35. LEAD

If you don’t already know that lead is toxic, you haven’t been paying attention. Lead is notoriously poisonous. Lead poisoning can be acute or chronic, both of which are very serious. Lead has detrimental effects on all of the organ systems in your body, but it hits the nervous system especially hard. This is because lead mimics calcium, an important player in the brain. Lead easily crosses the blood-brain barrier, where it builds up in nervous tissue; it also accumulates in bone, another organ system heavily dependent on calcium. It is toxic both when it is ingested and when it is inhaled as lead vapor or dust. Children are more vulnerable to lead because they are smaller, and their brains are still developing.

Since at least the late 1800s, it has been known that lead is poisonous. But toxicity aside, lead has some very desirable properties. It is a dense, malleable, abundant, easily mined metal that is resistant to decay, is impenetrable to radioactive particles, and has a low melting point. And it tastes sweet. The Romans used it to sweeten wine—an exceptionally bad idea in retrospect.

The overwhelming harm caused by lead has resulted in heavy regulations in the United States since 1980. And these regulations have significantly reduced the public’s exposure to lead. Average blood lead levels decreased by a factor of 10 between children studied in 1976–1980 and 2007–2008. This is great. Unfortunately, there is still a lot of lead out there. Some of it is legal (e.g., in car batteries, solder, hair dye, dental aprons), and some of it is illegal (e.g., in children’s toys, ceramic glazes), and a lot of it is legacy (e.g., in paint, pipes, dirt, crystal, jewelry). The list of things that historically contained lead is so long that it is difficult to compile and impractical to print. Lead is in seemingly everything (except pencils, which are filled with graphite).

The question then is not whether lead is bad for you, but how bad it really is. Most people who were born before regulations were passed in 1980, and those born in the next decade after, were exposed to lead as children. Leaded gasoline was sold until the late 1990s, and many people lived in houses that were built before lead paint was banned in 1978. Lead water pipes and fixtures were commonly installed in homes and schools before 1986, and many students learned to solder in high school with lead-based solder. And we’re fine, right? That’s difficult to say, because many of us may be suffering the adverse effects of lead exposure without attributing them to lead. Lead is associated with loss of IQ points, behavioral problems, tremor, cognitive decline, hearing problems, allergies, cardiovascular problems, kidney disease, and reproductive issues. Concerningly, a 2012 report by the National Toxicology Program (“NTP monograph on health effects of low-level lead”) found evidence for some of these health effects even at low blood concentrations (less than 10 micrograms per deciliter and in some cases less than 5 micrograms per deciliter). The CDC has revised the high blood lead level down from 25 micrograms per deciliter in 1985 to 10 in 1991 to 5 (the current level) in 2012. They emphasize that “no safe blood level in children has been identified,” but it is important to remember that the health effects of lead are not limited to children.

If a blood test reveals high lead concentrations, chelating agents can be used to reduce the burden of lead. However, after the body is damaged by lead, especially if this damage affects the nervous system, it is irreversible. So it’s worth trying to prevent lead exposure in the first place. According to the National Institute of Environmental Health Sciences, the most common sources of lead in the U.S. are lead-based paint, contaminated soil, household dust, drinking water, lead crystal, and lead-glazed pottery. Of these potential sources, it is easiest to avoid lead crystal and lead-glazed pottery. Don’t eat off it and don’t drink out of it.

Drinking water is trickier, because as individuals we don’t have the authority or resources to rip up and replace the city pipes (think Flint, Michigan). Most of us don’t even have the resources to rip out the lead pipes from our own homes. You can buy water filters that will remove lead and other heavy metals, but you need to make sure that the filter you are using is certified for that use.

Lead contamination in dirt is usually the result of either decaying lead paint or historical exposure to leaded gasoline fumes. Dirt around older homes or close to high-traffic areas is most likely to be contaminated. Exposure to lead in soil can be either direct (like children putting dirty fingers in their mouths) or through produce grown in the soil. Soil that is potentially contaminated can, and should, be tested.

The biggest problem in terms of lead exposure is paint. Old lead paint cracks, chips, and flakes. This poses a risk to children, who may eat paint chips (remember, it’s sweet), but it also produces a fine dust that can be ingested or inhaled by children, adults, and pets. This is a huge problem because there are so many residences painted with old lead paint. You should just assume that any older paint you find in your home has lead in it, but you can also buy lead paint test kits at the hardware store. The problem is, what do you do if you have a positive test? The best (but most expensive) option is to call in a lead abatement professional. If you are considering renting or buying a home or planning a remodel, have it tested for lead first.

Lead tends to accumulate in household dust because of decaying paint, contaminated soil, or both. So try to keep the dust levels in your home down (this is a good idea anyway). Make sure everyone in your family washes their hands frequently, and teach your children not to put nonfood items in their mouths (easier said than done). Also, buy high-quality children’s toys and pay attention to the Consumer Product Safety Commission recall list. Be aware that your home isn’t the only place you can be exposed to lead. You also need to think about workplaces, schools, day care centers, and playgrounds. Finally, if you’re worried about lead exposure, get a blood test.

If you grew up with lead paint, your IQ may have taken a permanent hit from lead. But if you take precautions, you may end up with kids that are smarter than you are. That might be its own kind of problem.

SUMMARY

Preventability (74)

There is a lot of legacy lead in buildings, water pipes, and even dirt. But if you take precautions, you can reduce your lead exposure.

Likelihood (80)

Even very small quantities of lead can have measurable negative outcomes.

Consequence (79)

Lead can have negative consequences for all of your organ systems, but it is especially bad for your brain.

REFERENCES

Centers for Disease Control and Prevention. (2017, May 17). What do parents need to know to protect their children? Retrieved from https://www.cdc.gov/nceh/lead/acclpp/blood_lead_levels.htm

Consumer Product Safety Commission. (n.d.) Recall list. Retrieved from http://www.cpsc.gov/Recalls

Eisinger, J. (1982). Lead and wine: Eberhard Gockel and the Colica Pictonum. Medical History, 26, 279–302.

Flora, G., Gupta, D., & Tiwari, A. (2012). Toxicity of lead: A review with recent updates. Interdisciplinary Toxicology, 5, 47–58.

National Toxicology Program. (2012). NTP monograph on health effects of low-level lead. Washington, DC: U.S. Department of Health and Human Services.

PennState Extension. (n.d.). Lead in residential soils: Sources, testing, and reducing exposure. Retrieved from http://extension.psu.edu/plants/crops/esi/lead-in-soil

Sanders, T., Liu, Y., Buchner, V., & Tchounwou, P. B. (2009). Neurotoxic effects and biomarkers of lead exposure: A review. Reviews of Environmental Health, 24, 15–45.

World Health Organization, International Programme on Chemical Safety. (n.d.). Lead. Retrieved from http://www.who.int/ipcs/assessment/public_health/lead/en/