Main sources and route of exposure of Pb
| Main sources | Sources | Route of exposure |
|---|---|---|
| Earth crust | Naturally enriched areas (e.g., black shale areas) | Ingestion and dermal contact |
| Dietary sources | Contaminated food, lead accumulated in plants (e.g., urban agriculture), game hunting meat | Ingestion |
| Medicinal sources | Some traditional medicines | Ingestion |
| Cosmetics | Lipstick, Nail polish | Intradermal (organic forms only) |
| Industrial sources | Lead-based paints, mining and smelting, lead acid battery production, solder and glassware production, recycling activities | Ingestion/Inhalation |
| Recreational activities | Use of indoor firearms, recreational shooting activities and/or fishing activities | Inhalation, dermal contact, ingestion |
| Air | Combustion of lead-based gasoline, tobacco smoke, leaded aviation fuel | Inhalation |
| Drinking water | Lead pipes | Ingestion |
| Soil | Contaminated soil | Ingestion (mainly in children) |
Symptoms of Pb toxicity at different blood lead concentrations [adapted from Rehman et al_ (103)]
| Acute Toxicity | Mild toxicity (40–60 μg/dL) | Moderate toxicity (60–100 μg/dL) | Severe toxicity (>100 μg/dL) |
|---|---|---|---|
| Metallic taste | Myalgia | Arthralgia (especially nocturnal) | Lead palsy (wrist or foot drop) |
| Abdominal pain | Paraesthesia | Muscular exhaustibility | A bluish black lead line on gums (Barton's line) |
| Constipation or diarrhoea | Fatigue | Tremor | Lead colic (intermittent severe abdominal cramps) |
| Vomiting | Irritability | Headache | Lead encephalopathy |
| Hyperactivity or lethargy | Abdominal discomfort | Diffuse abdominal pain | |
| Ataxia | Anorexia, metallic taste, vomiting | ||
| Behavioural changes | Constipation | ||
| Convulsions and coma | Weight loss | ||
| Hypertension |
Main sources and routes of exposure of As
| Main sources | Sources | Route of exposure |
|---|---|---|
| Earth crust | Rocks (e.g., volcanic eruptions), naturally enriched areas (e.g., serpentine areas) | Ingestion/ Inhalation |
| Dietary sources | Seafood, contaminated water, accumulation in food crops, fruits and grains | Ingestion |
| Medicinal sources | Arsenic trioxide treatment for acute promyelocytic leukemia Arsenic-based drugs in veterinary medicine | Ingestion |
| Cosmetics | Skin lightening products and fairness creams | Intradermal |
| Industrial sources | Pesticide production, wood preservatives, microelectronics production, microwave devices, and lasers | Ingestion/inhalation |
| Air | Use of pesticides and agrochemicals, industrial sources | Inhalation |