Candles are commonly used to create a warm atmosphere and introduce pleasant scents, but this practice has raised questions about their impact on indoor air quality and human health. A central concern is whether the chemicals released by common candles can interfere with the body’s delicate hormonal system. Investigating this issue requires examining the specific chemical releases, the ingredients used to make candles, and the biological mechanisms of hormonal disruption.
Understanding Endocrine Disrupting Chemicals
The endocrine system is a network of glands that produces hormones, which act as chemical messengers regulating nearly all bodily functions, including metabolism, growth, and reproduction. Endocrine Disrupting Chemicals (EDCs) are substances that interfere with this system’s normal functioning. These chemicals can interact with the body’s hormones in three primary ways.
The first mechanism involves the chemical mimicking a natural hormone, such as estrogen or testosterone, which then binds to the hormone’s receptor site and triggers an inappropriate response. EDCs can also function by blocking the receptor site, preventing the natural hormone from binding and signaling its intended message. A third way EDCs cause interference is by altering the production, transport, or metabolism of natural hormones, changing the overall level of hormones in the bloodstream. Even small changes in hormone levels can cause significant biological effects.
Chemical Emissions from Candle Combustion
When a candle burns, combustion releases several airborne substances into the indoor environment. This burning releases Volatile Organic Compounds (VOCs), which are chemicals that easily become vapors or gases at room temperature. Among the VOCs identified in candle smoke are compounds like benzene, toluene, and formaldehyde, which are known air pollutants.
Incomplete combustion, which is common during burning, is the main driver of these pollutant emissions. The flame also generates fine particulate matter (PM2.5), which are tiny airborne particles. These ultrafine particles can be inhaled deeply into the lungs, and they can sometimes carry other chemicals, including EDCs, deeper into the respiratory system.
Exposure to these combustion byproducts has been linked to respiratory and other health issues, contributing to poor indoor air quality. The concentration of these pollutants can become high in poorly ventilated spaces as they accumulate. While not all combustion products are EDCs, the overall mixture of VOCs and fine particulates creates a complex chemical exposure profile.
The Impact of Fragrance Ingredients and Wax Types
The specific ingredients used to formulate a candle significantly influence its potential to release EDCs and other pollutants. Phthalates, a group of chemicals often used in synthetic fragrances, are a primary concern because they help the scent last longer. These compounds are well-established EDCs, and their release during burning means they can be inhaled or absorbed. Phthalates have been linked to interfering with the production and regulation of reproductive hormones, leading many manufacturers to offer “phthalate-free” products.
The type of wax used also dictates the candle’s emission profile. Many mass-produced candles are made from paraffin wax, a byproduct of petroleum refining. When burned, paraffin can release aromatic hydrocarbons like benzene and toluene, although studies suggest a properly wicked, high-quality paraffin candle may not emit harmful levels of pollutants. Natural waxes, such as soy, beeswax, or coconut wax, are derived from renewable resources and marketed as cleaner-burning alternatives. However, even natural waxes release VOCs and particulate matter, and the cleanliness of the burn depends more on the candle’s overall construction and wicking than the wax type alone.
A final ingredient consideration involves the wick material, specifically the historical use of lead cores. Lead-cored wicks were used to help the wick stand upright. In 2003, the United States Consumer Product Safety Commission (CPSC) banned the manufacture and sale of candles with metal cores containing more than 0.06% lead by weight. This regulation addressed the hazard of lead being emitted into the air upon burning.
Strategies for Minimizing Exposure
Consumers can implement several practical strategies to reduce their potential exposure to unwanted chemical emissions from candles. Selecting candles labeled as “phthalate-free” is a direct step to avoid a common EDC used in synthetic fragrances. Opting for candles made with natural waxes, such as soy, beeswax, or coconut, may also reduce the potential for releasing petroleum-derived VOCs.
Proper candle maintenance is an effective way to limit combustion byproducts. This includes trimming the wick to about a quarter-inch before each burn to encourage a cleaner flame and reduce soot. Limiting the overall burn time is helpful, as pollutant concentrations increase in enclosed spaces. Ensuring the room is adequately ventilated by opening a window or using an air purifier helps disperse emitted VOCs and particulate matter.