WORTH NOTING ON TV

* FRIDAY

20/20 (ABC, 10-11 p.m.): Those toys you see kids playing with in the United States may be sold by American companies, but most of them are made in Asia. There, labor is cheap and working conditions - according to a segment on this week's edition of the documentary series - are not only oppressive, but also shockingly dangerous. Not long ago in Thailand, some 188 workers died in a fire occurring in a toy factory that, in the US, would have been condemned decades ago. It allegedly had no fire escapes or ex tinguishers, no sprinklers, and poor stairways.

Don't US firms have some moral stake in what happens at the factories they do business with? Lynn Sherr puts this question to toy-industry figures - who tend to disclaim ultimate responsibility - to labor figures like Lane Kirkland, president of the AFL-CIO, and to those most directly concerned: survivors of the fire. * SUNDAY

Antarctica: Planet of Ice (Discovery Channel, 8-11 p.m.): Here's a long but informative three-hour summertime visit to a continent still little known, where the sun sets in April and doesn't rise again until August, and where starfish and sea spiders get much bigger than their counterparts in milder climates. The first of three 60-minute episodes, "Emperors of Antarctica," follows a group of researchers in midwinter as they retrace the 1911 route of Capt. Robert Scott to Cape Crozier. Hundreds of penguin s are encountered, and the show notes how the species has evolved strangely effective ways of surviving the cold.

During Part 2, "The Longest Night," a team of New Zealand scientists remain at Scott Base in McMurdo Sound during the dark isolation of the Antarctic winter. Part 3, "Solid Water, Liquid Rock," explores Mt. Erebus - the earth's southernmost and Antarctica's only active volcano.

Booknotes (C-Span, 5-6 p.m.): The guest is Alexander Brook, author of "The Hard Way: The Odyssey of a Weekly Newspaper Editor."

Please check local listings for all these programs.