What is VOC Exposure?
VOC exposure refers to contact with volatile organic compounds—carbon-based chemicals that evaporate at room temperature and can be inhaled from both environmental and biological sources, including indoor air, consumer products, industrial settings, and even human exhaled breath. 1
Definition and Chemical Properties
Volatile organic compounds encompass a wide variety of chemical substances sharing the common feature of being carbon compounds that are volatile at ambient temperature 1. These compounds can be classified into different chemical families, each possessing distinct properties and varying degrees of toxicity 1.
Common VOC Categories Include:
- Aromatic hydrocarbons: benzene, toluene, ethylbenzene, xylene (BTEX compounds) 2
- Aliphatic hydrocarbons: n-hexane, n-heptane, n-octane, n-nonane, n-decane, pentane 2
- Chlorinated compounds: trichloroethylene, tetrachloroethylene, chloroform, carbon tetrachloride 3
- Ketones and alcohols: acetone, ethanol, methanol 4, 2
- Terpenes: pinenes 3
- Other compounds: styrene, isoprene, dimethyl sulfide 4
Sources of VOC Exposure
Environmental Sources
Indoor environments represent the primary source of VOC exposure for most people in high-income countries, where individuals spend the majority of their time indoors with minimal ventilation 5. Common indoor sources include:
- Consumer products: furniture, sealants, paints, cleaning products 5, 6
- Household activities: cooking practices, use of fragrances and air fresheners 3
- Building materials: various construction and finishing materials 6
- Occupational settings: paint production facilities, industrial workplaces 2
Biological Sources
VOCs are also produced endogenously by the human body and can be detected in exhaled breath 4. Exhaled VOC concentrations typically range from parts per billion to parts per trillion (nM to pM) 4. These endogenous VOCs include:
- Acetone, ethanol, isoprene, pentane, ethane, methanol, and dimethyl sulfide 4
- Compounds linked to pathogenic fungi and bacteria 4
- Biomarkers related to inflammation, obstructive lung diseases, and lung cancer 4
Exposure Patterns and Variations
Spatial and Seasonal Variations
VOC concentrations vary significantly by indoor environment type and season, with higher mean concentrations typically found in housing environments, offices, and during cold seasons 6. This variation reflects differences in:
- Ventilation rates (reduced outdoor air exchange in cold weather) 5
- Source activities and product use patterns 6
- Indoor versus outdoor concentration ratios 6
Occupational Exposure Levels
In industrial settings like paint production facilities, VOC concentrations can be substantially elevated 2. For example:
- m,p-xylene: up to 92,489.91 µg/m³ 2
- Ethylbenzene: up to 91,188.95 µg/m³ 2
- Toluene: up to 46,088.84 µg/m³ 2
Health Implications
Respiratory Effects
VOCs produce high levels of reaction with the airway epithelium and mucosa membrane and are linked with pulmonary diseases 5. Meta-analysis demonstrates:
- Medium-sized effect on asthma onset (effect size ~0.37; 95% CI = 0.25-0.49) 5
- Medium-sized effect on wheezing (effect size ~0.26; 95% CI = 0.10-0.42) 5
- Association with asthma and other respiratory symptoms/diseases 6
Carcinogenic and Non-Carcinogenic Risks
Many VOCs are classified as known or possible human carcinogens, irritants, and toxicants 6. In residential settings:
- Lifetime cancer risks may exceed 1 in 10,000 threshold for chloroform and benzene in 35-50% of simulations 3
- Combined risks from chloroform, benzene, and carbon tetrachloride may be unacceptable 3
- In occupational settings, total lifetime cancer risks range from 1.8 × 10⁻⁵ to 3.85 × 10⁻³, primarily from ethylbenzene and benzene 2
Important Confounding Factors
When assessing VOC exposure, several factors can influence measurements and health effects 4:
- Diet 4
- Exercise 4
- Smoking 4
- Pharmacological treatments 4
- Co-morbidities 4
- Inter-subject variability in drug elimination 4
Common practice includes prohibiting exercise, smoking, food and drink intake 2-3 hours prior to breath testing, though the effectiveness of these restrictions remains to be fully determined 4.