Incense may be contaminated with heavy metals such as lead. Burning the incense can result in inhalation of these metals and subsequent toxicity.
Primary mechanism of intoxication: smoke inhalation
Secondary mechanisms: handling incense, deposition in the environment
Risk factors for poisoning:
(1) frequent incense burning
(2) dense concentration of incense smoke, which may be associated with poor ventilation
(3) exposure over many years
(4) lack of controls on incense preparation
Clinical manifestations may include:
(1) anemia with basophilic stippling
(2) neuropathy
(3) nephropathy
(4) abdominal pain
(5) other symptoms of lead or heavy metal poisoning
Multiple people may be exposed, including families and religious communities.
Environmental sampling should be conducted. Analysis of incense may or may not be positive, since exposure could have been from previous lots. Dust and ceiling/wall washing can be tested.