What are total petroleum hydrocarbons (TPH)?
Total petroleum hydrocarbons (TPH) is a term used to describe a large family of several hundred chemical compounds that originally come from crude oil. Crude oil is used to make petroleum products, which can contaminate the environment. Because there are so many different chemicals in crude oil and in other petroleum products, it is not practical to measure each one separately. However, it is useful to measure the total amount of TPH at a site.
TPH is a mixture of chemicals, but they are all made mainly from hydrogen and carbon, called hydrocarbons. Scientists divide TPH into groups of petroleum hydrocarbons that act alike in soil or water. These groups are called petroleum hydrocarbon fractions. Each fraction contains many individual chemicals.
Some chemicals that may be found in TPH are hexane, jet fuels, mineral oils, benzene, toluene, xylenes, naphthalene, and fluorene, as well as other petroleum products and gasoline components. However, it is likely that samples of TPH will contain only some, or a mixture, of these chemicals.
What happens to total petroleum hydrocarbons (TPH) when they enter the environment?
- TPH may enter the environment through accidents, from industrial releases, or as by-products from commercial or private uses.
- TPH may be released directly into water through spills or leaks.
- Some TPH fractions will float on the water and form surface films.
- Other TPH fractions will sink to the bottom sediments.
- Bacteria and microorganisms in the water may break down some of the TPH fractions.
- Some TPH fractions will move into the soil where they may stay for a long time.
How might I be exposed to total petroleum hydrocarbons (TPH)?
- Everyone is exposed to TPH from many sources.
- Breathing air at gasoline stations, using chemicals at home or work, or using certain pesticides.
- Drinking water contaminated with TPH.
- Working in occupations that use petroleum products.
- Living in an area near a spill or leak of petroleum products.
- Touching soil contaminated with TPH.
How can total petroleum hydrocarbons (TPH) affect my health?
Some of the TPH compounds can affect your central nervous system. One compound can cause headaches and dizziness at high levels in the air. Another compound can cause a nerve disorder called “peripheral neuropathy,” consisting of numbness in the feet and legs. Other TPH compounds can cause effects on the blood, immune system, lungs, skin, and eyes.
Animal studies have shown effects on the lungs, central nervous system, liver, and kidney from exposure to TPH compounds. Some TPH compounds have also been shown to affect reproduction and the developing foetus in animals.
How likely are total petroleum hydrocarbons (TPH) to cause cancer?
- The International Agency for Research on Cancer (IARC) has determined that one TPH compound (benzene) is carcinogenic to humans. IARC has determined that other TPH compounds (benzo[a]pyrene and gasoline) are probably and possibly carcinogenic to humans. Most of the other TPH compounds are considered not to be classifiable by IARC.
Is there a medical test to show whether I’ve been exposed to total petroleum hydrocarbons (TPH)?
- There is no medical test that shows if you have been exposed to TPH. However, there are methods to determine if you have been exposed to some TPH compounds. Exposure to kerosene can be determined by its smell on the breath or clothing. Benzene can be measured in exhaled air and a breakdown product of benzene can be measured in urine. Other TPH compounds can be measured in blood, urine, breath, and some body tissues.
Total Petroleum Hydrocarbon analysis
Modern science includes a wide array of testing methods for thorough Total Petroleum Hydrocarbon analysis. Some of the most commonly used methods include:
- Gravimetric – A sample is extracted using an organic solvent and then evaporated to leave the grease residue behind. However, this method only measures heavy hydrocarbon ranges. It does not provide detailed information as to the carbon range.
- Immunoassay – This is a relatively new biochemical test used in field measurements of the concentration of total petroleum hydrocarbons in a solution. However, this method does not give information regarding the carbon range and results are prone to interference.
- Infrared Spectroscopy – A sample is extracted using an “IR transparent” solvent and the transmittance or absorbance is measured in an Infrared Spectrophotometer. The method is prone to interferences including solubility issues and does not give information as to carbon range
- Gas Chromatography – is perhaps the most commonly used TPH analysis method. Samples are extracted using methods such as tumbling, sonication, or microwave extraction. Extracts are then analyzed using gas chromatography. TPH compounds are detected in the order of boiling point and quantified by comparison to standards. The results are expressed in relation to hydrocarbon ranges:
Source: Agency for Toxic Substances and Disease Registry ASTDR