Overview: Levels of human exposure to PCBs (from environmental sources)* and Tolerable Daily Intake (TDI) The table below presents amounts of PCBs found in the environment or in food products in various studies, as well as the Tolerable Daily Intake (TDI) set by the WHO. The figures do not represent average exposure at a global level, but results of specific studies with a limited geographical and time scale. Direct comparisons between figures are thus not possible (even if the units presented are similar). Comparisons are further complicated by the fact that some studies measured the total amount of PCBs found in the environment, while others measured only certain types of PCBs, generally the most toxic ones which account for most though not all of the overall PCB toxicity. - Figures and Tables

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Overview: Levels of human exposure to PCBs (from environmental sources)* and Tolerable Daily Intake (TDI)
The table below presents amounts of PCBs found in the environment or in food products in various studies, as well as the Tolerable Daily Intake (TDI) set by the WHO. The figures do not represent average exposure at a global level, but results of specific studies with a limited geographical and time scale. Direct comparisons between figures are thus not possible (even if the units presented are similar). Comparisons are further complicated by the fact that some studies measured the total amount of PCBs found in the environment, while others measured only certain types of PCBs, generally the most toxic ones which account for most though not all of the overall PCB toxicity.
Type of Environment	Environmental Level*	Daily Intake	GreenFacts comments	See question
* Environmental PCB levels may have decreased since these measurements were made. In order to determine whether or not PCBs constitute a significant risk to the average human, the Average Daily Intake (ADI) can be compared with the Tolerable Daily Intake (TDI) which has been established for PCBs. The Tolerable Daily Intake (TDI) of PCBs for humans has been set at 20 ng per kg body weight per day** (over the whole life). This has been determined from the Lowest Observed Adverse Effect Level (LOAEL) of one specific PCB mixture, Aroclor 1254, on the immune systems of rhesus monkeys. The protective uncertainty factor of 300 used in calculating the human Tolerable Daily Intake (TDI) from this lowest observed LOAEL data is thought to protect humans sufficiently because Aroclor 1254 contains several quite toxic individual PCBs Rhesus monkeys are thought to be more sensitive to PCBs than humans
Outdoor Air				3.3
-Urban (N. America)	Average 5 ng per m³ Range 1 -10 ng/m³	On average approximately 1.5 ng per kg body weight per day	This average daily intake is calculated for an average adult male inhaling 23 m³ of Urban outdoor air per day and weighing 70 kg
-Rural (Arctic & Antarctic)	0.02 to 0.5 ng per m³	-	-
Indoor Air (in PCB disposal facilities, measured for various Aroclors)	850 to 40 000 000 ng per m³	-	Lower PCB levels found in homes and laboratories – e.g. 100-310 ng/m³	3.3
Drinking Water (in the USA)	less than 100 ng per litre	less than 3 ng per kg body weight per day (USA population)	This average daily intake is calculated for an average adult drinking 2 litres per day and weighing 70 kg	3.4
Food (USA)	-	3–5 ng per kg body weight per day (adults) 2–12 ng per kg body weight per day (children)	-	3.1
Breast milk (in a single study on breastfeeding Canadian women)	6 000 ng per kg whole breast milk	less than 1000 ng per kg body weight per day (during the intake from these 3 PCB’s accounts for 60%period of the overall toxicity found in Japanese foodbreast feeding)	This daily intake was calculated by GreenFacts from a single study assuming an infant weighing 6 kg that would drink less than a kg of breast milk.	3.2
Tolerable Daily Intake (TDI)**	-	20 ng per kg body weight per day (averaged over the whole life)**	Calculated by applying an uncertainty factor of about 300 to the above LOAEL**	7.2

Source: Greenfacts based on WHO Polychlorinated biphenyls : Human health aspects.
Concise international chemical assessment document ; 55

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PCBs Polychlorinated biphenyls

Other Figures & Tables on this publication:

Table 1: PCB nomenclature conversion table.a [Two different systems are used for naming PCBs: In the IUPAC system the numbers at the beginning of the name specify the sites where chlorines are attached to the two phenyl rings. In this table, the top row indicates the position of the chlorine atoms one one phenyl ring and the first column their position on the second phenyl ring. Another system developed by Ballschmiter & Zell (1980) assigns a separate number, from 1 to 209, to each of the 209 specific PCB congeners. These numbers are indicated inside the table below. An example how to relate the two systems is provided below the table.]

Table 7: Estimated daily dietary intake of PCBs in the USA. a

Overview: Levels of human exposure to PCBs (from environmental sources)* and Tolerable Daily Intake (TDI) The table below presents amounts of PCBs found in the environment or in food products in various studies, as well as the Tolerable Daily Intake (TDI) set by the WHO. The figures do not represent average exposure at a global level, but results of specific studies with a limited geographical and time scale. Direct comparisons between figures are thus not possible (even if the units presented are similar). Comparisons are further complicated by the fact that some studies measured the total amount of PCBs found in the environment, while others measured only certain types of PCBs, generally the most toxic ones which account for most though not all of the overall PCB toxicity.