{"id":21493,"date":"2026-05-30T21:27:20","date_gmt":"2026-05-30T21:27:20","guid":{"rendered":"https:\/\/www.europesays.com\/australia\/21493\/"},"modified":"2026-05-30T21:27:20","modified_gmt":"2026-05-30T21:27:20","slug":"university-students-bioremediate-agent-orange-chemicals-manufactured-for-vietnam-war-from-sydney-waterways","status":"publish","type":"post","link":"https:\/\/www.europesays.com\/australia\/21493\/","title":{"rendered":"University students bioremediate Agent Orange chemicals manufactured for Vietnam War from Sydney waterways"},"content":{"rendered":"

More than 50 years after the Vietnam War, uni students are removing remnants of Agent Orange chemicals from a waterway connected to Sydney Harbour.<\/p>\n

During the 20th century, Homebush Bay on the Rhodes peninsula, located about 19 kilometres west of Sydney’s CBD, was an industrial hotspot for herbicide, pesticide and preservative production.<\/p>\n

US company Union Carbide, which was responsible for the 1984 Bhopal disaster<\/a>, produced 2,4,5-T and 2,4-D at the site for the Vietnam War effort \u2014 two ingredients found in Agent Orange.<\/p>\n

\"A<\/p>\n

Union Carbide operated in Rhodes from 1928 to 1986. (Supplied: City of Canada Bay Local Studies Collection\/Paul Ife Horne)<\/p>\n

The mixture contained long-lasting compounds called ‘dioxins’, a persistent organic pollutant known to cause health issues in humans.<\/p>\n

According to Australia’s Department of Veterans’ Affairs (DVA), the US used the concoction as a defoliant to reduce food and shelter used by the enemy.<\/p>\n

Between 1962 and 1971, the US sprayed about 170 kilograms of the mixture over southern Vietnam.<\/p>\n

\"A<\/p>\n

The US military sprayed Agent Orange as a defoliant on dense jungle during the Vietnam War. (Wikimedia: US National Archives)<\/p>\n

The DVA estimated Agent Orange covered 3 million hectares of land and 20,000 Vietnamese villages.<\/p>\n

It also estimated 3 million Vietnamese people developed health conditions from the exposure, including cancers, deformities and neurological disorders.<\/p>\n

Union Carbide operated in Rhodes from 1928 to 1986.<\/p>\n

\"A<\/p>\n

An aerial view of Rhodes peninsula and Homebush Bay. (Supplied: Sharon Weismantel\/Douglass Baglin Pty Ltd)<\/p>\n

Smells and spills<\/p>\n

Sharon Weismantel’s first encounter with Rhodes was in 1986 when Union Carbide had begun to wind down its operations, after she started dating local resident and her now-husband, John Weismantel.<\/p>\n

She moved in with him a year later, when there were roughly 275 residents on their side of the tracks.<\/p>\n

Ms Weismantel said you could smell chemicals from nearby factories.<\/p>\n

“These reminded me of my old chemistry classes when we made esters,” Ms Weismantel said.<\/p>\n

“There was a time when there was some spill at Union Carbide \u2026 on the Thursday, and by Saturday, it was affecting the leaves on hydrangeas \u2014 they were withering.”<\/p>\n

\"A<\/p>\n

A photograph of the Union Carbide site taken in 1984. (Supplied: City of Canada Bay Local Studies Collection)<\/p>\n

Union Carbide and its parent company were contacted by the ABC for comment.<\/p>\n

Ms Weismantel said her father-in-law worked at the CSR Chemicals site in Rhodes which suffered spills.<\/p>\n

“The environmental people could never find it [the spill] because the product had actually gone through the soil. It was heavier than water and heavier than the soil,” she said.<\/p>\n

‘Layered chocolate mud cake’<\/p>\n

The real problem with Union Carbide’s operations emerged when it decided to reclaim land in Homebush Bay.<\/p>\n

During a time when environmental laws were not as stringent, the manufacturer would dump toxic waste into the bay, cover it with soil, and repeat.<\/p>\n

“If you look at aerial photos of the Rhodes peninsula, you’ll see that it used to be quite skinny at the northern end, and that skinniness disappeared,” Ms Weismantel said.<\/p>\n

\"Supplied:\"Aerial Aerial photographs comparing Rhodes peninsula in 1930 and 1965, after Union Carbide reclaimed land. \/ Supplied: City of Canada Bay<\/p>\n

She said there were concerns dioxins were making their way into the harbour.<\/p>\n

A clean-up was organised in 1993, but it failed, dashing hopes to build an athlete’s village in Rhodes for the Sydney 2000 Olympics.<\/p>\n

Another remediation attempt began in 2004 with a commercial-government partnership.<\/p>\n

“When they were doing the clean-up, they would give us tours of the site, and they showed us one time the layers. I described it as being like a layered chocolate mud cake,” Ms Weismantel said.\"Homebush<\/p>\n

Homebush Bay in Rhodes in 2026. (ABC News: Abubakr Sajid)<\/p>\n

When the rubbish layers were exposed, a “terrible smell” spread.<\/p>\n

She said the soil was dug up and taken to a shed on site to be superheated, so contaminants could be extracted as vapours.<\/p>\n

The successful remediation finished in 2011, with the local council stating it reportedly cost $200 million.<\/p>\n

Toxic dioxins in Sydney’s fish<\/p>\n

According to the World Health Organization, dioxins are “highly toxic” and accumulate in the food chain within the fatty tissue of animals.<\/p>\n

The Sydney Morning Herald reported in 2010 that dioxins from the former factory site were found more than 10 kilometres up and down the harbour.<\/p>\n

Loading…<\/p>\n

A commercial fishing ban west of the harbour bridge began in 2006, due to elevated dioxin levels in fish.<\/p>\n

University of New South Wales advanced science student, Dylan Freeman, is part of a program trying to bioremediate Homebush Bay and mitigate contamination of Sydney’s harbour.<\/p>\n

Bioremediation is a process which uses microorganisms to remove toxins from contaminated sites.<\/p>\n

\"Mr<\/p>\n

Mr Freeman says the team is trying to create a commercially viable method which can be used at any site, including Homebush Bay. (ABC News: Abubakr Sajid\u00a0)<\/p>\n

The team is refining an existing bioremediation technique to make it commercially viable for any clean-up.<\/p>\n

“Bioremediation is pretty non-invasive. All you really have to do is dig a well and pump liquid in, and then you leave it and monitor it,” Mr Freeman said.<\/p>\n

Traditional remediation methods involve digging massive pits with excavators and pumping large volumes of water.<\/p>\n

Using nature against itself<\/p>\n

The students went out to Homebush Bay’s mudflats in full protective gear and retrieved a sample of the sediment.<\/p>\n

They found it contained bacteria that had adapted to the dioxins.<\/p>\n

\"Two<\/p>\n

Two bioremediation researchers at Homebush Bay. (Supplied: UNSW)<\/p>\n

They grew more of the good bacteria and injected it back into the site with a plunger.<\/p>\n

After three months, research showed the dioxins, which can typically last hundreds of years, had “decreased quite significantly”.<\/p>\n

“These bacteria, we’re not 100 per cent sure what they’re doing yet, but they might be eating them [the dioxins],” Mr Freeman said.<\/p>\n

He said once dioxins broke down, the affected ecosystem would re-stabilise, which would benefit fishers and the community.<\/p>\n

Ms Weismantel said the project was interesting, but questioned how far down the injected solution could reach.<\/p>\n

“I think it does sound promising as long as it’s not going to get rid of the good stuff as well \u2026 especially with the mangroves,” she said.<\/p>\n","protected":false},"excerpt":{"rendered":"More than 50 years after the Vietnam War, uni students are removing remnants of Agent Orange chemicals from…\n","protected":false},"author":2,"featured_media":21494,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[20496,20490,20497,20489,20492,12397,20493,20501,3683,20491,20505,20508,20509,20507,3732,20502,20498,20500,9757,247,13127,20499,20494,6374,20495,20503,20504,20506],"class_list":["post-21493","post","type-post","status-publish","format-standard","has-post-thumbnail","category-sydney","tag-1960s","tag-agent-orange","tag-biological-remediation","tag-bioremediation","tag-chemical","tag-contamination","tag-dioxin","tag-economically-viable-remediation","tag-environment","tag-homebush-bay","tag-is-agent-orange-still-in-sydney-harbour","tag-is-homebush-bay-safe","tag-is-homebush-bay-toxic","tag-is-sydney-harbour-safe","tag-manufacturing","tag-mj-manefield","tag-rhodes-peninsula","tag-sediment","tag-students","tag-sydney","tag-sydney-harbour","tag-union-carbide","tag-unsw","tag-vietnam-war","tag-water-pollution","tag-what-is-agent-orange","tag-where-is-agent-orange-in-sydney-harbour","tag-where-was-agent-orange-manufactured"],"_links":{"self":[{"href":"https:\/\/www.europesays.com\/australia\/wp-json\/wp\/v2\/posts\/21493","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/australia\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/australia\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/australia\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/australia\/wp-json\/wp\/v2\/comments?post=21493"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/australia\/wp-json\/wp\/v2\/posts\/21493\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/australia\/wp-json\/wp\/v2\/media\/21494"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/australia\/wp-json\/wp\/v2\/media?parent=21493"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/australia\/wp-json\/wp\/v2\/categories?post=21493"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/australia\/wp-json\/wp\/v2\/tags?post=21493"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}