Semi-Volatile Organic Compounds (SVOCs) Explained

Semi-volatile organic compounds, or SVOCs, are – as their name suggests – less volatile than volatile organic compounds (VOCs). But SVOCs still pose significant implications for indoor air quality, environmental contamination, and human health.

What Are Semi-Volatile Organic Compounds?

SVOCs are a class of organic chemicals characterized by their intermediate vapor pressures, typically ranging from 10⁻¹¹ to 10² Pascals at room temperature.

This property places them between VOCs, which readily evaporate into the air, and non-volatile compounds, which tend to remain in solid or liquid form.

SVOCs include a wide variety of chemical families such as:

• Phthalates: Used as plasticizers
• Polybrominated diphenyl ethers (PBDEs): Used as flame retardants
• Polychlorinated biphenyls (PCBs): Formerly used in electrical equipment
• Pesticides (e.g., DDT, chlorpyrifos)
• Polycyclic aromatic hydrocarbons (PAHs): Byproducts of combustion

These compounds are typically found in both indoor and outdoor environments, often persisting in dust, on surfaces, and in the air.

Sources of SVOCs

SVOCs originate from a wide array of sources, both anthropogenic and natural. Common indoor sources include:

• Consumer products: Personal care items, cleaning agents, and air fresheners.
• Building materials: Paints, sealants, adhesives, and vinyl flooring.
• Furnishings: Upholstered furniture, carpets, and electronics.
• Combustion processes: Tobacco smoke, cooking, and heating appliances.

Outdoors, SVOCs are released through industrial emissions, vehicle exhaust, pesticide application, and the degradation of other organic compounds.

Behavior and Fate in the Environment

Unlike VOCs, which tend to dissipate quickly into the atmosphere, SVOCs exhibit a more complex behavior due to their dual-phase nature. They can exist in both the gas phase and adsorbed onto particles or surfaces. This characteristic leads to several important environmental behaviors:

• Partitioning: SVOCs partition between air, dust, water, and surfaces. Indoors, they often accumulate in settled dust and on surfaces like walls and furniture.
• Persistence: Many SVOCs are chemically stable and degrade slowly, leading to long-term environmental presence.
• Bioaccumulation: Some SVOCs, particularly those with high lipid solubility, can accumulate in the fatty tissues of living organisms, magnifying their effects through the food chain.

Health Impacts of SVOCs

Exposure to SVOCs can occur through inhalation, ingestion (especially of dust), and dermal contact. The health effects vary depending on the specific compound, concentration, duration of exposure, and individual susceptibility. Some of the documented and suspected health impacts include:

• Endocrine disruption: Certain phthalates and flame retardants can interfere with hormone systems, potentially affecting reproductive and developmental health.
• Respiratory issues: Inhalation of SVOCs may exacerbate asthma and other respiratory conditions.
• Neurotoxicity: Compounds like PBDEs have been linked to cognitive and behavioral effects, particularly in children.
• Carcinogenicity: Some SVOCs, such as PAHs and PCBs, are classified as probable or known human carcinogens.

Children are particularly vulnerable due to their developing systems and behaviors such as hand-to-mouth activity, which increases ingestion of contaminated dust.

SVOCs in Indoor Environments

Indoor environments are of particular concern because people spend most of their time indoors – at home, work, or school. SVOCs can be released slowly over time from materials and products, leading to chronic low-level exposure. Factors influencing indoor SVOC levels include:

• Ventilation: Poor ventilation can lead to accumulation of SVOCs.
• Temperature and humidity: Higher temperatures can increase SVOC emissions from materials.
• Cleaning practices: Dust removal can reduce SVOC reservoirs, but some cleaning products may also introduce new SVOCs.

Studies have shown that indoor dust can contain significant concentrations of SVOCs, making it a major exposure pathway, especially for young children.

Regulation and Standards

Regulatory oversight of SVOCs varies by region and compound. In the United States, several agencies play roles in monitoring and regulating SVOCs:

• Environmental Protection Agency (EPA): Regulates pesticides and industrial chemicals under laws such as the Toxic Substances Control Act (TSCA).
• Consumer Product Safety Commission (CPSC): Oversees safety of consumer products, including restrictions on phthalates in children's toys.
• Occupational Safety and Health Administration (OSHA): Sets exposure limits for certain SVOCs in workplace settings.

Internationally, the European Union’s REACH regulation and the Stockholm Convention on Persistent Organic Pollutants (POPs) also address SVOC risks.

Mitigation and Exposure Reduction

Reducing exposure to SVOCs involves a combination of source control, environmental management, and personal behavior. Key strategies include:

Source Identification and Substitution

• Choose products labeled as low-emission or free of specific SVOCs
• Avoid materials known to contain phthalates or flame retardants

Improved Ventilation

• Use mechanical ventilation systems or open windows to dilute indoor pollutants

Dust Control

• Regular vacuuming with HEPA filters and wet dusting can reduce SVOC-laden dust

Temperature and Humidity Control

• Maintain moderate indoor temperatures and humidity to limit SVOC emissions

Policy and Advocacy

• Support regulations that limit the use of harmful SVOCs in consumer products and building materials

Future Directions and Research

Ongoing research continues to uncover the complexities of SVOC behavior, exposure pathways, and health effects. Emerging areas of interest include:

• Cumulative risk assessment: Understanding the combined effects of multiple SVOCs and other pollutants.
• Green chemistry: Developing safer alternatives to SVOCs in industrial and consumer applications.
• Advanced monitoring technologies: Improving detection and quantification of SVOCs in various environments.

Semi-volatile organic compounds represent a significant yet often overlooked class of environmental contaminants. Their persistence, ubiquity, and potential for harm underscore the importance of awareness, regulation, and mitigation.

GPRS is the trusted leader for damage prevention in the environmental sector. Our project managers deliver results from the beginning of the initial investigation, throughout delineation and remediation, until project completion. With our nationwide network of Project Managers, we are equipped to mobilize to projects across the United States.

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Frequently Asked Questions

What do I get when I hire GPRS to conduct a utility locate?

Our Project Managers flag and paint our findings directly on the surface. This method of communication is the most accurate form of marking when excavation is expected to commence within a few days of service.

GPRS also uses a global positioning system (GPS) to collect data points of findings. We use this data to generate a plan, KMZ file, satellite overlay, or CAD file to permanently preserve results for future use. GPRS does not provide land surveying services. If you need land surveying services, please contact a professional land surveyor.

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Can GPRS Project Managers distinguish between different underground utilities that they locate?

In most situations, we can identify the utility in question without any problems, although it is not always possible to determine what type of utility is present. When this happens, we attempt to trace the utility to a valve, meter, control box, or other signifying markers to determine the type of utility buried.