Most cities and towns use chlorine or bromine to disinfect water. When the water is polluted, chlorine or bromine reacts with the pollution (agricultural runoff is probably a bigger problem here than traditional industrial pollution) to create what are called disinfection by-products (DBPs). DBPs are associated in humans with adverse pregnancy outcomes (usually miscarriage)*. Since DBPs damage DNA and are considered carcinogens at some level, researchers thought that it was likely that DBPs would affect sperm as well. Rodent studies show that some DBPs do harm sperm quality; however, there hasn’t been a human study on sperm quality in response to DBP exposure.
A study published recently in Environmental Health Perspectives looked at 228 men who were in a study of couples to look at DBP-induced spontaneous abortion. They were grouped into three levels of exposure: 1) low DBPs, 2) low brominated but moderate chlorinated DBPs, and 3) low chlorinated but moderate brominated DBPs. Moderate meant that the DBP levels were close to the EPA limits.
What the study found is quite surprising. No adverse effect was found for the different DBPs; in fact, there were higher sperm counts at the high exposures with no change in quality. There was a decrease in sperm count associated with the total DBP levels but there was no change in sperm quality which would be expected if there were a toxic effect on the sperm.
Caveats: The study was on people that haven’t been shown to have reproductive problems. A small decrease in sperm count would be more serious to someone with low counts already. Also, it’s not clear what might happen over the limits.
AT’s conclusion: Hey, toxicologists aren’t always the bearers of bad news! Women, drink purified water while pregnant or trying to get pregnant**; men who are trying, drink any water you want, unless it’s after the heavy fertilizing in the spring when many DBPs go over EPA limits (many water testers know when this is coming so they test around it. You can’t totally rely on the water report you get).
*Don’t blame your water provider for DBPs. They have to disinfect the water so you don’t get violently ill and are saddled with polluted water they can’t really control (Rock<->Water Provider<->Hard Place). It’s the upstream pollution that needs to be fixed. This is why NYC has such great water; for over a centruy NYC has protected it’s source water, and this saves it large money too. Clean water with lower costs? I wish all cities had that vision.
** When I say purified water I don’t mean bottled spring water or distilled water or purified by Britta filters or any of that stuff. I mean the 1 or 2.5 gallon jugs labeled “drinking water”. It’s usually purified by reverse osmosis (which is the best way to do it), and it’s the cheapest water you can buy at the store (usually can be found as a generic brand). Britta will get out a lot of DBPs but there’s a lot of junk it doesn’t get out. Most bottled water (Aquafina, Poland Spring,…ETC) is just some other place’s tap water.