Introduction

People with potentially high exposures to PCBs include

• Recreational and subsistence fishers who typically consume larger quantities of locally caught fish than the general population,
• Children with in utero and lactational exposure to PCBs from mothers who eat large quantities of contaminated fish during pregnancy and while nursing,
• Certain farmers and their families who consume PCB-contaminated food via their own farm-raised beef and dairy cattle, and
• People living near incinerators, other PCB-disposal facilities, or NPL hazardous waste sites where PCBs have been detected.

Although PCBs are no longer manufactured in the United States, workplace exposure potentially may exist. In occupational settings, persons who repair and maintain equipment with capacitors and transformers manufactured before 1977 could be exposed to PCBs.

Recreational and Subsistence Fishers

Due to the factors of culture and lifestyles, sport anglers and subsistence fishers may consume 10 times more fish and seafood than average U.S. consumers. Many of these subsistence fishers are American Indian, ethnic minority, or immigrant populations.

The special dietary practices of these populations can lead to significant exposures to persistent pollutants [Hovinga et al. 1993; Judd et al. 2004].

Children with Maternal Exposures

Children of mothers who eat large quantities of contaminated fish may be exposed to PCBs prenatally and while breastfeeding.

Several studies have reported that prenatal exposure to PCBs has been confirmed among children of consumers of contaminated fish and certain other groups [Fein et al. 1984; Jacobson JL et al. 1990b; Jacobson SW et al. 1985; Swain and Swain 1991]. Other studies have indicated that lactating women whose diets are high in PCB-contaminated fish potentially can increase the PCB exposure for their breastfeeding infants [Dewailly et al. 1989; Fitzgerald et al. 1998; Greizerstein et al. 1999; Rogan et al. 1985]. Fetuses and neonates are more sensitive to PCBs than are adults. During these early life stages, the hepatic microsomal enzyme systems that facilitate the metabolism and excretion of PCBs are not fully functional.

Farming Families

Farmers and their families who consume PCB-contaminated food via their own farm-raised beef and dairy cattle may be exposed.

During the 1940s and 1950s, the insides of concrete silos on many farms in the Midwest United States were coated with sealants containing PCBs. Over time, these sealants peeled off and became mixed with silage used to feed beef and dairy cattle. Farmers and their families who lived on these farms and who regularly ate farm-raised beef and dairy products were exposed to PCBs. Although most of these silos have been dismantled and removed, the remaining silos represent a potential source of exposure to PCBs [Hansen 1987; Humphrey 1983; Schantz et al. 1994].

People Living Near PCB Contaminated Sites

Persons living near incinerators, other PCB-disposal facilities, or NPL hazardous waste sites where PCBs have been detected may be exposed.

Persons living near incinerators, other PCB-disposal facilities, or any of the 500 current or former hazardous waste sites on the NPL sites where PCBs have been found may be also at increased risk for exposure to PCBs [ATSDR 1987; Hazdat 2000; Hermanson and Hites 1989; Robertson and Ludewig 2011; Stehr-Green et al. 1988; Wester et al. 1993].

Persons with Impaired Hepatic Function

PCBs are metabolized mainly in the liver, thus, persons with impaired hepatic function might be at increased risk because their ability to detoxify and excrete these compounds is diminished.

Persons with incompletely developed glucuronide conjugation mechanisms (such as Gilbert syndrome or Crigler-Najjar syndrome) have impaired liver function, as do persons with chronic liver diseases such as cirrhosis or hepatitis B [Calabrese et al. 1977; Lester et al. 1964].

Similarly, because hepatic function normally declines with age, elderly persons may be more susceptible to the effects of exposure to PCBs.

Children's Susceptibility

Infants and young children consume a greater amount of food per kilogram of body weight than do adults. Therefore, they have proportionately greater exposure to PCBs than do adults eating food with the same level of contamination [ATSDR 2000]. In addition, as mentioned earlier, fetuses and neonates are potentially more sensitive to PCBs than are adults because their hepatic microsomal enzyme systems that facilitate the metabolism and excretion of PCBs are not fully functional.

Exposure in the Workplace

PCB levels in blood and body tissues were 10-1,000 times higher in persons exposed to PCBs in the workplace than in non-occupationally exposed persons [Kreiss and Kreiss 1985; Wolff 1985; Yakushiji et al. 1978].

The United States no longer produces PCBs or products containing PCBs (e.g., capacitors, transformers, and electrical equipment), thus occupational exposure to PCBs no longer occurs in those settings. However, workers can have inhalation or dermal contact with PCBs when repairing or performing routine maintenance on older equipment or electrical transformers, and during accidents or spills involving PCBs [Fait et al. 1989; Schecter AJ and Charles 1991; Welsh 1995; Wolff 1985]. Exposure can also occur during the disposal of materials containing PCBs at hazardous waste sites, waste-site cleanup, or demolishing buildings containing PCBs [Luotamo et al. 1993; Robertson and Ludewig 2011].

Specific occupations with risk for exposure to PCBs in the National Occupational Exposure Survey (NOES)[NIOSH 1989] include

• Construction work,
• Demolition work,
• Electric cable repair,
• Electroplating,
• Emergency response,
• Firefighting,
• Hazardous waste hauling or site operation,
• Heat exchange equipment repair,
• Maintenance or cleaning,
• Medical laboratory technician or technologist,
• Metal finishing,
• Non-cellulose fiber industry,
• Paving and roofing,
• Pipefitting or plumbing,
• Semiconductor and related industries,
• Timber products manufacturing,
• Transformer or capacitor repair, and
• Waste-oil processing.

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