It’s one thing to hear about water contamination causing problems in a Third World country halfway around the globe. It’s quite another to see it in your backyard.

That’s what happened last week with the results of a study linking lower IQs in Maine schoolchildren with exposure to arsenic, which is frequently found in significant amounts in water wells across the state.

The study, one of the first to look at the issue in the United States, should be a wake-up call. More than 40 percent of Maine residents get their water from wells but less than half of well owners ever get them tested. More work is needed to increase the number of tests, so that homeowners can take corrective action, and students in their developmental years are not being exposed to a toxin that will put them behind from the start.

The negative health impacts of arsenic are well documented. Its use as a poison goes back centuries, and it has been linked more recently with everything from cancer and immune suppression to respiratory infections and low birth weight.

A clear connection between arsenic exposure and poor brain development came a decade ago from a study out of Bangladesh, where millions of people are exposed to high levels of the toxin. The study showed IQ levels got progressively lower the more arsenic a child ingested.

Interested to see if the effects were similar for students with better nutrition and comparatively low levels of arsenic exposure, the study group moved its research to Maine, where a type of bedrock containing arsenic is found in abundance.

The study involved 272 schoolchildren from the Augusta area and York County. It showed that even at low levels – 5 or more parts per billion, a tiny fraction of the levels in Bangladesh – arsenic exposure could lower IQ by 5 or 6 points.

That’s worrisome, considering how many Mainers are exposed to those levels.

A 2010 study, for example, estimated that 31 percent of the wells in the Augusta area contain arsenic above the federal standard, 10 parts per billion. That’s as many as 15,000 residents exposed to levels higher than those found by the study to cause deficiencies in that area alone.

What’s more, most of them will never know – according to the state, only 42 percent of well owners recall having their well tested for arsenic.

Something needs to be done, and it’ll have to be done at the state level.

The federal government last changed the standard for arsenic in drinking water in 2002, lowering it from 50 parts per billion to 10. Further studies on the risk of arsenic are being conducted now, and the results of those will have to match the Maine study before a lower standard is even considered.

Besides, that standard covers only municipal water supplies. There is no standard for well water, and even if there were a standard, there is no mandated test to find bad wells.

Mandated well tests during real estate transactions have been suggested in Maine before, but generally meet strong opposition from the real estate industry.

Those tests wouldn’t catch most problems, and many homebuyers already opt for a test. However, given the new evidence, lawmakers should revisit this issue.

The real need, however, is for outreach and education, so that homeowners are aware they may be exposed to arsenic.

Fortunately, the state, which offers some arsenic-related resources, recently received a $51,000 grant for just that purpose.

The money should be used to target families through schools, much in the same way kids are taught to remind parents to check smoke alarms.

Maine also should consider testing areas of particular concern and showing those results to nearby residents using wells.

In many cases, the new study shows, Mainers are being harmed a little bit every day, in a way that is not well known. The state should make sure that changes.