Why Is This Dog Blue?

ENVIRONMENT

Teachers, scroll down for a quick list of key resources in our Teachers Toolkit.

Discussion Ideas

Why are dogs in the Taloja neighborhood of Mumbai, India, blue? Consult the Nat Geo article, this Hindustan Times article, or the BBC video above for some help.
- Experts say the dogs took a dip in untreated industrial dye dumped as runoff in Mumbai’s Kasadi River. Nearly a thousand pharmaceutical, food, and chemical factories line the river.

Read through our short reference resource on runoff. According to the resource, “runoff from human activity comes from two places: point sources and nonpoint sources.” Is the Mumbai dye point-source pollution or nonpoint-source pollution?
- The dye is point-source pollution, defined as harmful chemicals that enter a body of water from a single source. The factory associated with the dye is a detergent manufacturer.

Is the blue dye harmful to the dogs?
- Not that we know of. Nat Geo reports that the dye washed off with a recent heavy rain.

So, why are residents of Mumbai worried?
- Scientists, citizens, and conservationists are less worried about blue dogs than they are about water pollution. The blue dogs are an unusually visible symptom of a mostly invisible problem.
  - According to the Hindustan Times, “levels of biochemical oxygen demand (BOD) — the concentration of oxygen required to sustain aquatic life — was 80 milligram a litre (mg/L).” Levels above 3 mg/L are unfit for human consumption.
  - The Kasadi River is a major fishery, and fishermen have expressed concern that the polluted water is impacting fish stock.
  - Allowing runoff directly into the river is illegal. “We will take action against the polluters as they are destroying the environment,” says a representative of the local pollution control board.

TEACHERS TOOLKIT

Nat Geo: Blue Dogs Spotted in India—What’s Causing It?

National Geographic Education Blog