Final answer:
The most appropriate initial treatment for a chemical exposure in the eye, such as from sparklers, is to irrigate the eye for at least 20 minutes to avoid potential injury or burning.
Step-by-step explanation:
The most appropriate initial treatment for a 10 year-old boy who got some sparkler substance, which is likely to be magnesium or a compound of magnesium, in his right eye would be to irrigate the eye for at least 20 minutes. This is crucial to ensure that any particulate matter and potentially harmful chemicals are flushed out of the eye as quickly as possible. Appropriate irrigation can prevent the chemicals from causing burns or further irritation to the eye. While a moistened cotton swab might be used to remove visible particles, it should only be done by a healthcare professional to avoid further injury. After irrigation, the child should be referred to an ophthalmologist for further evaluation. The use of Bacitracin ointment and a patch or a metal shield might be considered after proper evaluation and recommendation by a healthcare professional.