Abstract

Cumulative toxicity is a harmful effect of toxic substance resulting from successive doses. Any substance or drug will cumulate in the body, if rate of administration is more than the rate of elimination. Slowly eliminated substance or drugs are particularly liable to cause cumulative toxicity.

Among the others, Lead is a common cumulative poisonous metal, meaning once it enters the body, it accumulates in areas such as the blood, kidneys, liver, and brain. Lead is known from very ancient times, used in ayurvedic medicine, it is a steel-grey colored, heavy but soft metal, It can be mixed with other metals, it is a highly toxic element that can cause permanent and deadly damage to the human body. For many years, lead was an important ingredient in paint. There are plenty of items in the workplace still covered with lead-based paint, including window and door frames, various types of construction materials, including bricks and mortar, roofing material, insulation, pipes, metal objects of all kinds, contains lead.

Continuous contact of the lead vapours in colour or battery making factories, consumption of small amount of lead through prolonged use of medicines containing it or drinking water carried through lead pipe cause the symptoms of chronic poisoning of lead. Efforts are made in this paper to evaluate how lead can be a cumulative poison and what should be the preventive measures taken by the human beings, who are dealing with it in their day to day life.

Introduction

Lead is a soft blue-gray metal. its chemical formula is Pb (Plumbum), found in the natural environment was added to paint and gasoline in past, still used in consumer products. 40% of more than 6000 medicines in Ayurveda contain at least one heavy metal Thought by practitioners to have therapeutic properties and/or to increase the efficacy of other herbal contents, used most commonly for chronic disorders and so there is a greater risk of heavy metal accumulation. Lead get Into the Environment by Deterioration of lead-based paint, Leaded gasoline, Businesses that involve lead, Lead mines or smelters. People Exposed to Lead by Dust, paint, soil, Contaminated food, water, maximum consumption of soft drink based beverages,cosmetics, some imported home remedies and Endogenous exposure.

 Lead in the Environment

1) Varies from place to place
2) Soil near roadways (pre-1976 gasoline)
3) Elevated in soil, water, or air near lead mining or smelting facilities
4) Near smaller businesses and industries that involve lead

Lead in the Home Environment

1) Most exposure through leaded dust in home.
2) Childrens are at greatest risk
3) Lead dust levels have been directly correlated with children’s BLL (blood lead level)

People Exposed to Lead in Work Environments by

1) Swallowing lead dust
2) Breathing contaminated air
3) Lead contacting skin
4) Workers can expose their families if they bring lead home on their clothes or skin.

Jobs that involve Lead are

1) Lead smelting or mining
2) Construction/ remodeling
3) Automobile repair/ Automotive batteries repair
4) Plumbing/ Ceramic glazes preparing jobs
5) Police officers/military
6) Rasashala and Many others

Toxic Compounds

1) Lead Monoxide – Litharge - PbO.
2) Lead sulphide – Galena - PbS.
3) Lead Tetraoxide – Sindur - Pb3O4.

Absorption of lead in human being

1) Skin: little/no absorption
2) Inhalation (1µm): dust or lead fumes, absorb 50-70%
3) Oral: a) adults absorb 10%
b) children absorb 40-50%
c) increased absorption if low Fe, Ca

Note : Normal blood level of lead is 0.03mg%
Poisoning is suspected when blood level of lead is more than 0.8mg%

Excretion

1) Renal (90%) and biliary (10%)
2) Maximum excretion is ~ 3.5µg/kg/day
3) If intake 3.5 µg/kg/day accumulation will occur

Lead poisoning Storage & Distribution

1) Rapid turnover soft tissue pool: T1/2 30-40 days; blood, kidney, liver, CNS
2) Slow turnover skeletal pool: a) T1/2 10-20 years; 75% - 90% in skeletal pool
3) Chronic exposure results in a steady state distribution between bone and blood

Mechanism of Action

1) It inhibits sulphydryl (SH) group of enzymes.
2) The chronic symptoms are mainly due to fixation of lead in brain & peripheral nervous system.
3) Spasm of capillaries.

Chronic Signs and Symptoms (Plumbism/Saturnism)

1) Hypochromic Anemia, Arthralgia (large joints involvement)
2) Basophilic stippling, Bones- X-ray of long bones shows lead lines which are bands of increase density
3) Colicky pain in Abdomen, Chronic constipation (pain in abd relieve by pressure),

         Cardiorenal manifestation-
            a) Cardiac- increase BP, arterio sclerotic changes
            b) Renal - presence of albumin & lead, coproporphyrin – 3 in urine and nephrities.

4) Delirium, Wrist drop, Foot drop.
5) Encephalopathy, Eye changes- Retinal stippling & optic atrophy.
6) Facial pallor (due to vasospasm around the mouth).
7) Blue line at the junction of Gums and teeth called as Burtonian line (mostly in dirty teeth of upper jaw).
8) Genital - Female- Abortion, Degeneration of fetus, Menstrual disturbances; Male- Sterility.
9) Hair: may be alopecia.

Management of cumulative toxicity of lead

1) Most important step is removal of lead exposure.
2) Antidote- Physical- Demulsant
         Chemical- Sodium sulphate, Magnesium sulphate.
         Physiological- following chelating agents should be use
             a) Calcium edentate 1gm/day as I.V drip.
             b) Inj. BAL 3mg/kg/day… deep I.M.
             c) Cap D penicillamine- 250mg QID (20-100mg/kg)- 1day.
             d) EDTA- 50mg/kg- I.V infusion for 1 day.
             e) DMSA/Succimer- 30mg/kg/day orally.

Other Symptomatic Treatment

1) For pain – Injection Morphine & Atropine
2) I.V Calcium Gluconate.
3) Vit B,C,D & food containing calcium should be given.

Message

If you understand how dangerous lead can be, then you know that following safety procedures involving lead is very important to your health - and the health of your family!

• Use any personal protective equipment, such as gloves, face shields, or respirators, as instructed by your employer.
• Keep the work area as free as possible from lead contamination by regular cleaning with a toxic-dust filtered vacuum or with safe wet-mopping methods. Don't use compressed air or dry sweeping.
• Try not to touch your face, hair, or other parts of your body when you are working with lead-containing materials.
• Wash your hands and face thoroughly before lunch breaks or any break when you will be eating, drinking, smoking, applying makeup, or touching contact lenses, even if you have been wearing gloves.
• Don't keep your lunch box, purse, snacks, cigarettes, or makeup near your work area.
• Take showers at the end of your shift.You must change clothing before leaving work.
• Don't bring your work clothes home! This will bring lead contamination back to your house and your family.
• Children of workers who bring home lead dust on their bodies and clothing may be affected from very low levels of exposure. Such exposure can result in behavioral disorders and even mental retardation.
• Children living in older housing pregnant women and developing fetus are at high risk
• Infants/children get symptoms at lower levels

References

1) Saper RB, Kales SN, paquin j et al. Heavy metal content Ayurvedic herbal product. JAMA http://dx.doi.org
2) National Library of Medicine - National Institutes of Health. Retrieved July 14, 2012, from http://www.nlm.nih.gov/medlineplus/ency/article/003360.htm
3) Textbook of Agadtantra by Dr Huparikar and Dr V. P. Joglekar, R.S.M Pune.
4) Prof. S. K. Singhale’s Toxicology at glance, 8th Edition, T. N. B. D Mumbai.
5) Harrison’s Principles of Internal Medicine, Vol II 14th Edition 1998.
6) Information on lead safe work practices: www.epa.gov/lead/epahudrrmodel.htm