From the Material Safety Data Sheet for zinc and zinc oxide dust at http://www.naoxide.com/msdsnolm.html :
Section VIII - Health Hazards
May irritate eyes or skin. When zinc fumes are inhaled, they may
cause flu-like symptoms or fever, chills and nausea. Ingestion
may cause fever, stomach cramps and diarrhea.
Special Remarks on Chronic Effect
Zinc is an essential element. Zinc oxide fume is generated when
it is heated near or above it’s boiling point thereby causing
metal fume fever, a benign transient flu-like condition.
Routes of Entry
Skin contact, eye contact, inhalation and ingestion.
First Aid Procedures
Skin - Wash thoroughly with soap and water.
Eyes - Flush eyes with luke warm, gently running water. If
irritation persists, consult physician.
Inhalation - Consult physician immediately.
Ingestion - Consult physician immediately.
Does not meet WHMIS criteria for carcinogenicity, reproductive
effects, teratogenicity, mutagenicity. "
I don’t think that one should take up huffing zinc fumes, but it
appears that light exposure is relatively harmless. What do you
Bruce D. Holmgrain
Maryland’s first JA Certified Senior Bench Jeweler