Childhood lead exposure.

Introduction

Research scientists and health care providers often find themselves at cross-purposes. Scientists want to give policy-makers and the public a definite answer. They want something to hang their hat on and certainly don't want to have to retract their recommendations. This usually means running a concept up the scientific flagpole of in vitro studies, animal studies, clinical observations in a conceptual framework, case reports, case series, case control studies, cohort studies, randomized, clinical, double-blind studies, systematic reviews, and meta-analyses. That takes years: a long time to wait for answers. Doctors and their patients therefore find themselves using the science of today to choose a best course of action.

The researcher-clinician currents create a rip-tide in the medical information. The public is told nothing is certain, it can't be proven, and it saves lives all at the same time. Such has been the case with autism and heavy metal exposure. This article discusses the most-studied heavy metal, lead. A personal experience links the following lessons learned.

Ongoing Vigilance Is Important.

It's not easy to be on watch. It's human nature to be less vigilant when the threat seems remote. When you forget about something in public health, there's a good chance it might come back. Unfortunately, 2007 marks such a case for childhood lead exposure. Lead-painted toys prompted extensive recalls. Department stores across the country had empty shelves from the summer through the Christmas season. Suddenly, the country where the toy was manufactured became a determining factor for understandably wary parents.

Earlier that year, my husband and I made a point to have our daughter's blood lead level checked at age one year. Our home was built in the Victorian era and could be a source of lead paint exposure. The lead screen is a standard recommendation, although the Centers for Disease Control (CDC) report suggests that fewer than half of the children at the same pretest risk as my daughter are actually tested.

During our daughter's physical exam, no mention was made of the blood lead test results. When I asked for the results, I was told they were normal. "That's good. What would that normal number be?" On my persistence, the staff shuffled through the chart to find the lab result. Her level was 6 ug/dL. The lab print-out had the "normal range" as up to 9 ug/dL.

It is not "normal" to have any lead in the blood. A number as high as 5 ug/dL is generally considered to be medically acceptable but is by no means normal. Current CDC guidelines suggest that a level of 6-9 ug/dL might not be medically acceptable and warrants parent education and ongoing testing. One well-conducted study showed a lower intelligence score among children with lead levels persistently between 6 and 9 compared to those with lead levels below 5.

Guidelines are helpful, but they come with a downside. It's easy to apply them mechanically without taking into account the individual patient. It is important to consider the patient and the biologic basis of disease. For example, my daughter was a late walker, just beginning to explore her environment at the time of the blood test. What might happen to her lead level as she began to explore her environment more actively?

Time of year also makes a difference. Population-wide lead tests are lowest in the month of March, the month my daughter's test was taken. June is when they are highest. This is presumed to be because of increased outdoor activity and perhaps to the opening of the windows where dust, accumulated all winter, can aerosolize. Rising vitamin D levels or other metabolic changes have not been evaluated as a possible contributing factor to the seasonal variation.

Until I was the parent, I didn't appreciate how many barriers there are to monitoring a child's lead level. Drawing blood from a toddler is more traumatic than shots, and a child's memory for such events is problematically good. Mutual dread often engenders a less-than-welcoming response from lab personnel. The cost from the lab may be upwards of $70, a price that is then steeply negotiated by third-party payers. However, it's often not clearly stated to parents that third-party payers usually cover the entire lab expense. An appropriately concerned parent may be labeled as over-reactive by a health care team unaware of the recent guidelines.

The repeat lead test three months later was 9 ug/dL. Since the standard error for the test is +_ 2 ug/dL, my daughter's actual level could have been as high as 11 ug/dL, high enough to alert the health department in my state. The "bad news" was extremely helpful. Without vigilance, we would not have known that more needed to be done. What was the source?

Finding the Source Isn't Easy

My husband is an historic home specialist, so between the two of us we had a head-start in the detective work. However, it was by no means easy. At that point, we had ruled out water, breast milk, and toys as potential sources. Meanwhile, we puzzled over the guidelines. How many times do you wash a teething child's hands to avoid lead exposure when you aren't sure of the source?

The health department went beyond their call of duty and helped us with the detective work. Their mass spectrometer took over 100 readings. The base moldings and interior doors read lead paint concentrations that were off the scale. In other words, the interior lead dust had accumulated, and each bump against the wall and each swing of the door created more lead-containing dust. The summer-long work began--deep carpet cleaning, radiator stripping and repainting, abatement paint, door frame and door repair, wet-wiping the surfaces with phosphate-containing wipes, and washing.

Living in an historic neighborhood meant that lead dust could be tracked into the home, in the car, on the playground, and on our clothes. We used tack mats to catch anything we might track in. Each white mat ended the day looking black. Could that be enough to raise a lead level to 9 ug/dL?

Phosphates bind lead. Since phosphates have been removed from detergents to reduce environmental impact, they may possibly be less effective at removing lead. More frequent washing or use of phosphate-containing detergents may be helpful. Everything that could get washed did, including my daughter's favorite stuffed animal, a tiger named Stripes. Stripes emerged with a solid brown coat. Now my daughter wrinkles her forehead at her stuffed animal's name. He lost his stripes during the massive housecleaning. I think that's when my husband and I earned ours. Our reward came in three months when the repeat test had marched down to 4ug/dL.

Exposure Is Not the Same as Blood Levels

Two children with the same exposure to lead will probably have different blood lead levels, influenced largely by their diet, health, and nutrient status. Mineral deficiency states increase toxin absorption. Both iron deficiency and low calcium intake elevate lead absorption. Conversely, lead, mercury, cadmium, arsenic, and radioactive iodine levels can be lowered by repleting mineral stores. A study conducted in a region of Mexico where lead exposure was endemic showed that pregnant women who took calcium supplements of 500 mg a day experienced lower maternal and fetal lead levels. Following the Chernobyl accident, those people who were given potassium iodine had less uptake of radioactive iodine from food. Selenium can reduce mercury uptake. Eating a food rich in selenium, such as Brazil nuts, has been recommended as a way to counteract the possible presence of mercury in seafood.

Another well-substantiated intervention is the avoidance of sugar. Foods that push the metabolism in the acid direction can also increase the uptake of lead. Lowering the pH signals the increased uptake of bone minerals (and lead) needed to neutralize the sugary metabolism. Of course, cutting sugar is a healthful recommendation for everyone. However, the bit of information about lead comes in handy at birthday parties where children are routinely poisoned with sugary cake. I now tell other parents that my daughter has a medical condition where she can't eat sugar. That's the honest and very tame version of "Why are you sugar-poisoning your guests?"

In an additional effort to maximize my daughter's ability to not absorb lead, she was administered a daily dose of an oral spray called "Metal Free." The active ingredients are algae, probiotics, minerals, and antioxidant vitamins with mild chelating activity. There is a biologic basis to support the hypothesis that this product contributed to her speedy reduction in blood lead.

Blood Levels Do Not Have Equal Effects on Child Brain Development

When I learned that the most likely source of my daughter's lead exposure was paint, it raised another concern. What other heavy metals, which we don't measure, were in the paint dust? Was my daughter exposed to cadmium, arsenic, or mercury? Studies show that exposure to several heavy metals at the same time is harmful and more than additive. On the other hand, healthful cells are good gatekeepers. Essential fats, avoidance of trans fats, and the inclusion of adequate magnesium and potassium (intracellular electrolytes), alpha lipoic acid, and hydration can help brain cells thrive.

Summary

Managing a measurable heavy metal exposure is resource-intensive. Even in what may be a best-case scenario, avoiding exposure is close to impossible. Approach to any heavy metal exposure should go beyond avoiding exposure. It should employ nutritional strategies as soon as possible. Nutrition can both prevent absorption of heavy metals and reduce the impact of exposure on the developing brain.

by Ingrid Kohlstadt MD, MPH, FACH 

www.INGRIDients.com

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