Département de médecine sociale et préventive, Faculté de médecine, Université Laval, 1050 Avenue de la Médecine, Québec Québec, Canada G1V 0A6; Axe santé des populations et pratiques optimales en santé, Centre de recherche du CHU de Québec, 2705 Boulevard Laurier, Québec Québec, Canada G1V 2L9.
Direction de la santé environnementale et de la toxicologie, Institut national de santé publique du Québec, 945 Avenue Wolfe, Québec Québec, Canada G1V 5B3.
Environ Res. 2015 Feb;137:338-48. doi: 10.1016/j.envres.2015.01.005. Epub 2015 Jan 17.
Past studies have examined the effects of maternal exposure to water chlorination disinfection by-products (DBPs), such as trihalomethanes (THMs) and haloacetic acids (HAAs) during pregnancy. However, no human-based study has yet evaluated the effect of emerging DBPs, such as haloacetaldehydes (HAs) and haloacetonitriles (HANs) on small-for-gestational-age (SGA) status in newborns.
This study aims to assess the association between maternal multiroute exposure to HAs and HANs during the third trimester of pregnancy and SGA status at birth, among neonates delivered by women residing in the Quebec City area (Province of Quebec, Canada). We also evaluated the interaction between exposure to these emerging unregulated by-products and regulated DBPs also found in drinking water (THMs and HAAs), for which a positive association with adverse reproductive outcomes has been suggested in previous studies.
We conducted a population-based case-control study in the Quebec City area. SGA newborns (n=330) were compared to 1100 controls, with matching based on calendar week of birth. HA and HAN concentrations in drinking water at participant's tap were estimated using spatio-temporal strategy based on bimonthly measurements carried out at several locations in the participant's distribution system. A computer-assisted telephone interview was completed to collect information on individual habits of water consumption and water related activities in order to determine individual multiroute exposure. This enabled us to estimate the dose of HAs and HANs absorbed daily by each participant. Associations between total HA, HAN concentrations in drinking water and SGA were analyzed. Associations between the daily-absorbed doses of these emerging DBPs and SGA were also analyzed. Odds ratios (ORs) comparing the 4th quartile of exposure to the reference group (the first three quartiles) were obtained by means of conditional logistic regression, and controlling for potential confounders.
Globally, no evidence of increased risk of SGA was found with total HA and HAN concentrations in tap water when participants in the 4th quartile of exposure were compared to the first three quartiles (OR=1.0; 95% CI [0.7-1.5] and OR=0.8; 95% CI [0.6-1.2], respectively). Similarly, no association was found with the daily-absorbed doses of total HAs or HANs (OR=0.9; 95% CI [0.6-1.3] and OR=1.1; 95% CI [0.7-1.6], respectively). However, a small non statistically significant association was found between the dose of brominated HA and SGA (OR=1.4; 95% CI [0.9-2.1]). Also, in spite of the lack of interaction between other DBP classes, an unexpected negative interaction was observed between concentration of chloral hydrate (CH) (which represents the main HA species), and regulated DBPs (P=0.006).
In this population, exposure to low levels of HAs and HANs during the third trimester of pregnancy through drinking water was not associated to SGA status in newborns. Nonetheless, more research is needed to clarify possible effect of brominated compounds and interaction between different DBPs.
过去的研究已经考察了母体在怀孕期间暴露于水氯化消毒副产物（DBPs），如三卤甲烷（THMs）和卤乙酸（HAAs）的影响。然而，目前还没有基于人类的研究评估新兴 DBPs（如卤代乙醛（HAs）和卤代乙腈（HANs））对新生儿出生时的小于胎龄儿（SGA）状态的影响。
本研究旨在评估魁北克市地区（加拿大魁北克省）孕妇在妊娠晚期多途径暴露于 HAs 和 HANs 与 SGA 状态之间的关联。我们还评估了这些新兴未受监管的副产物与饮用水中发现的受监管 DBPs（THMs 和 HAAs）之间的相互作用，先前的研究表明这些受监管的 DBPs 与不良生殖结局呈正相关。
我们在魁北克市地区进行了一项基于人群的病例对照研究。将 SGA 新生儿（n=330）与 1100 名对照进行比较，根据出生周进行匹配。通过在参与者分配系统中的几个位置进行的双月测量的时空策略，估计了参与者水龙头饮用水中的 HA 和 HAN 浓度。通过计算机辅助电话访谈收集了个人饮水习惯和与水有关的活动信息，以确定个人的多途径暴露情况。这使我们能够估计每个参与者每天吸收的 HAs 和 HANs 的剂量。分析了饮用水中总 HA 和 HAN 浓度与 SGA 之间的关系。还分析了这些新兴 DBPs 的每日吸收剂量与 SGA 之间的关系。通过条件逻辑回归，获得了第 4 四分位组与参考组（前三个四分位组）之间暴露的比值比（OR），并控制了潜在的混杂因素。
总体而言，与前三个四分位组相比，第 4 四分位组暴露于水中的总 HA 和 HAN 浓度与 SGA 风险增加无关（OR=1.0；95%CI[0.7-1.5]和 OR=0.8；95%CI[0.6-1.2]）。同样，与每日吸收的总 HAs 或 HANs 剂量也没有关系（OR=0.9；95%CI[0.6-1.3]和 OR=1.1；95%CI[0.7-1.6]）。然而，在溴代 HA 剂量与 SGA 之间发现了一个小的无统计学意义的关联（OR=1.4；95%CI[0.9-2.1]）。此外，尽管其他 DBP 类别之间没有相互作用，但在氯醛（CH）（代表主要的 HA 种类）和受监管的 DBPs 之间观察到了意外的负相互作用（P=0.006）。
在该人群中，妊娠晚期通过饮用水摄入低水平的 HAs 和 HANs 与新生儿的 SGA 状态无关。然而，需要进一步研究来阐明溴化化合物的可能影响和不同 DBPs 之间的相互作用。
