Congener-specific analysis of PCBs in human milk from Kazakhstan

Spatial and temporal trends of the Stockholm Convention POPs in mothers' milk -- a global review

Persistent organic pollutants (POPs) have been of environmental and health concern for more than half a century and have their own intergovernmental regulation through the Stockholm Convention, from 2001. One major concern is the nursing child's exposure to POPs, a concern that has led to a very large number of scientific studies on POPs in mothers' milk. The present review is a report on the assessment on worldwide spatial distributions of POPs and of their temporal trends. The data presented herein is a compilation based on scientific publications between 1995 and 2011. It is evident that the concentrations in mothers' milk depend on the use of pesticides and industrial chemicals defined as POPs. Polychlorinated biphenyls (PCBs) and "dioxins" are higher in the more industrialized areas, Europe and Northern America, whereas pesticides are higher in Africa and Asia and polybrominated diphenyl ethers (PBDEs) are reported in higher concentrations in the USA. POPs are consequently distributed to women in all parts of the world and are thus delivered to the nursing child. The review points out several major problems in the reporting of data, which are crucial to enable high quality comparisons. Even though the data set is large, the comparability is hampered by differences in reporting. In conclusion, much more detailed instructions are needed for reporting POPs in mothers' milk. Temporal trend data for POPs in mothers' milk is scarce and is of interest when studying longer time series. The only two countries with long temporal trend studies are Japan and Sweden. In most cases, the trends show decreasing concentrations of POPs in mothers' milk. However, hexabromocyclododecane is showing increasing temporal concentration trends in both Japan and Sweden.

Application of Kohonen neural network for evaluation of the contamination of Brazilian breast milk with polychlorinated biphenyls

Due to the tendency of polychlorinated biphenyls (PCB) to accumulate in matrixes with high lipid content, the contamination of the breast milk with these compounds is a serious issue, mainly to the newborn. In this study, milk samples were collected from breastfeeding mothers belonging to 4 Brazilian regions (south, southeast, northeast and north). Twelve PCB were analyzed by HS-SPME-GC-ECD and the corresponding peak areas were correlated to the answers to a questionnaire of general habits, breastfeeding and characteristics of the living places. To realize this exploratory analyze, self-organizing maps generated applying Kohonen neural network were applied. It was possible to verify the occurrence of different PCB congeners in the breast milk relating to the region of the Brazil that the breastfeeding lives, the proximity to an industry, the proximity to a contaminated river or sea, the type of milk (colostrum, foremilk and hindmilk) and the number of past pregnancies.

The use of PowerPrep and HRGC/HRMS for biological monitoring of exposure to PCDD, PCDF and dl-PCB in Poland

PURPOSE

The aim of this study was to design the optimized laboratory protocol as a tool for human biomonitoring of selected Persistent Organic Pollutants (POPs) in Poland. In this study, we present the method developed for the determination of 29 congeners of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (dl-PCBs), as well as individual results of the measurements in 40 human breast milk samples collected in central Poland in 2008-2010.

METHODS

The protocol of sample preparation and quantitative analysis of PCDD/Fs and dl-PCBs was optimized for the isotopic dilution method with high resolution gas chromatography/high resolution mass spectrometry HRGC/HRMS. Fat content in the extracts was determined gravimetrically. The results were corrected by fat content in the samples.

RESULTS

The average sum of PCDD/F and dl-PCBs in the human milk samples from the urban area was 7.429 WHO-TEQpg/g fat (with the range 0.431-14.27), and in the rural area it was 6.448pg WHO-TEQ/g fat (0.539-12.61).

CONCLUSIONS

The results obtained in this study indicate that the mothers were exposed uniformly to PCDD/Fs and PCBs regardless of location. The significant difference of p<0.1 between the milk samples from the urban and rural mothers in 2,3,7,8-TCDD; 1,2,37,8,9-HxCDD and 2,3,4,6,7-HxCDF were observed. For the other 14 PCDD/F and 12 dl-PCB congeners, the observed differences were not significant. The total WHO-TEQ values are lower in comparison with the average results in Europe from the fourth round of a WHO-coordinated study.

Levels and trends of PCDD/Fs and PCBs in camel milk (Camelus bactrianus and Camelus dromedarius) from Kazakhstan

To date, despite the fact it represents a very important part of the national dairy production, no data are available concerning the concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) in camel milk from the Republic of Kazakhstan. Selected PCDDs, PCDFs, and PCBs were measured in pools of milk from camels (n=15) located in various places of Kazakhstan (Almaty, Atyrau, Aralsk, Shymkent) and sampled at two different seasons for two different species (Camelus bactrianus and Camelus dromedarius). Non-dioxin-like (NDL-)PCB concentrations (6.3±2.7 ng g(-1) fat, median 5.1 ng g(-1) fat, range 0.6-17.4 ng g(-1) fat) were far below the maximum value of 40 ng g(-1) fat proposed by the EU. Dioxin-like (DL-)PCB concentrations (1.7±0.7 ng g(-1) fat, median 1.5 ng g(-1) fat, range 0.3-4.2 ng g(-1) fat) and the NDL-PCB to DL-PCB ratio (4.3) were similar to what is reported in EU for cow-based dairy products. PCB 52 and PCB 101 appeared to be proportionally more present in Kazakh camel milk samples (>60% of the sum of the 6 indicator NDL-PCBs) than in European cow milk samples (<10% of the sum of the 6 indicator NDL-PCBs), indicating possible differences in the route of exposure to PCBs in Kazakhstan. PCB 105 and PCB 118 appeared to be present at higher concentrations in camel milk (>80% of the sum of the 12 DL-PCBs). PCB 105, PCB 118 and PCB 156 were the major congeners for DL-PCBs, accounting for 92% of the sum of concentrations of DL-PCBs (88% for Belgian cows). In terms of TEQ, PCB 126 and PCB 118 are the major contributors and represent, respectively, 80% and 14% of the DL-PCB TEQWHO05 concentrations. No significant interracial or geographical trends were observed for NDL- and DL-PCB profiles. However, concentrations of all DL-PCBs appeared to be significantly higher for samples collected in Atyrau region. 2,3,7,8-TCDD level (mean 0.08±0.07 pg g(-1) fat, median 0.08 pg g(-1) fat, range 0.00-0.18 pg g(-1) fat, 60%>LOQs) were very low for all samples and 2,3,4,7,8-PeCDF was the major contributor (27%) to the PCDD/F TEQWHO05. Considering the total TEQWHO05 (sum of DL-PCBs and PCDD/Fs), DL-PCB and PCDD/F contributed for 73% and 27%, respectively. A decrease of only 1% of the total TEQ was observed when using the TEFWHO05 scale instead of the TEFWHO98 scale. Two samples collected in the region of Atyrau exceeded the EU maximum level value of 6.00 pg TEQWHO98 g(-1) fat (6.4 pg TEQWHO05 g(-1) fat and 6.9 pg TEQWHO05 g(-1) fat). Both samples exceeded the EU action level for the sum of DL-PCBs. Based on the fact that camel milk is used to prepare popular traditional fermented drinks like shubat, this suggests that the human exposure in the Caspian Sea region of Atyrau should be expected to be higher than in the other regions studied here.

Survey of organochlorine pesticides and polychlorinated biphenyls in commercial pasteurized milk in Iran

The objective of this study was to investigate the presence of organochlorine pesticides (α-HCH, β-HCH, γ-HCH, HCB, dieldrin, o,p'-DDE, p,p'-DDE, p,p'-DDD, p,p'-DDT) and polychlorinated biphenyl (PCBs) congeners (28, 52, 101, 138, 153, 180) in pasteurized and sterilized milk containing 1.5%, 2.5%, and 3% fat from Tehran province (Iran). Considering the importance of milk and dairy products for human nutrition and the toxicity of these compounds, their daily intake (DI) through milk was also determined. The compounds γ-HCH (13.49 ng g(-1) fat), β-HCH (11.7 ng g(-1) fat), and PCB180 (7.56 ng g(-1) fat) were found at highest concentrations. The DI for all compounds was less than the acceptable daily intake established by FAO/WHO except for Σ PCBs which was more than the minimal risk level.

Principal component analysis of indicator PCB profiles in breast milk from Poland

Principal component analysis (PCA) was applied to a data set containing the levels of indicator polychlorinated biphenyls (PCBs) in human milk of mothers living in the Wielkopolska region, Poland, in order to investigate the information captured in the PCB patterns and to elucidate the relationship between PCB concentrations in milk and donor characteristics. According to the obtained PCA results milk fat content was the most influential factor affecting the PCB levels in milk of the Wielkopolska cohort. The lifestyle data collected from the questionnaire completed by the donors appeared to have no influence on PCB concentrations in breast milk. The score plots revealed the PCB contents of milk were quite low and uniform with a few outliers, without discrimination observed either between the primipareous and secundipareous females or between donors from the urban and rural areas. Comparison of the PCB levels and profiles of human milk from the Wielkopolska region and from various European and Asian locations made by PCA reflected a generally low background exposure and indicated the possible reasons for the outlying of some samples. In order to enhance the chances of observing the relationship between donor habits and PCB levels in breast milk it was suggested that the questionnaire be redesigned to gather information about vegetable product consumption and indoor air exposure.

Polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) in breast milk from the Pacific Northwest

Breast milk samples from 40 first-time mothers from the Pacific Northwest of the US and Canada were analyzed for polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs). Total PBDEs (summation operator PBDEs), calculated by summing values for the 12 PBDEs congeners analyzed, ranged from 6 to 321 ppb (lipid weight) (mean=96 ppb; median=50 ppb). In approximately 40% of the women (15/40), summation operator PBDEs>100 ppb lw in their milk, and four samples had levels >250 ppb lw. PBDE 47 was the dominant congener in most samples, whereas PBDE 153 was predominant in a few (3/40). summation operator PCBs were calculated by summing values for the 82 PCB congeners analyzed, and ranged from 49 to 415 ppb (lipid weight) (mean=147 ppb; median=126 ppb). approximately 30% of the mothers (13/40) have summation operator PBDEs> summation operator PCBs in their milk samples, and approximately 65% (25/40) have BDE 47>PCB 153 in breast milk samples, with BDE 47 averaging 3-fold greater levels than PCB 153. Clearly, the lower brominated PBDEs are surpassing PCBs as a major environmental concern in North America, and are likely affecting significant portions of the populations in these regions. PBDEs have become a major persistent organic pollutant. However, there are no positive correlations between levels of summation operator PBDEs and summation operator PCBs, or between levels of PBDE 47 and PCB 153, suggesting there may be some differences in exposure pathways for PBDEs and PCBs in humans.

Geographic variation of chlorinated pesticides, toxaphenes and PCBs in human milk from sub-arctic and arctic locations in Russia

The concentrations of HCB, alpha-, beta- and gamma-HCH, 3 chlordanes (CHLs), p,p'-DDE, p,p'-DDD, p,p'-DDT, and 30 PCBs (polychlorinated biphenyls) were determined in 140 human milk samples from Kargopol (n=19), Severodvinsk (n=50), Arkhangelsk (n=51) and Naryan-Mar (n=20). Pooled samples were used for determination of three toxaphenes (chlorobornanes, CHBs). The concentrations of HCB, beta-HCH and p,p'-DDE in Russian human milk were 2, 10 and 3 times higher than corresponding levels in Norway, respectively, while concentrations of sum-PCBs and sum-TEQs (toxic equivalent quantities) of the mono-ortho substituted PCBs were in the same range as corresponding levels in Norway. The PCB-156 contributed most to the sum-TEQs. Highest mean concentrations of HCB (129 microg/kg milk fat) and sum-PCBs (458 microg/kg milk fat) were detected in Naryan-Mar, while highest mean concentrations of sum-HCHs (408 microg/kg milk fat), sum-CHLs (48 microg/kg milk fat), sum-DDTs (1392 microg/kg milk fat) and sum-toxaphenes (13 microg/kg milk fat) were detected in Arkhangelsk. An eastward geographic trend of increasing ratios of alpha/beta-HCH, gamma/beta-HCH, p,p'-DDT/p,p'-DDE and PCB-180/28 was observed. In all areas the levels of sum-HCHs decreased with parity (number of children born). Considerable variation in levels of the analysed organochlorines (OCs) was found in all the studied areas. Breast milk from mothers nursing their second or third child (multiparas) in Naryan-Mar showed a significant different PCB profile compared to mothers giving birth to their first child (primiparas) from the same area and to primi- and multiparas in the other areas. Both p,p'-DDE and p,p'-DDT showed a significant, but weak, negative correlation with the infants birth weight.

Antagonism of aryl hydrocarbon receptor-dependent induction of CYP1A1 and inhibition of IgM expression by di-ortho-substituted polychlorinated biphenyls

Halogenated aromatic hydrocarbons (HAHs) are ubiquitous environment contaminants that produce many of their toxic effects by binding to the aryl hydrocarbon receptor (AhR). However, several investigations have demonstrated that certain polychlorinated biphenyl (PCB) congeners, principally di-ortho-chlorinated PCB congeners, or mixtures containing multiple di-ortho-chlorinated PCBs, inhibit AhR-mediated responses induced by other toxic HAHs. Most relevant to the present study are past reports demonstrating antagonism by these uniquely acting PCB congeners on AhR agonist-mediated inhibition of humoral immune responses. The mechanism responsible for antagonism of AhR agonists by certain PCBs is presently unknown. The present study evaluated the antagonist activity of several di-ortho-substituted PCB congeners [PCB47 (2,2',4,4'), PCB52 (2,2',5,5'), PCB128 (2,2',3,3',4,4'), and PCB153 (2,2',4,4',5,5')] when present in combination with AhR agonists [TCDD (2,3,7,8,-tetrachlorodibenzo-p-dioxin), PCB126 (3,3',4,4',5), and PCB77 (3,3',4,4')] on CYP1A1 induction and inhibition of lipopolysaccharide (LPS)-induced immunoglobulin production in the CH12.LX B cell line. In contrast to non-ortho-substituted PCB (PCB77), which showed additive effects on CYP1A1 induction in combination with TCDD, all of the di-ortho-substituted PCBs examined produced antagonism. Di-ortho-substituted PCB (PCB52) also antagonized TCDD- or PCB126- mediated inhibition of IgM secretion and immunoglobulin heavy chain mRNA expression in the LPS-activated B cells. In addition, PCB52 inhibited TCDD-induced AhR DNA binding to a dioxin-responsive element. Collectively, these results suggest that the mechanism responsible for antagonism by di-ortho-substituted PCB congeners of AhR agonist-mediated CYP1A1 induction and inhibition of antibody responses in B cells occurs through interference with agonist activation of the cytosolic AhR complex.

Reporting needs for studies of environmental chemicals in human milk

Studies of environmental chemicals in human milk have been carried out in many countries, but few have been conducted in the United States. These studies are useful for monitoring population trends in exposure to chemicals, for research into the determinants of environmental chemicals in milk and relationships between the levels found and the health status of the women and their infants, and for risk assessment. This article provides practical advice on data and information reporting for such studies. Participation in these studies comes at a difficult time for the breast-feeding mothers, so it is important that the mothers support the study and its goals. A key goal of any study of environmental chemicals in human milk must be to ensure that the breast-feeding process is not disrupted by unwarranted concerns about harm to the infant from chemicals in human milk. Therefore, it is essential that reporting of information be a two-way process. Information needs to be supplied to participating mothers before, during, and after their participation in the study. Information supplied before participation is necessary to satisfy the ethical requirement for informed consent; information supplied during participation includes advice on expressing, collecting, and storing milk samples, and how to avoid sample contamination; and information supplied to each participant at the end of the study includes a report of their individual results and a summary of study results and outcomes generally. The key instrument for obtaining data from the participants is the study questionnaire. This needs to be prepared in accordance with principles of good questionnaire development, and preferably should be interviewer administered. The questionnaire content will vary according to the objectives of the study. Although studies of environmental chemicals in human milk are logistically complex and demanding, they are practicable and, with careful planning and execution, yield important data.

Polychlorinated biphenyl-induced apoptosis of murine spleen cells is aryl hydrocarbon receptor independent but caspases dependent

Polychlorinated biphenyls (PCBs) are ubiquitous environmental contaminants and many of their toxic effects, including their immunotoxicities, are mediated by the activation of aryl hydrocarbon receptor (AhR). We previously reported that Aroclor 1254, one of the most widely used PCB mixtures, increased DNA fragmentation in mouse spleen cells, suggesting that apoptosis was correlated with the immunotoxicity of PCB (Yoo et al., Toxicol. Lett. 91, 83-89, 1997). In the present study we investigated the mechanism by which PCB induces apoptosis and the involvement of AhR in the PCB-mediated apoptosis of mouse spleen cells. Aroclor 1254 induced DNA fragmentation without AhR activation, and the apoptosis was unaffected by alpha-naphtoflavone, a well-known antagonist of AhR. Moreover, the PCB congeners (PCB 47, 52, 128, and 153), which have little affinity for AhR, induced DNA fragmentation, whereas congeners (PCB 77, 126, and 169) that have high affinity for AhR did not induce fragmentation. The di-ortho form of PCB (PCB 153) and Aroclor 1254 induced DNA fragmentation in the spleen cells of both AhR knockout mice and Ah low-response mice, whereas the non-ortho form of PCB (PCB 126) did not induce DNA fragmentation. In the light of these findings, it is evident that AhR is not involved in PCB-mediated apoptosis. PCB 153 significantly increased caspase-3 activity in both spleen cells and human leukemia cells, and z-VAD-fmk, a general inhibitor of caspases, prevented PCB-induced DNA fragmentation. Based on our findings, the most likely mechanism that can account for this biological effect involves the induction of caspase-dependent apoptotic cell death.

PCDDs, PCDFs, and PCBs concentrations in breast milk from two areas in Korea: body burden of mothers and implications for feeding infants

We determined breast milk concentration of polychlorinated dibenzo-p-dioxins (PCDDs)/polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) in 24 mothers living in Korea, and assessed the maternal body burden based on PCDDs/PCDFs and PCBs concentrations in breast milk and an infant intake rate through breast-feeding based on their concentration in breast milk. PCDDs/PCDFs and PCBs levels in breast milk from primipara mothers were found to be higher than those from multipara mothers. For total PCDDs/PCDFs TEQ level, 2,3,4,7,8-PeCDD was the predominant congener, and the proportion of 2,3,7,8-TCDD was less than 3% of total PCDDs/PCDFs TEQ level. For PCBs TEQ level, PCB-126 was the predominant congener. Maternal body burden levels of PCDDs/PCDFs and PCBs based on their concentrations in breast milk were 268-622 TEQ ng. The daily dioxin intakes of mothers were predicted to be 0.78-2.18 TEQ pg/kg/day for PCDDs/PCDFs and 0.34-0.66 TEQ pg/kg/ day for PCBs. For the first year, the body burden of an infant was predicted to be 212 TEQ ng and the daily intake of an infant was predicted to be 85 TEQ pg/kg/day, assuming the mean dioxin-related compounds concentration (27.54 TEQ pg/g fat).

Background levels of non-ortho-substituted (coplanar) polychlorinated biphenyls in human serum of Missouri residents

This study characterizes the levels of polychlorinated biphenyls (PCB) congeners PCB 77, PCB 81, PCB 126, and PCB 169, in a group of 150 men and women with no documented exposure to PCBs. Its purpose is to provide current referent levels of coplanar PCBs in Missouri residents and to compare those levels to levels reported in the literature from the United States and other countries. Although this study used an extensive questionnaire assessing potential sources of exposure, no positive relations were found between these exposure sources and participants' PCB levels. The PCB levels for the four congeners measured were lower than any reported in the literature. PCBs 126 and 169 are only two of the dioxin-like congeners; however, their contribution makes up 11% of the total TEQ. Age was significantly related to PCB 126 and PCB 169. For every one-year increase in age, both PCB congeners increased by approximately 0.4 parts per trillion (ppt). There was no gender difference for PCB 126; however, PCB 169 levels were 3 ppt higher in males than females.