the target organ(s) of effect or the most sensitive health effect)s) for a specific duration within a given route of exposure. MRLs are based on noncancerous health effects only and do not consider carcinogenic effects. MRLs can be derived for acute, intermediate, and chronic duration exposures for inhalation and oral routes. Appropriate methodology does not exist to develop MRLs for dermal exposure. 

DNA-protein cross links in target tissue as a measure of delivered dose. Relationships between formaldehyde air concentrations and rates of formation of DNA-protein cross links in nasal epithelial tissue of rats (Casanova et al. 1989) or of Rhesus monkeys (Casanova et al. 1991 Heck et al. 1989) and adjustments to continuous exposure were used to calculate lifetime human cancer unit risk estimates of 3.3x10 per ppm formaldehyde based on the monkey data, and 2.8x10 per ppm formaldehyde based on the rat data (see Section 2.4.3). 

Pharmacokinetic models to describe, as a function of formaldehyde air concentration, the rate of formation of formaldehyde-induced DNA-protein cross links in different regions of the nasal cavity have been developed for rats and monkeys (Casanova et al. 1991 Heck and Casanova 1994). Rates of formation of DNA-protein cross links have been used as a dose surrogate for formaldehyde tissue concentrations in extrapolating exposure-response relationships for nasal tumors in rats to estimate cancer risks for humans (EPA 1991a see Section 2. 4.3). The models assume that rates of cross link formation are proportional to tissue concentration of formaldehyde and include saturable and nonsaturable elimination pathways, and that regional and species differences in cross link formation are primarily dependent on anatomical parameters (e g., minute volume and quantity of nasal mucosa) rather than biochemical parameters. The models were developed with data from studies in which... 

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