Health Hazards of Eating Slate Pencils (Pica)

Consuming slate pencils (pica — persistent non-food ingestion) poses multiple health risks.

Composition and Toxicity

• Slate = metamorphic rock (clay, mica, chlorite, quartz, graphite).
• Contaminants: **lead, cadmium, arsenic, mercury** — neurotoxic, nephrotoxic, carcinogenic.
• No nutritional value; displaces nutrient-dense foods.

Physical Hazards

• Dental: Abrasion, fractures, enamel wear, TMJ strain.
• GI: Bezoar formation, obstruction, perforation, constipation.
• Choking/aspiration: Especially children.

Systemic Toxicity

• Lead: Neurodevelopmental deficits (children), anemia, neuropathy, renal, reproductive.
• Cadmium: Nephropathy (Fanconi syndrome), osteomalacia, lung cancer.
• Silica (quartz): Silicosis if inhaled as dust; GI irritation ingested.

Underlying Pica Causes

• Iron deficiency anemia (most common).
• Zinc deficiency.
• Pregnancy.
• Autism, intellectual disability, OCD, schizophrenia.
• Neglect, malnutrition.

Management

• Urgent: remove source, assess for obstruction (X-ray if symptomatic).
• Screen: CBC, ferritin, zinc, lead level (BLL), renal function.
• Treat deficiencies (iron, zinc).
• Behavioral: CBT, habit reversal, environmental modification.
• Psychiatric referral if comorbid condition.