From the Tap to the Womb: Chlorine Contamination

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A study by the California Department of Health published in March, 1998, tracked the drinking water consumption and the pregnancy outcomes of 5,144 pregnant women in a prepaid health plan during the period 1989-1991. The drinking water consumption of the women was ascertained as soon as their pregnancy was registered in the study's database. Later, the outcome of their pregnancy was compared with the amount of water they drank and the total amount of trihalomethanes (THMs) they received from water treated with chlorine (information received from the water companies).

The researchers found that 16 per cent of women drinking five or more glasses of water per day containing more than 75 ppb THMs had miscarriages, 1.8 times more often than women with low exposure. Furthermore, spontaneous abortion occurred, on average, a week earlier among women with high exposure (10.2 vs 11.2 weeks of gestation). The researchers also compared women who filtered their water or let the water stand before drinking it with women who drank water straight from the tap. (THMs are volatile and will slowly leave water that is allowed to stand.) The results were consistent with THMs causing spontaneous abortion.

Dangerous Exposure

Last January, the Agency for Toxic Substances and Disease Registry published a case-control study showing that serious birth defects (spina bifida or neural tube defects) are associated with THMs ingested in drinking water. (Neural tube defects are serious birth defects in which the spinal cord is not properly enclosed by bone.)

This statewide study in New Jersey found a doubled risk of neural tube defects among those with the highest exposures to THMs in drinking water. This study also pointed out that flushing toilets, showering and washing dishes and clothes can inject THMs into household air, exposing residents.

A previous study of 75 New Jersey towns by Frank Bove had examined 80,938 live births and 594 fetal deaths that occurred during the period between 1985 and 1988. This study examined public water company records and compared pregnancy outcomes to the amounts of THMs delivered to the home in drinking water. It did not examine the amount of water ingested. The study found no relationship to fetal deaths, but the likelihood of neural tube defects was tripled by exposure to THMs at levels exceeding 80 ppb.

Neural tube defects are known to be associated with vitamin B(12) deficiency. Studies show that vitamin B(12) use by the body can be disrupted by chloroform, one of the four main THMs in chlorinated drinking water.

An even earlier case-control study reported on pregnancy outcomes among women who delivered babies at Brigham and Women's Hospital in Boston during the years 1977-1980. Indicators of water quality were taken from public water supply companies. No data were available on the amount of water ingested. The water quality indicators were compared among 1,039 cases of babies born with birth defects, 77 stillbirths and 55 neonatal deaths (babies that died within a week of birth) vs 1,177 controls. Stillbirths were 2.6 times as common among women exposed to chlorinated surface water, compared to controls whose water was disinfected with chloramine instead of chlorine.

More recently, a study of drinking water and pregnancy outcomes in central North Carolina reported a 2.8-fold increased likelihood of miscarriage among women in the highest exposure group for THMs in drinking water.

Very recently, a second study from the California Department of Health has shown that, in one area of California, women who drank cold tap water had nearly a five-fold increased risk of miscarriage, compared to women who drank mostly bottled water.

Canadian Health Reform Products Ltd.

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By Peter Montague

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