What hypothesis can be formulated with respect to lead contamination in water, on skin, and in wall paint? What conclusions can be drawn given that test results are negative?
It can be hypothesized that water can become contaminated with lead through plumbing piping and fixtures. Copper pipes can be constructed using lead-containing solders. If the water passes over these solders, the water will become contaminated with lead. Lead can also be present in brass piping or faucets, and water can also become contaminated with lead if it passes through these (InspectAPedia, "How to Test for Lead Contamination in Water"). It can further be hypothesized that a person can become contaminated by lead through skin contact, although lead poisoning through skin contact is less likely to happen (United States Environmental Protection Agency, "Lead"). Absorption of lead through skin contact in the US is only considered a problem for workers who mine organic lead or industrial workers who work with lead. Most products US citizens can touch no longer contain lead (Agency for Toxic Substances & Disease Registry, "Lead Toxicity: How are People Exposed to Lead?"). It can further be hypothesized that individuals can become exposed to lead through both ingestion and inhalation if lead is present in lead paint. Ingestion is primarily a danger for children for, "As the lead paint deteriorates, peels, chips, or is removed," children may touch these fragments and then consume lead through "normal hand-to-mouth activity" ("Lead Toxicity"). Lead paint can also deteriorate to the point of becoming household dust, which can be inhaled ("Lead Toxicity").
Chemistry tests can be conducted to see if lead is present in either water, paint, or on the skin. If the tests come out negative, it means that no lead is present. If no lead is present, it can be concluded that the substance is not a threat for lead exposure or developing lead poisoning.