Table 3.

Chemical exposures and health outcome classifications.

Author-Defined Exposure	Exposure Measurement
Child labour in the presence of chemicals	Sector where chemicals are used (usually based on questionnaire. Sometimes sector is used as a blanket category of chemical exposure by researchers before the study)
Current work status/work history	Self-report questionnaire to determine number of hours at workplace where chemicals are used and number of years in sector
Scientific measurement using specialised equipment	Biomarkers of exposure (e.g., chemical concentrations or metabolite levels) Environmental assessment to measure workplace exposure to chemical levels (e.g., environmental air, water, soil, or food samples) *
Health Outcome Types	Examples
DNA damage	Oxidative stress and DNA damage
Biomarkers of effect	Toxin and metabolite levels (measured in blood, urine, hair, and saliva)
Organ e.g., lung, heart, liver, skin, kidneys	Cancer, diabetes, asthma, kidney disease, dermatitis
Body system e.g., Cardiovascular, endocrine, respiratory, neurological, reproductive, immune	Cardiovascular disease, neurotoxic symptoms, neurobehavioural deficits, hypothyroidism, hypertension, pulmonary function
Mental health	Mood disorders e.g., anxiety, depression
Non-specific symptoms	Wheezing, nail discolouration, fatigue

* in Table 4, “environmental exposure” is used to describe studies where authors use these measurements as exposures, while “environmental assessment” is used to describe studies where authors use measurements as an outcome.