A pilot study of seafood consumption and exposure to mercury, lead, cadmium and arsenic among infertile couples undergoing in vitro fertilization (IVF)

Bioaccumulation of Non-Essential Trace Elements Detected in Women's Follicular Fluid, Urine, and Plasma Is Associated with Poor Reproductive Outcomes following Single Euploid Embryo Transfer: A Pilot Study

This study aims to determine the association of non-essential trace elements present in follicular fluid, plasma, and urine with reproductive outcomes of women undergoing intracytoplasmic sperm injection (ICSI), preimplantation genetic testing for aneuploidies (PGT-A) and single frozen euploid embryo transfer (SET/FET). This single-center, prospective cohort study included sixty women undergoing ICSI with PGT-A and SET/FET between 2018 and 2019. Urine, plasma and follicular fluid samples were collected on the vaginal oocyte retrieval day to simultaneously quantify ten non-essential trace elements (i.e., Ba, Sr, Rb, Sn, Ti, Pb, Cd, Hg, Sb, and As). We found several associations between the levels of these non-essential trace elements and clinical IVF parameters. Specifically, the increased levels of barium in follicular fluid were negatively associated with ovarian function, pre-implantation development and embryo euploidy, while elevated strontium concentrations in this biofluid were negatively associated with impaired blastulation and embryo euploidy. Elevated plasma strontium levels were negatively associated with ovarian function, fertilization and blastulation. Enhanced presence of other trace elements in plasma (i.e., rubidium and arsenic) were associated with a diminished ovarian function and limited the number of recovered oocytes, mature oocytes and zygotes, respectively. Fully adjusted models suggested significantly lower odds of achieving a live birth when increased concentrations of barium and tin were found in urine.

Exposure to multiple toxic metals and the risk of early embryonic arrest among women undergoing assisted reproductive techniques

BACKGROUND

Early embryonic arrest is a great challenge for in vitro fertilization. Whether exposure to toxic metals is associated with an increased risk of early embryonic arrest warrants investigation.

OBJECTIVES

Here, we conducted a case-control study in infertile women to estimate the associations between blood barium (Ba), arsenic (As), mercury (Hg), and lead (Pb) exposure levels and the risk of early embryonic arrest.

METHODS

Ba, As, Hg, and Pb exposure levels in fasting blood collected from 74 infertile women (123 cycles) with early embryonic arrest and 157 infertile women (180 cycles) without early embryonic arrest were measured by ICP-MS. Bayesian kernel machine regression (BKMR) was used to assess the association of exposure level of toxic metals mixture with the risk of early embryonic arrest as well as to evaluate which metal playing a leading role in the association, and then generalized estimating equations (GEEs) were used to evaluate the relationship between the selected harmful metal and the risk of early embryonic arrest. Finally, the potential causes of early embryonic arrest originating from the harmful metal exposure were explored.

RESULTS

Blood Ba levels were significantly higher in the case group than that in the control group (p = 0.009) rather than As, Pb and Hg. Results from BKMR showed that exposure to toxic metals mixture increased the risk of early embryonic arrest, with Ba playing a leading role (PIP = 0.9612). GEE analysis showed that high Ba exposure level was related with the increased risk of early embryonic arrest (p < 0.05) and it impacted on the oogenesis significantly.

CONCLUSIONS

Our study found that exposure to toxic metals mixture was associated with the increased risk of early embryonic arrest, and Ba contributed most to the increased risk. Higher Ba exposure in whole blood corresponds to a higher risk of early embryonic arrest and impacted on the oogenesis significantly.

Toxic elements in follicular fluid adversely influence the likelihood of pregnancy and live birth in women undergoing IVF

STUDY QUESTION

Are follicular fluid (FF), arsenic (As), mercury (Hg), cadmium (Cd) and lead (Pb) concentrations associated with IVF outcomes among women undergoing IVF?

SUMMARY ANSWER

There was a non-linear association between higher FF Hg concentration and a lower likelihood of biochemical pregnancy and live birth. Higher FF Pb concentration was also associated with a lower probability of live birth.

WHAT IS KNOWN ALREADY

Previous research suggests that toxic elements may affect fertility among couples conceiving with and without assistance. However, the results have been inconsistent, possibly related in part to exposure misclassification. Very few studies have used ovarian FF to measure toxic elements, as it requires an invasive collection procedure, yet it may offer a more accurate estimate of a biologically effective dose than blood or urine.

STUDY DESIGN SIZE DURATION

This is a prospective study of 56 women undergoing IVF, from October 2015 to June 2017. FF was collected for analysis on the day of oocyte retrieval.

PARTICIPANTS/MATERIALS SETTING METHODS

As, Cd, Hg and Pb were determined in 197 FF specimens, using inductively coupled plasma tandem mass spectrometry. FF glutathione peroxidase, glutathione reductase, total glutathione-S-transferase, superoxide dismutase, arylesterase and paraoxonase (PON1p) activities were measured using kinetic enzyme assays.

MAIN RESULTS AND THE ROLE OF CHANCE

Non-linear associations were detected, in which the probabilities of biochemical pregnancy (P = 0.05) and live birth (P = 0.05) were lower in association with FF Hg greater than ∼0.51 µg/l Hg, adjusted for age, race, cigarette smoking and recent seafood consumption. Higher FF Pb was also associated with a lower likelihood of live birth (relative risk (RR) = 0.68, 95% CI: 0.46, 1.00; P = 0.05). We also found a suggestive, although imprecise, antagonizing mediating effect of PON1p activity on the association between FF Pb and live birth (-28.3%; 95% CI: -358%, 270%).

LIMITATIONS REASONS FOR CAUTION

The results should be interpreted judiciously given the limited sample size and difficulty accounting for correlated data in generalized additive models and mediation analyses. Additionally, women undergoing IVF are highly selected with respect to age and socioeconomic status, and so the generalizability of the results may be limited.

WIDER IMPLICATIONS OF THE FINDINGS

Overall, the results suggest that FF Hg was associated with a lower likelihood of biochemical pregnancy and live birth, with a potential threshold effect, and that higher FF Pb was associated with a lower probability of live birth. These results may help to guide clinical recommendations for limiting the exposure of patients to Hg and Pb and ultimately improve IVF success rates.

STUDY FUNDING/COMPETING INTERESTS

This work was funded in part by the National Institute of Environmental Health Sciences (NIEHS), grant number 1R56ES023886-01, to the University at Albany (M.S.B.), and in part by the National Institute of Environmental Health Sciences (NIEHS), grant number 1U2CES026542-01, to the Wadsworth Center (P.J.P.). The authors declare no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

Variability of essential and non-essential trace elements in the follicular fluid of women undergoing in vitro fertilization (IVF)

Both essential and non-essential elements have been associated with female reproductive function in epidemiologic investigations, including among IVF populations. To date, most investigators have used blood or urine to assess biomarkers of exposure, with few employing ovarian follicular fluid (FF). FF may offer a more direct "snapshot" of the oocyte microenvironment than blood or urine, however previous studies report follicle-to-follicle variability in FF constituents that may contribute to exposure misclassification. Our objectives were to investigate sources of trace element variability, to estimate FF biomarker reliability among women undergoing IVF (n = 34), and to determine the minimum number of follicles required to estimate subject-specific mean concentrations. We measured As, Hg, Cd, Pb, Cu, Mn, Se, and Zn in FF samples using inductively coupled plasma tandem mass spectrometry. Inter-subject (between-women) variability contributed most of the variability in FF element concentrations, with ovarian, follicular, and analytical as smaller sources of variability. The proportion of variability attributable to sources between-follicles differed by age, body mass index (BMI), race, and cigarette smoking for Cu, Se, and Zn, by BMI and cigarette smoking for As, by primary infertility diagnosis for Hg, Cu, Se, and Zn, and by ovarian stimulation protocol for Mn and Se. Four to five individual follicles were sufficient to estimate subject-specific mean Cu, Se, and Zn concentrations, while >14 were necessary for As, Hg, Cd, Pb, and Mn. Overall, our results suggest that FF is a suitable source of biomarkers of As and Hg exposure in ovarian follicles. Although limited in size, our study offers the most comprehensive exploration of biological variation in FF trace elements to date and may provide guidance for future studies of ovarian trace element exposures.

Seafood consumption is associated with higher follicular fluid arsenic (As) and mercury (Hg) concentrations in women undergoing in vitro fertilization (IVF)

Human exposure to non-essential toxic metals such as cadmium (Cd), mercury (Hg), and lead (Pb), and metalloids such as arsenic (As) commonly occurs through diet. Toxic trace element exposures have been reported in association with fertility and fecundity in epidemiologic studies even at low to moderate levels. While most previous studies employed blood and urine biomarkers of exposure, few have assessed toxic trace elements in ovarian follicular fluid (FF), which surrounds the developing oocyte and hence may better reflect concentrations potentially affecting reproductive outcomes. Our objective was to identify dietary predictors of FF toxic trace elements in n = 56 women (mean age: 38.3 years) undergoing in vitro fertilization (IVF) at the University of California at San Francisco. We determined As, Hg, Cd, and Pb in 197 FF specimens, collected on the day of oocyte retrieval, using inductively coupled plasma tandem mass spectrometry. A comprehensive food frequency questionnaire was used to assess the weekly and annual dietary "patterns" of participants. Consumption of specific seafood items and turkey were correlated with individual FF toxic trace elements. We also found that each unit higher seafood consumption in the past week dominated by mollusks, shrimp, and bass was associated with 60% higher FF As (95% confidence interval (CI): 25%, 105%) and FF Hg (95%CI: 7%, 136%) concentrations. Higher annual seafood consumption dominated by urchin, crab, and trout was associated with 16% higher FF As (95%CI: -2%, 38%) and 31% higher FF Hg (95%CI: 7%, 60%) concentrations per unit intake. No associations were noted between diet and Cd and Pb levels in FF. Overall, our results suggest that higher seafood consumption contributes to elevated levels of As and Hg in FF. These findings are consistent with previous IVF studies that assessed toxic trace element exposures in blood and urine. To our knowledge, this is the first study to report that diet might be a source of As, Hg, Cd, and Pb in FF.

Adherence to healthy dietary patterns and outcomes of assisted reproduction: a systematic review and meta-analysis

This systematic review and meta-analysis aimed to evaluate the association between adherence to a healthy dietary pattern and outcomes of assisted reproductive techniques (ARTs). PubMed, Embase and Web of Science were searched for eligible studies through December 2019 according to the population, intervention, comparison, outcome and study design (PICOS) criteria. Eight prospective cohort studies (S) reporting pregnancy outcomes (O) of higher vs lower adherence to a healthy dietary pattern (I/C) in women undergoing ART treatment (P) were included, involving a total of 2229 women with 2067 embryo transfer cycles. The pooled odds ratio (OR) for positive pregnancy test, clinical pregnancy and ongoing pregnancy/live birth was 0.82 (95% confidence interval [CI] 0.65-1.03), 0.99 (95% CI 0.68-1.44) and 1.30 (95% CI 0.81-2.09), respectively. In conclusion, greater adherence to a healthy dietary pattern rich in vegetables, fruits, whole grains, legumes and fish, may not be significantly related to ART success.

Toxicological and nutritional status of trace elements in hair of women with in vitro fertilization (IVF) pregnancy and their 9-month-old children

The objective of the present study was to assess toxic and nutritional trace element and mineral status in hair of women with IVF pregnancy and their children. Inductively-coupled plasma mass-spectrometry was used to assess hair trace element levels of 50 women with IVF pregnancy and 158 controls with spontaneous pregnancy and their children. Women with IVF pregnancy were characterized by significantly elevated hair As, Hg, Li, K, Na, and reduced Fe, Si, and Zn contents. Children from IVF pregnancy had significantly lower values of hair Cr, Fe, Mg, Sr, and Al content when compared to the control values, whereas hair Hg and Mo levels were higher. Hair trace element levels were associated with pregnancy complications and infertility, but not newborn characteristics. The results suggest the need for preconceptional monitoring and correction of the levels of toxic and essential elements in women in order to improve the course pregnancy and child development.

Hair Trace Element and Electrolyte Content in Women with Natural and In Vitro Fertilization-Induced Pregnancy

The objective of the present study was to perform comparative analysis of hair trace element content in women with natural and in vitro fertilization (IVF)-induced pregnancy. Hair trace element content in 33 women with IVF-induced pregnancy and 99 age- and body mass index-matched control pregnant women (natural pregnancy) was assessed using inductively coupled plasma mass spectrometry. The results demonstrated that IVF-pregnant women are characterized by significantly lower hair levels of Cu, Fe, Si, Zn, Ca, Mg, and Ba at p < 0.05 or lower. Comparison of the individual levels with the national reference values demonstrated higher incidence of Fe and Cu deficiency in IVF-pregnant women in comparison to that of the controls. IVF pregnancy was also associated with higher hair As levels (p < 0.05). Multiple regression analysis revealed a significant interrelation between IVF pregnancy and hair Cu, Fe, Si, and As content. Hair Cu levels were also influenced by vitamin/mineral supplementation and the number of pregnancies, whereas hair Zn content was dependent on prepregnancy anthropometric parameters. In turn, planning of pregnancy had a significant impact on Mg levels in scalp hair. Generally, the obtained data demonstrate an elevated risk of copper, iron, zinc, calcium, and magnesium deficiency and arsenic overload in women with IVF-induced pregnancy. The obtained data indicate the necessity of regular monitoring of micronutrient status in IVF-pregnant women in order to prevent potential deleterious effects of altered mineral homeostasis.

A content analysis of Internet resources about the risks of seafood consumption

Seafood consumption is a main source of human exposure to certain environmental contaminants. Therefore, it is valuable to assess the online health risk messages focused on this topic, as people in the US are increasingly accessing the Internet for health-related information. Previous research indicates that online health information tends to be written at a reading level that is more advanced than ability of the general population. The purpose of this research was to examine the content and readability of Internet resources targeted toward consumers in the US regarding the health risks from consumption of contaminated seafood. Sources for analysis were gathered through a targeted search of state and national government websites, as well as through a Google search. The overall mean readability level was Grade 9.21, which is slightly above the average reading level of US adults. Future research should evaluate the accuracy of the health risk messages, as well as consumer perceptions of risk.

Cadmium and lead in seafood from the Aratu Bay, Brazil and the human health risk assessment

This study aimed to evaluate cadmium (Cd) and lead (Pb) levels in seafood and perform a risk assessment based on individual food consumption frequency of inhabitants of the Aratu Bay, Brazil. From December 2013 to November 2014, ready-to-market seafood, including fish [pititinga (Lile piquitinga) and small green eel (Gobionellus oceanicus)], mollusks [mussel (Mytella guyanensis) and oyster (Crassostrea rhizophorae)], and crustaceans [white shrimp (Litopenaeus schmitti) and blue crab (Callinectes exasperatus)], were purchased bimonthly from a local artisanal shellfish harvester. Metal levels were analyzed by graphite furnace atomic absorption spectrometry (GFAAS). Based on the volunteer’ seafood consumption, estimates of the non-carcinogenic target hazard quotients (THQs) were calculated. The annual concentrations (μg/g, w/w) of Cd were 0.007 (±0.001) in crustaceans, 0.001 (±0.0003) in fish, and 0.446 (±0.034) in mollusks. Lead levels were <limit of detection (LOD) in crustaceans, 0.044 (±0.0032) in fish, and 0.111 (±0.009) in mollusks. All values were within the international guidelines. We observed that 90.9 % of the responders presented an average THQ < 1, which is classified as negligible risk; however, 9.1 % presented THQs between ≥1 and <9.9. These data are important to inform the community of the imminent exposure risk through communication strategies, with the purpose of minimizing exposure and, consequently, the health effects associated with it.

Hair mercury concentrations and in vitro fertilization (IVF) outcomes among women from a fertility clinic

Total hair mercury (Hg) was measured among 205 women undergoing in vitro fertilization (IVF) treatment and the association with prospectively collected IVF outcomes (229 IVF cycles) was evaluated. Hair Hg levels (median=0.62ppm, range: 0.03-5.66ppm) correlated with fish intake (r=0.59), and exceeded the recommended EPA reference of 1ppm in 33% of women. Generalized linear mixed models with random intercepts accounting for within-woman correlations across treatment cycles were used to evaluate the association of hair Hg with IVF outcomes adjusted for age, body mass index, race, smoking status, infertility diagnosis, and protocol type. Hair Hg levels were not related to ovarian stimulation outcomes (peak estradiol levels, total and mature oocyte yields) or to fertilization rate, embryo quality, clinical pregnancy rate or live birth rate.

Urine cortisol concentration as a biomarker of stress is unrelated to IVF outcomes in women and men

PURPOSE

Our primary objective was to assess associations between urine cortisol as a biomarker of psychological stress and in vitro fertilization (IVF) outcomes. A secondary objective was to assess associations between toxic metals and cortisol.

METHODS

Urine and blood specimens were collected from 52 women and 28 male partners completing a first IVF procedure, on the day of oocyte retrieval. Urine cortisol was measured with an enzyme-linked immunosorbent assay. Mercury (Hg), cadmium (Cd), and lead (Pb) were determined in blood and Cd in urine by inductively coupled plasma-mass spectrometry.

RESULTS

No associations were indicated for cortisol with IVF outcomes in multivariable regression models adjusted for covariates. However, we detected positive linear associations for cortisol and urine Cd (β = 9.96, 95%CI 1.52, 21.44) and blood Hg (β = 1.44, 95%CI 0.31, 3.18). An exploratory stratified analysis suggested a potential inverse association between urine cortisol and oocyte fertilization among women with low, but not high blood Hg.

CONCLUSION

While limited, these preliminary data suggest that psychological stress may not play a major role in IVF outcomes, which therefore could be one less concern for couples and their clinicians. Our data also raise the possibility for toxic metals to modify associations between cortisol and IVF outcomes among women. However, these preliminary results require corroboration in an experimental animal model and confirmation in a larger, more definitive observational study.

Toxic metals in seminal plasma and in vitro fertilization (IVF) outcomes

We measured toxic metals in seminal plasma collected from 30 men using vitro fertilization (IVF), to evaluate associations with semen quality and IVF outcomes. A doubling in Hg-adjusted Pb concentration was associated with 47% lower total motile sperm. Positive associations were suggested for Hg with pregnancy and live birth, adjusted for Cd or Pb. A negative association was suggested for Hg-adjusted Cd with pregnancy. These data add to evidence indicating that toxic metals impact IVF.

Metal status in human endometrium: relation to cigarette smoking and histological lesions

Human endometrium is a thick, blood vessel-rich, glandular tissue which undergoes cyclic changes and is potentially sensitive to the various endogenous and exogenous compounds supplied via the hematogenous route. As recently indicated, several metals including Cd, Pb, Cr and Ni represent an emerging class of potential metalloestrogens and can be implicated in alterations of the female reproductive system including endometriosis and cancer. In the present study, we investigated the content of five metals: Cd, Cr, Ni, Pb and Zn in 25 samples of human endometrium collected from Polish females undergoing diagnostic or therapeutic curettage of the uterine cavity. The overall mean metal concentration (analyzed using microwave induced plasma atomic emission spectrometry MIP-OES) decreased in the following order: Cr>Pb>Zn>Ni>Cd. For the first time it was demonstrated that cigarette smoking significantly increases the endometrial content of Cd and Pb. Concentration of these metals was also positively correlated with years of smoking and the number of smoked cigarettes. Tissue samples with recognized histologic lesions (simple hyperplasia, polyposis and atrophy) were characterized by a 2-fold higher Cd level. No relation between the age of the women and metal content was found. Our study shows that human endometrium can be a potential target of metal accumulation within the human body. Quantitative analyses of endometrial metal content could serve as an additional indicator of potential impairments of the menstrual cycle and fertility.