Elsevier

Environment International

Volume 44, 1 September 2012, Pages 106-111
Environment International

Number of persistent organic pollutants detected at high concentrations in a general population

https://doi.org/10.1016/j.envint.2012.02.005Get rights and content

Abstract

Background

Surveys of human exposure to environmental chemicals do not integrate the number of compounds detected per person and the concentration of each compound. This leaves untested relevant exposure scenarios, such as whether individuals with low concentrations of some compounds have high concentrations of the other compounds.

Objective

To analyze the number of persistent organic pollutants (POPs) detected at high concentrations.

Methods

Serum concentrations of 19 POPs were analyzed by gas chromatography with electron-capture detection in a representative sample of the general population of Catalonia, Spain (N = 919).

Results

Over 58% of participants had concentrations in the top quartile of ≥ 1 of the eight most prevalent POPs, and 34% of ≥ 3 POPs. 83% of women 60 to 74 years old had concentrations of ≥ 3 POPs in the top quartile; 56% of women 60 to 74 years had p,p′-DDE, HCB and β-HCH all in their respective top quartiles, and 48% had concentrations of ≥ 6 POPs in the top quartile. Over 30% of subjects had concentrations in the top decile of 1 to 5 of the eight most prevalent POPs. Half of the population had levels of 1 to 5 POPs > 500 ng/g. Less than 4% had all eight POPs in the lowest quartile.

Conclusions

More than half of the study population had concentrations in the top quartile of ≥ 1 POPs. Significant subgroups of the population accumulate POP mixtures at high concentrations. POP concentrations appear low in most of the population only when each individual compound is looked at separately.

Highlights

► 34% of participants had concentrations in the top quartile of ≥ 3 of 8 POPs. ► 48% of women 60–74 years old had concentrations of ≥ 6 POPs in the top quartile. ► It is not accurate to state that most of the population has low concentrations of POPs. ► We integrate the number of compounds detected per person and the dose of each compound. ► The indicators complement other measures of POP body burden in biomonitoring surveys.

Introduction

Studies monitoring human exposure to persistent organic pollutants (POPs) and other environmental chemical agents have traditionally addressed with difficulties the well-known fact that populations are contaminated by mixtures of chemicals at very different concentrations; in particular, analyses of the population distribution of the concentrations of a given compound usually show that most citizens have much lower concentrations than a certain minority (DHHS (Department of Health and Human Services), 2009, Health Canada, 2010, NRC (National Research Council), 2006, Patterson et al., 2009, Porta et al., 2008, Porta et al., 2010, Thornton et al., 2002). It is indeed important to assess the full population distribution of the concentrations of environmental chemicals and, as also recommended by a committee from the National Research Council, the number of chemicals detected per person (NRC, 2006). Yet, biomonitoring studies commonly report separately the number of compounds detected per person (if at all), and the concentration of each individual compound (DHHS (Department of Health and Human Services), 2009, Health Canada, 2010, Patterson et al., 2009, Porta et al., 2008, Porta et al., 2010, Thornton et al., 2002, Woodruff et al., 2011). Reasonably, the emphasis is usually on the latter: the number of compounds detected per person may be misleading, since it does not account for the corresponding concentrations, among other reasons. Yet, the analysis of the concentrations chemical-by-chemical does not tackle adequately the accumulation of multiple chemicals (Gladen et al., 2003, Kortenkamp et al., 2009, Porta et al., 2008). Combination effects may result from pollutants each of which produces small effects, if they are present in sufficiently large numbers. The existence of mixture effects (e.g., additive, synergistic, antagonistic) depends on the number of contaminants in the mixture, their respective concentrations, and the concentration–response curves. Two crucial factors for combination effects to occur are the number of chemicals and their concentrations (Kortenkamp et al., 2009, NRC (National Research Council), 2008).

So far, population surveys of human exposure to chemicals have not attempted to arithmetically integrate the two types of indicators — number of compounds detected per person and concentration of each compound. This gap hinders exposure assessment and leaves untested a relevant question (with two reciprocal dimensions): in a given population, a) do all individuals who have low concentrations of some compounds have low concentrations of the other compounds detected, and all individuals with high concentrations of some compounds have high concentrations of the other compounds detected? or b) do some individuals who have low concentrations of some compounds have high concentrations of the other compounds detected and, therefore, some individuals with high concentrations of some compounds have low concentrations of the other compounds detected? Here, we develop and apply some new indicators – notably, the ‘number of chemicals detected at high concentrations’ – and show that the answer is b).

Section snippets

Study population

The study population was described in detail elsewhere (DSGC (Departament de Salut de la Generalitat de Catalunya), 2004, Porta et al., 2009, Porta et al., 2010). Briefly, participants in the Catalan Health Interview Survey (CHIS) aged 18–74 years old were offered to take part in a health examination, which included a physical exam, a supplementary interview, and the collection of urine and blood samples. A total of 1374 individuals – who gave specific written informed consent – participated

Results

Over 58% of the 919 participants had concentrations of ≥ 1 of the eight most prevalent POPs equal to or greater than percentile 75 (Table 1), while 43.7% had ≥ 2 POPs, and 33.9% had ≥ 3 POPs in such top quartile (36.7% of women and 30.3% of men). One in five subjects had concentrations of two PCBs in the upper quartile; e.g., 21.9% of participants had both PCB 138 and PCB 153 in their respective upper quartiles. Simultaneous high concentrations of PCBs 138, 153 and 180 (i.e., all three congeners

Discussion

More than half of the study population had concentrations in the top quartile of ≥ 1 of the eight most commonly detected POPs, 34% had ≥ 3 such compounds in their respective top dose quartiles, and 32% ≥ 1 POPs in the top decile. Less than 4% of subjects had concentrations of all eight POPs in the lowest quartile. To our knowledge this type of findings has never been reported before. They are partly in contrast with the notion that human POP concentrations are low in the vast majority of the

Conclusions

Significant subgroups of the general population accumulate POP mixtures at high concentrations. It is misleading to state that most of the population has low concentrations of POPs. POP concentrations appear low in most of the population only when each individual compound is looked at separately. Based on our methods and findings, studies could analyze more systematically the number and type of compounds detected at high concentrations, integrate these indicators with traditional measures of

Conflict of interest

The authors declare that they have no competing financial interests.

Acknowledgments

Supported by research grants from the Department of Health Government of Catalonia; and CIBER de Epidemiología, Instituto de Salud Carlos III, Government of Spain. The authors gratefully acknowledge valuable technical and scientific assistance provided by Tomàs López, Ferran Ballester, Gemma Rovira, Montserrat Guillén, Mercè Garí, Joan Vila, Isaac Subirana, Conxa Castell, Eulàlia Roure, Laia Fina, Joan O. Grimalt, Ricard Tresserras, Esther Bigas, Xavier Llebaria, Antoni Plasència and Yolanda

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