Lead is a naturally occurring bluish-gray metal present in small amounts in the earth’s crust but activities such as fossil fuels burning, mining, and manufacturing contribute to its release in high concentrations in the environment. Today lead is used in everything from construction materials to batteries.

Long-term exposure to lead can cause serious health problems to everyone but babies and young children are at greatest risk — their smaller, growing bodies make them more susceptible to absorbing and retaining lead.

 

Routes of Exposure to Lead

Lead exposure usually results via inhalation of lead-contaminated dust particles from deteriorating household paints, lead in the work place, lead in crystals and ceramic containers that leaches into water and food, lead use in hobbies and cosmetics.

Several “new” sources of lead poisoning have made headlines over the last five years, including lead-contaminated candies (many imported from Mexico), lead-contaminated toys (mainly from China).

Other potential sources of lead can be: foods that are grown in soils contaminated with lead, canned foods, insecticides, tap water, some wines, car’s lead-acid batteries, lead glassware, crystal dishes and even lipstick [1].

 

Adults absorb 35 to 50% of lead through drinking water and the absorption rate for children may be greater than 50%.

 

Lead and the Connection to Children’s Health

Despite the fact that since the late 1970’s lead exposure has decreased significantly as a result of the elimination of lead in gasoline [2], a lot of children continue to have elevated blood lead levels (> 10µg/dL). This is especially  true of children under the age of six, because they tend to be more “auto-oral exploratory” (i.e., they put more things in their mouths). Hence, lead poisoning is one of the most common pediatric health problems today [3, 4, 5].

The largest source of lead poisoning in children comes from dust and chips from deteriorating lead paint on interior surfaces of older houses. It has been reported that among 16.4 million United States homes with more than one child younger than 6 years per household, 25% of homes still had significant amounts of lead-contaminated deteriorated paint, dust, or adjacent bare soil [1].  Even cleaned houses can be a risk factor since lead in dust and soil often re-contaminates them [2] and contributes to elevating blood lead concentrations in children who play on bare, contaminated soil [3].

 

How Lead Harms Your Child and Yourself

Lead is the most systemic toxicant that affects several organs in the body including the kidneys, liver, central nervous system, blood, endocrine system, and reproductive system [6].

Symptoms of lead poisoning in children include anemiamuscle weakness, gastrointestinal problems, anxiety, diarrhoea, loss of appetite, memory problems, blindness, seizures, paralysis, mental retardation.

The nervous system is the most vulnerable target of lead poisoning. Headache, poor attention spam, irritability, loss of memory and dullness are the early symptoms of the effects of lead exposure on the central nervous system [7, 8].

In children, studies have shown an association between blood level poisoning and diminished intelligence, lower IQ, delayed or impaired neurobehavioral development, decreased hearing acuity, speech and language handicaps, growth retardation, poor attention span, and anti-social behaviours [9, 10, 11].

 Hilary A. Godwin, Professor of Environmental Health Sciences at UCLA, refers to recent studies that suggest that these declines in cognitive outcomes often persist long after the source of exposure has been removed. Also treatment of children with chelation therapy who have blood lead levels between 25 and 44 µg/dL does not seem to significantly improve their cognitive outcomes later in life compared to children who received no chelation therapy but simply had the source of exposure removed.

Exposure to lead is also of special concern to pregnant women. Lead absorbed by the pregnant mother is readily transferred to the developing foetus [12]. Prenatal exposure to lead was linked with reduced birth weight and preterm delivery [13], and with neuro-developmental abnormalities in offspring [14]. Lead exposure may also trigger spontaneous abortions in women [15].

In men,high lead exposure was associated with reproductive effects such as decreased sperm count [16].

Chronic lead exposure may cause adverse effects on the blood, central nervous system, blood pressure, kidneys, and vitamin D metabolism [17, 18, 19, 20].

 

 

Mechanism of Lead Toxicity

One of the major mechanisms by which lead exerts its toxic effect is through its ability to inhibit or mimic the actions of calcium and to interact with proteins [21]. Within the skeleton, lead is incorporated into the mineral in place of calcium.

In the bloodstream, lead can damage red blood cells and limit their ability to carry oxygen to the organs and tissues that need it, thus causing anemia.

Lead binds to biological molecules such as enzymes thereby interfering with their function.

Lead may also compete with essential minerals for binding sites, inhibiting enzyme activity, or altering the transport of essential minerals such as calcium [22]. Lead is reactive with sulfur and selenium and can unable these two substances to protect the body from free radicals.

Lead can damage cells due to formation of free radicals [23].

Its negative effect on the brain is due to its interference with neuronal signalling and intracellular signal transduction that are calcium-dependent processes.

Lead also inhibits the release of certain neurotransmitters, a process that is similarly calcium-dependent [24].

Lead is potentially carcinogenic, inducing renal tumours in rats and mice [25, 26] and is therefore considered by the IARC as a probable human carcinogen [27].

Therapeutic Considerations

Apart from minimising exposure to lead in the environment, another measure of lowering lead’s impact on the body is adequate nutrition. It has been found that one of the major risk factors for lead toxicity in children is poor nutrition, particularly deficiencies of essential minerals, calcium, iron, and zinc (28). These nutrients as well as vitamin C help to decrease the body’s absorption of lead.

If you suspect you or your child are affected by high lead levels, please contact us at myantioxidantclub@gmail.com for more information and health advice.