We can thank billiard balls for our modern-day, plastic-filled lives. For most of human history, everyday items such as combs were made from expensive animal parts, like tortoise shells. Then, in the 1860s, billiards became a popular pastime. Unfortunately, elephants had to be killed so that their ivory tusks could be made into billiard balls, and soon elephants were rapidly being hunted to extinction. One enterprising New York billiards supplier even offered $10,000 in gold to anyone who could come up with a good substitute for ivory. After years of toil, John Wesley Hyatt, a journeyman printer from upstate New York, developed a whitish material that he called “celluloid.” Alas, while the material worked well for combs, it was too volatile for billiard balls. Nevertheless, plastic was born. And animals from elephants to tortoises were given a reprieve — for a time.

In the early 1900s, the modern plastics we are familiar with — thermoplastics, such as nylon, polystyrene, and polyethylene — were developed. These plastics melt at high temperatures and solidify when cooled. They are very cheap to make and can be molded, melted, and remolded repeatedly. Currently, thermoplastics constitute about 90 percent of all the plastics produced the world over.

Sadly, plastic’s legacy of sparing various animal species from extinction is in tatters. Today, plastic is wildlife’s enemy, threatening animal species with gross environmental contamination.

The garbage patch. In the middle of the Pacific Ocean, on Midway Island, the site of the famous World War II battle, a new battle is being waged: plastic versus wildlife. The plastic comes from the “Great Pacific Garbage Patch,” the planet’s largest collection of debris spanning across so many hundreds of miles in the northern Pacific Ocean that it makes Texas look small. Most of the waste is composed of tiny pieces of broken-down plastic that are trapped in currents spiraling around the ocean. And each year, thousands of albatross chicks die because their parents feed them these tiny pieces of plastic.

In fact, the plastic bits are so pervasive, they outnumber surface zooplankton by six to one. So it’s easy to see why marine mammals and birds think the plastic bits are food and feed on them. Unfortunately, instead of being nourished, marine creatures are literally choking to death on them: The plastic bits accumulate in their guts and kill them. By one estimate, fish in the northern Pacific ingest about 24,000 tons of plastic annually. Human-generated plastic devastates wildlife thousands of miles from any city.

While the garbage patch is a global problem, the United States produces the majority of the plastic waste. In 2010, the United States generated a whopping 31 million tons of plastic waste. Almost 14 million tons were containers and packaging (like all those water bottles and sandwich wraps), 11 million tons were durable goods (think outdoor tables and chairs), and almost 7 million tons were non-durable goods (easy-to-toss picnic plates and cups). Only 8 percent of all the plastic created in the United States in 2010 was recovered for recycling.

It gets worse. Globally, a staggering 300 million tons of plastic is produced each year. Just 10 percent is ever recycled. And around 7 million tons of the stuff winds up in the world’s oceans each year. Which is shameful, because most plastic — readily melted, remolded, and reused — is recyclable. So why isn’t more plastic collected and recycled?

Recycling challenges. In 2011, Moore Recycling and Associates conducted a study — funded by the Plastics Division of the American Chemistry Council — to determine the percentage of the American population with access to municipal or county plastic recycling. They surveyed almost 2,500 cities with populations of 10,000 or more along with 800 unincorporated counties. The study found many different plastic collection programs — ranging from some that collect only plastic bottles, others that collect “non-bottle rigid” containers (trays, deli containers, cartons), some that collect all “bulky rigid plastic” items (carts, buckets, toys), and others still that collect only specific types of plastic bottles. The survey also found that at least 94 percent of Americans have access to some type of bottle and cap recycling, and about 40 percent have access to recycling programs for all plastic bottles, caps, and non-bottle rigid containers.

Yet, despite the prevalence of US recycling programs, the study noted an important trend that might explain why widespread recycling has proved so hard to achieve: The majority of the cities and counties surveyed use confusing “resin identification codes” to describe the variety of acceptable types of plastics to be recycled. Unsurprisingly, most people don’t understand resin identification codes and they also don’t scour their used plastics for tiny embossed numbers. Confusion alone might be responsible for a reduction in our collective recycling efforts. My husband claims that I can’t figure out our municipal plastic recycling — he has to redo all of my efforts every other week. But can you figure out which plastic to recycle from this website? It’s not easy.

Resin identification codes indicate from what type of plastic an item is made. Numbers range from 1 to 7:

1. Polyethylene Terephthalate (PET): plastic water bottles, soft drink bottles, sports drink bottles, peanut butter jars, microwavable trays

2. High Density Polyethylene (HDPE): milk bottles, water bottles, cosmetics, shampoo, detergents, grocery bags, cereal box liners

3. Polyvinyl Chloride (PVC): blister packs, shrink-wrap, blood bags, medical tubing

4. Low Density Polyethylene (LDPE): bread bags, frozen foods, shrink- wrap, paper milk carton coatings, hot and cold beverage cups, container lids, squeeze bottles

5. Polypropylene (PP): yogurt containers, margarine containers, catsup bottles, syrup bottles

6. Polystyrene (PS): cups, plates, bowls, plastic cutlery, packing peanuts, hinged takeout containers (clamshells)

7. Other: three- and five-gallon reusable water bottles, some catsup bottles, citrus juice bottles

One shouldn’t need a degree in cryptology to sort plastic. A whole lot of plastic is falling through the cracks during the collection and processing of recycling.

And then there’s BPA. Some plastic containers with resin identification codes 3 and 7 have been manufactured with Bisphenol A (BPA), a chemical that is used in the production of hard plastic food containers, such as baby bottles, canned liquid infant formulas, and beverage can linings. Rodent studies have found an association between BPA and adverse effects on neurologic and endocrine function. The US Department of Health and Human Services is trying to stop the use of BPA in containers targeted for infants and children; though just last month, the Food and Drug Administration rejected a petition to prohibit BPA in all food and beverage packaging. (Meanwhile, Canada has officially declared BPA toxic, banned its use in plastic baby bottles, created an avenue to ban BPA from yet more products, and is looking at ways to cap how much BPA can be released into the air.) In short, a lot of that plastic we aren’t recycling — the stuff floating in the ocean and hanging around — has the added disadvantage of being potentially toxic.

Better recycling, better planet. The bottom line: We could be doing a much better job of recycling plastics. Just having a recycling program isn’t enough. Recycling programs need to be understandable and easy to use. Plastic recycling rates could dramatically increase by simply improving public education efforts and using clear protocols. This Earth Day, April 22, make a point of not contributing another piece of plastic to the ocean — either by recycling or simply not using plastic at all. (Reusable shopping bags and stainless steel water bottles are all the rage.) Then make another point of not contributing to the ocean’s plastic heap by doing it again the next day. And the next. What’s happening in the Pacific (and around the world) is not the result of one negligent corporate bad guy; it’s all of our responsibility — every plastic baggie, every bottle of water, every takeout container. Each one of us can start now to reduce plastic’s impact on the environment. We should make these efforts part of our daily existence before our planet becomes one giant garbage patch.

Editor’s note: This article was updated on April 25, 2012, to reflect the continuing uncertainty of the toxicity of BPA.