Abstract

Background:

Drinking water chlorination by-products have been associated with adverse reproductive outcomes, although the findings for congenital malformations are still inconclusive.

Objective:

We conducted a nationwide register-based prospective study to assess whether first trimester maternal exposure to the four most common trihalomethanes [total trihalomethanes (TTHM)] via municipal drinking water was associated with risk of congenital malformation among newborns.

Methods:

We included all births during 2005–2015 (live and stillbirths) of mothers residing in Swedish localities having $>\mathrm{10,000}$ inhabitants, two or fewer operating water works, and sufficient municipal TTHM monitoring data. Individual maternal first trimester exposure was obtained by linking TTHM measurements to residential information, categorized into no chlorination and $<5$, 5–15, and $>15\mathrm{\mu }\mathrm{g}$ TTHM/L. We also made chlorination treatment-specific analyses (exclusive use of chloramine or hypochlorite). Outcomes and covariates were obtained via linkage to health care and administrative registers. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by logistic regression.

Results:

Based on 623,468 births and a prevalence of congenital malformation of $\sim 2$ cases/100 births, we observed associations between TTHM exposure in areas using chloramine and malformations of the nervous system ($\text{OR}=1.82$; 95% CI: 1.07, 3.12), urinary system ($\text{OR}=2.06$; 95% CI: 1.53, 2.78), genitals ($\text{OR}=1.77$; 95% CI: 1.38, 2.26), and limbs ($\text{OR}=1.34$; 95% CI: 1.10, 1.64), comparing the highest exposed category with the unexposed. No associations were observed in areas using exclusively hypochlorite as the primary water treatment method. By contrast, for malformations of the heart, a significant inverse association was observed only in areas using hypochlorite.

Discussion:

TTHM exposure was associated with the increased risk of malformations of the nervous system, urinary system, genitals, and limbs in areas exclusively using chloramine. An association between chloramine-related chlorination by-products and congenital malformations has not previously been highlighted and needs further attention. https://doi.org/10.1289/EHP9122

中文翻译：

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饮用水消毒副产物和先天性畸形：一项基于全国注册的前瞻性研究

摘要

背景：

饮用水氯化副产物与不良生殖结果有关，尽管先天性畸形的研究结果尚无定论。

客观的：

我们进行了一项全国性的基于登记的前瞻性研究，以评估孕早期母亲通过市政饮用水接触四种最常见的三卤甲烷 [总三卤甲烷 (TTHM)] 是否与新生儿先天性畸形的风险相关。

方法：

我们纳入了 2005-2015 年间所有出生在瑞典地区的母亲（活产和死产）$>\mathrm{10,000}$居民，两个或更少的运营水厂，以及足够的市政 TTHM 监测数据。通过将 TTHM 测量值与住宅信息联系起来，获得个体孕产妇早孕期暴露，分为无氯化和$<5$, 5–15, 和$>15\mathrm{\mu }\mathrm{G}$TTHM/升。我们还进行了特定于氯化处理的分析（仅使用氯胺或次氯酸盐）。结果和协变量是通过与医疗保健和行政登记的联系获得的。通过逻辑回归估计优势比 (OR) 和 95% 置信区间 (CI)。

结果：

基于 623,468 名新生儿和先天性畸形的患病率$～2$例/100 名新生儿，我们观察到使用氯胺的地区的 TTHM 暴露与神经系统畸形之间的关联（$\text{要么}=1.82$; 95% CI: 1.07, 3.12), 泌尿系统 ($\text{要么}=2.06$; 95% CI: 1.53, 2.78), 生殖器 ($\text{要么}=1.77$; 95% CI：1.38, 2.26）和四肢（$\text{要么}=1.34$; 95% CI: 1.10, 1.64)，将最高暴露类别与未暴露类别进行比较。在仅使用次氯酸盐作为主要水处理方法的地区没有观察到相关性。相比之下，对于心脏畸形，仅在使用次氯酸盐的区域观察到显着的负相关。

讨论：

TTHM 暴露与仅使用氯胺的区域的神经系统、泌尿系统、生殖器和四肢畸形风险增加有关。与氯胺相关的氯化副产物与先天性畸形之间的关联以前没有被强调过，需要进一步关注。https://doi.org/10.1289/EHP9122