Sludge Watch ==> Lead in Water Linked to Coagulant - child poisoned in NC

[maureen.reilly at sympatico.ca]

Sludgewatch Admin:

I asked the Public Health Dept City of Toronto officials whether our switch 
from chlorine to chloramine was causing lead contamination of the drinking 
water.  I don't yet know if we also changed coagulants to the compounds 
mentioned in the story below.

Apparently in Toronto lead may still be a problem in older homes, 
businesses, or other facilities.
If you drink water from a faucet in an old building you may ask the Public 
Health Department to come out and test your water for copper and lead 
contamination.

I suggest you leave the aerator on so you can see what your water quality is 
like 'as ingested'.
.....................................................................................................................

http://pubs.acs.org/subscribe/journals/esthag/40/i17/html/090106news1.html

Journal of Environmental Science and Technology

Sept 1, 2006

Vol. 40, Iss. 17
pp 5164–5165ES&T News


Lead in water linked to coagulant


High levels of lead in drinking water that poisoned a child in Durham, N.C., 
probably resulted from a change in the coagulant used to remove organic 
matter, says a corrosion scientist who tested the Durham water. The incident 
raises the specter of similar undetected problems in other parts of the 
U.S., says Marc Edwards, a corrosion engineer at Virginia Polytechnic 
Institute and State University. This case is especially vexing because 
Durham’s routine water-quality monitoring, which is required by the U.S. 
EPA’s Lead and Copper Rule, failed to detect the problem in 2004.


Routine monitoring missed Durham, N.C.’s lead problem.Since the 2004 
Washington, D.C., lead crisis drew attention to lead in drinking water, a 
few cities that were once meeting the EPA action limit have developed 
problems. Until now, the prime suspect for these cases was a switch from 
free chlorine to chloramines for secondary disinfection—the established 
cause of D.C.’s problem.

Besides switching to chloramines, all of the cities changed from alum or 
another nonchloride coagulant to ferric chloride to better remove organic 
matter and further reduce disinfection byproducts. This change increased the 
ratio of chloride to sulfate in the drinking water. When this ratio is 
 >~0.58, galvanic corrosion occurs and erodes particles of solder, according 
to Edwards. This process takes place even when other aspects of the water 
chemistry—such as pH, alkalinity, and the use of a phosphate-based corrosion 
inhibitor—should prevent lead contamination of water, he says.

The chloride-to-sulfate ratio was first reported as an important factor in 
water corrosion in 1983 by scientists in the U.K. Edwards cited their work 
in a 1999 publication that indicated the ratio could be important at U.S. 
utilities. A 2005 American Water Works Association report made passing 
mention of the ratio. Even so, most corrosion scientists and utilities 
managers contacted by ES&T were unaware of the issue.

In Durham, a doctor spotted the child’s elevated blood lead level, >20 
µg/dL, during a routine examination this spring. Public-health officials 
linked the boy’s poisoning to drinking water after they found >800 ppb of 
lead in tap water and no other source of lead in his mother’s apartment, 
according to Durham County health officer Marc Meyer.

Paint, dust, or soil—not water—are generally considered major sources of 
lead exposure. Lead solder, banned in the mid-1980s, could be a significant 
source of lead in drinking water, according to Mary Jean Brown, head of the 
U.S. Centers for Disease Control and Prevention’s lead poisoning prevention 
branch. However, aging processes are thought to deposit various films or 
scales on top of the solder that protect it from corrosion. “If the aging 
process does not protect against this, then it would be new,” she says.

Plant managers say that the problem is new. After the switch to ferric 
chloride, Stafford, Va., plant manager Harry Critzer watched lead levels 
climb. After coagulants were changed, the lead levels quickly dropped below 
the action limit.

Greenville, N.C., had a similar experience. “We switched to ferric chloride 
at about the same time as we switched to chloramines,” says Greenville plant 
manager Barrett Lasater. “At first, we thought it was a dissolved-lead 
problem, so we changed our corrosion inhibitor, but this didn’t have much of 
an effect.”

Most corrosion controls focus on soluble-lead leaching, but this is 
different. It’s about physical processes. “Because these are particles, it 
means that flow rate is important; the aerator is important,” Lasater adds.

Aerators on or off, a seemingly minor detail, could explain why the Durham 
health department found a problem that the water company missed. The health 
department sampled with the aerators on. The water company took them off. 
Although the aerator on/off issue was highlighted in a previous ES&T article 
about sampling in Washington, D.C., schools, where EPA Region 3 agreed to an 
“aerators off” sampling protocol (Environ. Sci. Technol. 2006, 40, 
4333–4334), disagreement about how to sample still exists. “We want to get a 
real-world sample that reflects what people are drinking,” says Meyer, who 
advocates leaving the aerators on.

A Region 4 EPA spokesperson tells ES&T that the water utility sampled 
correctly and that the health department’s procedure “differed from what’s 
required by regulation,” but the spokesperson declined to explain the 
results. EPA’s proposed revisions to the Lead and Copper Rule, released on 
July 6, are silent on specific sampling issues. The proposals would require 
utilities to consult with state regulators when contemplating a treatment 
change that might lead to corrosion.

But on July 26, EPA Office of Water assistant administrator Benjamin 
Grumbles, in a letter to a Durham, N.C., newspaper, wrote, “The U.S. 
Environmental Protection Agency does not have stated guidelines concerning 
the removal of faucet aerators before testing for lead in drinking water. We 
were unaware that water-treatment facilities may be making such a 
recommendation. Since this matter came to our attention, we have begun 
looking into it to determine whether we need to provide supplemental 
guidance on the issue. We hope to make that determination soon.” —REBECCA 
RENNER