Post on 25-Jan-2020
Persistent Organic Pollutants: Foods, Prenatal Exposure to Birth Outcomes
Prof. Zongwei Cai
State Key Laboratory of Environmental
and Biological Analysis
Hong Kong Baptist University
2019 Food and Water Submit, Singapore, Sept 12
Persistent Organic Pollutants
Persistent Organic Pollutants (POPs) are groups of
pollutants (including dioxins) that cannot be easily
degraded, are strongly lipophilic, can easily be enriched
in food chains, and can be transported for long distance.
DDT, 滴滴涕 Dioxins, 二噁英
(made by human) (produced unintentionally)
They are only a part of the ugly truth……
• POPs - persistence, long-range transportable, bio-
accumulative & chronic toxicity
• Stockholm Convention on POPs – 12 chemicals in
2001, 9 emerging POPs included in 2009 (more
have coming)
• >95% of dioxin & PCBs intake by dietary, mainly
animal-origin food (WHO)
1. Persistent
2. Long-distance transportation
North Pole
Detected!
Dioxin
in water
Dioxin in
Daphnia
Dioxin
in fish
Dioxin
in duck
Bioconcentration
bioaccumulation
3. Biomagnification
生物積累
生物濃縮
105
水
蚤
鱼
鸭
Air
(1) POPs - Dioxin and PCBs in foods
Food Maximum level (pg WHO-TEQ /g fat) Action level (pg WHO-TEQ /g fat)
Beef and mutton 4.5 2.5
Poultry 4 3
Pigs 1.5 1.1
Livers of terrestrial animal 12 8
Fish muscle (except eel)* 8 6
Eel muscle * 12 9
Raw milk and products 6 4
Hen egg products 6 4
Mixed animal fat 3 2.25
Vegetable oil 1.5 1
Marine oil 10 7.5
* Fresh weight basis
⚫ It occurs, incidents happened - 1999 Belgian
“Chicken gate”, latest 2011 German egg products
scandal
⚫ EU maximum and action level of dioxin like
compounds in food
Risk assessment
Authorities Time Tolerable intake
WHO 1998 TDI=1-4 pg TEQ/kg b.w. day
JECFA 2001 TMI=70 pg TEQ/kg b.w. month
SCF 2001 TWI=14 pg TEQ/kg b.w. week
⚫ Estimation of potential dietary exposure to specific
contaminants of various subgroups
⚫ Compare with built tolerable intake level based on
toxicology
Chemical analysis of pooled food samples
(a total of 174)
Weigh 5-10 g sample, freeze dried
Spike internal standard, Soxhlet extraction
Liquid-liquid extraction
Lipid content determined gravimetrically
Acidic silica, acidic alumina, florisil cleanup
Active carbon (PCDD/Fs) GPC (PCBs)
High resolution gas chromatography/
high resolution mass spectrometry
(HRGC/HRMS)
HRGC-HRMS (Waters Autospec)
•Double
focusing
magnetic-sector
Instrument
• High-
resolution (>
10,000) mass
spectrometry
• Ultra low-level
trace (ppq – sub
ppt) detection
for dioxins and
other organic
pollutants
Dioxin & PCB concentrations in foods
of Hong Kong
Pork
Ruminant meat
Concentrations in food subgroups (lipid weight basis)
Poultry
Concentrations in chicken and duck (lipid weight basis)
Dioxin & PCB concentrations in foods
of Hong Kong
Fish
Total TEQ of various fish species (lipid weight basis)
Fish subgroups
Concentrations in fish subgroups (lipid weight basis)
Summary of dioxins in food
Food Total TEQ of all composite samples
( pg WHO-TEQ 1998/g fat)
Maximum level (pg WHO-TEQ
/g fat)
Action level (pg
WHO-TEQ /g fat)
Mean Median Max
Beef and
mutton
1.4 1.17 4.03 4.5 2.5
Poultry 0.986 0.957 1.47 4 3
Pigs 0.563 0.548 1.07 1.5 1.1
Fish
muscle*
0.65 0.513 2.4 8 6
Raw milk
and
products
1.27 1.26 2.21 6 4
Hen egg
products
2.69 2.61 5.43 6 4
Mixed
animal fat
0.268 0.243 0.541 3 2.25
* Fresh weight basis
Risk assessment of dietary intake of
dioxin & PCBs of H.K. residents• By combining food consumption data of H.K. residents,
the dietary exposure to dioxins and PCBs was estimated
• Two scenarios : average and high risk group (95th
percentile)
Overview of animal origin food intake of an average H.K. resident
H.K. population-based food consumption survey, final report
Are we safe?assumptions
• Both mean & median of dioxin & PCB
concentration were used for assessment
• Mean & 95th of food consumption used
• Food subgroup adjusted
We are safe, to some extent
Estimated daily intake of dioxin like compounds (A) TEQ 1998; (B) TEQ 2005
Estimated daily intake of NDL-PCBs
A B
High risk subgroup is in danger
Estimated weekly intake of dioxin like compounds (A) TEQ 1998; (B) TEQ 2005
Estimated monthly intake of dioxin like compounds (A) TEQ 1998; (B) TEQ 2005
A
A
B
B
Food group contribution of high risk
residents
Total TEQ
Mean concentration
21
(2) POPs - Organochlorine pesticides
➢ Organochlorine pesticides (OCPs) are chlorinated hydrocarbons usedextensively from the 1940s in agriculture and mosquito control.
Cl
Cl
Cl
Cl
Cl Cl
Hexachlorocyclohexane(HCH)
Cl
Cl
Cl
Cl
Cl Cl
Cl
Cl
Cl
Cl
Cl Cl
Cl Cl
Cl Cl
Cl
Cl Cl
Cl Cl
Dichlorodiphenyltrichloroethane(DDT) and metabolites
(DDE and DDD)
Cl Cl
Cl Cl
Cl Cl
Cl
Cl
Cl
Cl Cl
ClCl
Cl Cl
ClCl
Prenatal exposure
Birth outcomes
Hypothesis
OCP levels
22
➢ In fast-growing stages oflife, developing fetuses aremore vulnerable to thepotentially adverse effects.
23
Objectives
Exposure Levels Effects of Exposure
Method development:
Establish an accurate, sensitive and robust method for analysis of OCPs.
Effects of prenatal exposure:
Evaluate the associations of prenatal exposure and birth outcomes.
24
Challenges in the analysis of OCPs and other POPs
➢Various polarity of analytes➢Complicated matrix for biomonitoring studies
Plasma/Serum Breast milk Adipose tissue
➢ Low concentrations and limited sample volumes
Trace levels of POPs in human bodies
▪ ng/g lipid, pg/mL
Solution
➢ Sensitive➢ Accurate➢ Robust➢ High-throughput
➢ Large sample number
25
Typical instrumental analysis of OCPs
➢ Gas chromatograph-electron capture detector (GC-ECD)
The electronegative analytes capture electrons and reduce the current.
Require standards or referencefor identification
➢ Gas chromatograph-mass spectrometry (GC-MS)
Electron ionization (EI) Extent fragmentations in the source
Negative chemical ionization (NCI) Restricted to specific chemical
Triple quadrupole
➢ High sensitivity in complicated matrix
➢ More accurate & confident quantification
➢ Soft ionization provides high abundance of molecular ions
➢ High levels of matrix tolerance
➢ Ability to inject less sample matrix, reducing effect of contamination
➢ Capabilities for various MS detector
➢ Traditionally for LC-MS
➢ Now for GC-MS (APGC)
26
Atmospheric pressure chemical ionization
APCI
High intensity
EI
Extensive fragmentation
27
Soft ionization under APCI
➢ Under APCI, the mass spectrum only showed the molecular ion of p,p’-DDE.
➢ Under EI, the mass spectrum showed the fragment ion [M-Cl2]+ with high intensity.
• p,p’-DDE
Anal. Bioanal. Chem. 411(2019):4185-4191.
28
Method validations
• Linearity, recovery and repeatability
➢ The recoveries were acceptable, ranging from 74.0 to 126.7%.
➢ The relative standard deviations were lower than 20%.
➢ The calibration linearity ranged from 0.01 ng/mL to 10 ng/mL (R2>0.99)
• Limits of detection
J. Chromatogr. B 1040(2017) : 180-185
29
Method validations
• Sensitivity
APCI EI
➢ BDE-99 and BDE-100 was not detected in GC-EI-MS/MS analysis, but could be successfully quantified by GC-APCI-MS/MS.
➢ The sensitivity of GC-APCI-MS/MS was better than those of the GC-EI-MS/MS method.
Chemosphere 225(2019) : 288-294
30
Trouble and shooting
31
Accuracy of GC-APCI-MS/MS (APGC)
• Relative errors
32
Prenatal exposure
Maternal
Placental barrier
Fetus
➢ OCPs have been reported to transfer from mothersto infants by the placental transfer.
Prenatal Exposure to OCPs
33
Health risk of prenatal exposure
OCP exposure Birth outcomesAssociation
34
Study population and sample collection
• Collected during 2014 and 2015
• N = 1046
Selection criteria:
• <16 gestational weeks• singleton pregnancy• plan to give birth at the study
hospital• residents of Wuhan City• volunteer to take part in this
birth cohort
This study:
35
Study design
Instrumental analysis
Demographic information:• Maternal age• Prepregnancy BMI• Parity• Education & income• etc.
Anthropology parameters:• Birth weight & length• Sex• Gestational age• etc.
Statistical analyses:• Multiple linear regression models• Stratified analyses
36
Detection rates
HCHs DDTs
> Limits of detection (LODs)
➢ The presence of OCPs in cord serum indicated the prenatal exposure.
➢ Detection rates of HCHs and p,p’-DDT and its metabolites were larger than 50%.
➢ The β-HCH and p,p’-DDE were detectable in almost all samples.
37
Predictors of OCPs
➢ Maternal age ➢ Prepregnancy BMI
➢ Maternal education➢ Passive smoking
Ecotox. Environ. Safe. 174(2019): 263-269
38
Associations with birth weight
β : regression coefficientβ>0 : positive associationβ<0 : negative association
➢Birth weight were negativelyassociated with exposure to β-HCHand total HCH for male infants. (p< 0.05)
Sci. Total Environ. 654(2019): 678-683
39
Associations with birth length
➢Associations between the OCP levels and birth length were not significant.(p > 0.05)
40
Conclusion
A GC-APCI-MS/MS method was established with highersensitivity for the analysis of OCPs in serum samples.
A total of 1046 cord serum samples were analyzed and thepredominant OCPs were β-HCH and p,p′-DDE.
The OCP levels were associated with maternal age,prepregnancy BMI, education levels, and passive smoking.
Negative relationships of OCP levels with birth weight andponderal index were observed in boys but not in girls.
41
Publications
1) Comparison of different mass spectrometric approaches coupled to gas chromatography for the analysis of organochlorine pesticides in serum samples. Jing Fang, et al. J. Chromatogr. B 2017, 1040, 180-185.
2) Simultaneous determination of eighteen nitro-polyaromatic hydrocarbons in PM2.5 by atmospheric pressure gas chromatography tandem mass spectrometry, YanhaoZhang, et al, Chemosphere, 198 (2018) 303–310.
3) Determination of PM2.5-bound polyaromatic hydrocarbons and their hydroxylatedderivatives by atmospheric pressure gas chromatography-tandem mass spectrometry, Yanhao Zhang, et al, Talanta, 195 (2019) 757-763.
4) Evaluation of gas chromatography-atmospheric pressure chemical ionization tandem mass spectrometry as an alternative to gas chromatography tandem mass spectrometry for the determination of polychlorinated biphenyls and polybrominated diphenyl ethers. Jing Fang, et al. Chemosphere 2019, 225, 288-294.
5) Performance of atmospheric pressure gas chromatography-tandem mass spectrometry for the analysis of organochlorine pesticides in human serum. Jing Fang, et al. Anal. Bioanal. Chem. 2019, 411, 4185-4191.
6) Applications of atmospheric pressure chemical ionization coupled to gas chromatography mass spectrometry for the analysis of persistent organic pollutants. Jing Fang, et al. Trends Environ. Anal. 2019, (Accepted)
Acknowledgement
Collaborator Huazhong Uni of Sci and TechProf. Shunqing XuDr. Wei XiaDr. Yuanyuan Li
SKLEBA membersMiss Jing FangDr. Yanjun HongDr. Zhu YangDr. Hongzhi ZhaoMiss Jiufeng LiMiss Yanqiu ZhouOther lab members
Resaech Grants
NSFC 21437002GRF 12319716C2014-14E(Research Grant Council Hong Kong, SAR)
42
Department of Chemistry, HKBU
Dioxin Analyss laboratory, BKBU
Fuzhou UniversityDr. Yu HE
43
Concentrations of OCPs
➢ The predominant OCPs were β-HCH and p,p’-DDE .
➢ p,p‘-DDE accounted for 84.4% of ΣDDTs.
< LOD LOD/2
Co
nce
ntr
atio
ns
(ng/
g lip
id)