The Use of Henry's Law to Estimate Formaldehyde Inhalation Exposure Concentrations

ABSTRACT This article derives a recommended range of partial vapor pressures of formaldehyde (FA) above dilute solutions (0.01% to 0.1%) that are useful for determining inhalation exposure concentrations for risk assessment evaluation of professional and consumer products containing FA and FA-releasing biocides. Independently derived experimental datasets of the relationship between dilute aqueous FA concentrations and vapor phase concentrations were evaluated. These datasets were consistent with each other and Henry's Law principles. A range of partial vapor pressures, 0.00077 mmHg to 0.0074 mmHg, corresponding to solution concentrations ranging from 0.01% to 0.10% for application temperatures of 25°C and 0.0016 mmHg to 0.016 mmHg for 35°C is proposed. This approach is applicable to a wide range of aqueous-based consumer and professional applications.