Brief Report

Whitworth, Kristina W.; Haug, Line Småstuen; Sabaredzovic, Azemira; Eggesbø, Merete; Longnecker, Matthew P.

doi:10.1097/ede.0000000000000524

Cited by 12 publications

(3 citation statements)

References 23 publications

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“…2015a; Vestergaard et al. 2012; Whitworth et al. 2016) (further discussed below) suggests that there may not be a causal association between maternal PFAA exposures and the TTP.…”

Section: Discussionmentioning

confidence: 99%

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Conditioning on Parity in Studies of Perfluoroalkyl Acids and Time to Pregnancy: An Example from the Danish National Birth Cohort

Bach

Matthiesen

Olsen

et al. 2018

Environ Health Perspect

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Background: Previous studies have investigated the associations between perfluoroalkyl acids (PFAAs) in women and time to pregnancy (TTP). Inconsistent results may be explained by differences in conditioning on parity. Objectives: We used causal directed acyclic graphs to illustrate potential confounding related to previous pregnancies and exposure measurement error due to differences in the interpregnancy interval in pregnancy-based studies that include parous women. We exemplified the potential importance of these issues using data from the Danish National Birth Cohort. Methods: We used discrete time survival models to estimate associations between maternal plasma PFAAs in early pregnancy and TTP in 638 nulliparous and 613 parous women. Results: PFAA quartiles were not associated with the TTP in nulliparous women. In parous women, higher PFAA quartiles were associated with longer TTP. The strongest associations were estimated for perfluorohexane sulfonate and perfluorooctane sulfonate. PFAA concentrations were higher in women with longer interpregnancy intervals. Accounting for the interpregnancy interval attenuated the estimated associations. Conclusions: Associations between PFAAs and TTP in parous women may be biased by confounders related to previous pregnancies and exposure measurement error. To avoid these biases, studies that include parous women may need to condition on a ) common causes of PFAAs and the TTP in the index pregnancy, b ) previous births (a descendant of a collider), c ) PFAA levels or common causes of PFAA levels and the TTP in the previous pregnancy (to alleviate collider stratification bias caused by conditioning on previous births), and d ) the interpregnancy interval (in pregnancy-based studies). Alternatives would be to restrict studies to nulliparous women or to use toxicokinetic modeling to correct exposure estimates in parous women. These recommendations may be extended to studies of other chemicals with similar toxicokinetic properties. https://doi.org/10.1289/EHP1493

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“…2015a; Vestergaard et al. 2012; Whitworth et al. 2016) (further discussed below) suggests that there may not be a causal association between maternal PFAA exposures and the TTP.…”

Section: Discussionmentioning

confidence: 99%

“…2012; Whitworth et al. 2012, 2016). Only one epidemiological study showed an association between higher PFAAs and longer TTP in nulliparous women (Fei et al.…”

Section: Introductionmentioning

confidence: 99%

Conditioning on Parity in Studies of Perfluoroalkyl Acids and Time to Pregnancy: An Example from the Danish National Birth Cohort

Bach

Matthiesen

Olsen

et al. 2018

Environ Health Perspect

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“…Several studies have also reported an association between higher plasma levels of certain PFAS in women and longer time to pregnancy and reduced fertility/fecundity (Louis et al, 2013 ; Fei et al, 2009 ; Jørgensen et al, 2014 ; Vélez et al, 2015b ). However, other studies have reported no associations between PFAS levels and these reproductive outcomes (Bach et al, 2015 ; Whitworth et al, 2016 ).…”

Section: Pfasmentioning

confidence: 92%

The effects of endocrine‐disrupting chemicals on ovarian‐ and ovulation‐related fertility outcomes

Land

Miller

Fugate

et al. 2022

Molecular Reproduction Devel

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Exposure to endocrine‐disrupting chemicals (EDCs) is unavoidable, which represents a public health concern given the ability of EDCs to target the ovary. However, there is a large gap in the knowledge about the impact of EDCs on ovarian function, including the process of ovulation. Defects in ovulation are the leading cause of infertility in women, and EDC exposures are contributing to the prevalence of infertility. Thus, investigating the effects of EDCs on the ovary and ovulation is an emerging area for research and is the focus of this review. The effects of EDCs on gametogenesis, uterine function, embryonic development, and other aspects of fertility are not addressed to focus on ovarian‐ and ovulation‐related fertility issues. Herein, findings from epidemiological and basic science studies are summarized for several EDCs, including phthalates, bisphenols, per‐ and poly‐fluoroalkyl substances, flame retardants, parabens, and triclosan. Epidemiological literature suggests that exposure is associated with impaired fecundity and in vitro fertilization outcomes (decreased egg yield, pregnancies, and births), while basic science literature reports altered ovarian follicle and corpora lutea numbers, altered hormone levels, and impaired ovulatory processes. Future directions include identification of the mechanisms by which EDCs disrupt ovulation leading to infertility, especially in women.

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Long Chain Per/Polyfluoroalkyl Acids (C8 and Above)

Dourson,

Kougias,

Anderson

et al. 2024

Patty's Toxicology

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This chapter is about a series of per‐ and polyfluoroalkyl substances (PFAS) that can also be described as “long‐chain” perfluoroalkyl acids (PFAAs). The overall structure of PFAAs is a lengthy carbon chain with fluorine atoms substituting for hydrogen atoms and either a carboxylic or sulfonate head group. PFAAs are unusually chemically stable, water and oil resistant, and useful for many industrial applications, such as in the formation of polymers. In biological systems, these chemicals are generally well‐absorbed, resistant to metabolism, but also have the unusual property of widely different elimination kinetics among and within mammalian species. The range of estimated elimination half‐lives in humans for the perfluorooctanoic acid (PFOA), for example, is quite large ranging from one‐half to as much as 14 years, although a recent estimate from an international collaboration places this value closer to 1 year. The available literature on PFAAs is voluminous. This chapter will not attempt to review all this literature. Rather human studies will be emphasized, but since these studies nearly always suggest associations between PFAA exposure and health outcomes, this will be followed by studies in experimental animals that give insights into the human evidence. Afterward, a summary of attempts to estimate potential human risk by various international agencies will be described. What will become obvious, however, is that the overall uncertainty in the database of these chemicals has led to widely divergent risk assessment positions that need to be resolved. Risk management decisions on this class of chemistries are seen to be premature without such scientific resolution.

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Brief Report

Cited by 12 publications

References 23 publications

Conditioning on Parity in Studies of Perfluoroalkyl Acids and Time to Pregnancy: An Example from the Danish National Birth Cohort

Conditioning on Parity in Studies of Perfluoroalkyl Acids and Time to Pregnancy: An Example from the Danish National Birth Cohort

The effects of endocrine‐disrupting chemicals on ovarian‐ and ovulation‐related fertility outcomes

Long Chain Per/Polyfluoroalkyl Acids (C8 and Above)

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