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Safety & Public Awareness / PCB Overview

Date Requested: Jun 26 2019 1:16 AM
Printable Version
What are PCBs?

Polychlorinated biphenyls (PCBs) belong to a broad family of organic chemicals known as chlorinated hydrocarbons. The commercial production of PCBs began in 1929 and they were widely used as ingredients in the manufacture of heat transfer fluids, hydraulic fluids, and dyes and as cooling and dielectric fluids in electrical transformers, light ballasts, and electrical capacitors.

In the 1970's, Congress concluded, after completing one study that observed the effect of PCBs on mice, that PCBs could pose a threat to human health and the environment and issued a ban against the further production of PCBs. As a result of the ban, PCBs were last manufactured on an industrial scale in the U.S. in 1979.

Through the normal course of operating a natural gas pipeline system, pipeline liquids, mostly in the form of hydrocarbons, can drop out of the gas stream and accumulate throughout a pipeline network. Some of these liquids may contain Polychlorinated Biphenyls (PCBs). Until 1979, there were many sources of PCBs in the natural gas pipeline industry. Some pipeline companies used valve sealant that contained PCBs; some used turbine oil that contained PCBs and some fogged their lines with waste oil that contained PCBs.

What is Northern Natural Gas doing to control PCBs in the pipeline system?

Northern has installed filters at some locations and will continue to install filters in the future where liquids are found. If these liquids are captured, then the PCBs are also captured with the liquids. Northern is also pigging many of the lines to remove liquids that may be residing in the system. Northern has had a PCB management program in place since 1981. This program includes annual sampling of several liquid collection points and installing liquid collection appurtenances where required. Controlling the liquid movement throughout the pipeline system controls the migration of PCBs, if present.

Contact for more information

If you have additional questions regarding PCBs, please email or call your account representative or contact

PCB - Fast Facts
  • PCBs have been studied for nearly three decades.
  • As a result of these studies, allowable concentrations of PCBs have been established for food products, food grain for animals, oil concentrations, etc. by the FDA, EPA, and other federal agencies.
  • A great amount of time and money have been spent studying the health effects of PCBs. These studies have not been able to definitively correlate PCBs to any form of cancer for people exposed in the workplace.
  • Studies show that PCBs travel in liquid form. Therefore, the concentration of PCBs in a dry gas stream is negligible, if any. Residents using natural gas should not receive any liquids and therefore, any PCBs.
  • Not all oils contain PCBs. In fact, manufacturing of PCBs was ceased in 1979. Prior to 1979, PCBs were introduced in the pipeline industry as a constituent of valve sealant and turbine oil. Northern Natural Gas did not use turbine oil with PCBs, however, may have received this type of oil into its pipeline system through interconnects with other pipeline companies.
  • The gas system in the Minneapolis area is defined as a dry system (very little produced condensate). However, liquids are sporadically found in the pipelines for various reasons. For example, when gas cools down and the pressure is reduced, a minimal amount of liquids associated with the gas may fall out. There are also residual oils in the pipeline that can be stagnant for quite some time and then be moved by the gas, when the gas is moving at high enough velocities.
  • There are many existing liquid filters and knock-out drips on Northern Natural Gas's pipeline system. However, if PCB contaminated oils were to reach a burner tip at an industrial facility, research shows that the PCBs would burn with the oil (at approximately 700 F). Incomplete combustion constituents are minimal, if detectable.
PCB - History and Overview
History of PCBs in the natural gas pipeline industry​

In January 1981, PCBs were discovered in natural gas pipeline liquids in Long Island, N.Y. Pipeline liquids include pipeline condensate and other liquids that were intentionally or accidentally added to the pipeline. Pipeline condensates, primarily composed of hydrocarbon distillates, occur as a result of the movement of pressurized natural gas through a pipeline under varying temperature conditions. Examples of liquids that were intentionally added to natural gas pipelines include: methanol as an ice hydrate deterrent; inhibitor chemicals for corrosion protection; and waste oils sprayed into a pipeline (known as fogging the lines) for gasket protection. Adding liquids to the pipeline, intentionally, is no longer a common practice in the industry.

Due to the discovery of PCBs in some pipeline liquids, the EPA, state agencies and the natural gas pipeline industry formed a task force in January 1981 to address the PCB problem and to coordinate national activities. Under this task force, EPA headquarters took responsibility for major interstate transmission companies, while the EPA regions were asked to work with public service commissions and local distribution companies. Extensive EPA and industry sampling of the major transmission facilities found 13 companies with PCB contamination greater than 50 parts per million (ppm). PCB pipeline liquids contamination was also found at a number of local distribution companies.

In late 1981, EPA instituted a Compliance Monitoring Program (CMP) for the 13 companies found to have PCBs greater than 50 ppm. The 1981 CMP required each company to develop remedial plans with four basic objectives: (1) to ensure the proper storage and disposal of PCBs; (2) to contain PCB contamination to limited areas of the transmission system; (3) to eliminate any further entry of PCBs into the pipeline system; and (4) to remove remaining PCB contamination from the pipeline system. To achieve these objectives, most of the participants installed filter separators to collect condensate at several locations along their respective pipeline systems.

In addition, each company was asked to develop and submit PCB monitoring plans that included sampling key points within the contaminated area. Suggested sampling locations included major natural gas purchasers and large volume condensate collection points. Individual monitoring plans were finalized with each company in late 1981 and early 1982.

The EPA decided that it would not take enforcement action against such companies for the improper use of PCBs as long as they participated in an EPA compliance monitoring program. All companies were required to comply with all other aspects of the PCB rule, which included marking, record keeping, and disposal.

In 1992, Northern Natural Gas requested, from the EPA, to declassify the southern portion of the pipeline system, because PCB levels were either too low or non-existent. The southern portion consisted of everything south of, and including, the Beatrice, Neb., compressor station. This was eventually granted on June 24, 1992.

In 1998, the EPA issued the Mega Rule, which addressed how pipelines were to handle PCBs. In order to manage the PCBs remaining in the pipeline system, natural gas transmission companies must comply with many sampling and characterization requirements.

In 1999, following the installation of the Mega Rule, Northern Natural Gas sampled all PCB sources within its pipeline. These sources included natural gas compressors, natural gas scrubbers, natural gas filters, interconnects with other natural gas transmission companies, and pipeline liquid tanks and drips. The sampling has been repeated in subsequent years.

Characteristics of PCBs in the gas stream

A study published in 2001, conducted by the Gas Research Institute, indicates that PCBs travel in liquid form. Therefore, if liquids in the pipelines are controlled, the PCBs should be controlled. When the gas stream drops in pressure and velocity, the liquids fall out and remain in the pipeline. Therefore, gas delivered to residential homes should not have liquids entrained in the gas. The liquids will drop out prior to reaching the customer's home.

PCBs in Northern Natural Gas' Pipeline System

The PCBs found in Northern's pipelines entered the system several years ago. This is known because PCB use was discontinued in 1979. There are two types of PCBs that have been found in Northern's system. One type of PCB is from a turbine oil, which Northern suspects was delivered from another pipeline company through an interconnect because Northern did not use turbine oil that contained PCBs. The other type of PCB is from valve sealant that Northern did use on the north section of the pipeline system.

The valve sealant can enter the pipeline through the course of normal maintenance of the valves. Northern immediately ceased using valve sealant containing PCBs in 1979 when the EPA determined there were risks to public health.

Liquids that are introduced into the system through normal maintenance of the compressors, travel down the pipeline in the gas stream and can pick up the PCB contaminated valve sealant. Because of this action, Northern treats all of its liquids found north of the Beatrice station as PCB contaminated and follows all applicable regulations to test and remediate.

Northern rarely finds liquids that have concentrations above EPA's threshold levels that require the waste to be treated as PCB contaminated. Most of the liquids collected on Northern's system are well below these limits. Therefore, disposal of these wastes are handled as used oil.

In the rare event that the liquids test above EPA's threshold level, the waste is disposed of properly and the required testing and sampling is conducted according to the regulations.

Northern is focusing on removing these liquids from the system by using various types of equipment such as separators, drips, and coalescing filters. The type of equipment chosen depends on the size of pipeline and the range of the gas stream velocity. Northern is also removing liquids by pigging the lines throughout the northern half of the system. These pigs will sweep the existing liquids out through the pig receiver.

These filter installations and pig runs are ongoing and will continue to be performed to remove liquids, and therefore, PCBs from the system

Health effects of exposure to PCBs

The primary routes of potential human exposure to PCBs are ingestion and dermal contact. The release of PCBs from prior industrial uses, beyond the pipeline industry, and the persistence of the compounds in the environment previously resulted in widespread contamination of water and soil, with subsequent potential exposure to the general population.

The initial adverse findings, in regard to the health effects of exposure to PCBs, led to the creation of the complex PCB regulatory scheme in place today.

In 1996, the EPA reduced the toxic potency factor of PCBs from 7.7 to 2.0. This was reduced after the EPA issued a draft PCB cancer assessment in which it reviewed the more recent information. EPA's development of a revised PCB toxic potency factor and the evaluation of the non-cancer effects of PCBs are still underway.

In March 1999, researcher Renate Kimbrough, who first found the link between PCBs and cancer in laboratory rats, issued a comprehensive study finding no significant increase in cancer deaths among workers who were exposed to PCBs on the job.1

In December 2001, a comprehensive report entitled "A Weight-of-Evidence Review of the Human Studies of the Potential Cancer Effects of PCBs" was submitted to EPA urging the agency to re-examine the human cancer risks of PCBs. The report concludes that evidence demonstrates that exposure to PCBs is not a risk factor for breast cancer, that there is little credible evidence that PCBs have caused cancer in highly-occupationally-exposed workers, and that it is not evident that PCBs could cause cancer in humans at environmental exposure levels.1 Additional studies can be found at the websites listed below.

USWAG; June 30, 2003; PCB Health Effects

Frequently Asked Questions
Is the gas safe to use for cooking and for heat?

Studies conducted by the GRI indicate that as the gas streams velocity and pressure decreases as it enters residents' homes, the liquids, if present will fall out prior to reaching the burner tip. However, for industrial customers, if liquids do reach the burner tip, the PCBs will burn if the burner tip is at or above approximately 700?. The incomplete combustion of PCBs is minimal and is not considered a health effect.

What should I do if I discover oil in our line?

If oil is discovered in your natural gas line, you may contact your representative at Northern or you can call the Operations Communication Center at 1-888-367-6671. This information will be passed on to the operating personnel that can quickly act on this issue.

How do I protect my employees from PCBs if they are working near pipeline liquids?

Northern Natural Gas assumes, as a safety measure, that all liquids north of the north fence of Beatrice contain PCBs. Northern Natural Gas has written PCB handling procedures that require the employees to wear appropriate personal protective equipment. If liquids come in contact with the employees' skin, employees are instructed to wash the area with soap and water.

As noted in this document, the health studies cannot definitively correlate occupational exposure to PCBs with any type of cancer.

    As noted in this document, the health studies cannot definitively correlate occupational exposure to PCBs with any type of cancer.

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