For the past year and a half, citizens of Flint, Michigan have been struggling to get clean, safe water to drink. The city switched its water source from the Detroit water supply to the Flint river, causing a slew of public health problems, including high concentrations of E. coli bacteria and a recent outbreak of Legionnaires’ disease that killed 10. But most disturbing of all was the high concentration of lead that leached from Flint's old, outdated pipes into the water flowing to citizens' homes, which may have exposed thousands of children to the toxic substance. How, exactly, does lead exposure affect a child, and are the effects permanent?
How is lead introduced to the body?
Humans have long known that lead can cause detrimental health effects—some claim it contributed to the fall of the Roman Empire. But the substance’s effects were first documented in children about a century ago, says Jay Schneider, a neuroscientist at Thomas Jefferson University. However, lead was still common in many household products—especially paint, in which it was used to add color and stability the mixture, until it was banned in 1978.
Lead paint, turning into dust and chips as it falls from the walls of old houses, is one of the most common ways in which children are exposed to the substance. But it shows up in other surprising places, too—in many vinyl-based products like shower curtains and raincoats, telephone cords, and some that are even designed explicitly for children, such as lunch boxes and toys.
Lead can be ingested, through water or other contaminated substances--the Environmental Protection Agency limits the amount of lead in water to 15 micrograms per liter, though some toxicologists think that limit should be lowered to 10 micrograms per liter. Lead can also be inhaled or sometimes even absorbed through the skin, though lead can't move from water into skin, so it's safe to bathe in lead-contaminated water as long as you don't drink it.
Once it’s in the body, lead competes with calcium to be absorbed by the body. There are lots of factors that can affect just how much of the lead is absorbed, but there is an overall higher absorption rate for lead that is inhaled versus ingested. It sticks to red blood cells—doctors usually test the blood for proof of exposure to lead—and then moves into soft tissues, like the liver and lungs. If lead is absorbed into bones, it can stay there for decades and recirculate in the person’s blood if a bone is broken or when a woman is pregnant, potentially poisoning both the mother and the fetus.
What are the health effects and dangers of lead?
When cells in the brain absorb lead, it tends to affect the frontal cortex, the area responsible for abstract thought, planning, and attention, and the hippocampus, essential to learning and memory. But the resulting symptoms vary a lot between individuals, Schneider says. “You don’t often see the same kinds of cognitive dysfunction in all kids,” he says. “From what our research has shown, there are very significant differences in the way different brains respond to this particular toxin.”
Factors like age, sex, amount of lead in the body, and genetic makeup can drastically alter the particular combination of symptoms caused by lead poisoning in the brain--younger children and boys display the strongest neurological effects.
One thing is constant, however: lead is toxic, and if it makes its way into the still-developing brains of young children, many of the effects can be permanent. Lead can change how signals are passed within the brain, how memories are stored, even how cells get their energy, resulting in life-long learning disabilities, behavioral problems, and lower IQs.
“It can really change the programming of the brain, which will have considerable effects on subsequent behavioral and brain function,” Schneider says. “As we learn more about lead and its effects on the brain, even down to these molecular levels, if anything it’s even more dangerous than we thought.”
What are the treatments for lead exposure?
If you suspect that your child might have lead poisoning, Schneider recommends getting a complete evaluation from a pediatrician.
If a child has in fact been poisoned, however, there are woefully few treatments available. For very high levels of lead in the blood, doctors can give children chelation therapy, a chemical that binds to the lead so that the body can’t absorb it. “That can help to protect the peripheral organs, but most agents used for [treatment] don’t do anything to fix the damage that’s already been done,” Schneider says. There is no treatment for low levels of lead in the blood.
Schneider suggests that families take a preventative approach to lead poisoning. If you have young children and live in an old house or in an area with old water pipes, you should call an expert to test the water and paint in your home.
Scientists still have many more questions about just how lead affects the body. Schneider is curious about how lead can change a person’s genome — a field of study called epigenetics, which can modify a person’s behavior, and be passed down through generations. A better understanding of lead’s molecular and genetic effects might help scientists figure out how to reverse the damage of lead poisoning.
In the meantime, lead poisoning continues to be a public health concern, especially in low-income and minority communities.
In Flint, the situation has become dire. Late last year, the Michigan governor distributed thousands of faucet filters to take the lead out of contaminated water, but most experts think that's just a temporary solution since tainted water is still flowing into the homes of thousands of locals. The National Guard has been called in, and earlier this weekend, President Obama declared a state of emergency in the community. As a result of all the effort and attention, thousands of people will hopefully soon have clean water to drink and use. But with so much lead that has already made its way to thousands of local children, some fear that significant damage has already been done.