A team of scientists are surveying Bay of Plenty beaches for potentially dangerous tarballs following reports of oil washing ashore at Papamoa beach 18 months after Rena grounded.
University of Waikato researcher Phil Ross said a team from their marine field station would head to the beach to collect oil samples.
"Without doing a detailed chemical analysis it's hard to know where the oil is coming from," he said.
"It could be Rena oil already buried or new oil coming from Rena or oil from ships going past."
Former Papamoa resident Bridget Hogan said she and her husband found oil spots of varying sizes on the soles of their feet after walking along Papamoa beach at low tide recently.
Ms Hogan described the oil spots as "very sobering".
Beach Kids instructor Hayley Hart said she regularly noticed oil on her feet but was not concerned and neither were the parents of the children she instructed.
"It's nothing major.
"I think the toxicity of the oil has gone so there's no harm in that. It's just spots."
Ms Hart said she understood the oil would take a long time to break up so she expected oil spots to be around for several more years.
Mount Maunganui mum Stacey Kemp said she was often trying to remove oil spots from her children after being at Papamoa and Tay St beaches.
"It's more of an annoyance. It's comes off pretty easy."
Compared to this time last year, the oil was "much less gluey" and easier to remove.
Lifeguards at Papamoa said they still found oil coming out of the sand and mothers had complained of oil getting on their children's swimwear.
Bay of Plenty Regional Council shoreline programme leader for Rena Recovery Greg Meikle said easterly swells seemed to increase the amount of oil appearing "and we have had these conditions recently".
"Any remaining Rena oil would have been in the environment for over 16 months now, so it is very weathered and unlikely to contain any toxins that are a health risk," he said.
Shortly after the October 2011 grounding, health authorities issued health warnings around Rena oil, saying direct contact could cause a rash or nausea.
Anyone who came across oil should contact the Pollution Hotline on 0800 884 883 or the university marine field station at Sulphur Point on 07 578 5927.
for more articles from this region, go to BAY OF PLENTY TIMES